Browse Health
Surgical Specialist
27 years of experience

Education ?

Medical School Score Rankings
University of Florida (1983)
  • Currently 4 of 4 apples
Top 25%

Awards & Distinctions ?

Awards  
One of America's Leading Experts on:
Abdominal Aortic Aneurysm
Angioplasty
Blood Vessel Prosthesis Implantation
Associations
American Board of Surgery

Affiliations ?

Dr. Donayre is affiliated with 1 hospitals.

Hospital Affilations

Score

Rankings

  • Los Angeles County - Harbor - UCLA Medical Center
    1000 W Carson St, Torrance, CA 90502
    • Currently 3 of 4 crosses
    Top 50%
  • Publications & Research

    Dr. Donayre has contributed to 57 publications.
    Title Endovascular Management of Blunt Aortic Injury with an Associated Aberrant Right Subclavian Artery: a Report of Three Cases.
    Date January 2012
    Journal Annals of Vascular Surgery
    Excerpt

    Traumatic rupture of the aorta in the rare setting of the aberrant right subclavian artery (ARSA) requires special consideration to prevent the occurrence of a devastating posterior cerebral circulation stroke. We present three cases managed by using an endovascular approach, with a discussion of important preoperative and operative issues. Three patients involved in motor vehicle collisions with multiple injuries were managed at two institutions. Computed tomography revealed transection of the aorta with incidental ARSA. All three cases were managed with a different approach. One patient did not undergo a preoperative bypass because imaging confirmed an adequate landing zone distal to the origin of the left subclavian artery. Two patients received preoperative right carotid-to-subclavian bypass for anticipated endograft coverage of both subclavian arteries to preserve single vertebral arterial flow. In one patient, an endovascular occlusion device was deployed in the ARSA before aortic endograft deployment. In the other, ARSA occlusion was performed 4 days later for a persistent type II endoleak. The patient who underwent bypass and preoperative ARSA occlusion suffered a fatal posterior circulation stroke shortly after surgery. The other two patients had no procedural complications and have not required any reinterventions at follow-up after 2 and 5 years. One patient is still undergoing rehabilitation after 5 years of follow-up for traumatic brain injury unrelated to the endograft repair. Although the incidence of ARSA is very low, preoperative imaging and assessment of cerebral blood flow are critical to prevent a perioperative stroke. Revascularization, if required to achieve a secure proximal landing zone, must be performed before endograft deployment. Bilateral subclavian revascularization is indicated if anomalies of the cerebral circulation are present.

    Title Aortic Remodeling, Volumetric Analysis, and Clinical Outcomes of Endoluminal Exclusion of Acute Complicated Type B Thoracic Aortic Dissections.
    Date October 2011
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    Structural changes within the aorta after thoracic endovascular aortic repair (TEVAR) for acute complicated type B thoracic aortic dissections (ABAD) remain unknown. This study reviewed and analyzed morphologic changes, volumetric data, and clinical outcomes of patients with ABAD.

    Title Initial Clinical Experience with a Sac-anchoring Endoprosthesis for Aortic Aneurysm Repair.
    Date April 2011
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    All current aortic endografts depend on proximal and distal fixation to prevent migration. However, migration and rupture can occur, particularly in patients with aortic necks that are short or angulated, or both. We present our initial clinical experience with a new sac-anchoring endoprosthesis designed to anchor and seal the device within the aneurysm sac.

    Title Incidence and Risk Factors of Renal Dysfunction After Thoracic Endovascular Aortic Repair.
    Date December 2010
    Journal The Journal of Thoracic and Cardiovascular Surgery
    Excerpt

    The risk of renal failure after thoracic endovascular aortic repair is not widely established. The aim of this study was to assess the incidence and risk factors of renal failure.

    Title Distribution of Intimomedial Tears in Patients with Type B Aortic Dissection.
    Date September 2010
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    Thoracic endovascular aortic repair is a promising means of treating patients with complicated type B aortic dissection by excluding the intimomedial tears. This study aims to characterize the location of tears and to propose a classification of type B aortic dissections based on these findings.

    Title Current Status of Endovascular Management of Complicated Acute Type B Aortic Dissection.
    Date February 2010
    Journal Future Cardiology
    Excerpt

    Acute type B dissection is a catastrophic condition. Up to 20% of these patients develop severe complications such as rupture or branch vessel malperfusion. These challenging patients are usually triaged to surgical or endovascular management. The surgical approach has been the gold standard for treatment of complicated type B dissection. However, the management has been challenging even in centers of excellence. For these reasons, thoracic endovascular aortic repair of acute aortic dissection has gained increased interest as an initial treatment option. The goal of this therapy is to exclude the primary entry site, obliterate the false lumen, prevent aortic rupture, and relieve visceral and lower body malperfusion. The aim of this study is to review the contemporary outcome of patients undergoing endovascular treatment for complicated acute type B aortic dissection.

    Title Midterm Results of Endovascular Treatment of Complicated Acute Type B Aortic Dissection.
    Date September 2009
    Journal The Journal of Thoracic and Cardiovascular Surgery
    Excerpt

    The operative mortality and morbidity of patients with complicated acute type B aortic dissection remain high. The endovascular approach has been proposed as a potential alternative. The purpose of this study is to review the contemporary outcome of patients undergoing endovascular treatment for complicated acute type B aortic dissection.

    Title Use of Transcranial Doppler Ultrasound in Endovascular Repair of a Type B Aortic Dissection.
    Date July 2008
    Journal The Annals of Thoracic Surgery
    Excerpt

    Intraprocedural monitoring with transcranial Doppler ultrasound in thoracic endovascular aortic repair provides critical information regarding the occurrence of cerebral microemboli and adequacy of cerebral blood flow. We present the perioperative course of a patient with complicated Stanford type B aortic dissection undergoing thoracic endovascular aortic repair with continuous intraoperative transcranial Doppler ultrasound monitoring.

    Title Risk Factors for Early and Late Mortality After Thoracic Endovascular Aortic Repair.
    Date June 2008
    Journal The Journal of Thoracic and Cardiovascular Surgery
    Excerpt

    OBJECTIVE: The risk factors associated with death after thoracic endovascular aortic repair are poorly understood. The aim of this study is to analyze the risk factors associated with early and late mortality after thoracic endovascular aortic repair. METHODS: A total of 153 patients underwent 184 thoracic endovascular aortic repairs between 1998 and 2005. Prospectively collected data were entered into statistical software. Univariate and multivariate analyses were performed. RESULTS: The underlying pathologies included descending thoracic aortic aneurysm (n = 91), acute type B aortic dissection (n = 25), chronic type B aortic dissection (n = 42), aortic transection (n = 12), and penetrating aortic ulcer (n = 14). Thoracic endovascular aortic repair was technically successful in all but 3 patients. Another 3 patients required an open repair within the first month. Early and late mortality rates were 9.8% (n = 18) and 19% (n = 35) in a 16-month average period of follow-up, respectively. Type I procedural endoleak was the only significant predictor of early death in the multivariate model (P = .0036; odds ratio: 8.4; 95% confidence interval: 1.6-43.9). Multivariate Cox regression revealed chronic obstructive pulmonary disease (P = .024; odds ratio: 3.8; 95% confidence interval: 1.2-12.1), postoperative myocardial infarction (P = .0053; odds ratio: 9.7; 95% confidence interval: 2.0-48.4), and acute renal failure (P = .0006; odds ratio: 22.8; 95% confidence interval: 3.8-137.6) to be independent risk factors for late mortality. CONCLUSION: Procedural type I endoleak is an independent risk factor of early mortality after thoracic endovascular aortic repair. Chronic obstructive pulmonary disease, postoperative myocardial infarction, and acute renal failure are predictors of late death in the multivariate analysis.

    Title Endograft Exclusion of Acute and Chronic Descending Thoracic Aortic Dissections.
    Date October 2007
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    OBJECTIVES: To analyze the results of endograft exclusion of acute and chronic descending thoracic aortic dissections (Stanford type B) with the AneuRx (n = 5) and Talent (n = 37) thoracic devices and to compare postoperative outcomes of endograft placement acutely (<2 weeks) and for chronic interventions. METHODS: Patients treated for acute or chronic thoracic aortic dissections (Stanford type B) with endografts were included in this study. All patients (n = 42) were enrolled in investigational device exemption protocols from August 1999 to March 2005. Three-dimensional computed tomography reconstructions were analyzed for quantitative volume regression of the false lumen and changes in the true lumen over time (complete >95%, partial >30%). RESULTS: Forty-two patients, all of whom had American Society of Anesthesiologists (ASA) risk stratification > or =III and 71% with ASA > or = IV, were treated for Stanford type B dissections (acute = 25, chronic = 17), with 42 primary and 18 secondary procedures. All proximal entry sites were identified intraoperatively by intravascular ultrasound (IVUS). The procedural stroke rate was 6.7% (4/60), with three posterior circulation strokes. Procedural mortality was 6.7% (4/60). The left subclavian artery was occluded in 11 patients (26%) with no complaints of arm ischemia, but there was an association with posterior circulation strokes (2/11) (18%). No postoperative paraplegia was observed after primary or secondary intervention. Complete thrombosis of the false lumen at the level of endograft coverage occurred in 25 (61%) of 41 patients < or =1 month and 15 (88%) of 17 patients at 12 months. Volume regression of the false lumen was 66.4% (acute) and 91.9% (chronic) at 6 months. Lack of true lumen volume (contrast) increase and increasing false lumen volume (contrast) suggests continued false lumen pressurization and the need for secondary reintervention. Thirteen patients (31%) required 18 secondary interventions for proximal endoleaks in 6, junctional leaks in 3, continued perfusion of the false lumen from distal re-entry sites in 3, and surgical conversion in 4 for retrograde dissection. CONCLUSIONS: Preliminary experience with endografts to treat acute and chronic dissections is associated with a reduced risk of paraplegia and lower mortality compared with open surgical treatment, the results of medical treatment alone, or a combination.

    Title Principles and Devices.
    Date April 2007
    Journal Seminars in Vascular Surgery
    Excerpt

    The development of catheter-based ultrasound imaging began in the 1950s using large-diameter catheters and frequencies of between 1 and 10 MHz. In the 1970s, 360 degrees cross-sectional imaging of vessels was reported using multi-element or phase-array transducers. Since then, refinements in imaging frequency, catheter size, image quality, and computer-driven imaging platforms have transformed intravascular ultrasound (IVUS) from predominantly a research tool to an important clinical intervention.

    Title Intravascular Ultrasound Use in the Treatment of Thoracoabdominal Dissections, Aneurysms, and Transections.
    Date April 2007
    Journal Seminars in Vascular Surgery
    Excerpt

    Intravascular ultrasound (IVUS) has become an important adjunct in the endovascular treatment of thoracoabdominal aortic pathology. In this article, we hope to describe and define the expanding role of IVUS as a tool for the vascular surgeon in the treatment of thoracoabdominal aortic dissections, aneurysms, and transections. IVUS is of particular benefit in the treatment of aortic dissections and aortic transections.

    Title Risk Factors of Neurologic Deficit After Thoracic Aortic Endografting.
    Date March 2007
    Journal The Annals of Thoracic Surgery
    Excerpt

    BACKGROUND: Stroke and spinal cord injury (SCI) remain the most devastating complications of thoracic endovascular aortic repair (TEVAR). The risk factors associated with these complications are poorly understood. The aim of this study was to analyze the risk factors associated with neurologic deficits after TEVAR. METHODS: From 1998 to 2005, 153 patients underwent 184 TEVARs. Computed tomography scans, angiograms, and medical records were reviewed. TEVAR was completed in all but 3 patients. The underlying pathologies included descending thoracic aortic aneurysm in 91, acute type B aortic dissection in 25, chronic type B aortic dissection in 42, aortic transection in 12, and penetrating aortic ulcer in 14. RESULTS: Stroke developed in 8 patients, and SCI developed in another 8 patients (4 immediate, 4 delayed paraplegia/paraparesis). The procedure-associated stroke and SCI rate was 4.3% (8/184). Univariate statistical analysis revealed increased postoperative stroke with obesity, significant intraoperative blood loss, and evidence of peripheral vascular embolization/thrombosis. Aneurysmal pathology, iliac conduit, and hypogastric artery coverage were highly associated with postoperative SCI after TEVAR. Early and late mortality were 9.8% (n = 18) and 19% (n = 35) in a 16-month average period of follow-up. CONCLUSIONS: The incidence of stroke and SCI after TEVAR was 4.3% (8/184). The risk factors associated with postoperative stroke were obesity, intraoperative blood loss, and vascular embolization. Aneurysm as an underlying pathology, the use of an iliac conduit, and coverage of the hypogastric artery were all associated with SCI. These risk factors for SCI may be markers of tenuous collateral blood supply to the spinal cord.

    Title The Role of Aortic Neck Dilation and Elongation in the Etiology of Stent Graft Migration After Endovascular Abdominal Aortic Aneurysm Repair with a Passive Fixation Device.
    Date January 2007
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    OBJECTIVE: Endovascular repair of abdominal aortic aneurysm (AAA) is complicated by the potential for stent graft migration over time. Factors including the type of fixation, initial proximal fixation length, and dilation and elongation of the infrarenal aortic neck may contribute to device migration. We sought to determine when device migration is a real phenomenon with actual device movement that compromises aneurysm exclusion. METHODS: Computed tomographic (CT) scans and computer reconstructions of all patients undergoing endovascular AAA repair with a passive fixation device at our institution from June 1996 to October 2004 were retrospectively reviewed. The distance from the distal renal artery to the proximal end of the stent graft at the time of initial deployment was determined for each patient. Migration was defined as a distance increase greater than 5 mm in the follow-up period; proximal fixation length, aortic neck enlargement and elongation, and neck angle were then measured. Data were further analyzed with respect to AAA growth, development of endoleak, AAA rupture, and the need for reintervention. RESULTS: A total of 308 patients with endovascular AAA repairs using a passive fixation device had complete postoperative imaging data sets; 48 patients (15.6%) with stent graft migration of 5 mm or more were identified, and 25 (8.1%) of these had a migration of 10 mm or more. Seventeen (35.4%) of 48 migration patients had a total loss of the proximal seal zone (loss patients); their average migration distance was 17.7 +/- 12.0 mm, with a mean neck shortening of 13.6 +/- 14.2 mm, and the average proximal fixation length loss was 14.0 +/- 7.6 mm. Those 31 patients with an intact proximal seal zone (nonloss patients) showed an average migration of 9.4 +/- 3.7 mm, with a mean neck lengthening of 9.6 +/- 8.4 mm and an average proximal fixation length change of 0.7 +/- 8.0 mm. Univariate analysis demonstrated significant differences between the loss and nonloss patients in follow-up duration (65.9 +/- 20.4 months vs 45.9 +/- 26.4 months; P = .01), neck dilatation at the distal renal artery (4.6 +/- 4.5 mm vs 1.8 +/- 1.9 mm; P = .026), stent graft migration distance (17.7 +/- 12.0 mm vs 9.4 +/- 3.7 mm; P = .001), change in aortic neck length (-13.6 +/- 14.2 mm vs 9.6 +/- 8.4 mm; P < .0001), change in proximal fixation length (-14.0 +/- 7.6 mm vs 0.7 +/- 8.0 mm; P < .0001), change in AAA size (1.8 +/- 7.1 mm vs -3.6 +/- 9.7 mm; P = .033), and use of a stiff body stent graft (47.1% vs 19.4%; P = .043). However, only change in aortic neck length was statistically significant on multivariate analysis (odds ratio, 0.75; 95% confidence interval, 0.591-0.961; P = .022). There were no differences between the loss and nonloss patients in time to migration discovery, initial AAA size, initial aortic neck diameter or length, initial device oversizing, initial neck angle, neck angle increase, type II endoleak, or AAA rupture. Eight of the 17 loss patients have been treated with proximal aortic cuffs; the remainder have refused reintervention, died of unrelated causes, or elected to have open repair. CONCLUSIONS: Postoperative elongation of the infrarenal aortic neck may create the radiographic perception of migration without necessarily causing a loss of proximal stent graft fixation. Patients with a total loss of the proximal seal zone actually have infrarenal aortic neck shortening, with a degree of neck dilatation beyond initial device oversizing that may compromise proximal fixation length. Conversely, those with an intact proximal seal zone demonstrate aortic neck elongation equivalent to migration, with no loss of proximal fixation length; these patients have a benign natural history without intervention. Thus, aortic neck dilatation beyond oversizing, aortic neck shortening, and loss of proximal fixation length are more clinically relevant predictors of proximal stent graft failure than simple migration distance.

    Title Intraprocedural Imaging: Thoracic Aortography Techniques, Intravascular Ultrasound, and Special Equipment.
    Date March 2006
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Title Complications of Endovascular Repair of High-risk and Emergent Descending Thoracic Aortic Aneurysms and Dissections.
    Date September 2004
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    PURPOSE: The advent of endovascular prostheses to treat descending thoracic aortic lesions offers an alternative approach in patients who are poor candidates for surgery. The development of this approach includes complications that are common to the endovascular treatment of abdominal aortic aneurysms and some that are unique to thoracic endografting. METHODS: We conducted a retrospective review of 60 emergent and high-risk patients with thoracic aortic aneurysms (TAAs) and dissections treated with endovascular prostheses over 4 years under existing investigational protocols or on an emergent compassionate use basis. RESULTS: Fifty-nine of the 60 patients received treatment, with one access failure. Thirty-five patients received treatment of TAAs. Four of these procedures were performed emergently because of active hemorrhage. Twenty-four patients with aortic dissections (16 acute, 8 chronic) also received treatment. Eight of the patients with acute dissection had active hemorrhage at the time of treatment. Three devices were used: AneuRx (Medtronic; n = 31), Talent (Medtronic; n = 27), and Excluder (Gore; n = 1). Nineteen secondary endovascular procedures were performed in 14 patients. Most were secondary to endoleak (14 of 19), most commonly caused by modular separation of overlapping devices (n = 8). Other endoleaks included 4 proximal or distal type I leaks and 2 undefined endoleaks. The remaining secondary procedures were performed to treat recurrent dissection (n = 1), pseudoaneurysm enlargement (n = 3), and endovascular abdominal aortic aneurysm repair (n = 1). One patient underwent surgical repair of a retrograde ascending aortic dissection after endograft placement. Procedure-related mortality was 17% in the TAA group and 13% in the dissection group, including 2 acute retrograde dissections that resulted in death from cardiac tamponade. Overall mortality was 28% at 2-year follow-up. CONCLUSION: Although significant morbidity and mortality remain, endovascular repair of descending TAAs and dissections in patients at high-risk patients can be accomplished with acceptable outcomes compared with traditional open repair. The major cause for repeat intervention in these patients was endoleak, most commonly caused by device separation. Improved understanding of these complications may result in a decrease in secondary procedures, morbidity, and mortality in these patients. The need for secondary interventions in a significant number of patients underscores the necessity for continued surveillance.

    Title Endovascular Abdominal Aortic Aneurysm Repair Using the Aneurx Stent Graft: Impact of Excluding Accessory Renal Arteries.
    Date June 2004
    Journal Annals of Vascular Surgery
    Excerpt

    The aim of this study was to evaluate clinical sequelae of accessory renal artery exclusion during endo-AAA repair. Medical records and pre- and postoperative CT scans were reviewed from 114 AAA patients treated with the AneuRx stent graft between 1996-2001. Thirty-seven accessory renal arteries were identified in 32/114 patients (28%) with 19/32 patients having infrarenally located accessory renal arteries. In group I (11 patients), the stent graft excluded 11 accessory renal arteries. In group II (8 patients), eight accessory renal arteries were not excluded. Average infrarenal neck length was 24.9 mm in group I vs. 30.7 mm in group II (p = 0.07). The average length of device seal was similar in both groups (19.4 vs. 18.5 mm, p = 0.67). There were no perioperative deaths, significant postoperative hypertension, rise in serum creatinine, or postoperative renal infarctions in either group. Three of eight patients (38%) in the non-excluded group developed type I proximal endoleaks whereas none in the excluded patient group did (p = 0.06). Accessory renal arteries may be safely excluded during endovascular AAA repair and may result in a more secure proximal device fixation.

    Title Volume Regression of Abdominal Aortic Aneurysms and Its Relation to Successful Endoluminal Exclusion.
    Date January 2004
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    OBJECTIVES: Evaluating the success of endoluminal repair of abdominal aortic aneurysms (AAAs) is frequently based on diameter measurements and determining the presence of endoleaks. The use of three-dimensional volumetric data and observation of morphologic changes in the aneurysm and device have been proposed to be more appropriate for postdeployment surveillance. The purpose of this study was to analyze the long-term volumetric and morphologic data of 161 patients who underwent endovascular AAA exclusion and to assess the utility of volume measurements for determining successful AAA repair. METHODS: Patients with spiral computed tomography scans obtained preoperatively, within the first postoperative month, at 6 months, and annually thereafter, were included in this analysis. Computerized interactive three-dimensional reconstruction of each AAA scan was performed. Total aneurysm sac volume was measured at each time interval (mean preoperative volume 169.0 +/- 78.5 mL), and the significance of volume changes was determined by mixed linear modeling, a form of repeated measures analysis, to account for longitudinal data clustered at the individual level. Sixty-two patients (38%) developed endoleaks at some time during follow-up-15 type I leaks, 45 type II leaks, and 2 type III leaks. The patients with type I and type III leaks were treated with cuffs, and the type II leaks were treated either with observation, side-branch embolization, or required open conversion. RESULTS: Aneurysm sac volume increased slightly at 1-month follow-up (+3.3%), and then decreased steadily to -12.9% at 5 years (P <.0001). This effect remained unchanged after controlling for the three device types used in our study population. Patients who did not exhibit an endoleak (n = 99) showed a significant decrease in aneurysm volume across the entire follow-up duration when compared with those who did exhibit an endoleak (n = 62) (P <.0001). The presence of a 10% or greater decrease in volume at 6 months demonstrated a sensitivity of 64%, a specificity of 95%, a positive predictive value of 95%, a negative predictive value of 62%, and an accuracy of 75% for predicting primary clinical success defined by successful deployment of the device; freedom from aneurysm- or procedure-related death; freedom from endoleak, rupture, migration, or device malfunction; or conversion to open repair. CONCLUSIONS: Volumetric analysis may be used to predict successful endoluminal exclusion of AAAs. Volume regression appears to be device-independent and should be expected in most clinically successful cases. The presence of volume increases in the first 6 months is suspicious for an endoleak that is pressurizing the aneurysm sac and heralds the need for closer evaluation and possible intervention. A volume decrease of 10% or greater at 6 months and continuing regression over time is associated with successful endovascular repair.

    Title Results from the Endologix Powerlink Multicenter Trial.
    Date November 2003
    Journal Seminars in Vascular Surgery
    Excerpt

    The Endologix PowerLink system is a one-piece, bifurcated, fully supported endoluminal graft for the treatment of abdominal aortic aneurysms (AAA). In a recently completed multicenter trial, the device has proven to be effective with a high technical success rate, low morbidity and mortality rates, and a mean decrease in AAA size over time. A 16-month mean follow-up has found low endoleak and migration rates. There have been no ruptures to date. The Endologix PowerLink device compares favorably with previously published results of other endoluminal grafts.

    Title Accuracy of Three-dimensional Simulation in the Sizing of Aortic Endoluminal Devices.
    Date September 2003
    Journal Annals of Vascular Surgery
    Excerpt

    The purpose of this study is to examine the accuracy of a 3D simulation generated by inclusion of various intensity-selected portions of spiral CT data into a proprietary software program (Preview, Medical Media Systems, MMS) in preoperative and postoperative assessment of the anatomical features of abdominal aortic aneurysm (AAA). The accuracy of this software was measured against two other modalities-intravascular ultrasound (IVUS) and axial CT scan-using the IVUS as the reference. Eighty-five patients were included; 43 underwent AAA endovascular exclusion with Talent devices, and 42 with Aneurx devices. Measurement of proximal neck diameter was performed using IVUS, Preview software, and axial CT scan with manual calipers. Measurement of the AAA maximum diameter was performed using Preview software and axial CT scan; 253 measurements in the 85 patients were included. These measurements were compared by means of both linear regression and Bland-Altman agreement analysis. Our results showed that the 95% confidence interval between the Preview software and mean IVUS measurement of proximal AAA neck (3.1 and 2.5) is narrow enough for the software to be used in sizing AAA. This would be especially important for having the properly sized devices available preoperatively. The Preview software tended to be more accurate than CT scans although it was not statistically significant.

    Title Cardiac Risk Stratification in Patients Undergoing Endoluminal Graft Repair of Abdominal Aortic Aneurysm: a Single-institution Experience with 365 Patients.
    Date July 2003
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    OBJECTIVE: Patients undergoing abdominal aortic aneurysm repair have a high incidence of coexisting cardiac disease. The traditional cardiac risk stratification for open abdominal aortic aneurysm surgery may not apply to patients undergoing endoluminal graft exclusion. The purpose of this study was to examine predictive risk factors for perioperative cardiac events. METHODS: As part of multiple prospective endograft trials approved by the US Food and Drug Administration, data for 365 patients who underwent endoluminal graft repair from 1996 to 2001 were collected. Variables included for analysis were age and sex; history of smoking; presence of hypertension, diabetes mellitus, or renal insufficiency; Eagle clinical cardiac risk factors; American Society of Anesthesiologists index; type of anesthesia administered; estimated blood loss; preoperative hemoglobin level; preoperative use of beta-blocker therapy; duration of surgery; need for iliac artery conduit; and concomitant other vascular procedures. Univariate and multivariate logistic regression analysis were used to determine which variables were predictive of an adverse perioperative cardiac event, eg, Q wave and non-Q wave myocardial infarction (MI), congestive heart failure (CHF), severe arrhythmia, and unstable angina. RESULTS: The study cohort included 322 men and 43 women (mean age, 74.2 years). Fifty-two (14.2%) postoperative cardiac events occurred: severe dysrhythmia in 15 patients (4.1%), MI in 14 patients (3.8%), non-Q wave MI in 8 patients (2.2%), CHF in 8 patients (2.2%), and unstable angina in 7 patients (1.9%). Univariate analysis demonstrated that age 70 years or older (P =.034), history of MI (P =.018), angina (P =.004), history of CHF (P <.001), two or more Eagle risk factors (P <.001), and lack of use of preoperative beta-blocker therapy (P =.005) were predictors of perioperative cardiac events. Multivariate analysis identified only age 70 years or older (P =.026), history of MI (P =.024) or CHF (P =.001), and lack of use of preoperative beta-blocker therapy (P =.007) as independent risk factors for an adverse cardiac event. CONCLUSIONS: Age 70 years or older, history of MI or CHF, and lack of use of preoperative beta-blocker therapy are independent risk factors for perioperative cardiac events in patients undergoing endoluminal graft repair.

    Title Stent-graft Migration Following Endovascular Repair of Aneurysms with Large Proximal Necks: Anatomical Risk Factors and Long-term Sequelae.
    Date April 2003
    Journal Journal of Endovascular Therapy : an Official Journal of the International Society of Endovascular Specialists
    Excerpt

    PURPOSE: To evaluate the outcome of aortic endografts deployed in large infrarenal necks and to identify any association of preoperative aneurysm characteristics and postoperative morphological changes with the incidence of neck dilatation and device migration in this patient subset. METHODS: The records of 47 patients (41 men; mean age 74, range 55-84) with large aortic neck diameters treated with Talent stent-grafts from 1998 to 2001 were reviewed. Patients with anatomical criteria that precluded aneurysm exclusion with currently available devices were preferentially selected. Mean baseline aneurysm morphology included 27.6-mm (range 18-33.4) suprarenal and 28.1-mm (range 24-34) infrarenal neck diameters; the infrarenal neck length was 26 +/- 16 mm with angulation of 37 degrees +/- 18 degrees. Computed tomographic (CT) angiograms up to 3 years were analyzed using specialized interactive software; migration was defined as >1-cm change in the distance from the lower renal artery to the top of the device. Pre- and postoperative morphological characteristics of the aneurysm were compared between patients with and without migration. RESULTS: Of the 45 patients successfully treated, 40 had complete CT data for analysis. During a mean 17-month follow-up, 7 (17.5%) of the 40 devices exhibited distal migration. Six patients required secondary procedures; 5 were in the migration cohort. No preoperative anatomical characteristic or degree of neck dilatation over time was predictive of stent-graft migration. Aneurysm sac regression was significant at 1 (-0.09 +/- 4.90 mm) and 2 (-1.48 +/- 2.56 mm) years in endografts without migration (p<0.001). Distal endograft migration >1 cm predicted the need for secondary interventions (p<0.001), with 83% sensitivity and 94% specificity. CONCLUSIONS: Endovascular repair is successful in patients with large infrarenal necks and complex neck morphology. Changes in aneurysm remodeling over time were similar to reported observations in patients with more favorable neck criteria. Although no anatomical factor associated with migration could be identified from this analysis, distal displacement >1 cm correlated with the need for a secondary intervention.

    Title Endovascular Exclusion of Leaking Thoracic Aortic Aneurysms.
    Date January 2003
    Journal Journal of Endovascular Therapy : an Official Journal of the International Society of Endovascular Specialists
    Excerpt

    PURPOSE: To describe the endovascular exclusion of leaking thoracic aortic aneurysms (TAA). CASE REPORT: Two elderly patients with leaking TAAs who were at high risk for surgical intervention were transferred to our institution for possible endovascular treatment. Both patients underwent successful endovascular exclusion of the leaking TAAs using multiple stacked AneuRx thoracic endoprostheses. One patient remains alive and well at 1 year with an excluded aneurysm; the other patient died from heart failure 2 months after endografting. CONCLUSIONS: While the early results of the endovascular exclusion of leaking TAAs are promising, the use of thoracic endoprostheses remains investigational.

    Title Endovascular Exclusion of Abdominal Aortic Pathology in Patients with Concomitant Malignancy.
    Date June 2002
    Journal Annals of Vascular Surgery
    Excerpt

    The advent of endoluminal aortic repair has gained increasing popularity as an alternative to traditional open surgery in the setting of multiple comorbid disease states. This study analyzes a single center experience of excluding aortic disease in patients with concomitant malignancy. As part of a Federal Drug Administration FDA-approved trial, 318 patients underwent aortic stent-graft repair between June 1996 and February 2001. During that period five patients with advanced-stage neoplasia were treated. Endovascular management of symptomatic abdominal aortic aneurysms (AAA) with a mean diameter of 7.8 cm (range, 6-10 cm), was performed in four patients. In the fifth patient, a custom-made aortic prosthesis was utilized to exclude a paraanastamotic abdominal aneurysm (PAAA) from a previous open AAA repair. Malignancies included esophageal, lung, renal, prostate, and urinary bladder cancers. A mean follow-up of 10.1 months was available. Successful endoluminal repair was accomplished in all five patients with minimal in-hospital morbidity. Mean length of stay was 3.4 days. There were no device-related mortalities and no persistent endoleaks detected for the duration of follow-up. Aneurysm sac enlargement was not seen in any of the patients and complete resolution of the PAAA was noted at one year. Exclusion of AAA and other aortic pathology in patients with an associated malignancy can be performed with a relatively low procedure-related morbidity and mortality. In this population, stent-graft repair remains an individualized option with a multidisciplinary team necessary to explore this therapeutic approach.

    Title Failed Aaa Endograft Exclusion Due to Type Ii Endoleak: Explant Analysis.
    Date December 2001
    Journal Journal of Endovascular Therapy : an Official Journal of the International Society of Endovascular Specialists
    Excerpt

    PURPOSE: To report the patient history and analysis of an explanted modular bifurcated endograft that was implanted to exclude an abdominal aortic aneurysm (AAA). CASE REPORT: An 80-year-old man with a 6-cm AAA underwent uneventful endovascular implantation of a bifurcated AneuRx stent-graft. His postprocedural clinical course was uneventful, although persistent contrast enhancement of the aneurysm remained via the inferior mesenteric artery (IMA). By 6 months, an endoleak connecting to the lumbar and mesenteric arteries became apparent. Over the ensuing 12 months, the endoleak and aneurysm enlarged; branch artery embolization was attempted in 4 percutaneous procedures. Despite successful IMA occlusion, the aneurysm continued to increase in diameter and volume, necessitating conversion to a conventional bypass at 20 months. Analysis of the explanted specimen revealed an intact endograft with fibrous incorporation of the stent framework at the proximal and distal fixation sites only; no incorporation of the endograft was noted within the aneurysm. The feeding channel for the endoleak was not identified. CONCLUSIONS: Serial imaging is a vital component of endograft surveillance, and persistent type II endoleaks that cannot be completely embolized endanger the longevity of the aneurysm exclusion. Explant analysis can play an important role in understanding the mechanisms of endograft failure.

    Title Healing Response of Normal Canine Aorta and Iliac Artery to a Nitinol Stent Encapsulated in Carbon-lined Eptfe.
    Date December 2001
    Journal Journal of Endovascular Therapy : an Official Journal of the International Society of Endovascular Specialists
    Excerpt

    PURPOSE: To evaluate the healing response of normal canine arteries to a self-expanding nitinol stent encapsulated in carbon-lined expanded polytetrafluoroethylene (ePTFE). METHODS: Twenty-eight dogs were divided into aortic (n = 18) or iliac (n = 10) groups. In the latter, 2 animals were assigned to implantation intervals of 7, 30, and 90 days, respectively; 4 were designated for 180-day implantation. Half of the animals in each subgroup received a second overlapping stent-graft in one iliac artery. In the aortic cohort, 6 animals were assigned to the 180-day implantation group (2 with dual devices) and 3 to each of the others (1 dual implantation in each group). The devices were evaluated with angiography and intravascular ultrasound at implantation and explantation. After harvesting and gross examination, the specimens were examined microscopically and with scanning electron microscopy. RESULTS: The 49 implanted devices (24 aortic and 25 common iliac) were all widely patent at explantation, save for 2 iliac stents that had moderate (<40%) stenosis. No neointima was present at the 7-day interval. All stents were covered by thin neointima (<150 microm) at 30 days. At 180 days, an endothelial lining was present in the proximal and distal segments of all stents; in 4 of the 6 aortic stents, this endothelial lining was complete, whereas none of the iliac devices had endothelium in the midsegment at 180 days. At 1 year, 2 of the aortic specimens had an incomplete endothelial lining, whereas the lining was complete in the third. There was no evidence of stent-graft migration or inflammation associated with any device. CONCLUSIONS: The carbon-lined ePTFE-encapsulated stent is a novel approach to arterial stenting. The progressive endothelialization and lack of inflammatory reaction may provide improved long-term patency. Further study of this stent-graft design is warranted.

    Title Abdominal Pain and Hemoperitoneum: Sole Presenting Symptoms for "leaking Aaa" After Endovascular Repair.
    Date October 2001
    Journal Journal of Endovascular Therapy : an Official Journal of the International Society of Endovascular Specialists
    Excerpt

    PURPOSE: To describe an unusual presentation of impending aortic endograft rupture and successful endovascular rescue. CASE REPORT: A 77-year-old man with an enlarging aortic aneurysm was treated with a Talent bifurcated endoprosthesis; a moderate endoleak that appeared to be related to either proximal or distal fixation sites was noted in the body of the aneurysm. The patient was observed for 1 month, and repeat imaging demonstrated persistent endoleak without major increase in the aneurysm diameter. Another examination was scheduled for 3 months hence, but, 2 months later, the patient presented with abdominal pain and a hemoperitoneum. A proximal extension cuff resolved the leak and led to resolution of the hemoperitoneum. CONCLUSIONS: A leaking aneurysm can be repaired using endovascular techniques in patients with an existing endograft. The need for frequent imaging surveillance of patients with endoleak is underscored.

    Title Endovascular Exclusion of Descending Thoracic Aortic Aneurysms and Chronic Dissections: Initial Clinical Results with the Aneurx Device.
    Date June 2001
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    OBJECTIVE: The objective of this study was to analyze a single-center experience in which descending thoracic aortic aneurysms (TAAs) were treated with a new self-expanding endovascular prosthesis (Medtronic AVE). METHODS: Twenty-six patients (13 men, 13 women) with American Society of Anesthesiology grades II to IV and ages ranging from 53 to 92 years (average, 74 years) consented as part of a Phase I Food and Drug Administration-approved trial. Treated lesions included TAAs that were 5 to 10 cm in diameter, 12 diffuse dilations or fusiform aneurysms, and four saccular aneurysms. There were also nine chronic dissections (2 aneurysmal dilations and 7 symptomatic acute recurrent dissections). Three patients (2 with diffuse/fusiform and 1 with dissection) presented with hemothorax, contrast extravasation, or both. RESULTS: Twenty-five of the 26 patients who consented (96% technical success) were treated successfully with no surgical conversions. Eighteen patients have been followed up from 1 to 22 months (average, 9 months). One patient is lost to follow-up, and six patients have died (24%). One procedure-related death (4%) occurred within the 30-day postoperative period and was caused by diffuse embolization. There were no device-related deaths. Five additional patients (20%) have died during the study of comorbid conditions. Complications included one massive myocardial infarction 24 hours after the procedure requiring balloon counterpulsation and long-term dialysis, one cardiac tamponade resulting from central line placement before the procedure, one progression of aneurysm dilation proximal to the device at 1 year, and one bilateral lower extremity paralysis occurring 12 hours after successful deployment. Seven patients (5 women) had femoral artery reconstructions or iliac artery grafts to repair injuries during deployment catheter passage. Other significant parameters included average procedure time (2 hours 40 minutes; range, 1 hour 30 minutes to 5 hours 30 minutes), 450 cc average blood loss (n = 25; 100-3000 cc) being replaced by means of autotransfusion with only two patients receiving banked blood products, and an average 2 days to resumption of normal diet, 1 day in the intensive care unit, and 5 days' hospitalization postprocedure in uncomplicated cases (n = 22). One patient had an endoleak immediately after the procedure that sealed without treatment. Follow-up of all patients ranging from 1 to 22 months (average, 9 months; n = 18) demonstrates continued exclusion of the aneurysm with no endoleaks and either stable or decreasing aneurysm volume, except in one patient with volume increase and no obvious etiology who continues to be investigated. CONCLUSIONS: The study suggests that endovascular prosthesis exclusion of TAAs with an AneuRx self-expanding tubular device may be effective in many patients who are at significant risk for open surgical repair and substantiates further clinical investigation to confirm these findings.

    Title Computed Tomography Assessment of Abdominal Aortic Aneurysm Morphology After Endograft Exclusion.
    Date March 2001
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    OBJECTIVES: Assessment of the long-term function of endografts to exclude abdominal aortic aneurysm (AAA) includes determination of aneurysm dimensions and morphologic changes that occur after implantation. This study reports the dimensional analysis of patients treated with AneuRx bifurcated endoprostheses with postintervention, 1-year (n = 51), 2-year (n = 28), and 3-year (n = 10) postimplantation contrast computed tomography data. METHODS: Maximal diameter (D) and cross-sectional area (CSA) of the AAA were measured from axial computed tomography images. Total volume, AAA thrombus volume (AAA volume minus the volume of the device and luminal blood flow), diameter of the aorta at the level of the renal arteries and within the device, distance from the renal arteries to the device, length of the device limbs, and the angle of the proximal neck were also determined at the same follow-up intervals after deployment with computed tomography angiograms reconstructed in an interactive environment. RESULTS: Fifty-one of 98 consecutively treated patients with the AneuRx bifurcated prosthesis (29 "stiff" and 22 "flexible" body devices) had complete data from the postprocedure and follow-up computed tomography studies available for analysis. Max D, CSA, total volume of the AAA, and AAA thrombus volume decreased sequentially from year to year compared with the postimplantation values. D and CSA decreased or were unchanged in all except four patients, two who had unrestricted enlargement of the aneurysm with eventual rupture and one who had surgical conversion for continued expansion despite four diagnostic angiograms and attempted embolizations. Total volume of the AAA increased in 11 of 51 patients at 1 year, eight of whom had endoleaks at some interval during the follow-up. Thrombus volume increased more than 5% in four of these patients, including the two with eventual rupture and the one conversion. Patients with endoleaks who had spontaneous thrombosis or were successfully treated either remained at the same volume or had decreased volume on subsequent examinations. D at the renal arteries increased an average of 0.9 mm during the first year, with a concomitant increase of 2.8 mm within the proximal end of the device related to the self-expanding nature of the Nitinol suprastructure. Subsequent enlargement of the proximal neck continued at a slow rate in some cases but never exceeded the diameter of the endoluminal device. The distance from the renal arteries to the device increased by an average of 3 mm over the first year, with the greatest increases occurring in patients with a "stiff" body device and those with rapid regression (>10% total volume) in 1 year. As regression of the AAA occurred, the angle of the proximal neck varied from -5 degrees to +25 degrees from the original alignment. Limb length varied from -8 mm to +10 mm, with no consistent pattern for the change, that is, ipsilateral or contralateral limb. CONCLUSION: Significant variation in the quantitation of aneurysm size occurs depending on the technique of computed tomography assessment used. In most patients diameter assessment is adequate, although volumetric analysis appears to be very helpful in certain patients who do not show aneurysm regression, or in whom the diameter increases or where endoleaks persist. Three-dimensional reconstruction and volumetric analysis are also useful to assess the mechanism by which the endovascular device accommodates to morphology changes and to determine criteria for reintervention.

    Title The Impact of Intravascular Ultrasound (ivus) on Endovascular Interventions.
    Date February 2000
    Journal Seminars in Vascular Surgery
    Excerpt

    Intravascular ultrasound (IVUS) has undergone rapid evolution with the recent expansion of endovascular techniques and devices. This device can aid the surgeon, cardiologist, and interventional radiologist by increasing the accuracy of imaging and by adding important information to peripheral vascular and coronary interventions. Modern intravascular ultrasound provides a detailed view of the lumen, wall, and surrounding structures of blood vessels. Compared with other modalities, the diagnostic advantages of IVUS for examining arterial wall architecture and lesion morphology are evident. IVUS can determine lesion shape, length, and configuration, as well as identifying and examining the origins of branches and tributaries. Using this information, IVUS can guide the choice of appropriate angioplasty techniques, aid in the placement of endovascular devices, and assess and follow the efficacy of such interventions. IVUS helps reduce the use of radiation and contrast agents. Even though intravascular ultrasound requires additional equipment, personnel, and interpretative skills, it can be invaluable as a sensitive real-time imaging tool for complex endovascular interventions, therapeutic challenges, and diagnostic dilemmas.

    Title Cardiac Morbidity and Operative Mortality Following Lower-extremity Amputation: the Significance of Multiple Eagle Criteria.
    Date April 1999
    Journal Annals of Vascular Surgery
    Excerpt

    The ability of the Eagle criteria (age >70 years, angina, diabetes, Q wave on EKG, history of congestive heart failure) to predict adverse cardiac events following major vascular surgery has previously been demonstrated. However, the utility of these criteria for lower-extremity amputation is not well established. To determine the value of the Eagle criteria for predicting cardiac morbidity and operative mortality following major lower-extremity amputation, we reviewed 214 consecutive procedures performed at two institutions over a 3-year period. Mean age was 62.7 years and 85% of the patients were male. Diabetes was the most frequent Eagle criterion (74%). The mean number of Eagle criteria was 1.6. Fifty-six percent of the amputations were below the knee, 24% were above the knee, and 20% were guillotine. On multivariate regression analysis, the presence of two or more Eagle criteria (16% vs. 4%, p = 0.04) and decompensated heart failure (39% vs. 7%, p = 0.003) were predictive of adverse cardiac events. The only predictor of postoperative mortality was the presence of two or more Eagle criteria (15% vs. 4%, p = 0.004). Our evaluation of the results of this study led us to conclude that patients requiring major lower-extremity amputation for major vascular disease who have multiple Eagle criteria or decompensated congestive heart failure are at high risk for adverse cardiac events and postoperative death. These findings should be used to guide perioperative cardiac evaluation and therapy.

    Title Iliac to Popliteal Artery Bypass Through the Iliac Wing: An Alternative Extracavitary Route for Management of Complex Groin Injuries.
    Date April 1999
    Journal Annals of Vascular Surgery
    Excerpt

    Extracavitary bypass through the iliac wing allows placement of the grafts into the posterior thigh and is another alternative route when an obturator bypass is not possible, or an axillary-popliteal bypass is to be avoided. The transiliac wing bypass is relatively simple and easy to perform. The bypass route is short and direct, has excellent inflow, and is accompanied by minimal neurological or bleeding risks. An illustrative case is presented with a complete description of the operative technique. Review of the literature is also included.

    Title The Use of Vascular Endoprostheses for Bifurcation Lesions of the Abdominal Aorta.
    Date March 1999
    Journal Advances in Surgery
    Title Aortic Aneurysm Morphology for Planning Endovascular Procedures.
    Date December 1997
    Journal Texas Heart Institute Journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital
    Excerpt

    Endovascular prosthesis repair of abdominal aortic aneurysms is based upon the development of low-profile devices that can be expediently deployed within the aneurysm, excluding it from intraluminal pressure. Many factors affect the treatment of patients in this manner, including the morphology of the proximal and distal fixation sites, the diameter and disease state of the access vessels, and the ability of the device to conform to the many anatomic variations of aneurysms. In addition, preliminary data suggest there is progressive shrinkage and morphologic change in the configuration of an aneurysm following exclusion, which not only affects the alignment of the device but may also influence its healing and stability. This paper reviews the morphologic parameters of aneurysms relevant to endovascular repair and describes the imaging technologies used to assess these parameters before, during, and after intervention.

    Title Modular Bifurcation Endoprosthesis for Treatment of Abdominal Aortic Aneurysms.
    Date October 1997
    Journal Annals of Surgery
    Excerpt

    OBJECTIVE: The authors analyzed a single group's experience treating abdominal aortic aneurysms (AAAs) with a new self-expanding, modular, bifurcated device. SUMMARY BACKGROUND DATA: Successful exclusion of AAAs by prototype devices has led to several controlled clinical trials evaluating prostheses designed and manufactured specifically for this application. METHODS: Sixteen patients (15 males, 1 female) of American Society of Anesthesiologists grade 2 through 4 and average age of 72 years had AAAs (average 57-mm diameter) treated as part of a phase I Food and Drug Administration-approved trial. RESULTS: All patients were treated successfully with no surgical conversions. No endoleaks or aneurysm enlargement was noted either predischarge by contrast computed tomography or on follow-up at 1 month by duplex ultrasound examination. At 6 months, 12 of 13 patients who were observed for this interval had no endoleaks, whereas one patient (patient 3) showed a small area of extravasation that appeared to arise from the device in an area that was traumatized at the time of deployment. One procedure-related mortality (6%) occurred in a patient who died of septic complications secondary to a gangrenous gallbladder diagnosed 1 day after the procedure. There were no device-related mortalities. Complications included two iliac artery dissections, two groin wound infections, and two transient elevations of serum creatinine. Other significant variables including median procedure length (5 hours), intensive care unit stay (1 day), hospitalization postprocedure (4.5 days), and blood loss (1100 mL) all decreased as the study progressed. Blood replacement in all but three patients was accomplished by autotransfusion or banked-autologous blood replacement. At 6-month follow-up in 13 patients, the maximum diameter of the aneurysm decreased by an average of 5.6 mm (range, 0-15 mm), and the maximal cross-sectional area decreased an average of 20.3% (range, 0-72%). CONCLUSIONS: This study suggests that endovascular prosthesis exclusion of AAAs using a self-expanding modular device may be effective in many patients who are otherwise surgical candidates for repair if further clinical studies confirm these observations.

    Title Deployment and Healing of an Eptfe Encapsulated Stent Endograft in the Canine Aorta.
    Date September 1997
    Journal Annals of Vascular Surgery
    Excerpt

    This study evaluated deployment mechanics and long-term healing of an endoluminally placed stent/graft in normal canine aortas. The endoluminal graft (ELG) consisted of a 8.5 cm segment of expanded polytetrafluoroethylene (ePTFE) graft material (Impra, Inc., Tempe, AZ) encapsulating a series of six Palmaz P-128 stents (Johnson & Johnson Interventional Incorporated, New Brunswick, NJ) along the length of the graft. The prostheses were deployed via the femoral artery using a 14Fr delivery system that contained a balloon catheter to expand the ELG in the infrarenal aorta. Twenty-one prostheses were deployed and evaluated at 1 week (n = 3), 1 month (n = 3), 3 months (n = 3), 6 months (n = 9), and 1 year (n = 3). Dimensions of the infrarenal aorta were determined with intravascular ultrasound (IVUS) and angiography prior to deployment of devices. Real-time fluoroscopy and IVUS were used to monitor device deployment with both imaging modalities repeated following implantation. Gross inspection and microscopic evaluation was performed on the explanted specimens following in vivo evaluation by CT scan, IVUS, and angiography prior to retrieval of the specimens. The prostheses were easily deployed from the femoral access site. Oversizing of the deployment balloon compared to the aortic diameter was necessary to accommodate the 10% device recoil observed following balloon deflation, however, all devices were seated against the aortic wall as evidenced by IVUS. At explant, all devices ware widely patent with limited luminal thrombosis observed in four specimens (19%). Devices were well-incorporated by cellular ingrowth into the ePTFE with the formation of neointima. No device migration or postdeployment recoil was observed. ePTFE graft material between stents protruded slightly into the vessel lumen accounting for a 10% luminal reduction. Fully supported ELG's consisting of balloon expandable stents encapsulated in ePTFE are easily deployed using a low-profile delivery system. Specimens demonstrated uniform long-term patency and healing up to 1 year in a canine aortic model. Those preliminary findings support further study of this fully supported prosthesis in the treatment of arterial disease.

    Title Asymptomatic Carotid Artery Stenosis Screening in Patients with Lower Extremity Atherosclerosis: a Prospective Study.
    Date September 1997
    Journal Annals of Vascular Surgery
    Excerpt

    Eighty-nine male veterans presenting to a vascular surgery clinic with symptomatic lower extremity atherosclerosis were prospectively screened by duplex scan for asymptomatic carotid artery stenosis (CAS). Their chief complaint was: claudication (90%), rest pain (6%), and ischemic ulcer or gangrene (4%). The mean ankle-brachial index (ABI) was 0.77. Twenty-five CAS > 50% were detected in 18 (20%) patients. Twelve CAS > 75% were detected in 11 (12%) patients. There was no difference between patients with and without CAS > 50% with regards to mean ABI, history of angina, diabetes, hypertension, prior coronary artery bypass, or history of smoking. Carotid bruit was associated with ipsilateral CAS > 50% [p < 0.0001, sensitivity (52%), specificity (88%), positive predictive value (41%), negative predictive value (92%)]. As a result of the screening, eight elective carotid endarterectomies have been performed to date in six (7%) patients with one transient twelfth cranial nerve paresis as the only postoperative complication. We conclude that: (1) male patients presenting with symptomatic lower extremity atherosclerosis have a 20% prevalence of asymptomatic CAS > 50%, (2) there is no correlation between the degree of lower extremity ischemia and CAS > 50%, (3) carotid bruit is significantly associated with CAS > 50%, but has a low sensitivity, and (4) routine CAS screening should be considered for all male patients with symptomatic lower extremity atherosclerosis regardless of whether a bruit is present.

    Title Intravascular Ultrasound Guidance for Peripheral Vascular Interventions.
    Date September 1997
    Journal Journal of Endovascular Surgery : the Official Journal of the International Society for Endovascular Surgery
    Excerpt

    Intravascular ultrasound (IVUS) imaging during peripheral endovascular interventions adds important information regarding the distribution of disease by providing controlled measurements of the cross-sectional area of the vessel lumen and wall prior to and following procedures. IVUS is useful in determining the mechanism and efficacy of balloon angioplasty, in guiding atherectomy devices, and in assuring appropriate placement of intravascular stents. The incorporation of an IVUS element into catheter-based interventional devices may improve the immediate and long-term results of endovascular interventions by decreasing complications from dissection and perforation of the arterial wall. Combined IVUS-stent prototype catheters are being developed to enable imaging and deployment simultaneously. Similar devices are being explored to enhance expedient, precise delivery of endoluminal grafts. Future studies of endovascular techniques should include IVUS, when possible, to accurately quantitative the initial efficacy of devices and to determine the nature and distribution of recurrent lesions.

    Title Regression of an Abdominal Aortic Aneurysm After Endograft Exclusion.
    Date August 1997
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    We describe the regression of a 6.5 cm diameter abdominal aortic aneurysm in a 71-year-old patient within 1 year of aortic endograft placement. The aneurysm decreased in size to 4 cm at 3 months and was 3.3 cm at 8 months on duplex examination. By 1 year a spiral computed tomographic study confirmed complete regression of the aneurysm, with mild shortening and angulation of the unsupported body of the aortoiliac endoluminal prosthesis. The case demonstrates a potential of endograft treatment of aortic aneurysms and decribes the changes in prosthesis configuration and position that occurred after implantation.

    Title Evaluation of a Modular Endovascular Bifurcation Prosthesis in a Canine Aortic Aneurysm Model.
    Date July 1997
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    PURPOSE: The study evaluated the deployment and healing of a novel self-expanding modular bifurcation endovascular prosthesis in a canine abdominal aortic aneurysm model. The endoluminal prosthesis consists of self-expanding nitinol stents lined by a synthetic prosthesis. One component of the device is a bifurcated body with a 12- to 14-mm diameter aortic segment and an integral 7- to 8-mm diameter iliac limb. The bifurcated body also has a stent-reinforced opening (pant-leg) for subsequent insertion of a contralateral 7- to 8-mm diameter iliac limb component. METHODS: Seventeen bifurcated prosthesis were placed; 7 were inserted through the left common carotid artery and 10 from the femoral arteries. With either route of access the 16F or 17F aortoiliac limb and the 13F iliac limb delivery catheters enabled easy passage and secure positioning of the bifurcated prostheses. Predeployment and postdeployment inspection of the dimensions and continuity of the aortoiliac prosthetic components were evaluated by cinefluoroscopy and intravascular ultrasonography (IVUS). RESULTS: After deployment was done, interval patency was assessed with angiography, IVUS, and contrast-enhanced computed tomography with the prostheses removed for analysis at 1 week (n = 4), 1 month (n = 3), 3 months (n = 4), and 6 months (n = 6). Five of the first seven implanted prostheses had occlusion of segments of the device. In two dogs the bifurcated body and both legs were occluded. In the other three the nonoccluded leg and bifurcation body were fully patent. In the first seven animals IVUS at implantation showed compression of an iliac leg by the orifice of the contralateral iliac component. After concentric fixation of the flow divider was performed, only one additional iliac limb occlusion occurred in the next 10 animals. Cinefluoroscopy, computed tomography, IVUS imaging, and histologic analysis of retrieved specimens demonstrated healing of the aortoiliac prostheses without evidence of perigraft leaks. CONCLUSIONS: This feasibility study demonstrates the ability to deploy and maintain acceptable patency of a self-expanding endoluminal, modular bifurcation prosthesis in a canine aortic model. Clinical evaluation of the device is planned for the near future.

    Title Utility of Intravascular Ultrasound in Peripheral Interventions.
    Date May 1997
    Journal Texas Heart Institute Journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital
    Excerpt

    Endovascular imaging techniques encompass a variety of methods, including angiography, computed tomography, magnetic resonance imaging, angioscopy, and intravascular ultrasound. Each method provides unique information regarding the continuity of vascular structures and the morphology and distribution of lesions. Although arteriography has been the "gold standard" for imaging arterial anatomy, recent data have confirmed that even sophisticated arteriographic imaging substantially underestimates the degree of residual lesions, and that future observations and end-points for treatment will most likely be determined by data accumulated by computed tomography, magnetic resonance imaging, angioscopy, and intravascular ultrasound. Successful therapeutic applications of endovascular devices have developed because of improved patient selection using computed tomography, spiral computed tomography, magnetic resonance imaging, and computerized high-resolution angiography. Procedural success has been enhanced by improved mobile cinefluoroscopy, angioscopy, intraluminal ultrasound monitoring of angioplasty procedures, and the use of intravascular ultrasound for stent and stent-graft sizing and deployment. Newly developed methods and low-profile delivery systems enabling deployment and fixation of vascular prostheses by an endoluminal approach have heightened the interest of many interventionalists, particularly surgeons, in the use of endovascular surgical techniques. The evolution of this method promises to add a new dimension to the treatment of vascular lesions and relies heavily on the incorporation of miniaturized imaging systems, such as intravascular ultrasound, as a means to provide precise placement of devices.

    Title Endoluminal Graft Exclusion of a Proximal Para-anastomotic Pseudoaneurysm Following Aortobifemoral Bypass.
    Date April 1997
    Journal Journal of Endovascular Surgery : the Official Journal of the International Society for Endovascular Surgery
    Excerpt

    PURPOSE: To describe a case of endoluminal graft exclusion of a proximal para-anastomotic pseudoaneurysm that occurred 17 years following aortobifemoral bypass for occlusive disease. METHODS AND RESULTS: The lesion was found on abdominal ultrasound examination as part of a work-up for acute abdominal pain and upper gastrointestinal bleeding in a 67-year-old male. A 5-cm saccular pseudoaneurysm was confirmed by preintervention aortography and spiral computed tomography (CT) scanning. Because of the patient's acute symptoms and high-risk medical condition (cardiomyopathy), he was deemed a candidate for endoluminal bypass. At the time of intervention, intravascular ultrasound (IVUS) interrogation identified a 3.5-cm-long separation of the existing aortic graft from the proximal aortic stump with a large pseudoaneurysm. The lesion was isolated and repaired by placement of an aortic-to-right iliac endoluminal bypass, ligation of the left limb of the aortofemoral graft, and femorofemoral bypass to restore blood flow to the lower extremities. Spiral CT scans at 48 hours and 3 months following the procedure confirmed complete isolation of the lesion. CONCLUSIONS: This case illustrates the feasibility of endografting for repair of aortic para-anastomotic pseudoaneurysms, and it also highlights the potential role of IVUS imaging in endoluminal graft deployment.

    Title Current Use of Low Molecular Weight Heparins.
    Date March 1997
    Journal Seminars in Vascular Surgery
    Title Results of Revascularization for Peripheral Arterial Insufficiency in Chronic Renal Failure Patients.
    Date February 1997
    Journal Seminars in Vascular Surgery
    Title Preliminary Clinical Outcome and Imaging Criterion for Endovascular Prosthesis Development in High-risk Patients Who Have Aortoiliac and Traumatic Arterial Lesions.
    Date December 1996
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    PURPOSE: This report reviews our preliminary experience of prospective treatment of arterial lesions with endoluminal grafts in a Food and Drug Administration (FDA)-approved, investigator-sponsored Investigation Device Exemptions study. The utility and accuracy of various imaging methods, including angiography, cinefluoroscopy, computed tomography (CT), intravascular ultrasonography (IVUS), and duplex scanning, in performing the procedures was also assessed. METHODS: Thirty-one patients were evaluated; 17 patients were treated, including 11 with abdominal aortic aneurysms, one with an aortic occlusive lesion, two with iliac artery aneurysms, and three with traumatic arteriovenous fistulas. Twelve of the 14 patients who had aorta and iliac artery lesions were high-risk. The mean follow-up of patients treated was 9 months (range, 6 to 15 months). RESULTS: Aortoaortic endoluminal interposition procedures were not successful for treating abdominal aortic aneurysms early in the study (n = 3). Aortoiliac endoluminal bypass, contralateral iliac artery occlusion, and femorofemoral bypass procedures were successful in seven of eight subsequent cases (88%), with no incidence of endoleaks at either the proximal or distal fixation sites using the deployment methods described in this report. The 30-day operative mortality rate on follow-up evaluations for patients who underwent aortoiliac procedures was 14% (two of 14). Other major complications included transient renal failure in three patients that required short-term (two to eight times) dialysis, one arterial perforation and one dissection, and one prolonged intubation. No myocardial infarctions or strokes occurred. After major complications or identification of limitations in the study, the protocol was modified with the approval of the FDA to help avoid the recurrence of the same problems. There were no deaths or complications in the trauma cases. CONCLUSIONS: Contrast-enhanced CT (axial images and spiral reconstructions) was the most accurate method to determine candidacy for aortoiliac procedures and to choose the site for deployment of the devices. Angiographic scans were misleading in several patients regarding the critical determinants of patient candidacy and device deployment, particularly regarding the presence of a distal aortic neck. Cinefluoroscopy was used in all patient and was particularly useful for determining the continuity of vascular structures and the anatomy of branch arteries and for enabling precise positioning of stent devices. Determination of fixation sites and assessing dimensional information by cinefluoroscopy and angiography were limited by inaccuracies produced by image magnification, parallax, and uniplanar views. IVUS was used to determine the morphologic features of vascular structures (i.e., calcium, thrombus), to perform real-time observation of the expansion of devices, and to assure firm fixation of balloon-expanded stents before the procedures were completed. Duplex scanning was very helpful in assessing and identifying precisely the location of arteriovenous fistulas before intervention and provided assessment at follow-up intervals. Three-dimensional reconstruction imaging technologies such as spiral CT were particularly helpful for assessing the morphologic features of vascular anatomy before the intervention and at follow-up intervals, whereas 3-D IVUS provided a similar real-time perspective during the procedure.

    Title Deployment Technique and Histopathological Evaluation of an Endoluminal Vascular Prosthesis Used to Repair an Iliac Artery Aneurysm.
    Date October 1996
    Journal Journal of Endovascular Surgery : the Official Journal of the International Society for Endovascular Surgery
    Excerpt

    PURPOSE: To describe the deployment technique, function, and gross healing of an endoluminal vascular prosthesis deployed in a high-risk patient for treatment of a common iliac artery (CIA) aneurysm. METHODS: An 82-year-old, high-risk male with a 4-cm-diameter CIA aneurysm approximately 4.5 to 5 cm long was treated with endoluminal exclusion of the lesion using a 6-cm-long, 14-mm-internal diameter Dacron vascular prosthesis with Palmaz 308 stents sutured to either end of the graft. Intravascular ultrasound (IVUS) imaging facilitated sizing of the endograft and its accurate positioning so as to occlude both the aneurysm and the hypogastric artery, which was a potential source of retrograde flow to the aneurysm. Exclusion of the lesion and occlusion of the hypogastric artery were demonstrated on delayed angiographic images and contrast computed tomography scans obtained at 16 days postprocedure. Unfortunately, the patient died 67 days following implantation from a nonprocedure-related gastrointestinal complication. RESULTS: At autopsy, the aortoiliac segment was excised and examined grossly and histologically; the evaluation confirmed complete isolation of the aneurysm by the fully expanded endoluminal prosthesis. The surface of the vascular graft was covered by a glistening, thin, fibrinous membrane. The graft material was filled with hypocellular compact fibrinous material with no evidence of endothelialization. These observations confirm preliminary sealing and isolation of the iliac artery aneurysm as healing of the endograft progressed. CONCLUSIONS: The data acquired from the analysis of this specimen provide information regarding the utility and early healing of an endograft used for iliac artery aneurysm exclusion. This case also exemplifies the utility of IVUS in endograft deployment.

    Title The Ideal Guidance Imaging System for Endovascular Interventions.
    Date September 1996
    Journal The Journal of Cardiovascular Surgery
    Excerpt

    Endovascular interventions enable a minimally invasive approach to a variety of cardiovascular lesions. Small catheter-based delivery systems have rapidly evolved, diversifying endovascular therapeutic options. Coronary and peripheral vascular occlusive lesions may be amenable to angioplasty dilatation, intravascular stenting and ablation with mechanical atherectomy devices or lasers. New experimental transluminally placed endovascular stented grafts (TPEGs) have demonstrated feasibility for treating aneurysmal arteries, arteriovenous fistulas, and atherosclerotic occlusions. Improvements in imaging systems have provided better resolution of lesions, have improved patient selection and interventional strategy, and are invaluable for precise performance of procedures. The ideal guidance system should provide realtime imaging by a combination of complimentary modalities. These include cinefluoroscopy and contrast angiography, catheter-based intravascular ultrasound and angioscopy.

    Title Vascular Imaging Before, During, and After Endovascular Repair.
    Date August 1996
    Journal World Journal of Surgery
    Excerpt

    Endovascular techniques for repair of vascular lesions are developing rapidly. Imaging modalities are critical in this evolution from several perspectives. Device development and evaluation rely on precise imaging to ensure fixation of devices, isolation of lesions, and assessment of healing at various intervals. Clinical implementation of endovascular techniques requires a spectrum of imaging methods to choose patients appropriately for procedures, to deploy devices expediently and precisely, and to evaluate long-term efficacy in a minimally invasive manner. This paper reviews the utility of available imaging methods for performing these assessments.

    Title Forward-looking Intravascular Ultrasonography: in Vitro Imaging of Normal and Atherosclerotic Human Arteries.
    Date October 1994
    Journal The American Surgeon
    Excerpt

    Inadequate guidance of angioplasty devices limits the endoluminal treatment of high grade atherosclerotic stenoses and total occlusions. Conventional intraluminal ultrasound systems (IVUS) enable lateral cross-sectional imaging of tomographic sections of the vessel wall, but do not offer imaging in front of the catheter. This study describes our initial experience with a forward-looking intravascular ultrasound (FL-IVUS) system (Echoeye, EchoCath, Inc., Princeton, NJ). The acoustic beam from a 25.5 MHz piezoelectric transducer on a 7.5 Fr catheter is mechanically rotated in a forward-looking spiral fashion at 300 cycles/second. Sixty-four axially aligned, cross-sectional, real time images are obtained from a truncated, 60 degree conical volume located 5 to 10 mm from the catheter tip. Luminal dimensions (n = 51) of human cadaveric femoral arteries (cast in agar and submerged in saline) measured by the FL-IVUS were compared to histologic cross-sections of the vessel with a correlation of r = 0.92. FL-IVUS accurately imaged the narrowing lumen in front of total occlusions and the geometry at vessel branches, and identified the location of lesions and the shape and morphology of vessel wall thickness. The 7.5 Fr FL-IVUS over-estimated luminal dimensions in vessels larger than 5 mm. We conclude that FL-IVUS imaging shows promise as a new, accurate method for identifying and characterizing high grade atherosclerotic stenoses and total occlusions, and expands the current capabilities of conventional IVUS systems.

    Title Nd:yag Laser-welded Canine Arteriovenous Anastomoses.
    Date June 1994
    Journal Lasers in Surgery and Medicine
    Excerpt

    This preliminary report describes formation of femoral arterio-venous fistulas (n = 10) in six dogs using a 1.32-microns wavelength Nd:YAG laser welding technique. Stay sutures (6-0 polypropylene) were placed at 5-7 mm intervals along the anastomoses for vessel apposition. Delivery of laser energy through a 400-microns diameter fiber optic was controlled by a new computer-based software system. At 3 mm distance above the anastomosis, energy fluences of 110-260 J/mm2/cm length of anastomosis were used for laser welding. One or two additional hemostatic sutures were required in seven of the ten anastomoses. Flow was maintained for 1-2 hours prior to tissue harvesting. No thrombosis or delayed anastomotic failures were observed after initial welding and repair. Histologic examination revealed good apposition and adherence between wall layers and a fibrinous coagulum at the intimal junctions. Mild thermal injury of the wall was present at some anastomoses. This early investigation suggests that a 1.32 microns Nd:YAG laser welding technique can successfully create large vessel arteriovenous fistulas in the canine.

    Title Future Alternatives to Heparin: Low-molecular-weight Heparin and Hirudin.
    Date May 1992
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    The antithrombotic effects of standard heparin were compared with those of low-molecular-weight heparin (LMWH) and hirudin by use of an in vitro perfusion system. Fresh blood collected from human volunteers was treated with varying doses of these three agents and perfused in a recirculating system over everted porcine vein segments. A low shear rate (100/sec) was selected to simulate conditions in large arteries and veins. Platelet and fibrinogen deposition were evaluated with indium 111 and iodine 125 radiolabels, respectively. Anticoagulant activity was assessed by measuring the activated clotting time (ACT). Anti-Xa activity was assayed to determine the degree to which these agents used antithrombin III pathways. Low-molecular-weight heparin was the weakest anticoagulant, requiring 32 micrograms/ml blood to double the ACT. By contrast, the ACT doubled with only 0.75 and 1.10 micrograms/ml blood of heparin and hirudin, respectively. Heparin and hirudin inhibited platelet and fibrin deposition at equivalent doses. Low-molecular-weight heparin was a less potent inhibitor of fibrin than heparin or hirudin. Hirudin, a direct thrombin inhibitor, exhibited minimal anti-Xa activity, contrasted with 0.14 anti-Xa units/micrograms for LMWH and 0.13 anti-Xa units/mg for heparin. These data suggest that heparin and hirudin are more potent anticoagulants and antiplatelet agents than LMWH.

    Title Low Dose Heparin Therapy: in Vitro Verification of Antithrombotic Effect.
    Date December 1991
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    Low dose heparin therapy has been used routinely for prophylaxis of deep venous thrombosis, yet in vitro data regarding its antithrombotic effects are sparse. The effects of heparin on venous thrombus formation were studied in an in vitro perfusion system. Fresh blood collected from human volunteers was treated with varying heparin doses and perfused at a shear rate of 100 sec-1 over everted, injured porcine vein segments, simulating conditions in the venous circulation. Platelet and fibrin deposition were measured by use of indium 111 and iodine 125 radiolabels, respectively. The effects of heparin on the intrinsic coagulation cascade were monitored by the activated clotting time. Increasing doses of heparin resulted in significant reductions in fibrin and platelet deposition (ANOVA F = 2.67 and 3.17, respectively, p less than 0.05). At a dose of only 0.19 USP units/ml blood, equivalent to a 1000 unit bolus of heparin in a 70 kg man, a noticeable reduction in both fibrin and platelet deposition was observed without an increase in the activated clotting time. These data confirm the antithrombotic effects of heparin at low dose ranges and may explain the clinically observed phenomenon of deep venous prophylaxis without an appreciable alteration in the conventional coagulation assays.

    Title Exertional Disruption of Axillofemoral Graft Anastomosis. 'the Axillary Pullout Syndrome'.
    Date May 1990
    Journal Archives of Surgery (chicago, Ill. : 1960)
    Excerpt

    Five cases of exertional disruption of the axillary anastomosis occurred at intervals of 13 to 30 days after axillofemoral polytef (polytetrafluoroethylene [PTFE]) graft insertion. Graft evulsion was preceded by effort and heralded by axillary pain, an expanding hematoma, and a pseudoaneurysm formation. Proximal control of the subclavian artery by a supraclavicular approach or balloon allowed safe wound exploration. Successful reconstruction required lengthening of the graft or replacement. Secondary disruption occurred with simple repair. Although temporary postoperative brachial plexus neuropathy was common, no significant hand ischemia was noted. Twenty-two reports of axillary anastomotic disruption were made to the Food and Drug Administration, Washington, DC, during a 2-year period, and one manufacturer of polytef grafts provided data on 10 reports received throughout 7 years. Surface anatomy measurements in 20 control patients demonstrated that arm abduction and lateral flexion of the body increased the distance between the axillary and femoral arteries by a mean of 15.5%. Similar measurements taken from the proximal axillary artery showed a mean length increase of less than 10%. This complication may be avoided by inserting the polytef graft with several centimeters of excess length and positioning the axillary anastomosis medial to the pectoralis minor muscle.

    Title Initial Human Evaluation of Argon Laser-assisted Vascular Anastomoses.
    Date June 1989
    Journal Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
    Excerpt

    Forearm Brescia-Cimino arteriovenous fistulas were chosen for the initial clinical evaluation of argon laser-assisted anastomosis of human vessels. Ten patients with chronic renal failure had side-to-side radial artery/cephalic vein fistulas fused by laser. Incisions 1.2 to 1.5 cm in length were made in adjacent segments of artery and vein and were aligned for application of laser energy by four 6-0 polypropylene sutures. The sutures divided each fistula into four segments that were 5.0 to 6.5 mm long. Each segment was sealed satisfactorily in 75 to 100 seconds by use of 0.5 W, 1130 to 1520 joule/cm2 argon laser energy fluence. Seven (17.5%) of 40 bonds required an additional 7-0 biodegradable suture to close small gaps that did not fuse adequately. Serial prospective follow-up studies of the patients by physical examination and duplex scanning for periods of 12 to 20 months (15.4 +/- 2.8, n = 7) postoperatively have shown uniformly patent, compliant anastomoses with no evidence of hematomas, false aneurysms, or luminal narrowing. Histologic examination of two patent fistulas that were excised during revision procedures at 4 and 5 months postoperatively showed healing of the entire circumference of the anastomosis similar to that noted in extensive preclinical canine studies. We conclude from these preliminary results that argon laser vascular tissue fusion is possible in humans when reliable primary sealing of vascular anastomoses is achieved, and that healing occurs without aneurysmal dilatation during follow-up of up to 20 months.

    Title Mechanism of Tissue Fusion in Argon Laser-welded Vein-artery Anastomoses.
    Date May 1988
    Journal Lasers in Surgery and Medicine
    Excerpt

    The mechanism of laser vascular tissue welding remains unknown. This study compared the acute tissue response and long-term healing of sutured and laser-welded anastomoses of vein segments used to bypass ligated canine femoral arteries. For each procedure, one anastomosis was formed using running 6-0 polypropylene suture (control), and the other anastomosis was formed using argon laser tissue welding (experimental). The vein grafts were harvested at 4 (n = 2), 8 (n = 1), 12 (n = 1), and 16 (n = 2) weeks, and selected samples were evaluated by histologic examination, electron microscopy, tensile strength testing, and by measuring the formation of [3H]hydroxyproline as an index of collagen synthesis. Examination of successful laser fusions immediately after they were formed showed bonding of collagen to collagen and elastin to collagen. Follow-up evaluations showed that the precision of tissue apposition affected the rate of healing and tensile strength. Laser-welded anastomoses demonstrated a progression of healing similar to sutured repairs, with remodeling of fibrous tissue and collagen being the primary component of weld integrity. This study demonstrates that sutured and argon laser-welded vein-artery anastomoses heal comparably up to 16 weeks postoperatively, and that laser welding is a satisfactory alternative to sutured anastomoses.

    Title Pathogenesis Determines Late Morbidity of Axillosubclavian Vein Thrombosis.
    Date September 1986
    Journal American Journal of Surgery
    Excerpt

    The late consequences of axillosubclavian vein thrombosis were evaluated through a clinical follow-up of 41 patients (45 limbs) treated from July 1975 to December 1985. The causes of the obstruction were classified into two main groups: Intrinsic damage, consisting of thrombophlebitis due to intravenous drug abuse (11 patients), central venous catheterization (10 patients), and hypercoagulability state (2 patients); and extrinsic obstruction, involving effort-induced or thoracic outlet obstruction (9 patients), underlying neoplastic disease (5 patients), trauma (3 patients), and congenital venous malformation (1 patient). Clinical diagnosis was confirmed by upper arm venography in all 41 patients, and all were initially treated by anticoagulation with heparin for 1 to 2 weeks, usually followed by oral warfarin for a variable period of 1 week to 5 years. Only three patients had an operation (rib resection for thoracic outlet obstruction, thrombectomy and clavicle fixation, and repair of a congenital venous malformation). Major early morbidity consisted of a documented pulmonary embolus in five patients, two in Group I and three in Group II, for an overall incidence of 12 percent. Clinical follow-up of up to 5 years revealed that chronic morbidity was related to our classification. Thrombosis secondary to intrinsic damage rarely caused persistent symptoms and responded well to anticoagulation alone. Conversely, when extrinsic obstruction was the cause, only 50 percent of patients were symptom-free, whereas many had disabling intermittent arm swelling and pain. Repeat venography in severely symptomatic patients revealed persistent obstruction with no recanalization. We conclude that patients with axillosubclavian venous thrombosis due to intrinsic damage do not require treatment other than anticoagulants, whereas patients with extrinsic obstruction often have poor long-term results from conventional therapy and therefore should be considered for adjunctive treatment with thrombolysins or operative intervention.

    Title High-dose Adenosine-induced Asystole Assisting Accurate Deployment of Thoracic Stent Grafts in Conscious Patients.
    Date
    Journal Annals of Vascular Surgery
    Excerpt

    Adenosine has been used to induce asystole and assist deployment of endoluminal grafts. However, application of high-dose adenosine in conscious patients has not been described. In this prospective study, we administered high-dose adenosine in patients undergoing thoracic stent grafting. Asystole duration in relationship to the dosage of adenosine, safety, and side effect profiles was investigated. All patients who underwent thoracic stent grafting between 1998 and 2006 were the potential study subjects. They received monitored anesthesia care and local anesthesia unless contraindicated. Adenosine was given via rapid intravenous bolus immediately prior to the deployment of the stent graft. Every patient received a dose of 36 mg. If needed, a second dose of 18 mg was given. Duration of asystole was recorded after each administration. Patients' vital signs before and after administration were also documented. Side effect profiles were collected intra- and postoperatively. A total of 46 patients received adenosine (34 men, 12 women). Mean age was 60.4 +/- 17.5 years. American Society of Anesthesiologists scores were II in one patient (2%), III in six patients (13%), and IV in 39 patients (85%). Eighteen patients received a single dose of 36 mg adenosine, 15 were given a second dose of 18 mg, and 13 received nonstandard dosages. Asystole durations were 18.8 +/- 8.8 and 11.6 +/- 5.5 sec for 36 and 18 mg, respectively. Technical success was achieved in all cases. The differences achieved statistical significance (p = 0.0009). There were no severe cardiac or pulmonary complications. High-dose adenosine can be given safely in conscious patients. The dose-response was predictable and reproducible. The dosages used in our study induce sufficient duration of asystole, which ensured accurate deployment of thoracic stent grafts.

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