Cardiologists
27 years of experience
Video profile
Accepting new patients
Maxey Park
Covenant Cardiac Arrhythmia Services
3506 21st St
Ste 302
Lubbock, TX 79410
806-725-1908
Locations and availability (3)

Education ?

Medical School
Universidad Peruana Cayetano Heredia (1983)
Foreign school

Awards & Distinctions ?

Awards  
Compassionate Doctor Recognition (2009)
Associations
Heart Rhythm Society
American Board of Internal Medicine

Affiliations ?

Dr. Rizo-Patron is affiliated with 6 hospitals.

Hospital Affilations

Score

Rankings

  • University Medical Center - Lubbock
    Cardiology
    602 Indiana Ave, Lubbock, TX 79415
    • Currently 4 of 4 crosses
    Top 25%
  • Lubbock Heart Hospital
    Cardiology
    4810 N Loop 289, Lubbock, TX 79416
    • Currently 4 of 4 crosses
    Top 25%
  • Covenant Hospital Plainview
    Cardiology
    2601 Dimmitt Rd, Plainview, TX 79072
    • Currently 3 of 4 crosses
    Top 50%
  • Covenant Medical Center
    Cardiology
    3615 19th St, Lubbock, TX 79410
    • Currently 2 of 4 crosses
  • Covenant Children's Hospital
    3610 21st St, Lubbock, TX 79410
    • Currently 2 of 4 crosses
  • Covenant Hospital Levelland
    Cardiology
    1900 College Ave, Levelland, TX 79336
    • Currently 1 of 4 crosses
  • Publications & Research

    Dr. Rizo-Patron has contributed to 14 publications.
    Title Percent Right Ventricular Pacing Predicts Outcomes in the David Trial.
    Date December 2005
    Journal Heart Rhythm : the Official Journal of the Heart Rhythm Society
    Excerpt

    BACKGROUND: The Dual-Chamber and VVI Implantable Defibrillator (DAVID) trial demonstrated a worse outcome in patients with implantable cardioverter-defibrillators (ICDs) programmed to DDDR at 70 bpm compared with patients who had ICDs programmed to VVI backup pacing at 40 bpm. Pacing was more frequent in the DDDR group. OBJECTIVES: The purpose of this study was to determine whether right ventricular pacing (RV) is an independent predictor of outcome in the DAVID trial. METHODS: We evaluated the relationship of percent RV pacing to the composite endpoint of death or hospitalization for congestive heart failure. Patients who had a 3-month follow-up and who had not yet reached an endpoint were included in the study. Using Cox regression analysis (VVI group N = 195; DDDR group N = 185), we examined multiple factors, including percent RV pacing at 3-month follow-up, that might be associated with adverse outcomes. RESULTS: Percent RV pacing as a continuous variable was correlated with the primary endpoint. As a dichotomous variable, the best separation for predicting endpoints occurred with DDDR RV pacing > 40% vs DDDR RV pacing < or = 40% (P = .025). Patients with DDDR RV pacing < or = 40% had similar or better outcomes to the VVI backup group (P = .07). Correction for baseline variables predictive of the composite outcome in the (nonpaced) VVI group (use of nitrates, increased heart rate, and increased age) did not change the findings for RV pacing (P = .008). In contrast, atrial pacing was not predictive of worse outcomes. CONCLUSION: These results suggest, but do not prove, a causal relationship between frequent RV pacing and adverse outcomes in patients with left ventricular ejection fraction < or = 40%.

    Title Coronary Sinus Mapping Through a Persistent Left Superior Vena Cava in Wolff-parkinson-white Syndrome.
    Date January 2005
    Journal Texas Heart Institute Journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital
    Excerpt

    Persistent left superior vena cava is not an uncommon finding in patients undergoing evaluation for preexcitation syndromes. In such patients, this anatomical configuration might be used advantageously for mapping and ablation of a left-sided accessory pathway during electrophysiologic studies. We successfully used this mapping approach in a 16-year-old boy undergoing evaluation for Wolff-Parkinson-White syndrome. The patient was found to have a persistent left superior vena cava confluent with the coronary sinus. During electrophysiologic studies, mapping of the left-sided accessory pathway was facilitated by retrograde entry into the coronary sinus through the persistent left superior vena cava. Mapping was also performed in the conventional manner, yielding identical results and thus validating this new technique.

    Title Cryosurgical Modification of the Atrioventricular Node for Treatment of Atrioventricular Junctional Reentrant Tachycardia.
    Date January 2005
    Journal Texas Heart Institute Journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital
    Excerpt

    Surgical correction of atrioventricular nodal reentrant tachycardia with preservation of atrioventricular nodal conduction in a 28-year-old woman is reported. At surgery, electrophysiologic mapping techniques were used during tachycardia to reveal and enable ablation of the appropriate site of atrial activation. Postoperative electrophysiologic studies indicated successful atrioventricular nodal modification.

    Title High Incidence of Pacemaker Syndrome in Patients with Sinus Node Dysfunction Treated with Ventricular-based Pacing in the Mode Selection Trial (most).
    Date June 2004
    Journal Journal of the American College of Cardiology
    Excerpt

    OBJECTIVES: We evaluated the incidence, predictors, and treatment of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based (VVIR) pacing in the Mode Selection Trial (MOST). BACKGROUND: Pacemaker syndrome, or intolerance to VVIR pacing, consists of cardiovascular signs and symptoms induced by VVIR pacing. METHODS: The definition of pacemaker syndrome required that a patient with single-chamber VVIR pacing develop either congestive signs and symptoms associated with retrograde conduction during VVIR pacing or a >or=20 mm Hg reduction of systolic blood pressure during VVIR pacing, associated with reproducible symptoms of weakness, lightheadedness, or syncope. RESULTS: Of 996 patients randomized to VVIR pacing, 182 (18.3%) met criteria for pacemaker syndrome in follow-up. Pacemaker syndrome occurred early in most patients (13.8% at 6 months, 16.0% at 1 year, increasing to 19.7% at 4 years). Baseline univariate predictors of pacemaker syndrome included a lower sinus rate and higher programmed pacemaker rate. Previous heart failure, ejection fraction, and drop in systolic blood pressure with VVIR pacing at implantation did not predict the development of pacemaker syndrome. Post-implantation predictors of pacemaker syndrome were a higher percentage of paced beats, higher programmed low rate, and slower underlying spontaneous sinus rate. Quality of life decreased at the time of diagnosis of pacemaker syndrome and improved with reprogramming to atrial-based pacing. CONCLUSIONS: Severe pacemaker syndrome developed in nearly 20% of VVIR-paced patients and improved with reprogramming to the dual-chamber pacing mode. Because prediction of pacemaker syndrome is difficult, the only way to prevent pacemaker syndrome is to implant atrial-based pacemakers in all patients.

    Title Predictors and Clinical Impact of Atrial Fibrillation After Pacemaker Implantation in Elderly Patients Treated with Dual Chamber Versus Ventricular Pacing.
    Date February 2004
    Journal Pacing and Clinical Electrophysiology : Pace
    Excerpt

    The Pacemaker Selection in the Elderly (PASE) trial was a prospective, multicenter, single blind, randomized comparison of single chamber, rate adaptive, ventricular pacing (VVIR) with dual chamber, rate adaptive pacing (DDDR) in 407 patients aged > or =65 years(mean 76 +/- 7 years, 60% male)with standard bradycardia indications for dual chamber pacemaker implantation. The incidence, predictors, and clinical consequences of atrial fibrillation (AF) developing after pacemaker implantation in the PASE trial were studied prospectively. During a median follow-up of 18 months, AF developed in 73 (18%) patients. Kaplan-Meier estimated cumulative incidences of AF in patients with sinus node dysfunction (n=176) at 18 months were 28% in the VVIR and 16% in the DDDR groups (P=0.08). After adjustment for other clinical variables using a Cox multivariate regression model, randomization to VVIR compared with DDDR pacing mode among patients with sinus node dysfunction was independently associated with a 2.6-fold increased relative risk (RR) of developing AF after pacemaker implantation (P=0.01). Other independent clinical risk factors for development of postimplant AF included a preimplant history of hypertension (P=0.02) or supraventricular tachyarrhythmias(P<0.04). Patients who developed AF had similar health related quality of life scores and cardiovascular functional status after 18 months of pacing as patients who remained free of AF. The RR of death, stroke, or heart failure hospitalization was not increased in patients who developed AF. Thus, in the elderly patients with sinus node dysfunction requiring permanent pacing, DDDR pacing mode protected against the development of AF. However, development of AF after pacemaker implantation in this population was not associated with a significant impact on quality-of-life, functional status, or other clinical endpoints during 18 months of follow-up.

    Title Do Arrhythmia Patients Improve Survival by Participating in Randomized Clinical Trials? Observations from the Cardiac Arrhythmia Suppression Trial (cast)and the Antiarrhythmics Versus Implantable Defibrillators Trial (avid).
    Date October 2003
    Journal Controlled Clinical Trials
    Excerpt

    It is debatable whether patients benefit directly from participation in a randomized clinical trial. We attempt to address this question for participants in the Cardiac Arrhythmia Suppression Trial (CAST) and the Antiarrhythmics Versus Implantable Defibrillators (AVID) studies. Survival rates were compared between eligible patients who enrolled in the trials and eligible patients who did not enroll, adjusting for baseline covariates. In CAST, despite that the active therapy was found to confer an almost threefold increased risk of death, survival was similar between the 3163 enrolled and the 1363 nonenrolled eligible patients. However, when patients were under study management, their risk of death was approximately 20% lower than when they left study management. In AVID, overall survival was similar between the 1016 enrolled and the 1246 nonenrolled eligible patients. However, mortality was substantially higher among patients not enrolled because the referring physician mandated the type of therapy. Overall these observational analyses suggest a net improvement in survival for the participants in these two trials.

    Title Effect of Surgical Revascularization in Patients with Coronary Artery Disease and Ventricular Tachycardia or Fibrillation in the Antiarrhythmics Versus Implantable Defibrillators (avid) Registry.
    Date June 2002
    Journal American Heart Journal
    Excerpt

    BACKGROUND: Patients who undergo resuscitation from near-fatal ventricular arrhythmias often have significant coronary artery disease, and revascularization has been shown to reduce myocardial ischemia and cardiac arrest episodes in this patient population. The magnitude of benefit attributed to revascularization has varied by study, and the use of adjunct implantable cardioverter defibrillator (ICD) therapy has not been well-characterized. METHODS AND RESULTS: The Antiarrhythmics Versus Implantable Defibrillators (AVID) registry included 3117 patients with life-threatening ventricular arrhythmias, of whom 2321 (77%) had documented coronary artery disease and 281 (17%) underwent a coronary artery bypass grafting revascularization procedure after the index event. Patients who underwent a revascularization procedure were younger, had a lower incidence rate of prior myocardial infarction and ventricular arrhythmia, had a higher left ventricular ejection fraction, had less congestive heart failure, and were more likely to have had ventricular fibrillation as the presenting arrhythmia. Patients who underwent revascularization had a better survival rate than did those who did not undergo such a procedure after the index event, and adjustment for differing baseline patient covariates did not alter the relative survival rate benefit. Further, ICD implantation offered a similar survival rate advantage to those patients in the AVID registry with coronary artery disease independent of revascularization. CONCLUSION: Coronary revascularization in the AVID registry patients with coronary artery disease effected a survival rate benefit that was not attributable to differences in baseline patient characteristics. The benefit of ICD on patient survival rate was not attenuated by a revascularization procedure.

    Title Lead- and Device-related Complications in the Antiarrhythmics Versus Implantable Defibrillators Trial.
    Date March 2001
    Journal American Heart Journal
    Excerpt

    BACKGROUND: Implantation of transvenous implantable cardioverter defibrillators (ICDs) by use of a nonthoracotomy approach has become routine therapy for survivors of life-threatening tachyarrhythmias. The purpose of this study was to identify and prospectively characterize the frequency of lead- and ICD-related complications from the Antiarrhythmics versus Implantable Defibrillators (AVID) Trial. METHODS AND RESULTS: Between June 1, 1993, and April 7, 1997, 539 patients received nonthoracotomy ICDs either as initial treatment assignment (477) or as crossover from medical management (62). A total of 62 first complications occurred. The subclavian route of insertion resulted in more complications than the cephalic vein route, 46 of 339 (14%) versus 6 of 135 (4%), P = .005, as did the abdominal versus pectoral generator site, 31 of 238 (13%) versus 17 of 291 (6%), P<.02. Most dislodgements and system infections tended to occur in the 3 months after implantation, whereas lead fractures continued to occur throughout follow-up. Failure to use perioperative antibiotics was a predictor of system infection (P = .001). CONCLUSIONS: These data suggest that cephalic vein access and pectoral generator site may result in fewer complications. The continued occurrence of lead fractures and the need for premature system revision supports the practice of close routine ICD system surveillance.

    Title Radiofrequency Catheter Ablation for Management of Symptomatic Ventricular Ectopic Activity.
    Date October 1995
    Journal Journal of the American College of Cardiology
    Excerpt

    OBJECTIVES. This study assessed the useful role of intracardiac mapping and radiofrequency catheter ablation in eliminating drug-refractory monomorphic ventricular ectopic beats in severely symptomatic patients. BACKGROUND. Ventricular ectopic activity is commonly encountered in clinical practice. Usually, it is not associated with life-threatening consequences in the absence of significant structural heart disease. However, frequent ventricular ectopic beats can be extremely symptomatic and even incapacitating in some patients. Currently, reassurance and pharmacologic therapy are the mainstays of treatment. There has been little information on the use of catheter ablation in such patients. METHODS. Ten patients with frequent and severely symptomatic monomorphic ventricular ectopic beats were selected from three tertiary care centers. The mean frequency +/- SD of ventricular ectopic activity was 1,065 +/- 631 beats/h (range 280 to 2,094) as documented by baseline 24-h ambulatory electrocardiographic (ECG) monitoring. No other spontaneous arrhythmias were documented. These patients had previously been unable to tolerate or had been unsuccessfully treated with a mean of 5 +/- 3 antiarrhythmic drugs. The site of origin of ventricular ectopic activity was accurately mapped by using earliest endocardial activation time during ectopic activity or pace mapping, or both. RESULTS. During electrophysiologic study, no patient had inducible ventricular tachycardia. The ectopic focus was located in the right ventricular outflow tract in nine patients and in the left ventricular posteroseptal region in one patient. Frequent ventricular ectopic beats were successfully eliminated by catheter-delivered radiofrequency energy in all 10 patients. The mean number of radiofrequency applications was 2.6 +/- 1.3 (range 1 to 5). No complications were encountered. During a mean follow-up period of 10 +/- 4 months, no patient had a recurrence of symptomatic ectopic activity, and 24-h ambulatory ECG monitoring showed that the frequency of ventricular ectopic activity was 0 beat/h in seven patients, 1 beat/h in two patients and 2 beats/h in one patient. CONCLUSIONS. Radiofrequency catheter ablation can be successfully used to eliminate monomorphic ventricular ectopic activity. It may therefore be a reasonable alternative for the treatment of severely symptomatic, drug-resistant monomorphic ventricular ectopic activity in patients without significant structural heart disease.

    Title Effects of Internal Defibrillation on an Implanted Pacing System with Programmable Polarity.
    Date May 1995
    Journal Pacing and Clinical Electrophysiology : Pace
    Excerpt

    Management of multiple cardiac arrhythmias in some patients with both an implantable cardioverter defibrillator (ICD) and a pacemaker has demonstrated several advantages. In such circumstances, it is imperative that pacemaker function and its programmed parameters be preserved following a defibrillation shock. This article describes the effects encountered by a specific programmable polarity pacemaker (RelayR 294-03) when subjected to electrical defibrillation in a canine model. Three pacemakers were repeatedly tested in three separate dog experiments. Each pacemaker, with its leads implanted in the right atrium and the right ventricle, was subjected to a minimum total number of 24 high energy biphasic and monophasic shocks (600-700 V) delivered by a coexisting ICD system using three different defibrillating lead configurations. None of the pacemaker systems showed any failure in function; all pacemakers continued to function within preshock specification and conversion to unipolar pacing and/or backup mode was not observed in any of the tests. Intracardiac electrical potentials measured directly off the ICD and the pacemaker leads, during a defibrillation shock (mean 566.6 V; 23.7 J), showed that potentials measured in a bipolar configuration (tip-ring: mean 21.0 V in atrium, 12.0 V in ventricle) were significantly less than potentials measured in a unipolar configuration (tip-can: mean 387.9 V in atrium, 394.0 V in ventricle; ring-can: mean 405.6 V in atrium, 395.4 V in ventricle). Our compatibility tests demonstrate that use of this programmable-polarity pacemaker in concert with an ICD system appears to be safe. Testing similar to the present study should be conducted prior to complete clinical acceptance of combined ICD and pacemaker implantation.

    Title The Art and Science of Mixing and Matching.
    Date August 1994
    Journal Journal of the American College of Cardiology
    Title The Role of Pacing for the Management of Neurally Mediated Syncope: Carotid Sinus Syndrome and Vasovagal Syncope.
    Date May 1994
    Journal American Heart Journal
    Excerpt

    The role of permanent cardiac pacing for the management of neurocardiogenic syncope is controversial; however, it does have a secondary role in appropriately selected individuals. Neurocardiogenic syncope includes vaso-vagal and enhanced antagonism of sympathetic-parasympathetic mechanisms. Differentiation of the so-called cardiac inhibitory, vasodepressor, and mixed forms of these disorders is frequently misleading when establishment of effective treatment strategies is attempted. Cardiac pacing can artificially restore near-normal heart rate and atrioventricular synchrony during a neurocardiogenic syncopal episode; however, cardiac pacing does not alter the peripheral vasodilatation, nor does it prevent the occurrence of the reflux response. Syncopal patients with carotid sinus hypersensitivity or vasovagal responses that include marked bradycardia and loss of atrioventricular synchrony can be supported by dual-chamber cardiac pacing in combination with other therapeutic interventions that diminish the severity of the reflex response. The conditions of patients with carotid sinus syndrome and carotid sinus hypersensitivity are frequently improved with cardiac pacing, and the conditions of elderly patients with vasovagal syncope are commonly improved with artificial pacing. The classic younger patient with malignant vasovagal syncope derives less benefit from artificial pacing; however, in carefully selected persons dual-chamber pacing combined with drug therapy and education decreases syncopal episodes and permits a return to normal activities.

    Title A New Manifestation and Treatment Alternative for Heparin-induced Thrombosis.
    Date January 1991
    Journal Chest
    Excerpt

    We treated a coronary artery bypass patient whose postoperative course was complicated by heparin-induced thrombocytopenia and resultant pulmonary artery and saphenous vein graft thromboses. The pulmonary thromboemboli were found first, and pulmonary blood flow was restored with intravenously administered tissue plasminogen activator (tPA). A short time later, the vein grafts were found to be occluded, and we subsequently performed multivessel percutaneous transluminal coronary angioplasty (PTCA) using tPA as an adjuvant to oral warfarin sodium therapy with excellent results. We conclude that heparin-induced thromboses in the pulmonary arteries are amenable to thrombolytic therapy, including tPA, whereas this regimen appears to have little effect on saphenous vein grafts. We also found that a combination of warfarin and thrombolytic therapy is an alternative regimen for heparin-intolerant patients who require PTCA.

    Title Percutaneous Transluminal Coronary Angioplasty in Octogenarians with Unstable Coronary Syndromes.
    Date November 1990
    Journal The American Journal of Cardiology

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