Trends in reported industry payments to physicians practicing cardiac electrophysiology from 2013 to 2018 in the United States.

INTRODUCTION: The need for transparency in financial relationships in the healthcare system, has culminated in Open Payments database, managed by the Center for Medicare and Medicaid Services (CMS). Since its inception in 2013, the trend in such payments to physicians practicing cardiac electrophysiology was not examined. METHODS AND RESULTS: Payment information reported to CMS from January 2013 to December 2018 was obtained from the publicly available Open Payments data set using the online query tool. The data were analyzed by an individual provider and by state. An in-depth analysis of payments in the year 2018 payments was performed. From 2014 to 2018, there was an 18% increase in the total number of payments reported from 88 877 payments in 2014 to 105 000 in 2018. Despite the increase in the total number of payments reported, the average payment steadily decreased over time, resulting in an overall reduction in the total amount of payments from 2014 to 2018 ($34.9 million to $28.2 million). Payments to the top 5% of individual recipients have also decreased over this time. In 2018, 2888 unique providers received reportable payments, a total of 105 000 payments, with a median payment amount of $1378 (interquartile range: $165-$5781). The majority of these payments were for food and beverage (82%) and travel/lodging (10%). The top five payers include Boston Scientific, Medtronic Vascular, Abbott Laboratories, Janssen Pharmaceuticals, and Biotronik. CONCLUSION: Among cardiac electrophysiologists, there is increased reporting of payments in the Open Payments program over time, with a notable decrease in the payment amount.

Stellate ganglion block and cardiac sympathetic denervation in patients with inappropriate sinus tachycardia.

BACKGROUND: Inappropriate sinus tachycardia (IST) remains a clinical challenge because patients often are highly symptomatic and not responsive to medical therapy. OBJECTIVE: To study the safety and efficacy of stellate ganglion (SG) block and cardiac sympathetic denervation (CSD) in patients with IST. METHODS: Twelve consecutive patients who had drug-refractory IST (10 women) were studied. According to a prospectively initiated protocol, five patients underwent an electrophysiologic study before and after SG block (electrophysiology study group). The subsequent seven patients had ambulatory Holter monitoring before and after SG block (ambulatory group). All patients underwent SG block on the right side first, and then on the left side. Selected patients who had heart rate reduction ≥15 beats per minute (bpm) were recommended to consider CSD. RESULTS: The mean (SD) baseline heart rate (HR) was 106 (21) bpm. The HR significantly decreased to 93 (20) bpm (P = .02) at 10 minutes after right SG block and remained significantly slower at 97(19) bpm at 60 minutes. Left SG block reduced HR from 99 (21) to 87(16) bpm (P = .02) at 60 minutes. SG block had no significant effect on blood pressure or HR response to isoproterenol or exercise (all P > .05). Five patients underwent right (n = 4) or bilateral (n = 1) CSD. The clinical outcomes were heterogeneous: one patient had complete and two had partial symptomatic relief, and two did not have improvement. CONCLUSION: SG blockade modestly reduces resting HR but has no significant effect on HR during exercise. Permanent CSD may have a modest role in alleviating symptoms in selected patients with IST.

Mortality and Cerebrovascular Events After Heart Rhythm Disorder Management Procedures.

BACKGROUND: Recognition of rates and causes of hard, patient-centered outcomes of death and cerebrovascular events (CVEs) after heart rhythm disorder management (HRDM) procedures is an essential step for the development of quality improvement programs in electrophysiology laboratories. Our primary aim was to assess and characterize death and CVEs (stroke or transient ischemic attack) after HRDM procedures over a 17-year period. METHODS: We performed a retrospective cohort study of all patients undergoing HRDM procedures between January 2000 and November 2016 at the Mayo Clinic. Patients from all 3 tertiary academic centers (Rochester, Phoenix, and Jacksonville) were included in the study. All in-hospital deaths and CVEs after HRDM procedures were identified and were further characterized as directly or indirectly related to the HRDM procedure. Subgroup analysis of death and CVE rates was performed for ablation, device implantation, electrophysiology study, lead extraction, and defibrillation threshold testing procedures. RESULTS: A total of 48 913 patients (age, 65.7±6.6 years; 64% male) who underwent a total of 62 065 HRDM procedures were included in the study. The overall mortality and CVE rates in the cohort were 0.36% (95% confidence interval [CI], 0.31-0.42) and 0.12% (95% CI, 0.09-0.16), respectively. Patients undergoing lead extraction had the highest overall mortality rate at 1.9% (95% CI, 1.34-2.61) and CVE rate at 0.62% (95% CI, 0.32-1.07). Among patients undergoing HRDM procedures, 48% of deaths directly related to the HDRM procedure were among patients undergoing device implantation procedures. Overall, cardiac tamponade was the most frequent direct cause of death (40%), and infection was the most common indirect cause of death (29%). The overall 30-day mortality rate was 0.76%, with the highest being in lead extraction procedures (3.08%), followed by device implantation procedures (0.94%). CONCLUSIONS: Half of the deaths directly related to an HRDM procedure were among the patients undergoing device implantation procedures, with cardiac tamponade being the most common cause of death. This highlights the importance of the development of protocols for the quick identification and management of cardiac tamponade even in procedures typically believed to be lower risk such as device implantation.

Effect of Ventricular Arrhythmia Ablation in Patients With Heart Mate II Left Ventricular Assist Devices: An Evaluation of Ablation Therapy.

BACKGROUND: Patients with advanced heart failure (HF) are predisposed to ventricular arrhythmias (VAs), particularly following implantation of a left ventricular assist device (LVAD). There is minimal evidence for appropriate management strategies. OBJECTIVES: This study aimed to compare the burden of VA and response to ablation performed either before or following LVAD implantation. METHODS: We created a retrospective cohort of patients who underwent both VA ablation and Heart Mate II (Thoratec, Pleasanton, CA, USA) LVAD implantation at Mayo Clinic (Rochester, MN, USA). Patients were stratified based on whether they underwent VA ablation before (pre-LVAD) or after LVAD (post-LVAD) implantation. Descriptive analyses assessed 6-month arrhythmia burden in relation to LVAD implantation and VA ablation. RESULTS: A total of 9 patients underwent both LVAD implantation and VA ablation. There were 3 and 6 patients, respectively, in the pre-LVAD and post-LVAD cohorts. Among patients in the pre-LVAD cohort, the median number of VAs tended to increase after ablation (9 vs. 72) and decreased after LVAD implantation (72 vs. 63). Similarly among patients in the post-LVAD cohort, the median burden of VAs increased after LVAD implantation (1 vs. 22) and the median burden decreased after ablation (22 vs. 13). Two of 6 patients had substrate related to the LVAD inflow cannula site, while other substrate was not related directly to the cannula. CONCLUSIONS: In patients with progressive HF and LVAD implantation, ablation is associated with reduced VA rates. In LVAD patients, most VAs arise from substrate unrelated to the inflow cannula site.

Prolonged Ventricular Conduction and Repolarization During Right Ventricular Stimulation Predicts Ventricular Arrhythmias and Death in Patients With Cardiomyopathy.

OBJECTIVES: The goal of this study was to evaluate whether prolonged ventricular conduction (paced QRS) and repolarization (paced QTc) times observed during ventricular stimulation predict ventricular arrhythmic events and death. BACKGROUND: Abnormal ventricular conduction and repolarization can predispose patients to ventricular arrhythmias. METHODS: Consecutive patients with left ventricular dysfunction (ejection fraction <50%) undergoing electrophysiology studies from January 2002 until May 2014 were identified at Mayo Clinic (Rochester, Minnesota). Patients were followed up until December 2014 for occurrence of ventricular arrhythmias and death. RESULTS: Among the 501 patients included (mean age 65 years; mean left ventricular ejection fraction 33.1%), longer paced ventricular conduction was associated with longer baseline QRS duration, longer QT interval, and lower ejection fraction. On multivariable analysis, longer paced QRS duration was associated with higher risk of ventricular arrhythmia (hazard ratio [HR]: 1.11 per 10-ms increase; 95% confidence interval [CI]: 1.07 to 1.16; p < 0.001) and all-cause death or arrhythmia (HR: 1.09; 95% CI: 1.09 to 1.13; p < 0.001). A paced QRS duration >190 ms was associated with a 3.6 times higher risk of ventricular arrhythmia (HR: 3.6; 95% CI: 2.35 to 5.53; p < 0.001) and a 2.1 times higher risk of death or arrhythmia (HR: 2.12; 95% CI: 1.53 to 2.95; p < 0.001), independent of left ventricular function or baseline QRS duration. Longer QTc interval during ventricular pacing was associated with a higher risk of ventricular arrhythmia (HR: 1.03 per 10-ms increase; 95% CI: 1.02 to 1.12; p < 0.001) independent of paced QRS duration. CONCLUSIONS: Longer paced QRS duration and paced QTc interval predict ventricular arrhythmias in patients with cardiomyopathy. Ventricular conduction and repolarization prolongation during right ventricular pacing can determine the risk of ventricular arrhythmias.

Blood Pressure Responses to Endovascular Stimulation: A Potential Therapy for Autonomic Disorders With Vasodilatation.

BACKGROUND: We have previously shown that sympathetic ganglia stimulation via the renal vein rapidly increases blood pressure. This study further investigated the optimal target sites and effective energy levels for stimulation of the renal vasculatures and nearby sympathetic ganglia for rapid increase in blood pressure. METHODS: The pre-study protocol for endovascular stimulations included 2 minutes of stimulation (1-150 V and 10 pulses per second) and at least 2 minutes of rest during poststimulation. If blood pressure and/or heart rate were changed during the stimulation, time to return to baseline was allowed prior to the next stimulation. RESULTS: In 11 acute canine studies, we performed 85 renal artery, 30 renal vein, and 8 hepatic vasculature stimulations. The mean arterial pressure (MAP) rapidly increased during stimulation of renal artery (95 ± 18 mmHg vs. 103 ± 15 mmHg; P < 0.0001), renal vein (90 ± 16 mmHg vs. 102 ± 20 mmHg; P = 0.001), and hepatic vasculatures (74 ± 8 mmHg vs. 82 ± 11 mmHg; P = 0.04). Predictors of a significant increase in MAP were energy >10 V focused on the left renal artery, bilateral renal arteries, and bilateral renal veins (especially the mid segment). Overall, heart rate was unchanged, but muscle fasciculation was observed in 22.0% with an output >10 V (range 15-150 V). Analysis after excluding the stimulations that resulted in fasciculation yielded similar results to the main findings. CONCLUSIONS: Stimulation of intra-abdominal vasculatures promptly increased the MAP and thus may be a potential treatment option for hypotension in autonomic disorders. Predictors of optimal stimulation include energy delivery and the site of stimulation (for the renal vasculatures), which informs the design of subsequent research.

Electrophysiologic characteristics of ventricular arrhythmias arising from the aortic mitral continuity-potential role of the conduction system.

INTRODUCTION: Catheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown. METHODS: Procedural records of 528 consecutive patients undergoing ablation of VA at Mayo Clinic, Rochester, MN, were reviewed. The electrocardiographic and electrophysiologic characteristics of patients with successful ablation at the AMC were analyzed to characterize the underlying arrhythmogenic substrate. RESULTS: Of the 21 patients (mean age 53.2 ± 13.4 years, 47.6% male) who underwent ablation of VA at the AMC with acute success, prepotentials (PPs) were found at the ablation sites preceding the ventricular electrogram (VEGM) during arrhythmias in 13 (61.9%) patients and during sinus rhythm in 7 (53.8%) patients. VAs with PPs were associated with a significantly higher burden of premature ventricular complexes (PVCs; 26.1 ± 10.9% vs. 14.9 ± 10.1%, P = 0.03), shorter VEGM to QRS intervals (9.0 ± 28.5 milliseconds vs. 33.1 ± 8.8 milliseconds, P = 0.03), lower pace map scores (8.7 ± 1.6 vs. 11.4 ± 0.8, P = 0.001), and a trend toward shorter V-H intervals during VA (32.1 ± 38.6 milliseconds vs. 76.3 ± 11.1 milliseconds, P = 0.06) as compared to those without PP. A strong and positive correlation was found between V-H interval and QRS duration during arrhythmia in those with PPs (B = 2.11, R(2) = 0.97, t = 13.7, P < 0.001) but not in those without PPs. CONCLUSION: Local EGM characteristics and relative activation time of the His bundle suggest the possibility of conduction tissue as the origin for VA arising from the fibrous AMC. Specific identification and targeting of PPs when ablating VAs at this location may improve procedural success.

Performance of an automatic arrhythmia classification algorithm: comparison to the ALTITUDE electrophysiologist panel adjudications.

INTRODUCTION: Adjudication of thousands of implantable cardioverter defibrillator (ICD)-treated arrhythmia episodes is labor intensive and, as a result, is most often left undone. The objective of this study was to evaluate an automatic classification algorithm for adjudication of ICD-treated arrhythmia episodes. METHODS: The algorithm uses a machine learning algorithm and was developed using 776 arrhythmia episodes. The algorithm was validated on 131 dual-chamber ICD shock episodes from 127 patients adjudicated by seven electrophysiologists (EPs). Episodes were classified by panel consensus as ventricular tachycardia/ventricular fibrillation (VT/VF) or non-VT/VF, with the resulting classifications used as the reference. Subsequently, each episode electrogram (EGM) data was randomly assigned to three EPs without the atrial lead information, and to three EPs with the atrial lead information. Those episodes were also classified by the automatic algorithm with and without atrial information. Agreement with the reference was compared between the three EPs consensus group and the algorithm. RESULTS: The overall agreement with the reference was similar between three-EP consensus and the algorithm for both with atrial EGM (94% vs 95%, P = 0.87) and without atrial EGM (90% vs 91%, P = 0.91). The odds of accurate adjudication, after adjusting for covariates, did not significantly differ between the algorithm and EP consensus (odds ratio 1.02, 95% confidence interval: 0.97-1.06). CONCLUSIONS: This algorithm performs at a level comparable to an EP panel in the adjudication of arrhythmia episodes treated by both dual- and single-chamber ICDs. This type of algorithm has the potential for automated analysis of clinical ICD episodes, and adjudication of EGMs for research studies and quality analyses.

Electrophysiological and hemodynamic characteristics associated with obesity in patients with atrial fibrillation.

OBJECTIVES: The authors sought to characterize the left atrial (LA) and pulmonary vein (PV) electrophysiological and hemodynamic features in obese patients with atrial fibrillation (AF). BACKGROUND: Obesity is associated with increased risk for AF. METHODS: A total of 63 consecutive patients with AF who had normal left ventricular (LV) ejection fraction and who underwent catheter ablation were studied. Atrial and PV electrophysiological studies were performed at the time of ablation with hemodynamic assessment by cardiac catheterization, and LA/LV structure and function by echocardiography. Patients were compared on the basis of body mass index (BMI): <25 kg/m(2) (n = 19) and BMI ≥30 kg/m(2) (n = 44). RESULTS: At a 600-ms pacing cycle length, obese patients had shorter effective refractory period (ERP) in the left atrium (251 ± 25 ms vs. 233 ± 32 ms, p = 0.04), and in the proximal (207 ± 33 ms vs. 248 ± 34 ms, p < 0.001) and distal (193 ± 33 ms vs. 248 ± 44 ms, p < 0.001) PV than normal BMI patients. Obese patients had higher mean LA pressure (15 ± 5 mm Hg vs. 10 ± 5 mm Hg, p < 0.001) and LA volume index (28 ± 12 ml/m(2) vs. 21 ± 14 ml/m(2), p = 0.006), and lower LA strain (5.5 ± 3.1% vs. 8.8 ± 2.8%; p < 0.001) than normal BMI patients. CONCLUSIONS: Increased LA pressure and volume, and shortened ERP in the left atrium and PV are potential factors facilitating and perpetuating AF in obese patients with AF.

Implantable cardioverter defibrillator electrogram adjudication for device registries: methodology and observations from ALTITUDE.

BACKGROUND: The increasing use of remote monitoring with the associated large retrievable databases provides a unique opportunity to analyze observations on implantable cardioverter-defibrillator (ICD) therapies. Adjudication of a large number of stored ICD electrograms (EGMs) presents a unique challenge. The ALTITUDE study group was designed to use the LATITUDE remote monitoring system to evaluate ICD patient outcomes across the United States. METHODS AND RESULTS: Of 81,081 patients on remote monitoring, a random sample of 2,000 patients having 5,279 shock episodes was selected. The ALTITUDE EGM review committee was comprised of seven electrophysiologists from four institutions. An online EGM adjudication system was designed. Episodes were classified as appropriate (70% of shock episodes) or inappropriate ICD therapies (30%). Light's Kappa was used to assess agreement. Interobserver and intraobserver Kappa scores for dual-chamber ICDs were 0.84 (0.71-0.91) and 0.89 (0.82-0.95), consistent with substantial agreement. Interobserver and intraobserver Kappa scores for single-chamber ICDs were 0.61 (0.54-0.67) and 0.69 (0.59-0.79). The rhythm categories of "nonsustained arrhythmia" and "polymorphic and monomorphic ventricular tachycardia" resulted in the greatest degree of discordant adjudication between reviewers. CONCLUSIONS: This method of adjudication of a large volume of stored EGM data prior to device therapies will allow new observations in regards to device performance and has the potential to improve device programming and design. There was substantial interreviewer agreement for rhythm classification. Agreement was greater for dual-chamber compared to single-chamber devices, indicating the atrial lead adds diagnostic value in rhythm interpretation.

Effect of ablation of complex fractionated atrial electrogram on vagal modulation in dogs.

BACKGROUND: Clinical observations have shown that the complex fractionated atrial electrogram (CFAE) associates with ganglionated plexus activity in the cardiac autonomic nervous system. This study aimed to investigate the impact of CFAE ablation on vagal modulation to atria and vulnerability to develop atrial fibrillation (AF). METHODS: Ten adult mongrel dogs were involved. Cervical sympathovagal trunks were decentralized and sympathetic effects were blocked. CFAE was color tagged on the atrial 3-dimensional image and ablated during AF induced by S1S2 programmed stimulation plus sympathovagal trunk stimulation. Atrial effective refractory period (ERP) and vulnerability window (VW) of AF were measured on baseline and at vagal stimulation at 4 atrium sites. Serial tissue sections from ablative and control specimens received hematoxylin and eosin staining for microscopic examination. RESULTS: Most CFAE areas were localized at the right superior pulmonary quadrant, distal coronary sinus (CS(d)) quadrant, and proximal coronary sinus (CS(p)) quadrant (21.74%, separately). Sinus rhythm cycle length (SCL) shortening did not decrease significantly after ablation at the sites, including right atrial appendage, left atrial appendage, CS(d), and CS(p) (P > 0.05). ERP shortening during vagal stimulation significantly decreased after ablation (P < 0.01); the VW to vagal stimulation significantly decreased after ablation (P < 0.05). The architecture of individual ganglia altered after ablation. CONCLUSIONS: CFAE has an autonomic basis in dogs. The decreased SCL and ERP shortening to vagal stimulation after CFAE ablation demonstrate that CFAE ablation attenuates vagal modulation to the atria, thereby suppressing AF mediated by enhanced vagal activity. CFAE ablation could suppress AF mediated by enhanced vagal activity.

Pneumopericardium following radiofrequency ablation for atrial fibrillation: insights into the natural history of atrial esophageal fistula formation.

We present a case of large pneumopericardium resulting from an esophageal pericardial fistula following ablation for atrial fibrillation (AF). The presentation, evaluation, and management of this specific patient, along with a review of present techniques to diagnose esophageal injury, provide a unique insight into the pathophysiology of left atrial-esophageal fistula formation.

Atrioventricular nodal ablation predicts survival benefit in patients with atrial fibrillation receiving cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) benefits patients with advanced heart failure. The role of atrioventricular nodal (AVN) ablation in improving CRT outcomes, including survival benefit in CRT recipients with atrial fibrillation, is uncertain. OBJECTIVE: The purpose of this study was to assess the impact of AVN ablation on clinical and survival outcomes in a large atrial fibrillation and heart failure population that met the current indication for CRT and to determine whether AVN ablation is an independent predictor of survival in CRT recipients. METHODS: Of 154 patients with atrial fibrillation who received CRT-D, 45 (29%) underwent AVN ablation (+AVN-ABL group), whereas 109 (71%) received drug therapy for rate control during CRT (-AVN-ABL group). New York Heart Association (NYHA) class, electrocardiogram, and echocardiogram were assessed before and after CRT. Survival data were obtained from the national death and location database (Accurint). RESULTS: CRT comparably improved left ventricular ejection fraction (8.1% +/- 10.7% vs 6.8% +/- 9.6%, P = .49) and left ventricular end-diastolic diameter (-2.1 +/- 5.9 mm vs -2.1 +/- 6.7 mm, P = .74) in both +AVN-ABL and -AVN-ABL groups. Improvement in NYHA class was significantly greater in the +AVN-ABL group than in -AVN-ABL group (-0.7 +/- 0.8 vs -0.4 +/- 0.8, P = .04). Survival estimates at 2 years were 96.0% (95% confidence interval [CI] 88.6%-100%) for +AVN-ABL group and 76.5% (95% CI 68.1%-85.8%) for-AVN-ABL group (P = .008). AVN ablation was independently associated with survival benefit from death (hazard ratio [HR] 0.13, 95% CI 0.03-0.58, P = .007) and from combined death, heart transplant, and left ventricular assist device (HR 0.19, 95% CI 0.06-0.62, P = .006) after CRT. CONCLUSION: Among patients with atrial fibrillation and heart failure receiving CRT, AVN ablation for definitive biventricular pacing provides greater improvement in NYHA class and survival benefit. Larger-scale randomized trials are needed to assess the clinical and survival outcomes of this therapy.

Use of an autologous blood recovery system during emergency pericardiocentesis in the electrophysiology laboratory.

INTRODUCTION: Emergency pericardiocentesis during electrophysiology procedures is often associated with significant aspiration of pericardial blood, requiring transfusion. We sought to assess the feasibility of urgent use of an autologous blood recovery system in the electrophysiology laboratory to autotransfuse blood aspirated from the pericardium. METHODS AND RESULTS: We retrospectively analyzed Mayo Clinic electrophysiology records for patients who had ablation procedure-related pericardial effusions requiring emergency pericardial drainage during an 8-month period. An autologous blood recovery system was used during pericardiocentesis to separate and clean packed red blood cells from the pericardial aspirate. These cells were returned acutely to the patient intravenously. The procedural safety, aspirated and autotransfused volumes, and efficacy of this approach were evaluated. During the study period, nine patients underwent pericardial drainage with autotransfusion using a cell-salvage instrument during electrophysiology procedures. The mean aspirated volume was 1,078 mL, with a mean autotransfused volume of 390 mL. For four patients, all with aspirated volumes of 1,100 mL or less, autotransfusion alone was sufficient to maintain hemodynamic stability and avoid allogeneic transfusion. One patient required surgical intervention because of ongoing pericardial bleeding. The ablation procedure was completed after aspiration in two patients. No procedural complications related to the use of the cell-salvage system occurred. CONCLUSION: Autologous blood recovery during pericardiocentesis is safe, convenient, and feasible. With early use it may decrease or eliminate the need for allogeneic blood transfusion and, in selected cases, may permit completion of the ablation procedure.

Utilization of retrograde right bundle branch block to differentiate atrioventricular nodal from accessory pathway conduction.

INTRODUCTION: Defining whether retrograde ventriculoatrial (V-A) conduction is via the AV node (AVN) or an accessory pathway (AP) is important during ablation procedures for supraventricular tachycardia (SVT). With the introduction of ventricular extrastimuli (VEST), retrograde right bundle branch block (RBBB) may occur, prolonging the V-H interval, but only when AV node conduction is present. We hypothesized that when AP conduction was present, the V-A interval would increase less than the V-H interval, whereas with retrograde nodal conduction, the V-A interval would increase at least as much as the V-H interval. METHODS AND RESULTS: We retrospectively reviewed the electrophysiological studies of patients undergoing ablation for AVN reentrant tachycardia (AVNRT) (55) or AVRT (50), for induction of retrograde RBBB during the introduction of VEST, and the change in the measured V-H and V-A intervals. Results were found to be reproducible between independent observers. Out of 105 patients, 84 had evidence of induced retrograde RBBB. The average V-H interval increase with induction of RBBB was 53.7 ms for patients with AVRT and 54.4 ms for patients with AVNRT (P = NS). The average V-A interval increase with induction of RBBB was 13.6 ms with AVRT and 70.1 ms with AVNRT (P < 0.001). All patients with a greater V-H than V-A interval change had AVRT, and those with a smaller had AVNRT. CONCLUSIONS: Induction of retrograde RBBB during VEST is common during an electrophysiological study for SVT. The relative change in the intervals during induction of RBBB accurately differentiates between retrograde AVN and AP conduction.

Mechanisms and utility of discrete great arterial potentials in the ablation of outflow tract ventricular arrhythmias.

BACKGROUND: Outflow tract ventricular tachycardia originating above the semilunar valves has been reported in a small number of studies. Discrete potentials in the great arteries (above the semilunar valves) have been rarely described in patients undergoing electrophysiology evaluation and radiofrequency ablation for ventricular arrhythmias. The mechanisms of these discrete potentials in the great arteries and the utility of such potentials in guiding radiofrequency ablation are unknown. METHODS AND RESULTS: Twelve patients with outflow tract ventricular arrhythmia originating above the semilunar valves with discrete arterial potentials were studied. The clinical characteristics, properties of the arterial potentials, electrophysiological evaluation and ablation, and short- and long-term outcomes were reviewed. Of the twelve patients, 8 (67%) were women. The patients' average age was 41+/-14 years. The average ejection fraction was 0.52+/-0.16 (range: 0.16 to 0.75). Contact mapping in the great artery demonstrated discrete near-field electrograms that were separate from far-field ventricular electrograms in all patients (8 above the pulmonary valve and in 4 the aortic valve). One or more of the following electrophysiological characteristics, supportive of an arrhythmogenic substrate, were observed in 10 of 12 patients: (1) A fixed or reproducibly variable pattern of discrete potential-ventricular arrhythmia relationship was present at baseline or during pacing; (2) the discrete potential-ventricular electrogram relationship during sinus rhythm was the reverse of that during the ventricular arrhythmia; (3) during sustained ventricular tachycardia, spontaneous variation of the ventricular (V-V) cycle length was preceded by a similar variation of arterial spike potential-spike potential cycle length; and (4) ablation guided by the discrete arterial potential successfully eliminated the clinical arrhythmia. Ablation was successful in these patients. In the remaining 2 patients, the potentials were believed to be bystanders. Over 10+/-4 months (range: 5 to 32 months) of follow-up, there have been no recurrences of the premature ventricular complex or ventricular arrhythmia. CONCLUSIONS: Discrete potentials are present in the great arteries of a select group of patients with outflow tract ventricular tachycardia originating above the semilunar valves. When an arrhythmogenic relationship can be demonstrated, discrete potentials are useful in guiding ablation within the great vessels, despite significant anatomic complexity.

Bioenergetic protection of failing atrial and ventricular myocardium by vasopeptidase inhibitor omapatrilat.

Deficient bioenergetic signaling contributes to myocardial dysfunction and electrical instability in both atrial and ventricular cardiac chambers. Yet, approaches capable to prevent metabolic distress are only partially established. Here, in a canine model of tachycardia-induced congestive heart failure, we compared atrial and ventricular bioenergetics and tested the efficacy of metabolic rescue with the vasopeptidase inhibitor omapatrilat. Despite intrinsic differences in energy metabolism, failing atria and ventricles demonstrated profound bioenergetic deficiency with reduced ATP and creatine phosphate levels and compromised adenylate kinase and creatine kinase catalysis. Depressed phosphotransfer enzyme activities correlated with reduced tissue ATP levels, whereas creatine phosphate inversely related with atrial and ventricular load. Chronic treatment with omapatrilat maintained myocardial ATP, the high-energy currency, and protected adenylate and creatine kinase phosphotransfer capacity. Omapatrilat-induced bioenergetic protection was associated with maintained atrial and ventricular structural integrity, albeit without full recovery of the creatine phosphate pool. Thus therapy with omapatrilat demonstrates the benefit in protecting phosphotransfer enzyme activities and in preventing impairment of atrial and ventricular bioenergetics in heart failure.