Chapter 63: Ventricular tachycardia and ventricular fibrillation

ISBN: 978097901648

Zero-Fluoroscopy Cavotricuspid Isthmus Ablation Using Carto Mapping System as Sole Guiding Method

Background: Catheter ablation of the cavotricuspid isthmus (CTI) is traditionally performed using fluoroscopy and electroanatomical mapping systems. Zero-fluoroscopy approaches have recently been studied, mostly using the EnSite® mapping system (St. Jude Medical Inc., St. Paul, MN). We studied the feasibility and efficacy of zero-fluoroscopic mapping and ablation of the CTI using the Carto® 3 system (Biosense Webster Inc., South Diamond Bar, CA). Purpose: To evaluate the efficacy and safety of a zero-fluoroscopic approach to CTI ablation. Methods: We included 9 patients with typical atrial flutter for whom mapping and ablation of the CTI was done using Carto mapping as the sole guiding modality. Zero fluoroscopy was achieved in all of them. Another group of 9 matched patients whose ablations were done using the traditional method (i.e. fluoroscopy and Carto guidance) were included as a control. Results: Both groups had similar baseline characteristics. The total fluoroscopy time and radiation dose in the control group were 12.8 ± 4.8 minutes, 230.2 ± 131.9 mGy, respectively. The zero-fluoroscopy group were done while wearing no lead aprons. The average total procedure time was 114.8 ± 16.9 minutes in the zero-fluoroscopy group, significantly less than that of the control group (138.6 ± 24.3 minutes; P = 0.0286). The total radiofrequency time was similar in both groups (15.2 ± 7.4 minutes in zero-fluoroscopy group vs 16 ± 2.9 minutes in control group; P = 0.9294). Bidirectional block was achieved in all patients of both groups. No complications were encountered in either group. Conclusion: To our knowledge, this is the first study of a zero-fluoroscopic approach using the Carto mapping system for ablation of the cavotricuspid isthmus in the United States. The approach is feasible and effective in achieving bidirectional block with less average total procedure time

Three-dimensional electroanatomic mapping of the coronary veins during cardiac resynchronization therapy implant: feasibility and possible applications

PURPOSE: Left ventricular (LV) electrical activation pattern could determine optimal LV lead placement site during cardiac resynchronization therapy (CRT) device implant. We sought to determine the feasibility of using EnSite NavX™ electroanatomic mapping system (St. Jude Medical Inc., St. Paul, MN) to assess LV electrical activation during CRT implant. METHODS: Patients (n = 32; NYHA III, LVEF%, QRSd \u3e120 ms) underwent NavX™ mapping during CRT implant. Left bundle branch block (LBBB) was present during sinus rhythm in group A (n = 17), whereas LBBB was induced by permanent RV apical pacing in group B (n = 15). Following coronary sinus (CS) cannulation, a coil tip 0.014-in. guidewire was introduced into all available CS branches as a mapping electrode. Each patient\u27s unipolar activation map was successfully constructed within 10 min, using the onset of surface QRS as reference. RESULTS: LV activation patterns were complex and varied in both groups. Earliest activation was usually apical, but latest activation was more heterogenous. The lateral or posterolateral branches were the sites of latest activation in 47 % of group A and 73 % of group B. An LV lead positioned conventionally by a physician blinded to the mapping data was concordant with the latest activated segment in 18 % of group A and none of group B patients. CONCLUSIONS: Electroanatomic mapping of the CS tributaries is feasible and clinically practicable. Mapping revealed heterogenous conduction patterns that vary between patients in each group and between groups. An LV lead empirically placed in a lateral branch rarely paces the optimal, latest activated vein segment

Clinical feasibility of exercise-based A-V interval optimization for cardiac resynchronization: a pilot study

BACKGROUND: One-third of eligible patients fail to respond to cardiac resynchronization therapy (CRT). Current methods to optimize the atrio-ventricular (A-V) interval are performed at rest, which may limit its efficacy during daily activities. We hypothesized that low-intensity cardiopulmonary exercise testing (CPX) could identify the most favorable physiologic combination of specific gas exchange parameters reflecting pulmonary blood flow or cardiac output, stroke volume, and left atrial pressure to guide determination of the optimal A-V interval. METHODS: We assessed relative feasibility of determining the optimal A-V interval by three methods in 17 patients who underwent optimization of CRT: (1) resting echocardiographic optimization (the Ritter method), (2) resting electrical optimization (intrinsic A-V interval and QRS duration), and (3) during low-intensity, steady-state CPX. Five sequential, incremental A-V intervals were programmed in each method. Assessment of cardiopulmonary stability and potential influence on the CPX-based method were assessed. RESULTS: CPX and determination of a physiological optimal A-V interval was successfully completed in 94.1% of patients, slightly higher than the resting echo-based approach (88.2%). There was a wide variation in the optimal A-V delay determined by each method. There was no observed cardiopulmonary instability or impact of the implant procedure that affected determination of the CPX-based optimized A-V interval. CONCLUSIONS: Determining optimized A-V intervals by CPX is feasible. Proposed mechanisms explaining this finding and long-term impact require further study

Cardiac resynchronization therapy in patients with challenging anatomy due to venous anomalies or adult congenital heart disease

BACKGROUND: Cardiac resynchronization therapy (CRT) has proven salutary effects in patients with congestive heart failure, systolic dysfunction, and electromechanical dyssynchrony in the setting of ischemic, nonischemic, and congenital cardiomyopathy. While CRT device implants have become routine in the adult ischemic or nonischemic cardiomyopathy populations, patients with congenital heart disease offer special challenges due to unusual anatomic variations. METHODS: A comprehensive assessment of anatomic abnormalities is essential prior to implant. In addition, implant techniques and equipment must be tailored to the expected anatomy. A flexible approach is necessary-implant may require equipment and techniques adapted from vascular intervention. CONCLUSION: This article describes our approach to CRT implant in patients with congenital heart disease, and is illustrated by reports of several cases

Implantable cardioverter defibrillators in diabetics: efficacy and safety in patients at risk of sudden cardiac death

Diabetes mellitus is a major risk factor for arrhythmogenesis and is associated with a two-fold increase in all-cause mortality and a four-fold increase in cardiovascular mortality including sudden cardiac death when compared with nondiabetics. Implantable cardioverter defibrillators (ICD) have been shown to effectively reduce arrhythmic death and all-cause mortality in patients with severe myocardial dysfunction. With a high competing risk of nonarrhythmic cardiac and noncardiac death, survival benefit of ICD in patients with diabetes mellitus could be reduced, but the subanalysis of diabetic patients in randomized clinical trials provides reassurance regarding a similar beneficial survival effect of ICD and cardiac resynchronization therapy in diabetics, as observed in the overall population with advanced heart disease. In this article, the authors highlight some of the clinical issues related to diabetes, summarize the data on the efficacy of ICD in diabetics when compared with nondiabetics and discuss concerns related to ICD implantation in patients with diabetes

C-PO04-116: Atrial fibrillation as a surrogate marker for mortality and hospital readmission post typical atrial flutter ablation

BACKGROUND: There is strong evidence to suggest an association between typical cavotricuspid isthmus (CTI) dependent atrial flutter (AFL) and atrial fibrillation (AF). The long-term morbidity and mortality of typical AFL ablation has been well defined; however, the effect of AF on morbidity and mortality post typical AFL ablation has not been described. We predict AF will be associated with a less favorable long-term morbidity and mortality after CTI ablation for typical AFL.OBJECTIVE: Retrospective observational cohort study to compare the outcomes of typical AFL ablation in patients with and without a history of AF.METHODS:Five hundred and forty-seven patients who underwent (CTI) ablation without pulmonary vein isolation between November 2011 and December 2015 were included in the study and followed for a mean of 30.1 months. Twelve-lead ECG, Holter monitor, event monitor, and device interrogations were reviewed to accurately confirm rhythms. Comparison testing was conducted to determine outcome differences between patients with and without pre-existing AF.RESULTS: Among the 547 patients there were 256 patients with a history of AF prior to CTI ablation (group hxAF) and 291 patients without a history of AF prior to CTI ablation (group NohxAF). The mean age was 65.3±10.3 years old in hxAF and 64.5±12.2 years old in NohxAF (p=0.389). All other demographics of both groups were the same except the hxAF group had fewer males (65.2% vs. 77.7%, p=0.001) and more Caucasians (88.7% vs. 82.1, p=0.04). Both groups had similar echocardiogram findings (LVEF, left atrial volume index, mitral valve, aortic valve, and pulmonary artery systolic pressure). As expected, recurrence of AF at 12 months was significantly increased in the hxAF group (69.9% vs. 21.6%, p\u3c0.001). In addition, the use of anticoagulation, antiarrhythmics and beta blockers at 12 months was higher in the hxAF group (43% vs. 20.6%, 32.8% vs. 10.3%, and 51.6% vs. 40.5%, respectively, with p\u3c0.01). One-year all-cause mortality was higher in group hxAF (5.1% vs. 1.4%, p=0.013). The 1-year readmission rate for any cause also was higher in the hxAF group (57.0% vs. 45.0%, p=0.005). CONCLUSIONS: AF increases the all-cause mortality and hospital readmission at 12 months post typical AFL ablation