Carlos Macias

Relationship Between Sinus Rhythm Late Activation Zones and Critical Sites for Scar-Related Ventricular Tachycardia Systematic Analysis of Isochronal Late Activation Mapping

Background—It is not known whether the most delayed late potentials are functionally most specific for scar-related ventricular tachycardia (VT) circuits. Methods and Results—Isochronal late activation maps were constructed to display ventricular activation during sinus rhythm over 8 isochrones. Analysis was performed at successful VT termination sites and prospectively tested. Thirty-three patients with 47 scar-related VTs where a critical site was demonstrated by termination of VT during ablation were retrospectively analyzed. In those who underwent mapping of multiple surfaces, 90% of critical sites were on the surface that contained the latest late potential. However, only 11% of critical sites were localized to the latest isochrone (87.5%–100%) of ventricular activation. The median percentage of latest activation at critical sites was 78% at a distance from the latest isochrone of 18 mm. Sites critical to reentry were harbored in regions with slow conduction velocity, where 3 isochrones were present within a 1-cm radius. Ten consecutive patients underwent ablation prospectively guided by isochronal late activation maps, targeting concentric isochrones outside of the latest isochrone. Elimination of the targeted VT was achieved in 90%. Termination of VT was achieved in 6 patients at a mean ventricular activation percentage of 78%, with only 1 requiring ablation in the latest isochrone. Conclusions—Late potentials identified in the latest isochrone of activation during sinus rhythm are infrequently correlated with successful ablation sites for VT. The targeting of slow conduction regions propagating into the latest zone of activation may be a novel and promising strategy for substrate modification.

Percutaneous interventricular septal access in a patient with aortic and mitral mechanical valves: A novel technique for catheter ablation of ventricular tachycardia

Catheter ablation of ventricular tachycardia (VT) is typically performed using either the atrial transseptal approach or a retrograde aortic approach in order to gain access to the left ventricle (LV). However, neither approach is feasible in the setting of mechanical aortic and mitral valve replacements, given the risk of catheter entrapment and death.1, 2 Therefore, approaches that avoid traversing these valves, such as a percutaneous trans-apical approach, have been developed.3-6 However, the trans-apical approach is associated with a significant rate of access related complications, particularly bleeding at the puncture site, and necessitates the placement of closure devices in the LV.7, 8 We describe a novel percutaneous inter-ventricular transseptal puncture technique and placement of a sheath across the inter-ventricular septum for catheter ablation of VT. This method allowed for stable LV access and spontaneous closure of the septal access site.

Catheter ablation of scar-based ventricular tachycardia: Relationship of procedure duration to outcomes and hospital mortality

BACKGROUND Ablation has become an important option for treatment of ventricular tachycardia (VT). The influence of procedure duration on outcomes remains unexamined. OBJECTIVE The purpose of this study was to determine the influence of procedure duration on outcomes and complications over an 8-year period METHODS Patients referred for scar-mediated VT ablation from 2004 to 2011 were retrospectively analyzed. Procedure duration was defined as the time from the insertion of catheters through the femoral vein to the time of their withdrawal. Procedure duration was analyzed in relationship with baseline and intraoperative covariates, acute procedural outcomes, complications, and 6-month clinical outcomes. RESULTS One hundred forty-eight patients underwent VT ablation with mean procedure duration of 5.7 ± 1.8 hours. VT recurrence and survival at 6 months were 46% and 82%, respectively, and were not associated with procedure duration. Hospital mortality increased with intraoperative intraaortic balloon pump insertion (adjusted odds ratio [OR] 13.7, 95% confidence interval [CI] 2.35-79.94, P = .004) and was improved with successful ablation of the clinical VT as a procedural end-point (adjusted OR 0.13, 95% Cl 0.03-0.54, P = .005). The association between procedure duration and hospital mortality remained after adjusting for significant baseline variables (adjusted OR 1.75, 95% CI 1.14-2.68, P = .0098) and intraoperative variables (adjusted OR 1.6, 95% CI 1.12-2.29, P = .0104). CONCLUSION Hospital mortality was significantly increased by unsuccessful clinical VT ablation as a procedural end-point and intraoperative intraaortic balloon pump insertion. However, after adjusting for significant baseline and intraoperative covariates, procedure duration still was associated with increased hospital mortality. Procedure duration had no impact on VT recurrence and survival at 6 months.

Limitations of 12-lead ECG wide complex tachycardia algorithms in a patient with left atrial flutter and large myocardial infarction

Cardiac devices, even externally placed devices such as atrial clips, may cause local endocardial scar that can contribute to slow conduction and be a set-up for reentrant arrhythmias. Introduction The use of algorithms to distinguish ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with aberrancy when wide complex tachycardia (WCT) is encountered are well validated, with a sensitivity and specificity as high as 90%. Some electrocardiogram (ECG) findings such as initial R wave in lead aVR have a specificity and positive predictive value reported nearing 100%. We present a case of a patient with WCT in whom clinical and ECG algorithms were highly suggestive of VT, but electrophysiological findings proved a macroreentrant left atrial (LA) flutter related to an AtriClip left atrial appendage (LAA) exclusion system (AtriCure, Mason, OH). Detailed mapping of atrial tachycardia/atypical atrial flutter is imperative in identifying the mechanism and for successful ablation. Case report A 58-year-old male patient with a history of paroxysmal atrial fibrillation, aortic valve replacement for severe aortic stenosis, ischemic cardiomyopathy with an unrevascularized left anterior descending infarct, and left ventricular ejection fraction of 20%–25% was transferred to our institution with incessant, hemodynamically tolerated WCT. WCT was consistent with VT based on an atypical right bundle morphology with QRS duration of 160 ms, possible capture beats, and prominent R wave in lead aVR (Figure 1). QRS morphology during sinus rhythm was not known at the time of his presentation. Intravenous adenosine given at the transferring facility reportedly had no effect on the tachycardia; however, rhythm strips were not available for review. The ECG morphology, while meeting all VT criteria, had a somewhat sharp initial component. This was potentially explained by a VT

FACTORS ASSOCIATED WITH LEAD EXTRACTION COMPLICATIONS

Lead extraction can have serious complications, such as vascular avulsion or cardiac perforation. Evaluation of success and complication rates in single centers is important as there is no well-defined reported complication prediction model for this procedure. All patients undergoing lead

Novel approach to intraprocedural cardiac tamponade: Dual-site drainage with continuous suction

Introduction Pericardial effusion and cardiac tamponade is an infrequent complication of invasive electrophysiologic procedures, with an estimated risk of 1%–3%. The most common procedures with increased risk for myocardial perforation are complex ablation during endocardial mapping and/or ablation, transseptal access, and lead placement for device therapy. Although early recognition with supportive management and immediate drainage with pericardiocentesis are necessary to prevent acute hemodynamic instability, the threshold for recommending surgical correction compared to conservative management is not well established. In this article, we discuss a practical hands-on approach to tamponade, the threshold for open surgical exploration and repair, and present a case series of large-volume tamponade successfully managed with a continuous suction approach with dual-site drainage.

INFLUENCE OF VENTRICULAR PACING WAVEFRONTS ON MYOCARDIAL SCAR DETECTION DURING ELECTROANATOMIC VOLTAGE MAPPING

The effects of varying pacing wavefronts on left ventricular scar characterization has not be systematically assessed. Patients referred for ablation of scar-related ventricular tachycardia underwent substrate-based ablation where bipolar voltage maps were first created during sinus rhythm or RV