Robert A. Schweikert

Focal atrial tachycardias originating from the left atrial appendage present unique anatomic challenges for successful ablation. We describe the role of minimally invasive percutaneous epicardial mapping and ablation in the management of two patients with ectopic atrial tachycardias arising from the left atrial appendage following failure of a conventional endocardial approach to achieve cure.

Introduction: Balloon‐based catheters are an emerging technology in catheter ablation for atrial fibrillation, which aim to achieve consistent and rapid ablation encirclement of pulmonary veins (PVs). Recent emphasis has been placed on achieving more proximal electrical isolation within the PV–left atrial (LA) junction. We sought to evaluate the precise anatomic level of PV electrical disconnection with current design balloon‐based catheters. Methods and Results: Thirteen patients with drug‐refractory paroxysmal atrial fibrillation undergoing balloon catheter ablation with the endoscopic laser system (CardioFocus) or the high frequency‐focused ultrasound system (ProRhythm) underwent electroanatomic mapping (EAM) of the left atrium. Intracardiac echocardiographic (ICE) imaging was used for visualization of the position of the balloon catheter during energy delivery. Detailed point analysis of the location of electrical disconnection was then documented on EAM and with ICE.Successful electrical isolation was achieved in all 52 PVs. Despite ICE imaging confirming balloon catheter position at the antrum of the PVs, the location of electrical disconnection was demonstrated to be at or near the tubular ostium of the PVs on EAM and on ICE in all patients. Conclusion: Current generation balloon‐based catheter ablation achieves electrical isolation distal in the LA–PV junction. This may limit the results of such systems in treating nonparoxysmal forms of atrial fibrillation.

Background— The epicardial location of an arrhythmia could be responsible for unsuccessful endocardial catheter ablation. Methods and Results— In 48 patients referred after prior unsuccessful endocardial ablation, we considered percutaneous, subxiphoid instrumentation of the pericardial space for mapping and ablation. Thirty patients had ventricular tachycardia (VT), 6 patients had a right- and 4 had a left-sided accessory pathway (AP), 4 patients had inappropriate sinus tachycardia, and 4 patients had atrial arrhythmias. Of the 30 VTs, 24 (6 with ischemic cardiomyopathy, 3 with idiopathic cardiomyopathy, and 15 with normal hearts) appeared to originate from the epicardium. Seventeen (71%) of these 24 VTs were successfully ablated with epicardial lesions. The other 7 VTs had early epicardial sites that were inaccessible, predominantly because of interference from the left atrial appendage. Six of these were successfully ablated from the left coronary cusp. In 5 of the 10 patients with an AP, the earliest activation was recorded epicardially. Three of these were right atrial appendage–to–right ventricle APs, and epicardial ablation was successful. No significant complications were observed. Conclusions— Failure of endocardial ablation could reflect the presence of an epicardial arrhythmia substrate. Epicardial instrumentation and ablation appeared feasible and safe and provided an alternative strategy for the treatment of patients with a variety of arrhythmias. This was particularly true for VT, including patients without structural heart disease.