Percutaneous Epicardial Ablation of Ventricular Arrhythmias Arising From the Left Ventricular Summit

Abstract

Background-Percutaneous epicardial ablation of ventricular arrhythmias arising from the left ventricular summit is limited by the presence of major coronary vessels and epicardial fat. We report the outcomes of percutaneous epicardial mapping and ablation of ventricular arrhythmias arising from the left ventricular summit and the ECG features associated with successful ablation. Methods and Results-Between January 2003 and December 2012, a total of 23 consecutive patients (49±14 years; 39% men) with ventricular arrhythmias arising from the left ventricular summit underwent percutaneous epicardial instrumentation for mapping and ablation because of unsuccessful ablation from the coronary venous system and multiple endocardial LV/right ventricular sites. Successful epicardial ablation was achieved in 5 (22%) patients. In the remaining 18 (78%) cases, ablation was aborted for either close proximity to major coronary arteries or poor energy delivery over epicardial fat. The Q-wave amplitude ratio in aVL/aVR was higher in the successful group, with a ratio of >1.85 present in 4 (80%) patients in the successful group versus 2 (11%) in the unsuccessful group (P=0.008). The ratio of R/S wave in V1 was greater in the successful group, with 4 (80%) patients in the successful group having a R/S ratio of >2 in V1 versus 5 (28%) in the unsuccessful group (P=0.056). None of the patients in the successful group had an initial q wave in lead V1, as opposed to 6 (33%) in the unsuccessful group. The presence of at least 2 of the 3 ECG criteria above predicted successful ablation with 100% sensitivity and 72% specificity. Conclusions-Epicardial instrumentation for mapping and ablation of ventricular arrhythmias arising from the left ventricular summit is successful only in a minority of patients because of close proximity to major coronary arteries and epicardial fat. A Q-wave ratio of >1.85 in aVL/aVR, a R/S ratio of >2 in V1, and absence of q waves in lead V1 help identify appropriate candidates for epicardial ablation.

Epicardial Radiofrequency Ablation Failure During Ablation Procedures for Ventricular Arrhythmias

“…13 Proximity to a coronary artery frequently impeded RFA along the anterior wall of the LV and especially in the LV summit region, which is known to be a challenging area for RFA. 20,25,26 RFA targeting this region was successful only in the minority of cases (11%). The other main reason for failed RFA in this area was failure to identify an epicardial target for RFA because of overlying fat or a deep intramural focus out of reach for radiofrequency energy.…”

Idiopathic Outflow Tract Ventricular Arrhythmia Ablation

“…20 The most striking differences were observed between endocardial/intramural VAs and epicardial VAs, which is in line with previous reports. 7,20,21 In particular, epicardial VAs presented higher R wave amplitude ratio in leads III/II and Q wave amplitude ratio in leads aVL/aVR, higher Editorial Based on the Study by Yamada et al maximum deflection index, and overall longer electrogram-to-QRS at the earliest site. These findings are particularly useful to decide when to access the coronary venous system for mapping and ablation in the individual patients.…”

“…5 However, the complex 3-dimensional anatomic relationships between different adjacent structures in the right and left ventricular OTs pose substantial difficulties to mapping and ablation of VAs arising from this region. [7][8][9] The reasons underlying ablation failure are multifactorial and include lack of accurate localization because of minimal ectopy available to map, 10 safety concerns with ablation at the target site(s), 7,11 recurrence of different VAs, 4 and inability to access critical sites for mapping or ablation. 7,[12][13][14] In this regard, currently available mapping tools allow direct mapping and ablation of endocardial structures (ie, endocardial right or left OTs), coronary or pulmonic cusp region, 15,16 or the epicardium via either a direct percutaneous approach or via the coronary venous system.…”

“…[7][8][9] The reasons underlying ablation failure are multifactorial and include lack of accurate localization because of minimal ectopy available to map, 10 safety concerns with ablation at the target site(s), 7,11 recurrence of different VAs, 4 and inability to access critical sites for mapping or ablation. 7,[12][13][14] In this regard, currently available mapping tools allow direct mapping and ablation of endocardial structures (ie, endocardial right or left OTs), coronary or pulmonic cusp region, 15,16 or the epicardium via either a direct percutaneous approach or via the coronary venous system. 7,9 Intramural sites cannot be accessed for detailed mapping and ablation, and a definite determination of the site of origin of intramural VAs or of the best accessible adjacent anatomic site to deliver ablation (and the optimal ablation approach) are major challenges.…”

“…7,[12][13][14] In this regard, currently available mapping tools allow direct mapping and ablation of endocardial structures (ie, endocardial right or left OTs), coronary or pulmonic cusp region, 15,16 or the epicardium via either a direct percutaneous approach or via the coronary venous system. 7,9 Intramural sites cannot be accessed for detailed mapping and ablation, and a definite determination of the site of origin of intramural VAs or of the best accessible adjacent anatomic site to deliver ablation (and the optimal ablation approach) are major challenges. [12][13][14]17 In select instances, direct intramural recording from a small caliber multipolar catheter or from partially insulated unipolar recording/pacing wires advanced to a septal perforator branch of the anterior interventricular vein has been shown to identify intramural VAs.…”