Great cardiac venography by contrast injection through an external irrigation catheter

Alternative strategies to improve success rate of mitral isthmus block

Achieving bidirectional conduction block (BDB) across the mitral isthmus (MI) is technically challenging. We describe our experience using different ablation strategies for achieving successful MI block.We reviewed the records of patients who had undergone MI ablation for peri-mitral (PM) flutter at our institution from January 2010 to May 2015. We investigated ablation strategies for achieving MI block and their long-term outcomes in terms of recurrence of atrial tachyarrhythmia.Single endocardial MI ablation with or without distal coronary sinus (CS) ablation achieved MI block in 129 out of 236 (54.7%) patients. After failure of MI block, a new MI line ablation, ablation targeting the vein of Marshall (VOM), or anterior line ablation was performed in selected patients. The MI block was achieved in 13 (52.0%) out of 25 patients with new MI line ablation and in 13 (68.4%) out of 19 patients with VOM ablation. Anterior line ablation was tried in 23 patients and the line of block was achieved in 12 (52.2%) patients. Finally, overall PM BDB (PMB, MI block or anterior line block) was achieved in 167 (70.8%) of 236 patients. The incidence atrial tachyarrhythmia was similar between the patients with successful PMB and those with failed PMB (32.9% vs 42.0%, P = .18). In multivariable Cox regression analysis, the PMB was not associated with recurrence of atrial tachyarrhythmia (hazard ratio [HR]: 0.70, 95% confidence interval [CI]: 0.43-1.12).In conclusion, single endocardial MI line with or without distal CS ablation showed limited success for achieving MI block. Additional substrate modifications such as a new MI line ablation, anterior line ablation, or ablation targeting the VOM may improve the success rate of PMB block. However, the benefits of PMB were not clear in this study.

Challenging Radiofrequency Catheter Ablation of Idiopathic Ventricular Arrhythmias Originating From the Left Ventricular Summit Near the Left Main Coronary Artery

Background—

Radiofrequency catheter ablation (RFCA) of idiopathic ventricular arrhythmias (VAs) originating from the basal portion of the left ventricular (LV) summit, which is divided from the apical LV (A-LV) summit by the great cardiac vein (GCV), is challenging. This study investigated the efficacy of RFCA and electrocardiographic and electrophysiological characteristics of these VAs.

Methods and Results—

Forty-five consecutive patients with symptomatic idiopathic LV summit VAs were studied. RFCA was successful within the main trunk of the GCV in 16 patients and within a branch of the GCV traversing the basal LV (B-LV) summit in 7. Transpericardial RFCA was successful on the epicardial surface in the A-LV summit in 6 patients and was abandoned in 14 with the B-LV summit VAs because of the close proximity to the coronary arteries and thick fat pads. RFCA was successful at the aortomitral continuity in 3 patients (2 with a failed transpericardial RFCA), and left coronary cusp in 1. The RFCA success rate of the A-LV summit VAs including the GCV VAs was 100% (22/22), whereas that of the B-LV summit VAs was 48% (11/23). The B-LV summit VAs could be differentiated from the A-LV summit VAs by left bundle branch block pattern, QRS duration ≤175 ms, precordial transition ≥V1, and maximum deflection index of ≥0.55.

Conclusions—

This study revealed that ≈50% of the B-LV summit VAs could be eliminated by a direct approach through a GCV branch running below the proximal left coronary arteries and a remote approach from the adjacent endocardial sites.