Bipolar ablation of therapy-refractory ventricular arrhythmias: application of a dedicated approach

Abstract

Aims Bipolar radiofrequency ablation (B-RFA) has been reported as a bail-out strategy for the treatment of therapy refractory ventricular arrhythmias (VA). Currently, existing setups have not been standardized for B-RFA, while the impact of conventional B-RFA approaches on lesion formation remains unclear. Methods and results (i) In a multicentre observational study, patients undergoing B-RFA for previously therapy-refractory VA using a dedicated B-RFA setup were retrospectively analysed. (ii) Additionally, in an ex vivo model lesion formation during B-RFA was evaluated using porcine hearts. In a total of 26 procedures (24 patients), acute success was achieved in all 14 ventricular tachycardia (VT) procedures and 7/12 procedures with premature ventricular contractions (PVC), with major complications occurring in 1 procedure (atrioventricular block). During a median follow-up of 211 days in 21 patients, 6/11 patients (VT) and 5/10 patients (PVC) remained arrhythmia-free. Lesion formation in the ex vivo model during energy titration from 30 to 50 W led to similar lesion volumes compared with initial high-power 50 W B-RFA. Lesion size significantly increased when combining sequential unipolar and B-RFA (1429 mm3 vs. titration 501 mm3 vs. B-RFA 50 W 423 mm3, P < 0.001), an approach used in overall 58% of procedures and more frequently applied in procedures without VA recurrence (92% vs. 36%, P = 0.009). Adipose tissue severely limited lesion formation during B-RFA. Conclusion Using a dedicated device for B-RFA for therapy-refractory VA appears feasible and safe. While some patients need repeat ablation, success rates were encouraging. Sequential unipolar and B-RFA may be favourable for lesion formation.

Successful bipolar radiofrequency catheter ablation in a case of scar-related ventricular tachycardia with intramural critical isthmus in basal posterior right ventricle identified by coherent mapping

“…In previous reports, Bi-ABL has been primarily performed for the treatment of ventricular arrhythmias originating from the LV free wall, interventricular septum, LV outflow tract, LV papillary muscles, or His bundle region that were refractory to conventional endocardial and/or epicardial Uni-ABL. 6 , 7 , 8 , 9 , 10 , 11 In the current case, RF energy was delivered between the distal electrodes of 2 irrigated catheters, which were placed in the endocardial and epicardial basal posterior RV. To our knowledge, ours is a rare case in which Bi-ABL has been applied with an endo-epicardial approach to a location in the RV.…”

“…Although the methodology of Bi-ABL is well established, severe complications such as cardiac tamponade owing to myocardial injuries by steam pop or atrioventricular block owing to Bi-ABL in the interventricular septum have been reported. 6 , 7 , 8 , 9 , 10 Thus, care is necessary in setting the power level and ablation duration of bipolar RF applications. John et al concluded that ablation duration is the most significant factor in producing durable lesions, whereas the power setting is the most significant factor affecting the incidence of steam pops based on assessment of an ex-vivo Bi-ABL model (11).…”

“… 1 , 2 Difficulty in mapping VT substrate that lies deep within the ventricular myocardium and difficulty in creating transmural lesions with Uni-ABL for such deep substrate are considered to be among the major causes of VT recurrence. 3 , 4 , 5 Meanwhile, some reports have described the efficacy of bipolar ablation (Bi-ABL) for eliminating intramural VT circuits, especially in patients with recurrence after Uni-ABL for scar-related VT. 6 , 7 , 8 , 9 , 10 , 11 We report a rare case of nonischemic scar-related VT that had an intramural critical isthmus deep in the basal posterior right ventricle (RV) that was successfully eliminated by endocardial-epicardial Bi-ABL.…”

Impedance‐decline‐guide power control long application time bipolar radiofrequency catheter ablation

“…The following impedance indexes were measured 1 ; initial impedance when starting RF application, 2 minimum impedance during ablation, 3 total impedance decline (TID), which was calculated as initial minus minimum impedance during ablation, and 4 %‐TID, which was calculated as percent TID from the initial impedance.…”

“…Bipolar (BIP) radiofrequency (RF) catheter ablation, which can create deep lesions, has recently been used for the treatment of arrhythmias originating from inside the thick myocardium 1–3 . Several clinical studies indeed reported that unipolar ablation refractory arrhythmias from deep inside the myocardium were successfully ablated following BIP ablation with excellent acute and long‐term outcomes 4,5 . BIP ablation is useful, but its efficacy seems insufficient for the majority of patients.…”