Characterization of Lesions Created by a Heated, Saline Irrigated Needle-Tip Catheter in the Normal and Infarcted Canine Heart

Abstract

Background - Inability to eliminate intramural arrhythmogenic substrate may lead to recurrent ventricular tachycardia after catheter ablation. The aim of the present study was to evaluate intramural and full thickness lesion formation using a heated saline-enhanced radiofrequency (SERF) needle-tip catheter, compared to a conventional ablation catheter in normal and infarcted myocardium. Methods - Twenty-two adult mongrel dogs (30-40 kg, 15 normal and 7 myocardial infarct group) were studied. Lesions were created using the SERF catheter (40W/50°C) or a standard contact force (CF) catheter in both groups. Results - Comparing SERF to CF ablation, the SERF catheter produced larger lesion volumes than the standard CF catheter - even with >20 g of CF - in both normal (983.1 ± 905.8 mm3 vs. 461.9 ± 178.3 mm3; p=0.023) and infarcted left ventricular myocardium (1052.3 ± 543.0 mm3 vs. 340.3 ± 160.5 mm3; p=0.001). SERF catheter lesions were more often transmural than standard CF lesions with >20 g of CF in both groups (59.1% vs. 7.7%; p<0.001 and 60.0% vs. 12.5%; p=0.017, respectively). Using the SERF catheter, mean depth of ablated lesions reached 90% of the left ventricular wall in both normal and infarcted myocardium. Conclusions - The SERF catheter created more transmural and larger ablative lesions in both normal and infarcted canine myocardium. SERF ablation is a promising new approach for endocardial intramural and full thickness ablation of ventricular tachycardia substrate that is not accessible with current techniques.

Ablation of Refractory Ventricular Tachycardia Using Intramyocardial Needle Delivered Heated Saline-Enhanced Radiofrequency Energy: A First-in-Man Feasibility Trial

“…Ablation seeks to destroy viable strands of muscle participating in these reentry circuits or channels. 2,[46][47][48][49] Fibrous scar tissue surrounds areas of both surviving and damaged myocytes and creates the reentry substrate, which can be subendocardial, subepicardial, intramural, or transmural. Portions of reentry circuits commonly extend deep to the endocardium and are a recognized reason for failure of VT ablation.…”

“…A previous trial with a longer needle also observed that needle insertion into the myocardium is relatively safe. 56 SERF ablation can produce very large lesions, 27,34,48 raising concern for a risk to viable myocardium outside of the VT substrate scar and worsening ventricular function. One patient in this study, who had extensive substrate and received the largest number of radiofrequency applications in multiple areas around an extensive infarct scar did develop fatal cardiogenic shock.…”

A Force Awakens: Return of Needle Catheter Radiofrequency Ablation for Targeting Intramural Ventricular Arrhythmias

“…10 With irrigation now feasible via multiple ports covering a larger surface area along a shorter and smaller-gauge needle, and radiofrequency ablation lesion size primarily generated by resistive and thermal-conductive heating augmented by adding convective heating during radiofrequency, an ingenious synergy has been achieved to allow larger lesions with greater width and depth compared to standard irrigated radiofrequency ablation. 10,12 Should this needle catheter and ablation system fare better than the first needle catheter design, it could truly advance our ability to more effectively manage the most difficult-to-control ventricular arrhythmias, ostensibly averting need for cardiac transplantation, at least among those transplanted primarily for refractory, recurrent ventricular arrhythmias. However, several important caveats should be acknowledged.…”

“…10 With irrigation now feasible via multiple ports covering a larger surface area along a shorter and smaller-gauge needle, and radiofrequency ablation lesion size primarily generated by resistive and thermal-conductive heating augmented by adding convective heating during radiofrequency, an ingenious synergy has been achieved to allow larger lesions with greater width and depth compared to standard irrigated radiofrequency ablation. 10,12…”

Needle Ablation for Ventricular Tachycardia: From Bench to Bedside

“…This catheter has been developed and tested in preclinical models. 18,19 It is likely that this needle ablation catheter is effective through a different mechanism. The larger irrigation volume and heating of the irrigant likely lead to a greater degree of convective heating, rather than resistive heating.…”