Comparative study of lesions obtained with radiofrequency between irrigated ablation catheter with flexible tip and non-irrigated catheter in ex vivo porcine heart slices
Authors: De Raffele M , Vitali F , Azzolini G , Malagu' M , Balla C , Campo G , Bertini M 
Published: May 2024

Abstract

Background
Lesion formation through radiofrequency (RF) is related to various parameters, including power, contact force, duration of energy delivery and temperature. Notably, the characteristics of the lesions differ when comparing irrigated to non-irrigated catheters. Non-irrigated catheter lesions present a larger surface area and shallower depth, while irrigated catheters induce deeper lesions with higher volumes. Particularly, flexible-tip open-irrigated catheter exhibit unique irrigation characteristics and the resulting lesions may show a reduced surface area but extend deeper into the tissue. Main drawbacks of using non-irrigated catheter are the risk of clot formation and of steam pops, both possibly avoidable with an irrigated catheter.

Purpose
The aim of the study was to demonstrate that flexible-tip open-irrigated catheter generate lesions with a smaller surface area and deeper extension when compared to non-irrigated catheter.

Methods
An ex vivo model consisting of porcine heart slices in a warmed saline chamber was used. A flexible-tip open-irrigated ablation catheter and a non-irrigated catheter were positioned with a stable tissue contact weight ranging from 10 to 20 g of force in perpendicular position. RF was delivered at powers of 20, 30 and 40 Watt for 60s. Lesion dimensions were analyzed. The occurrence of steam pop was registered.

Results
The ablations were conducted using flexible-tip open-irrigated (n=55) and non-irrigated (n=39) catheters in a power-control mode. Superficial length and width of lesions were greater with the non-irrigated catheter than with the irrigated catheter, irrespective of the power delivered (superficial length: p=0,0001 at 20W, p=0,002 at 30 W and p=0,0001 at 40 W; superficial width: p=0,001 at 20 W, p=0,019 at 30 W and p=0,003 at 40 W). When computing superficial areas, lesions performed with the non-irrigated catheter were significantly wider, regardless of the power delivered (p=0,001 at 20 W, p=0,005 at 30 W and p=0,001 at 40 W). The irrigated catheter determined significantly greater values of lesion maximum depth at high power delivery (40 W, p=0.007). No steam pop was observed using the irrigated ablation catheter, while 12 steam pops occurred with the non-irrigated catheter.

Conclusions
This study highlights that RF ablation using flexible-tip open-irrigated catheter has the potential to generate smaller lesion areas when compared to a non-irrigated tip. Furthermore, it may contribute to decrease steam pops, even with escalating power output. This irrigated catheter might be a preferable choice when precision is crucial, particularly in determining superficial area of lesions. Specifically, it might be advantageous for procedure as atrioventricular nodal reentry tachycardia (AVNRT) ablation, minimizing the risk of iatrogenic conduction disturbance related to RF delivery in the region of the compact AV node, located superficially at a millimeter distance from the ablation site.Experiment setting, lesion measurementsLesion superficial area