Uncovering the Structural Effects of Radiofrequency Ablation on the Papillary Muscle-Chordae Tendineae Junction

Although radiofrequency ablation is effective for treating left ventricular papillary muscle (PM) arrhythmias, procedural complications like catheter entrapment and risk of PM injury are incompletely understood. Furthermore, cardiac catheters lack tensile force monitoring at the catheter tip, creating procedural blind spots that prevent the detection and potential mitigation of such complications. Therefore, this study aimed to evaluate the force required to rupture PMs before and after ablation, providing insights into procedural safety and potential risks associated with PM ablation.

Thirty-six samples were excised from fresh porcine hearts. Samples were divided equally into control and ablated groups. Ablations were performed at 50 W, 60 s, and 30 g. All samples underwent tensile testing until failure. The mean ultimate tensile strength (UTS) was compared between groups, and each sample underwent histological analysis to examine the failure site and ablative structural changes.

The ablated group had a lower mean UTS than the control group, but this difference was not significant. The ablated group had the only samples to fail at less than physiological systole peak force (6 N). The ablated samples had myocyte necrosis and denaturation of collagen fibers in the chordae tendineae (CT). Both groups had myocardial tearing inferior to the insertion point instead of at the PM-CT junction.

RF ablations at the PM create changes in the structure of the PM-CT junction that could raise procedural concerns. Future work will explore in vivo tensile testing, more varied ablation conditions, and any associated fibrotic healing that could affect clinical outcomes.