Epicardial Ablation With Cooled Tip Catheter Close to the Coronary Arteries is Effective and Safe in the Porcine Heart if the Ventricular Potential is Being Monitored in the Epicardium and Endocardium

Abstract

ndocardial catheter ablation is a popular treatment for various types of arrhythmias, but it has limitations, including the inability to access foci or critical circuits of arrhythmia located in the epicardium. Technological improvements, such as cooled-tip or largertip ablation catheters and different energy sources for tissue ablation, have not completely solved this problem. Mapping of the arrhythmic foci or circuits in the epicardium has been done in open-chest heart surgery 1 and with radiofrequency (RF) ablation catheters in 2 ways. First, a 2F electrode catheter is inserted into the coronary sinus and then into the branches. Epicardial circuits can sometimes be identified with this approach, but only when the veins are near the circuit or foci. 2 There is a possibility of damage to coronary arteries (CA) if the coronary sinus runs parallel to the CA, even if the circuit or foci are near the coronary sinus. Second, transthoracic epicardial ablation of ventricular tachycardia (VT) has recently been shown to be feasible, primarily in patients with Chagas heart disease, 3-5 ischemic cardiomyopathy, 6-8 and dilated cardiomyopathy. 9,10 However, the acute success rate of epicardial catheter ablation for VT using a standard RF catheter is only about 60%, because the catheter electrode is inadequately cooled by the blood and the effect of epicardial fat in the vicinity of the CA. The lack of convective cooling of the catheter-tip by the blood would be expected to limit power delivery in the pericardial space; hence, the use of cooled-tip catheter ablation might be more appropriate than conventional catheter ablation for larger and deeper epicardial lesions. Furthermore, the safety of cooled-tip catheter ablation in the vicinity of the CA is unclear. The aim of the present study was to use an animal model to characterize the size of lesions produced by ablation with a cooled-tip catheter and to establish the safety of delivering RF pulses in the vicinity of major coronary vessels. MethodsThe current study was done according to the Guidelines for the Care and Use of Laboratory Animals published by the US National Institute of Health. The study protocol was reviewed by the Committee of the Ethics on Animal Experiments of Showa University. Background Transthoracic epicardial ablation can be an alternative to conventional treatment for critical pathways of ventricular tachycardia located in the epicardium. However, the usefulness and safety of epicardial ablation close to the coronary arteries (CA) is not clear. The purpose of the present experimental animal study was to analyze the efficacy and safety of epicardial radiofrequency (RF) ablation close to the CA. Methods and ResultsOf the left ventricle-epicardium ablated sites, 35 lesions (20 with cooling and 15 without cooling) were close to the CA (left anterior descending artery ≤15 mm) and 33 lesions (23 with cooling and 10 without cooling) were further from the CA. For sites close to the CA, epicardial ablation was effective in 77% (15/20) with cooling and in 40% ...

Idiopathic Ventricular Arrhythmia Originating From the Cardiac Crux or Inferior Septum

“…It was previously reported using porcine hearts that ablation sites ≥5 mm away from the coronary vessels was safe. 18 Coronary artery angiography was performed for some patients with basal crux VA and for all patients with apical crux VA who underwent epicardial ablation. Successful epicardial ablation sites were located ≥10 mm away from the right coronary artery and its branches.…”

Venice Chart International Consensus Document on Ventricular Tachycardia/Ventricular Fibrillation Ablation

“…RF pulses delivered near an artery may result in intima hyperplasia and thrombosis 139 . On the other hand, ablation near large vessels, with increased arterial and venous flow, might preclude myocardial lesion development underneath the vessels that could be involved in the reentrant circuit 355 . Therefore, accessing the coronary venous system should be a good alternate in case of a perivascular VT substrate 46,356 .…”

“…139 On the other hand, ablation near large vessels, with increased arterial and venous flow, might preclude myocardial lesion development underneath the vessels that could be involved in the reentrant circuit. 355 Therefore, accessing the coronary venous system should be a good alternate in case of a perivascular VT substrate. 46,356 Direct visualization of the epicardial surface through a customized pericardial endoscope might also facilitate a safer epicardial RF delivery.…”

Comparison of Endocardial and Epicardial Lesion Size Following Large-Tip and Extra-Large-Tip Transcatheter Cryoablation

“…27 Another study showed that cooled-tip RF ablation is safe if the ablation sites are located 5 mm from the major coronary arteries, but the LAD was injured in 4 of 7 ablation lesions created above or within 5 mm of the LAD. 31 Thus, cryoablation might be safer than…”