Left Ventricular Volume Reduction by Radiofrequency Heating of Chronic Myocardial Infarction in Patients With Congestive Heart Failure

Abstract

Background-Myocardial infarct expansion and left ventricular (LV) remodeling are integral components in the evolution of chronic heart failure and predict morbidity and mortality. Radiofrequency (RF) heating and patch placement of chronic LV aneurysms caused a sustained reduction in LV infarct area and volume in an ovine infarct model. This study evaluated the effect of RF heating and epicardial patch as an adjunct to coronary artery bypass graft on LV volumes in patients with prior myocardial infarction, evidence of akinetic/dyskinetic scar, and LV ejection fraction Յ40%. Methods and Results-Ten patients (3 female; mean age, 64Ϯ11 years) scheduled for coronary artery bypass graft were enrolled (Canadian Cardiovascular Society angina class 2.1Ϯ1.1; New York Heart Association class 3.1Ϯ0.5).Intraoperative digital photography demonstrated an acute 39% reduction in infarct area (nϭ5; Pϭ0.01), and transesophageal ECGs demonstrated a 16% acute reduction in LV end-diastolic volumes (nϭ9; Pϭ0.002) after RF treatment. There were no intraoperative or procedure-related postoperative complications, and during an average follow-up of Ͼ180 days, there have been no safety issues. All patients had complete relief of their angina and improvement in exercise tolerance. Serial transthoracic ECGs over the 6 months of follow-up after RF treatment demonstrated persistent reductions in LV end-diastolic volume (29%; PϽ0.0001) and LV end-systolic volume (37%; PϽ0.0001) with improved ejection fraction (PϽ0.02). Conclusions-RF heating and patch placement in these 10 patients resulted in acute reduction in infarct area and ventricular volumes that were maintained 180 days after procedure. This technique may reduce the incidence of congestive heart failure and mortality in these patients and warrants investigation in larger clinical trials. (Circulation.

Left Atrial Contractility is Preserved After Successful Circumferential Pulmonary Vein Ablation in Patients with Atrial Fibrillation

“…Most patients with a successful ablation showed a decrease in both LAmax and LAmin volumes and preserved contractility. Whether the LAmin volume reduction in these cases occurred immediately after ablation due to tissue shrinking as a result of the radiofrequency delivery, 24 or if it was subsequent to a mid‐term reverse remodeling secondary to the maintenance of stable sinus rhythm, 25 remains inconclusive in the present study. Another hypothesis that may be taken into account is that the PVs isolation may lead to loss of their contractile capability, and this could cause blood regurgitation from the LA through the PVs during atrial systole.…”

Development of a Simultaneous Cryo-Anchoring and Radiofrequency Ablation Catheter for Percutaneous Treatment of Mitral Valve Prolapse

“…6,9,31 Specifically, the 21 For our purposes, the target of RF ablation is the disrupted or distended collagen architecture of the MV leaflets; collagen has been shown to denature and contract when heated to temperatures greater than 65°C. 42 Using biaxial mechanical testing, we have demonstrated that RF ablation effectively reduces MV leaflet geometry and alters biomechanical compliance in vitro. 36 Previously, RF ablation treatment of myxomatous MVP has been shown to be feasible in a surgical canine model in which an acute in vivo study was performed on beagles with MR under open-heart surgery, demonstrating a mean 49.6% reduction in post-ablation MR. 43 Additionally, a chronic in vivo study was performed on healthy beagles to assess the ability to apply RF energy percutaneously and to assess the durability of the procedure at 6 weeks.…”

“…Previously, the triple-helical structure of collagen has been shown to denature and contract when heated to greater than 65°C. 42 Following treatment with RF ablation, collagenous tissues undergo shortening in the direction of collagen alignment.…”

Left Atrial Anatomic Remodeling in Atrial Fibrillation

“…LA size has been shown to decrease, 13 but controlled studies have shown a depression of systolic LA function after the procedure 14 . LA reduction after extensive ablation could be due, not to functional improvement, but, at least in part, to tissue shrinking by fibrous scarring 15 . Muscle damage produced by circumferential ablation can be so extensive as to produce massive LA wall edema, 16 leading to congestive heart failure in the acute stage.…”