Acute and Chronic Effects of Extensive Radiofrequency Lesions in the Canine Caval Veins: Implications for Ablation of Atrial Arrhythmias

Abstract

In this model, extensive RF ablation in the caval veins may result in significant vascular stenosis. These findings may have implications for catheter ablation of arrhythmias originating within the caval veins.

Effects of Corticosteroid Therapy on the Long‐Term Outcome of Radiofrequency Lesions in the Swine Caval Veins

“…Severe stenosis and occlusions did not occur. The lesser degree of acute stenosis in this pig model as compared to our dog model 15 may be ascribed to the shorter duration of RF application (6 vs 3 minutes) and to the greater diameter of the swine caval veins (13–16 mm vs 10–15 mm). Of note, no deaths occurred acutely or during follow‐up.…”

“…We recently showed in dogs that extensive (6–7 minutes of energy delivery) RF ablation inside the caval veins consistently promotes venous stenosis 15 . In five acute animals, luminal narrowing was noted in 10/10 (100%) targeted veins (mild in two; moderate in three, and severe in 5, including two total occlusions).…”

“…Attempting to reduce the 40% mortality of our canine model, 15 we have explored the acute and long‐term (11 weeks) effects of a more limited ablation procedure (3 minutes of energy delivery) in the caval veins of minipigs. This approach produced mild or moderate acute luminal narrowing in 19/20 (95%) inferior veins and in 13/20 (65%) superior veins.…”

“…The mechanism by which venous stenosis may develop after RF ablation remains elusive. We have recently demonstrated in dogs that extensive RF ablation within the caval veins consistently results in caval vein narrowing or complete occlusion, which is characterized acutely by vasospasm, thrombus formation, and tissue edema; and chronically by proliferation of the intima and elastic lamina, vessel wall contracture, and fibrosis 15 . Corticosteroids have powerful anti‐inflammatory actions, including decrease of scar formation, 16 and have been shown to limit RF‐induced damage to muscular tissues in animal models 17,18 .…”

The Role of Superior Vena Cava Isolation in the Management of Atrial Fibrillation

“…Fenelon et al raised awareness of this potential complication by demonstrating that RFA in canine caval veins was associated with luminal narrowing in 100% of the cases examined, and was moderate or severe in 50%. 28 However, in clinical practice, there is a very low incidence of clinically significant SVC stenosis. Callans et al described that RFA in the SVC of humans for inappropriate sinus tachycardia resulted in an average acute luminal narrowing of 24%, with some lesions associated with small thrombi.…”