Ablation of atrial-ventricular junction tissues via the coronary sinus using cryo balloon technology

Introduction: The coronary sinus ( CS) can provide access to targets across and within the atrioventricular ( AV) junction. Methods: In 12 dogs ( 32 +/- 3 Kg), cryo balloons (10 - 19 mm) were applied to regions of the AV junction for 3 minutes at a temperature of - 75.9° +/- 9° C ( ranging - 57 to - 83). Electrical activity and pacing within the CS were assessed pre and post ablation and at least 3 months later in 9 dogs. In the 3 other dogs, hearts were examined immediately after cryo ablation. CS and circumflex angiography was performed pre and post ablation. The hearts, CS, and Cx were then examined for structural injury. The AV junction was sectioned and the hearts were immersed in Tetrazolium, and the lesions were inspected for transmurality across the AV groove. Results: In 3/12 dogs the distal CS cryo lesions resulted in inferior ST segment depression that resolved within 5 minutes. There was no arrhythmia or hemodynamic changes. No CS electrical activity was noted post ablation. The pacing threshold increased from 2 +/- 2.3 mA to 7.4 +/- 3.6 mA ( p < 0.001). Pathological examination of 3 acute hearts revealed hematomas. There was no pericardial effusion. No evidence of stenosis or thrombosis was seen within the CS and the circumflex artery. After 3 months of recovery, transmural lesions across the AV groove were present in all of the targeted AV regions. Conclusion: Intra-CS cryo balloon ablation is safe and can potentially replace endocardial RF ablation targeting the AV junction and the CS muscular sleeve.