Daniel M. Lafontaine

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.

Advances in transcatheter endocardial mapping and radiofrequency ablation of ventricular arrhythmias

Transcatheter localization (‘mapping’) of critical conduction regions, followed by radiofrequency (RF) energy delivery for targeted ablation of appropriate cardiac tissues, have proved highly successful for eliminating susceptibility to the most common types of paroxysmal reentrant supraventricular tachycardias (i.e., reentry within the AV node and reentry utilizing accessory pathways). Similarly, specialized forms of ventricular tachycardia (bundle-branch reentry, right ventricular outflow tract tachycardia, and certain idiopathic left ventricular tachycardias) can be readily mapped and treated by these techniques [1–4]. In contrast, conventional transcatheter mapping and RF ablation have proven less reliable in the setting of paroxysmal ventricular tachycardia associated with the most prevalent forms of structural heart disease, particularly ischemic heart disease [1, 5, 6].