A new intraoperative approach for endocardial mapping of ventricular tachycardia

Results of operation for control of ventricular tachycardia have improved since endocardial mapping techniques have been developed that allow a directed approach to the problem. In some patients, a limitation of established techniques has been difficulty in initiating the arrhythmia after a ventriculotomy has been made to allow introduction of endocardial recording electrodes. This paper describes a transatrial approach for endocardial mapping with a balloon array of 112 electrodes, which has been used intraoperatively in 15 patients. Surgical success in this group has been compared to that obtained in a similar group of patients in whom standard techniques of intraoperative mapping were used. With our new balloon technique we have been able to easily induce and map multiple episodes of ventricular tachycardia in all cases. On the basis of detailed endocardial maps, the locations of earliest activation and possible reentry loops have been identified and ablated with either endocardial excision or application of the cryoprobe. When indicated, concomitant procedures including aneurysm resection (9/15) and bypass grafting (14/15) have been performed. Hospital mortality in this group was 20%. None of the deaths have been related to recurrent ventricular tachycardia or complications of the mapping technique. Postoperative electrophysiologic studies performed at 2 weeks have been normal in 11 of 12 or 92% of patients. To date (mean follow-up 12 +/- 6 months) there has been no clinical recurrence or evidence of ventricular tachycardia by Holter monitoring in these patients. We conclude that the transatrial balloon approach to endocardial mapping facilitates intraoperative induction of ventricular tachycardia, allows complete mapping during multiple runs of the arrhythmia without prolonging cardiopulmonary bypass time, and improves results of operation using standard ablation techniques.