Laser ablation of ventricular tachycardia.

About 5-10% of patients after myocardial infarction experience sustained ventricular tachycardias. Drug therapy is successful only in 60% of these patients, so that a number of them is on a high risk of a sudden cardiac death. Indirect surgical approaches like myocardial revascularization, or aneurysm resection have proven to be ineffective in the treatment of these malignant tachycardias. By the development of electrophysiologic techniques a mechanism of the ventricular tachycardias could be identified as a micro-reentry at the border of myocardial infarction. On this base different direct surgical approaches were advocated by Guiraudon, proposing an encircling endocardial ventriculotomy and by Josephson and Harken recommending a subendocardial resection technique. The results of these direct procedures were much better than those of the prior indirect techniques. The mortality in this series was around 10% and there still was a postoperative recurrence of the tachycardia in about 20-30%. Our group started a study in which a Nd:YAG laser was used to photocoagulate areas of myocardium responsible for the initiation of ventricular tachycardia. By its deeper penetration depth the Nd:YAG laser was preferrable to other laser systems like CO2 and Argon-laser. In contrast to cryothermy the Nd:YAG showed three special advantages: First, it was more effective in the normothermic myocardium, it showed not peripheral zone of temporary myocardial injury, potentially causing late failures, and third equal ablation of tissue could be achieved in much shorter time. Patients were considered operative candidates when drug therapy failed. Preoperative investigations included formal cardiac catheterization and an electrophysiologic testing with induction and mapping of the ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)