Endocardial mapping by simultaneous recording of endocardial electrograms during cardiac surgery for ventricular...

A technique was developed for the simultaneous recording of 30 endocardial electrograms during cardiac surgery in patients undergoing aneurysmectomy or endocardial resection, or both, for medically intractable ventricular tachycardia. An inflatable balloon covered with 30 terminals at distances of 1.5 to 2 cm was used to record from the entire endocardial surface; a smaller silicone rubber sheet with 30 terminals at distances of 0.7 cm was used to obtain a better spatial resolution. The multielectrodes were inserted into the left ventricular cavity by way of an incision in the aneurysm. A transportable minicomputer was used for the acquisition and analysis of the signals. After initiation of ventricular tachycardia by programmed stimulation, signals of a 1.5 second period were stored and analyzed. The earliest activated terminal could be determined within 2 to 5 minutes. The technique was applied in 32 patients and proved especially useful in those patients in whom sustained tachycardia could not be evoked and in whom conventional mapping with a roving electrode would have been impossible or very time consuming. In all patients, the isochronic maps showed that the ectopic impulses originated from a rather localized area and no evidence was found for large endocardial circus movements, thereby excluding these as a mechanism underlying the tachycardia. Isochronic maps, depicting activation sequences during consecutive ectopic beats with the same QRS morphologic features, showed the same site of origin in all but six patients.(ABSTRACT TRUNCATED AT 250 WORDS)