SIMULTANEOUS ENDOCARDIAL MAPPING IN THE HUMAN LEFT-VENTRICLE USING A NONCONTACT CATHETER - COMPARISON OF CONTACT AND RECONSTRUCTED ELECTROGRAMS DURING SINUS RHYTHM

Background-Catheter ablation of ventricular tachycardia is limited in part by difficulty in identifying suitable sites for ablation. A nonco ntact multielectrode array (MEA) has been developed that allows recons truction of 3360 electrograms, using inverse-solution mathematics, tha t are superimposed onto a computer-simulated model of the endocardium. This study assesses the accuracy of timing and morphology of reconstr ucted unipolar electrograms compared with contact unipolar electrogram s from the same endocardial site. Methods and Results-The MEA was depl oyed in the left ventricles of 13 patients (end-diastolic diameters, 6 1.7+/-8.4 mm [mean+SD]), We recorded contact electrograms at 76 points equatorial and 32 points nonequatorial to the MEA during sinus rhythm using a catheter-locator signal to record direction and distance from the MEA. Morphology (crosscorrelation) and timing of maximum -dV/dt o f contact and reconstructed electrograms were compared at different di stances from the MEA center to endocardium (M-E) and from the MEA equa torial plane. For equatorial data, the M-E was 32.12+/-12.12 mm. The t iming of reconstructed with respect to contact electrograms was -1.94/-7.12 ms for M-E <34 mm and -14.16+/-19.29 ms at M-E >34 mm (P<0.001) . Cross-correlation of electrograms was 0.87+/-0.12 (95% CI, 0.84 to 0 .91) and 0.76+/-0.18 (95% CI, 0.69 to 0.83) for M-E <34 mm and >34 mm, respectively. Nonequatorial points were 32.33+/-10.81 mm (range, 16.9 to 55.6 mm) from the MEA equatorial plane; electrogram timing differe nce was -8.97+/-15.75 ms and was unrelated to this distance from the e quator. Conclusions-This noncontact mapping system accurately reconstr ucts endocardial unipolar electrograms from the human left ventricle. At M-E distances >34 mm, timing accuracy of reconstruction decreases.