Determination of Human Ventricular Repolarization by Noncontact Mapping

Abstract

Background-Noncontact mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. Methods and Results-MAPs were recorded from a total of 355 beats at 46 sites in the left or right ventricle of 9 patients undergoing ablation of ventricular tachycardia guided by NCM (EnSite system). Measurements were made during sinus rhythm, constant right ventricular pacing, and ventricular extrastimuli during restitution-curve construction. The EnGuide locator signal was used to document MAP catheter locations on the endocardial geometry. UE-determined activation-recovery interval (ARI) measured at the maximum derivative of the T wave (Wyatt method) and the minimum derivative of the positive T wave (alternative method) was correlated with MAP measured at 90% repolarization (MAP90%) at the same sites. ARI correlated with MAP90% during steady state by the Wyatt method (rϭ0.83, PϽ0.001) and the alternative method (rϭ0.94, PϽ0.001). Restitution curves constructed from MAP and UE data exhibited the same characteristics, with a mean correlation coefficient of 0.95 (range, 0.90 to 0.99, PϽ0.001). The error between ARI and MAP90% was greater over a shorter diastolic coupling interval but was not influenced by distance of the sampling site from the multielectrode array. Conclusions-NCM accurately determines steady-state and dynamic endocardial repolarization in humans. Global, high-density, NCM data could be used to characterize abnormalities of human ventricular repolarization. (Circulation.

Modulated dispersion of activation and repolarization by premature beats in patients with cardiomyopathy at risk of sudden death

“…In humans with preserved ventricular function, TRT is also dependent on activation-repolarization coupling, such that reduced coupling increases TRT dispersion when measured during steady-state pacing (7,9,24,25). We evaluated coupling by measuring the slope of the AT-ARI relationship, and a slope deviating from Ϫ1 indicated less coupling (7,26). During the basic drive in our patients, the AT-ARI slope at early sites (Ϫ0.5) deviated to the same extent from Ϫ1 as the AT-ARI slope of late sites (Ϫ1.5), thereby producing similar TRT dispersion.…”

“…For biphasic T waves, local repolarization was computed from the midpoint between the two phases of the T wave (20,24,25). Although Coronel et al (5) have argued that the original Wyatt method more accurately measures the end of local repolarization in isolated pig hearts, in vivo human studies (4,26) have consistently shown significant underestimation with this method when the T wave is positive. In these studies, the modified Wyatt method provided better correlation with monophasic action potential duration (MAP 90) than the original Wyatt method, so the former approach continues to be implemented to define the local repolarization in humans (10).…”

Parasympathetic dysfunction and antiarrhythmic effect of vagal nerve stimulation following myocardial infarction

“…ARI was calculated by subtracting activation time from repolarization time. ARI has been previously validated and shown to correlate well with local action potential duration (56)(57)(58)(59). In addition, it serves as a method of recording action potential duration without causing myocardial injury.…”

Mechanisms of Ventricular Fibrillation in Canine Models of Congestive Heart Failure and Ischemia Assessed by In Vivo Noncontact Mapping

“…The methodology has been described extensively and validated previously. 18,21,22 A multielectrode basket catheter 23 was used to record 32 unipolar contact electrograms from the RV simultaneously with the noncontact mapping signals. In addition to the endocardial mapping signals from the RV and LV, wide bipole signals were recorded between the distal electrodes of the standard EP catheters each placed in the RV free wall and left atrial free wall.…”