Kazuki Iwata

Relationship between QRS duration and repolarization abnormalities in patients with wolff-parkinson-white syndrome

Marked T wave abnormalities in 12-lead electrocardiograms often appear after radiofrequency ablation in patients with Wolff-Parkinson-White (WPW) syndrome. Durations of the QRS complex before ablation have been reported to be significantly greater in patients with repolarization abnormalities after ablation than in those with normal repolarization. However, there has been no report concerning the relationship between QRS duration and repolarization abnormalities before ablation. It has been reported that QRST isointegral maps are dependent on local cellular repolarization properties but largely independent of activation sequence, and that they provide quantitative information about repolarization abnormalities. Isointegral maps were constructed from data recorded in 34 patients with WPW syndrome and QRS durations of 0.1 second or longer (21 patients with left-sided accessory pathways and 13 with right-sided pathways) in order to investigate the relationship between QRS duration and abnormalities in repolarization properties during preexcitation. Body surface ECGs were recorded with an 87-lead system at a sampling interval of 1 ms. The QRST values (mean +/- 2SD) from 607 normal individuals were taken to represent the normal range. The area with abnormally low QRST values was designated as the -2SD area and the sum of the QRST values (sigma QRST) in this area was calculated. The QRS duration was found to be significantly related to sigma QRST. These results demonstrate that the patients with WPW syndrome had abnormalities in local repolarization properties that were significantly related to QRS duration during preexcitation. The degree of preexcitation may be important in producing these abnormalities in patients with manifest WPW syndrome. This may result in T wave abnormalities after ablation of the accessory pathway attributable to cardiac memory.

Inverse relation of body-surface activation-recovery interval and recovery time to activation time in normal subjects: stronger correlation and more heterogeneous distribution in activation-recovery interval than in recovery time.

The activation‐recovery interval (ARI), measured directly from the myocardium, has shown a good correlation with the action potential duration (APD) in experiments. APD has been reported to be inversely related to the activation time (AT). However, no studies have examined the correlation between the body‐surface ARI and AT in normal subjects. Fifty normal subjects (25 men and 25 women) were studied to elucidate the relationship between the body‐surface ARI and AT. The body‐surface AT was defined as the duration between the QRS onset and the minimum dV/dt of the QRS wave, and ARI as the interval between the minimum dV/dt of the QRS wave and the maximum dV/dt of the T wave in each lead of an 87 unipolar lead system. We also measured the recovery time (RT) defined as the duration between the QRS onset and the maximum dV/dt of the T wave. ARI was inversely correlated with AT (r = ‐0.73). RT was also inversely correlated with AT (r = ‐0.61), however, RT had a less heterogeneous distribution than ARI (148 ms vs 159 ms). There were no differences between male and female subjects in the relation between ARI and RT or in the body‐surface distribution of ARI and RT. These findings suggest that the body‐surface ARI may reflect recovery properties over the cardiac surface and that APD may distribute inhomogsneously over the human cardiac surface with a longer RT over an area with a shorter AT. ARI calculated from body‐surface ECG may be a useful noninvasive and repeatedly measurable estimate of APD.