The QT and Tp-e intervals in left and right chest leads: comparison between patients with systemic and pulmonary hypertension.

Abstract: Background: Action potential duration in the right ventricle is normally shorter than that in the left. We tested the hypothesis that there may be intrinsic differences in the QT and T_p-e (an interval from the peak to the end of the T wave) intervals between the left and right chest leads that can be exaggerated by systemic hypertension but attenuated by pulmonary hypertension in humans. Methods: Electrocardiograms in the left (V₄L-V₆L) and right (V₄R-V₆R) chest leads were obtained in 40 healthy individuals, 29 patients with systemic hypertension and left ventricular hypertrophy, and 15 patients with pulmonary hypertension. Results: In healthy individuals, the corrected QT (QTc) and corrected T_p-e [T_(p-e)c] intervals were 421 ± 5 and 86 ± 3 milliseconds in V₄L through V₆L, respectively, significantly longer than those recorded from V₄R through V₆R (383 ± 5 and 62 ± 4 milliseconds, respectively; P < .01). Left ventricular hypertrophy prolonged the QTc interval in V₄L through V₆L (456 ± 5 milliseconds), exaggerating the difference in the QTc interval between the left and right chest leads (61 ± 4 vs 40 ± 3 milliseconds in healthy control subjects; P < .01). Left ventricular hypertrophy also resulted in a small but significant increase in the T_(p-e)c interval in V₄L through V₆L (97 ± 3 vs 86 ± 3 milliseconds in control subjects; P < .05) but exerted no significant effect on the T_(p-e)c interval in the right. In contrast, pulmonary hypertension lengthened the QTc interval in the right chest leads, reducing the difference in the QTc interval between the left and right chest leads (3 ± 8 vs 40 ± 3 milliseconds in control subjects; P < .01). Conclusions: There are intrinsic differences in the QT and T_p-e intervals between V₄L-V₆L and V₄R-V₆R that are significantly amplified by systemic hypertension but markedly attenuated by pulmonary hypertension. [Copyright &y& Elsevier]