Original study
The genesis of bifid T waves: experimental demonstration in isolated perfused rabbit hearts

https://doi.org/10.1016/0167-5273(84)90240-7Get rights and content

Abstract

In an attempt to elucidate the genesis of bifid T waves, we recorded transmembrane potentials of subepicardial ventricular muscle fibers simultaneously with a bipolar ventricular electrogram in isolated, perfused rabbit hearts, and the timing of the two apices of the T wave (aT1, aT2) was correlated with ventricular repolarization. The following results were obtained. (1) In seven of the nine hearts in which the repolarization process was mapped on the anterior and posterior surfaces of both ventricles, the 80% repolarization times of the left and the right ventricles were scattered around aT1 and aT2, respectively, and their average values closely corresponded to Q-aT1 and Q-aT2 intervals. This suggested that aT1 and aT2 depended on repolarization of the left and the right ventricles, respectively. (2) In one heart, aT1 appeared to reflect repolarization of the posterior ventricular wall, and aT2 that of the anterior wall. (3) In the remaining heart, aT2 coincided with repolarization of the anterobasal portion of the right ventricle, and aT1 that of the remaining portions of the ventricles. Even when ventricular repolarization was modified by low K+, low Ca2+ or procainamide perfusion, or by premature atrial stimulation, the close temporal correlation of the left and right ventricular repolarization with the two apices of the T wave was maintained. Selective cooling of the perfusate in either the left or the right coronary artery resulted in the production of bifid T waves in which aT2 coincided with the delayed repolarization of the cooled ventricle. We conclude that either physiologically or pathologically delayed repolarization in certain portions of the ventricles is most likely the cause of bifid T waves.

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Cited by (8)

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    Citation Excerpt :

    However, the genesis of the electrocardiographic T wave as well as the interpretation of the T wave parameters such as Tpeak–Tend interval remains uncertain. The key role in the determination of the T wave morphology has been ascribed to the transmural (Higuchi and Nakaya, 1984; Yan and Antzelevitch, 1998), apicobasal (Noble and Cohen, 1978) and interventricular (Nishimura et al., 1984) differences in the timing of repolarization. To discern a pivotal gradient responsible for the generation of the T wave, a simultaneous determination of repolarization times across and along the ventricular wall is needed.

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This study was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan.

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