| Autor: |
Euler, David E., Scanlon, Patrick J. |
| Zdroj: |
Journal of Electrophysiology; Dec1987, Vol. 1 Issue 6, p490-499, 10p, 2 Charts, 4 Graphs |
| Abstrakt: |
The effects of sympathetic imbalance with left dominance on the electrocardiogram was studied in 12 open-chest anesthetized dogs. Heart rate was held constant (80 or 150 bpm) by right vagal stimulation and atrial pacing. To minimize vagal-sympathetic interactions, the intensity of vagal stimulation was well below the threshold for asystole. Electrocardiographic recordings were obtained from three ECG leads (II, X, and Z). Transection of the right stellate increased the T-wave amplitude in lead II (0.12 ± 0.05 mV, P < 0.05) but had no effect on the QT interval in any lead. Left stellate transection after right transection decreased the T-wave amplitude in lead II (0.13 ± 0.06 mV, P < 0.05) but did not alter the QT interval in any lead. Electrical stimulation of the decentralized left stellate for periods of 3 or 15 sec prolonged the QT interval by as much as 21 msec, but the average changes were considerably less ( < 6.0 msec) and were not significant. Left stellate stimulation for 30 or 60 seconds shortened the QT by as much as 30 msec (P < 0.05). All periods of left stellate stimulation significantly increased the T-wave amplitude in lead II. The electrocardiographic changes induced by sympathetic imbalance were similar at both heart rates. The results do not support the presence of a significant degree of "silent" repolarization after the end of the T wave in the normal canine electrocardiogram. [ABSTRACT FROM AUTHOR] |
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