運動負荷とQ-Tc

Effects of exercise for QT interval

　以前より，運動負荷心電図によるS-T,R波，P波の変化については数多くの報告がみられる^1〜3）。しかし，Q-T時間の変化についての検討はほとんど見られない。Q-T時間の延長は，相対的不応期の延長につながり，心室性不整脈の出現や急死と深い関係がある。われわれは，虚血性心臓病における，安静時およびMaster運動負荷試験によるQ-T時間の変化につぎ若干の知見を得たので報告する。

We investigated the alterations of QT interval during exercise. The QT interval was measured from the standard 12-lead ECG and corrected for heart rate (QTc) using Buzett's formula. The 107 patients were studied, 34 with myocardial infarction, 30 with angina effort and 43 without coronary artery disease. All patients underwent Master's stress test and coronary angiography using the femoral approach. The QTc at rest was 444±4.82 (M±SE) msec in myocardial infarction and it was significantly longer (p<0.001) than 413±2.99 msec in angina group, 411±2.49 msec in normal group. Prolongation of QTc was noted in angina and normal group with excercise. But QTc in myocardial infarction fails to prolong with exercise.The QTc was 436±4.57 msec during angina attack and it was longer (p<0.001) than 413±2.99 msec at rest. The mechanism of QTc prolongation is not clear. In a recent study, cardiac sympathetic nerve may play a role of QTc prolongation.