Abstract
The changes in the systolic time intervals (STI) and indices for myocardial oxygen consumption were compared between upright and supine exercise tests, using a treadmill and a bicycle ergometer, respectively. These values were determined not only in a recumbent position but also in an upright position. Although the heart rate of 150/min was used as the point at which to stop the exercises in a healthy group (12 cases), exercises done in the supine position were discontinued in 6 cases before reaching this point, because of fatigue of the lower extremities. In the angina group (20 cases), exercises were continued until anginal pain and/or ischemic ST deviation appeared.
The heart rate at the induction of angina was higher (p < 0.02) in the upright position (119±18/min) than in the recumbent position (110±17/min), indicating a lower threshold in the recumbent position. The percentage increase of the heart rate after the exercises was larger (p < 0.01) in the supine exercises. There was no difference in the healthy group. After doing exercises in both postures systolic blood pressure increased in both groups without any significant differences.
Although the left ventricular ejection time (LVET) was influenced by the heart rate, regression equations relating the heart rate and LVET obtained before and after the exercises were almost the same in both postures. Therefore, LVETc (=LVET/i/RR) proposed by Spodick was used as a corrected value at any heart rate. LEVT immediately after the exercises was longer (p < 0.01) in the angina group than in the control group in both positions, although it was significantly shortened after both exercises in both groups. LVETc was significantly shortened (p < 0.05) by the upright exercise but not in the supine exercise in the control groups, while prolongation was observed (p < 0.01) after both exercises in the angina group.
Pre-ejection period was longer (p < 0.05) in the angina group than in the control group immediately after the supine exercise, indicating the presence of heart failure in the former.
Katz index, double product, triple product and RPQ index, which are regarded as the indices of myocardial 02 consumption, were elevated at the time of exercise in both groups. Katz index and double product immediately after the exercises were higher (p < 0.01) in the upright position than in the supine position in both groups, but triple product and RPQ index did not show any differences in both positions. The percent changes of these indices were significantly lower in the upright exercise than in the supine exercise in the angina group, but there was no significant difference in the control group.
These results indicate that there are some differences between angina pectoris induced by the upright and that induced by the supine exercises.
