[Effect of crankshaft position on the results of supine bicycle ergometry testing. Hemodynamics in coronary heart disease patients with normal and impaired left ventricular function].

In 50 patients with coronary heart disease (CHD), 44 of them with a recent history of myocardial infarction, 2 tests on the bicycle-ergometer in the supine position, one with the crankshaft on the level of the examination cot and one with an elevation of the pedal axle by 30 cm were carried out within 30-minute intervals after initiating a flow directed right heart catheterization. In chronological sequence of the recruitment the patients began the ergometric tests alternately with a low or an elevated crank. The applied exercise loads of 50 and 75 watts lasted 3 minutes each. The results show clinically relevant differences between the 2 positions of the pedal axle, being in many cases statistically significant (p less than or equal to 0.01). The pressure of the pulmonary artery (PAP) was elevated at rest and under exercise load when the pedal axle was elevated. The changes of the pressure of the pulmonary artery through the exercise load are greater in patients with an impaired left ventricular function at rest with both pedal axle positions than in patients with a normal left ventricular function. We observed under increasing exercise load a diverging more pronounced elevation of PAP-curves only as a trend in the group of patients with an impaired left ventricular function. Heart rate and systolic blood pressure were on average likewise higher with the elevated crank then with the low one, however the mean variations were considerable. The oxygen saturation of the blood was somewhat less at rest and during exercise load when the pedal axle was elevated compared to the findings with the low pedal axle. The decrease of the oxygen saturation under exercise load was most pronounced in patients having already at rest an impaired left ventricular function. However, with both positions of the pedal axle the behaviour was identical.