Influence of verapamil and oxygen on pulmonary hypertension and right ventricular function.

The study was designed to elucidate verapamil action on the pulmonary vascular bed and right ventricular function and to compare it with the effect of oxygen in view of the fact that calcium antagonists can attenuate hypoxic pulmonary vasoconstriction. 16 patients with secondary, and 4 with primary, pulmonary hypertension and with a mean pulmonary artery systolic pressure of 68.6 +/- 28.7 mmHg were examined. After determination of initial haemodynamic values, the oxygen test (OT) was performed; later on, when the values returned to the initial ones, verapamil was infused into pulmonary artery. Measurements were carried out in the 10th min of OT and until the 30th min after verapamil. While verapamil decreased statistically significantly pulmonary artery pressures and resistances, it did not deteriorate right ventricular systolic function, although it lowered its stiffness significantly. The effect of oxygen was comparable with that of verapamil though the magnitude of changes was smaller.