Pulmonary artery pressure changes in primary pulmonary hypertension after verapamil and oxygen

A comparison of verapamil (V) and oxygen (O) effect on pulmonary artery pressures (PAP) was carried out in 7 patients with primary pulmonary hypertension (PPH). The changes of PAP were examined, first, after O breathing, then after 10 mg of V infused into the pulmonary artery and, finally, after a second oxygen test repeated at the peak of V action. A 15% decrease in PA systolic and diastolic pressures and total pulmonary resistance after V was used as the criterion of a positive effect. The same increase in these parameters was called a negative effect and the remaining changes were considered absence of an effect. The fact of different reactivity of pulmonary vessels to V was confirmed. In 2 patients with a positive response to V, a decrease in pulmonary pressure after O was observed. In 3 patients, the effect of V on PAP was negative and, in the remaining 2, there was no effect at all. In these 5 patients with PAP and total pulmonary resistance values higher than those of the other 2, oxygen did not decrease PAP either. The comparable in magnitude response of PAP on O and V was observed in individual patients with PPH.