[Decrease in arterial PO2 with captopril administration in secondary pulmonary hypertension and right heart failure]

The ventilation-perfusion match under therapy with captopril was registered in 14 patients with secondary pulmonary hypertension and right heart failure caused by chronic obstructive lung disease. In none of the cases, changes of cranialisation of the perfusion or increasing ventilation-perfusion mismatch was found, but a significant fall in O2 was seen in all patients. This O2-depression is due to decreasing stroke volume of the right to left shunt.