Pulmonary function differences in patients with chronic right heart failure secondary to pulmonary arterial hypertension and chronic left heart failure

BACKGROUND Pulmonary abnormalities are found in both chronic heart failure (CHF) and pulmonary arterial hypertension (PAH). The differences of pulmonary function in chronic left heart failure and chronic right heart failure are not fully understood. MATERIAL AND METHODS We evaluated 120 patients with stable CHF (60 with chronic left heart failure and 60 with chronic right heart failure). All patients had pulmonary function testing, including pulmonary function testing at rest and incremental cardiopulmonary exercise testing (CPX). RESULTS Patients with right heart failure had a significantly lower end-tidal partial pressure of CO2 (PetCO2), higher end-tidal partial pressure of O2 (PetO2) and minute ventilation/CO2 production (VE/VCO2) at rest. Patients with right heart failure had a lower peak PetCO2, and a higher peak dead space volume/tidal volume (VD/VT) ratio, peak PetO2, peak VE/VCO2, and VE/VCO2 slope during exercise. Patients with right heart failure had more changes in ∆PetCO2 and ∆VE/VCO2, from rest to exercise. CONCLUSIONS Patients with right heart failure had worse pulmonary function at rest and exercise, which was due to severe ventilation/perfusion (V/Q) mismatching, severe ventilation inefficiency, and gas exchange abnormality.