[Influence of pulmonary hemodynamics on right ventricular ejection fraction in chronic obstructive pulmonary disease]

Right ventricular dysfunction is common in patients with chronic obstructive pulmonary disease. Right ventricular function might be influenced by the afterload, which depends on pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR). To evaluate the influence of the right ventricular afterload on right ventricular performance, we investigated 30 patients with chronic obstructive pulmonary disease without clinical signs or history of left heart failure or coronary heart disease. The study includes lung function tests, analysis of blood gases and right heart catheterisation. RV function was assessed by a thermodilution technique using a pulmonary artery catheter equipped with a rapid response thermistor (produced by Baxter, USA). There are 9 patients with normal, 12 with latent and 9 with fixed pulmonary hypertension. Median RVEF was measured to be 33.3% (19-44%). There was a significant correlation between RVEF and PAP (r = -0.66; p < 0.0001) and RVEF and PVR (r = -0.54; p < 0.0018). RVEF was not directly influenced by lungfunction or pulmonary capillary wedge pressure (PCWP). Under treadmill exercise RVEF and cardiac index increased without a change of PCWP. A low RVEF at rest seems to be a predictive value for a reduced exercise capacity. A reduced RVEF has a predictive value of pulmonary hypertension with a sensitivity of 66% in patients with unstable and 89% in patients with lasting pulmonary hypertension. In a subgroup of 6 cases treadmill exercise led to a RVEF decrease. These patients showed no difference in afterload, blood gases or lung function-tests compared with the total group. In conclusion, right ventricular ejection fraction seems to be influenced by PVR and PAP which determinate the right ventricular afterload. The validity of the method depends on the severity of pulmonary hypertension, and hence measurement of RVEF might not provide a reliable estimation of pulmonary arterial pressure in patients suffering from mild to moderate pulmonary hypertension.