AIMS: To investigate the physiological correlates of indices of RV function in a model of chronic pressure overload. METHODS AND RESULTS: Chronic pulmonary hypertension (PH) was induced in piglets by ligation of the left pulmonary artery (PA) followed by weekly embolization of right lower lobe arteries for 5 weeks (the PH group, n = 11). These animals were compared with sham-operated animals (controls, n = 6). At 6 weeks, a subgroup of five PH pigs underwent surgical reperfusion of the left lung and four others were followed until 12 weeks without treatment. Right ventricular function was assessed using echocardiography and conductance catheter measurements. At 6 weeks, mean PA pressure was higher in PH group compared with controls (35 ± 9 vs. 14 ± 2 mmHg, P