We sought to explore the pulmonary haemodynamic changes in rheumatic mitral stenosis patients with secondary pulmonary hypertension.

The pulmonary artery resistance and compliance of 35 patients with rheumatic mitral stenosis and 12 controls without cardiopulmonary vascular disease were evaluated by using an improved method, which is based on making calculations with parameters obtained from right heart catheterisation.

The results are as follows: (1) pulmonary artery compliance in patients with secondary pulmonary hypertension was significantly lower than that of the control group (P<0.01); (2) linear correlation analyses showed that preoperative mean pulmonary artery pressure (mPAP) closely correlated with zero-pressure compliance in the mitral stenosis group (r=−0.745, P<0.05); (3) PAP and pulmonary vascular resistance decreased significantly in both groups with mitral stenosis after infusing 0.5μgkg⁻¹min⁻¹ of sodium nitroprusside (P<0.01). The pulmonary zero pressure compliance and mean pressure compliance increased significantly in the group with mild pulmonary hypertension; whereas in the severe group, the mean compliance changed with significance as the mPAP decreased (1.51±0.59 vs 1.81±0.77ml/mmHg), however no significant change occurred in the pulmonary zero pressure compliance (2.35±1.24ml/mmHg vs. 2.24±1.53ml/mmHg, P>0.05)

The walls of pulmonary artery vessels in patients with pulmonary hypertension secondary to rheumatic mitral stenosis appeared to be remodelled by varying degrees as indicated by their haemodynamic properties. Structural remodelling may be a factor affecting preoperative pulmonary artery pressure. Mitral stenosis patients with severe pulmonary hypertension have significantly lower responses to sodium nitroprusside possibly due to aggradation and deposition of collagen in the artery walls, decreasing constriction and dilation, or atrophy of smooth muscle cells.