Influence of isosorbide dinitrate (ISDN) on compliance of the pulmonary venous system

Irreversible poor pulmonary venous compliance can worsen the natural course of patients with high pulmonary capillary wedge pressure, especially those with mitral stenosis, but nitrates (isosorbide dinitrate--ISDN), which have venodilatory properties, could increase this compliance in most patients. The aim of this study was to assess the hemodynamic effects of ISDN in patients with mitral stenosis, with special emphasis on the pulmonary venous compliance. Pulmonary venous compliance was estimated according to the Hirakawa equation (dV/dp = 0.4 x k2 x sV/(v-d)) in 39 patients with mitral stenosis during preoperative right heart catheterization with Vygon 5155-180 thermodilution catheters at rest and during exercise (25 W) in the supine position. This procedure was repeated after the application of 3.75 mg of Iso-Mack spray. Overall, ISDN increased pulmonary venous compliance significantly both at rest and during exercise (6.0 to 7.5 ml/mmHg and 6.0 to 7.6 ml/mmHg, respectively). The patients were divided into two groups according to their level of ISDN response; those with a good response of an increase of 15% or more in pulmonary venous compliance (Group I), and those with an increase of less than 15% (Group II). There were significant differences between these two groups in stroke volume index and heart rate. In Group I, while the mean right atrial pressure, mean pulmonary artery pressure and mean pulmonary wedge pressure all decreased significantly, there was a simultaneous insignificant decrease in the stroke volume index and an also insignificant increase in the heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)