[Left cardiac output curve and pulmonary venous return curve in patients with various heart diseases].

This study assessed the cardiac function of humans by drawing simultaneous left cardiac output and pulmonary venous return curves using radionuclide angiocardiography and right heart catheterization which allows recording of the pressure-flow relationship. Thirty-one subjects with various cardiac diseases were divided into two groups [18 patients with New York Heart Association (NYHA) functional class I and 13 patients with NYHA classes II or III]. Mean pulmonary filling pressure (Pmp) was calculated from the formula of Guyton, using pulmonary arterial compliance which was measured by Reuben's method and pulmonary venous compliance measured as reported previously. On the pressure-flow plane, the down slope of the pulmonary venous return curve was drawn by joining the points of (Pmp, 0) and (mean pulmonary capillary wedge pressure, cardiac output). To construct the cardiac output curve, two levels of lower body negative pressure were used to regulate the venous return to the heart. Pmp and the resistance to pulmonary venous return in NYHA II or III patients were significantly higher than those in NYHA I patients (Pmp: 16.3 +/- 1.5 vs 9.0 +/- 0.5 mmHg, p < 0.01; resistance to pulmonary venous return: 0.75 +/- 0.09 vs 0.43 +/- 0.04 mmHg/l/min, p < 0.01, respectively). The slope of pulmonary venous return curve in NYHA II or III patients was smaller than that in NYHA I patients and the pulmonary venous return curve in NYHA II or III patients shifted rightward. The slope of cardiac output curve in NYHA II or III patients was significantly smaller than that in NYHA I patients. This curve in NYHA II or III patients shifted downward and rightward. These results indicate that simultaneous cardiac output and pulmonary venous return curves may be a useful method for assessing the cardiac function in patients with various heart diseases.