HUMAN PULMONARY VASCULAR AND VENOUS COMPLIANCES ARE REDUCED BEFORE AND DURING LEFT-SIDED HEART-FAILURE

Human pulmonary vascular and venous compliances were measured in 41 pa tients with or without left-sided heart failure. Two methods were used . Method 1 was based on analysis of pulmonary capillary wedge (PCW) pr essure tracings according to C-v,C-PCW = (SF/100)(0.075PCW + 0.90)SV/[ (v - d)(PCW) + 1], where C-v,C-PCW is compliance of pulmonary venous s ystem, SF is systolic fraction of pulmonary venous flow [related to pu lmonary capillary wedge pressure (PCW) as SF = 82 - 2.01PCW], (v - d)( PCW) is pulse pressure in PCW position, and SV is stroke volume. The ( 0.075PCW + 0.90) term equals k'', i.e., systolic run-off ratio. Method 2 was used to measure to pulmonary vascular volume-pressure (V-P) rel ationship and pulmonary vascular compliance (C-vasc) and is based on m easurement of pulmonary blood volume (PBV) and its increase with passi ve elevation of the legs to calculate C-vasc. Assuming the proportion of blood entering pulmonary venous system (in increase of PBV) during passive leg elevation to be 0.8, pulmonary venous compliance (C-v,C-PB V) was calculated as C-v,C-PBV = 0.8C(vasc). C-v,C-PCW correlated fair ly closely with C-v,C-PBV (r = 0.81, coefficient of variation = 31%). This fair agreement between two independent methods suggests strongly that both methods may be valid, although other interpretations are pos sible. C-v,C-PCW, C-vasc, and C-v,C-PBV decreased going from New York Heart Association class I to classes II and III. When PBV was plotted vs. PCW, average V-P line for class II patients was flatter and shifte d downward to the right compared with that for class I. This suggests pulmonary vasoconstriction as well as other factors. Average V-P line for class III patients is flatter but not displaced compared with that for class II. Another previously reported series of 50 patients, most of whom had ischemic heart disease, are included in this study.