Human pulmonary vascular and venous compliances are reduced before and during left-sided heart failure

Abstract

Human pulmonary vascular and venous compliances were measured in 41 patients with or without left-sided heart failure. Two methods were used. Method 1 was based on analysis of pulmonary capillary wedge (PCW) pressure tracings according to Cv,PCW = (SF/100)(0.075PCW + 0.90)SV/[(v - d)PCW + 1], where Cv,PCW is compliance of pulmonary venous system, SF is systolic fraction of pulmonary venous flow [related to pulmonary 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) relationship and pulmonary vascular compliance (Cvasc) and is based on measurement of pulmonary blood volume (PBV) and its increase with passive elevation of the legs to calculate Cvasc. Assuming the proportion of blood entering pulmonary venous system (in increase of PBV) during passive leg elevation to be 0.8, pulmonary venous compliance (Cv,PBV) was calculated as Cv,PBV = 0.8Cvasc. Cv,PCW correlated fairly closely with Cv,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 possible. Cv,PCW, Cvasc, and Cv,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 shifted 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.

Pulmonary Blood Volume in Mitral Regurgitation in Cavalier King Charles Spaniels

“…Results of the present study indicate that PBV increases in dogs with CHF attributable to MMVD. This is in accordance with previous reports in humans with MMVD 5,7 and ischemic heart disease or left sided heart failure 7,10,23 . PBVI in healthy humans 5,7,9 was in the same range as we found in dogs.…”

“…As MR progresses, the LA remains compliant and can receive the regurgitant blood volume, while increased lymphatic drainage of the pulmonary interstitium protects from pulmonary edema 38 . Only in a very late stage of chronic MR does the stiffness and pressure volume curve shift toward reduced compliance, 23,39–41 causing dramatic increase in PBV (Fig 2). As this is related to concurrent exercise sensitivity to rise in pulmonary blood pressures 33,34 and decrease in alveolar‐capillary membrane conductance 23,41 dogs with MR become at risk of pulmonary edema 23 …”

“…Another source of variation is that PBV varies with work load, 9 venous return and body position, 23 and total blood volume, 7,9 while PTT may vary with variations in regional blood flow in lung lobes caused by gravity and posture, 42–44 the recruitment level of bronchial anastomoses affecting resistance, as well as equal lobe distribution of the tracer 5 and inaccuracy in timing and tightness of the tracer bolus 4,5 . However, we made all FPRNAs in standard positions after resting animals and checking for unbroken boluses.…”

How changes in venous capacitance modulate cardiac output

“…That the capacitance of the pulmonary circulation also decreases was demonstrated in patients by Hirakawa et al [18]. Using a canine model of acute myocardial infarction and heart failure (i.e., microsphere embolization of the left coronary artery to raise LV enddiastolic pressure to 20 mmHg and decrease cardiac output by approximately 50% [39]), we studied the effects heart failure and subsequent treatment with nitroglycerin, enalaprilat, or hydralazine on splanchnic vascular pressure-volume relations [43].…”

Pulmonary Blood Volume Variation Decreases after Myocardial Infarction in Pigs: A Quantitative and Noninvasive MR Imaging Measure of Heart Failure

“…Another approach to assess heart failure is by measuring to what extent reduced left ventricular function leads to an increase in the pulmonary blood volume (PBV) or a decrease in the PBV variation ( 8,9 ). The PBV has been measured as the product of cardiac output and pulmonary transit time (PTT) by using catheter-based dye-indicator techniques ( 10,11 ).…”