Comparative Pulmonary and Systemic Venous Responses to Reduction of Venous Return

Summary Thirty‐five patients with chronic heart disease were subjected to infraxiphisternal lower body negative pressure, a procedure which causes immediate reduction of venous return to the heart. Responses were charted for right atrial and pulmonary capillary venous pressures. Pressure fall (x) did depend on the height of initial supine pressure (Y), but in the presence of pathologically elevated pressures, the responses of the two venous circuits were different: Y = 6.8x ‐ 23 (r.70, P < .01, Sy, x = 8) for right atrial pressures; and Y = 1.8x + 1 (r.88, P < .01, Sy, x = 5) for pulmonary capillary venous pressures. These differences in response suggest that the volume and capacity of the systemic venous system (but not the pulmonary venous system) can be greatly increased in heart failure.