Radionuclide analysis of sequential changes in central circulatory volumes: inspiration, expiration, and the Valsalva maneuver

We evaluated the effects of deep inspiration, expiration, and the Valsalva maneuver on composite cardiac (left and right ventricular) and pulmonary volumes using equilibrium radionuclide angiography in 15 adult males without left or right ventricular dysfunction. The additional effects of nitroglycerin during these maneuvers were also examined. Midexpiration was used as the control point and data analyzed as a ratio (e.g., inspiration counts divided by midexpiration counts). Left ventricular volume (LVV) declined with inspiration (0.90 +/- 0.08 inspiratory/midexpiration) and with the Valsalva maneuver (0.89 +/- 0.08 Valsalva/midexpiration). Similar changes occurred after nitroglycerin, although the effects of the Valsalva maneuver on LVV were exaggerated when compared to the initial control intervention (0.79 +/- 0.09, vs 0.88 +/- 0.07, p less than .05). Right ventricular volume (RVV) increased with inspiration and decreased with the Valsalva maneuver; these changes were similar after nitroglycerin. Pulmonary blood volume (PBV) was greater with inspiration than expiration (1.02 +/- 0.10 vs 0.95 +/- 0.05, p less than .05), and was reduced with the Valsalva maneuver. Nitroglycerin reduced significantly all volumes and the reduction was similar for each compartment when respiratory interventions were compared. We conclude that blood pool imaging can be used to characterize abrupt fluxes in central circulatory volumes. Blood pool imaging of the heart and lungs should be considered a technique for monitoring the distribution of blood volume during acute pharmacologic and physiologic alterations.