Ventricular suction under zero source pressure for filling.

We quantified ventricular suction flow, volume, and pressure under hydrostatically zero source pressure for filling. A large-bore electromagnetic flow probe was placed in the valve-free mitral annulus of the dog heart that had been excised and was cross circulated with the left atrium widely opened. With the heart immersed in a blood pool, ventricular suction flow and transmural pressure were measured. After a rapid ejection flow [peak: 110 +/- 47 (SD) ml . s-1 . 100 g left ventricle-1] during systole, a slow suction flow (peak: 26 +/- 20 ml . s-1 . 100 g-1) occurred during diastole despite the zero source pressure for filling. Peak transmural pressure during ejection was 6 +/- 3 mmHg, and peak negative transmural pressure during suction was 2 +/- 1 mmHg. Suction volume, which was equal to ejection volume in steady state, was 8 +/- 3 ml/100 g left ventricle. Increases in paced heart rate markedly decreased suction volume by curtailing diastolic filling time. Epinephrine, propranolol, calcium, and verapamil variably changed suction volume, and these effects were primarily accounted for by the accompanied heart rate changes.