Influence of right atrial pressure pulse on instantaneous vena caval blood flow.

BRAWLEY, ROBERT K., H. NEWLAND OLDHAM, JOHN S. VASKO, R. PETER HENNEY, AND ANDREW G. MORROW. Am. J. Physiol. 2 I I (2) : 347-353. 1g66.-The patterns of instantaneous blood flow in the superior and inferior venae cavae were determined, and related to right atria1 and right ventricular pressure events in 40 dogs. The character of the normal right atria1 pressure pulse was changed by producing tricuspid regurgitation or pulmonary stenosis, and the normal sequence of right atria1 and right ventricular pressure events was altered by the experimental induction of nodal rhythm, atria1 fibrillation, or complete heart block. In all dogs, in the control state and during the various experimental conditions, there was a constant and inverse relationship between the contour of the right atria1 pressure pulse and the instantaneous vena caval flow pattern. The lack of a constant relationship between ventricular systole and the acceleration of caval blood flow during cardiac arrhythmias indicates that the phasic pattern of instantaneous thoracic vena caval flow is determined by right atria1 pressure events which predominate over any effects attributable to “ventricular systolic suction.”