The Annals of Thoracic Surgery, Vol 43, 478-483, Copyright © 1987 by The Society of Thoracic Surgeons
Preload dependence of right ventricular blood flow: I. The normal right ventricle
CM Dyke, LA Brunsting, DR Salter, CE Murphy, A Abd-Elfattah and AS Wechsler
Right ventricular (RV) failure is commonly treated with intravascular
volume expansion to increase the RV-left atrial pressure gradient and
improve left-sided filling. As RV pressure rises, chamber distention occurs
and wall tension increases. These studies were designed to determine if
increased wall tension might impede RV myocardial blood flow in the normal
canine right ventricle and thus contribute to RV failure. Hemodynamic data,
the septal-RV free wall dimension, and RV myocardial blood flow were
obtained at low and high levels of preload and in both the autoregulated
and vasodilated (adenosine, 2 mg per kilogram of body weight per minute)
states. Elevated filling pressure decreased RV myocardial blood flow in
both the autoregulated (0.85 +/- 0.18 to 0.67 +/- 0.15 ml/min/gm; p less
than .05) and vasodilated (2.25 +/- 0.50 to 0.85 +/- 0.25 ml/min/gm; p less
than .05) states but did not change the transmural distribution of blood
flow to the right ventricle. Vasodilator reserve was markedly impaired in
the high- preload state. These observations suggest that preload is an
important determinant of RV myocardial blood flow. Volume loading to treat
RV dysfunction may be limited by impairment of RV myocardial blood flow.