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Increased extravascular forces limit endothelium-dependent and -independent coronary vasodilation in congestive heart

J H Traverse1, Y Chen, M Crampton

  • 1Department of Medicine, Division of Cardiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.

Cardiovascular Research
|December 12, 2001
PubMed

Insights

In congestive heart failure (CHF), coronary blood flow (CBF) responses to vasodilators are impaired. However, this impairment is not due to endothelial dysfunction but rather increased extravascular forces limiting blood flow.

Area of Science:

  • Cardiovascular Physiology
  • Heart Failure Pathophysiology
  • Endothelial Function

Background:

  • Endothelium-dependent vasodilation is crucial for regulating coronary blood flow (CBF).
  • Congestive heart failure (CHF) is associated with reduced CBF responses to vasodilators, suggesting endothelial dysfunction.
  • Elevated left ventricular diastolic pressure (LVEDP) in CHF may increase extravascular compressive forces, potentially affecting CBF.

Purpose of the Study:

  • To investigate whether reduced CBF responses in CHF are due to endothelial dysfunction or increased extravascular compressive forces.
  • To differentiate the roles of endothelial function and mechanical compression on coronary vasodilation in a canine model of CHF.

Main Methods:

  • Measured CBF responses to acetylcholine, bradykinin, and sodium nitroprusside in dogs before and after inducing CHF via rapid ventricular pacing.
  • Assessed zero-flow pressure (P(zf)) to estimate extravascular compressive forces and correlated it with LVEDP.
  • Corrected coronary vascular resistance (CVR) for estimated coronary back pressure.

Main Results:

  • CHF significantly decreased CBF and increased heart rate and LVEDP.
  • Responses to endothelium-dependent and independent vasodilators were reduced in CHF.
  • After correcting for elevated LVEDP, the response of CVR to endothelium-dependent vasodilators remained normal, indicating preserved endothelial function.

Conclusions:

  • Endothelium-mediated vasodilation is preserved in CHF.
  • Increased extravascular compressive forces, secondary to elevated LVEDP, limit the increase in CBF in CHF.
  • These findings highlight the mechanical component influencing coronary hemodynamics in heart failure.
Abstract

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