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Myocardial microvascular function during acute coronary artery stenosis: effect of hypertension and

Xiang-Yang Zhu1, Elena Daghini, Alejandro R Chade

  • 1Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.

Cardiovascular Research
|May 9, 2009
PubMed

Insights

Early atherosclerosis risk factors like high cholesterol and hypertension protect the heart during coronary artery obstruction by promoting new microvessels. These microvessels may act as recruitable coronary collateral arteries (CCA).

Area of Science:

  • Cardiovascular Research
  • Atherosclerosis Pathophysiology
  • Myocardial Ischemia

Background:

  • Coronary collateral arteries (CCA) are crucial for reducing cardiovascular events.
  • Early atherosclerosis may involve microvessel proliferation offering myocardial protection.
  • Acute subtotal coronary artery obstruction (CAO) is a critical clinical event.

Purpose of the Study:

  • To test if proliferating microvessels in early atherosclerosis protect the heart during acute subtotal CAO.
  • To investigate the role of high-cholesterol (HC) diet and renovascular hypertension (HTN) in this protective mechanism.
  • To determine if these microvessels function as recruitable CCA.

Main Methods:

  • Induction of acute left anterior descending CAO in pigs using a balloon catheter.
  • Dietary interventions: 12 weeks of HC diet, HTN, or normal control.
  • In vivo assessment using electron beam computed tomography (CT) for cardiac structure and perfusion.
  • Ex vivo micro-CT for intra-myocardial microvessel evaluation and immunoblotting for growth factors.

Main Results:

  • Myocardial perfusion decline during CAO was attenuated in HC and abolished in HTN pigs compared to normal controls.
  • CAO-induced increase in anterior wall microvascular permeability was significantly attenuated in HC and HTN groups.
  • Elevated microvascular (<200 microm) spatial density and increased myocardial growth factor expression were observed in HC and HTN groups.

Conclusions:

  • Early exposure to HC and HTN confers protection against myocardial perfusion decrease during acute subtotal CAO.
  • This protection is associated with, and potentially mediated by, pre-emptive development of intra-myocardial microvessels.
  • These newly developed microvessels may function as recruitable coronary collateral arteries (CCA).
Abstract

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