Decrease in coronary blood flow reserve during hyperlipidemia is secondary to an increase in blood viscosity

Se Joong Rim, Howard Leong-Poi, Jonathan Lindner, Kevin Wei, Nicholas G. Fisher, Sanjiv Kaul

Research output: Contribution to journalArticle

77 Scopus citations


Background - During maximal hyperemia, capillaries provide the greatest resistance to flow. A major determinant of capillary resistance is viscosity. We, therefore, hypothesized that abnormal coronary blood flow (CBF) reserve observed during hyperlipidemia is secondary to increased blood viscosity and not abnormal coronary vasomotion. Methods and Results - Maximal hyperemia was induced in 9 dogs using adenosine. Serum triglyceride levels were increased by incremental doses of Intralipid. A good correlation was noted between serum triglyceride levels and blood viscosity (r=0.82). Neither total coronary blood volume nor myocardial blood volume changed with increasing serum triglyceride levels, indicating lack of vasomotion. Myocardial vascular resistance (MVR) increased with increasing triglyceride levels (r=0.84), while hyperemic myocardial blood flow (MBF) decreased (r=-0.64). The decrease in hyperemic MBF was associated with a decrease in blood velocity (r= -0.56). These findings were confirmed with direct intravital microscopic observations in the mice cremaster muscle. Conclusions - Increasing lipid levels in a fully dilated normal coronary bed causes no change in large or small vessel dimensions. Instead, the increase in blood viscosity causes capillary resistance to rise, which attenuates hyperemic CBF. Therefore, the abnormal CBF reserve associated with hyperlipidemia is due to increase blood viscosity and not abnormal vascular function.

Original languageEnglish (US)
Pages (from-to)2704-2709
Number of pages6
Issue number22
Publication statusPublished - Nov 27 2001
Externally publishedYes



  • Lipids
  • Microcirculation
  • Risk factors

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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