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Effect of intracoronary nitroglycerin administration on phasic pattern and transmural distribution of flow during

M Goto1, A E Flynn, J W Doucette

  • 1Department of Medical Engineering and Systems Cardiology, Kawasaki Medical School, Kurashiki, Japan.

Circulation
|June 1, 1992
PubMed

Insights

Intracoronary nitroglycerin may fail to relieve angina due to increased systolic reverse flow, which impairs subendocardial blood flow despite increased subepicardial flow in ischemic hearts.

Area of Science:

  • Cardiovascular Physiology
  • Pharmacology

Background:

  • Nitroglycerin effectively relieves myocardial ischemia.
  • Intracoronary nitroglycerin can fail to alleviate angina and may negatively impact subendocardial blood flow.
  • Mechanisms underlying these effects require investigation.

Purpose of the Study:

  • To investigate the direct effects of nitroglycerin on coronary circulation in ischemic hearts.
  • To elucidate the relationship between nitroglycerin administration and coronary blood flow patterns.

Main Methods:

  • Utilized an 80-channel, 20-MHz pulsed Doppler ultrasound flowmeter to measure intramyocardial coronary arterial flow.
  • Employed radioactive microspheres to assess transmyocardial blood flow distribution.
  • Studied effects in anesthetized open-chest dogs with induced coronary artery stenosis.

Main Results:

  • Nitroglycerin administration decreased distal systolic and diastolic pressures in stenosed coronary arteries.
  • Nitroglycerin increased diastolic forward flow but significantly augmented systolic reverse flow.
  • Subepicardial flow increased with nitroglycerin, while subendocardial flow did not, leading to a reduced subendocardial-to-subepicardial flow ratio.

Conclusions:

  • Increased systolic reverse flow following intracoronary nitroglycerin is a key factor.
  • This augmented systolic reverse flow is closely linked to the failure of subendocardial blood flow to improve.
  • The findings suggest a potential mechanism for nitroglycerin's limited efficacy in certain ischemic conditions.
Abstract

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