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Reduced subendocardial myocardial perfusion as one mechanism for congestive heart failure
1Department of Medicine, Harvard Medical School, Brigham & Women's Hospital, Boston, Massachusetts.
Insights
Heart failure may stem from insufficient blood flow to the heart muscle. Studies show impaired coronary vasodilation in hypertrophied hearts, particularly affecting the subendocardium during stress.
Area of Science:
- Cardiovascular Physiology
- Heart Failure Pathophysiology
Background:
- Cardiac hypertrophy can lead to heart failure.
- Myocardial perfusion is critical for maintaining cardiac function.
Purpose of the Study:
- To investigate the role of myocardial perfusion in the decompensation of hypertrophied hearts.
- To examine coronary vasodilator responses in experimental models of cardiac hypertrophy and failure.
Main Methods:
- Utilized experimental models of right and left ventricular hypertrophy and failure.
- Assessed reactive hyperemia following coronary artery occlusion.
- Measured vasodilation in response to adenosine.
- Evaluated endocardial/epicardial blood flow ratios under baseline and stress conditions.
Main Results:
- Blunted reactive hyperemic responses were observed in hypertrophied and failing hearts.
- Reduced vasodilation to adenosine occurred when coronary reserve was most impaired in the subendocardium.
- The normal coronary vasodilator response during exercise was blunted.
- Endocardial/epicardial blood flow ratios decreased further with stress in heart failure.
Conclusions:
- Inadequate myocardial perfusion, especially to the subendocardium, is a potential mechanism for the decompensation of hypertrophied hearts to failure.
- Impaired coronary vasodilator reserve contributes to heart failure progression.
Abstract:
One mechanism for the eventual decompensation of the hypertrophied to the failing heart may involve inadequate myocardial perfusion. In support of this concept are studies in experimental models of both right and left ventricular hypertrophy and failure. These studies demonstrate blunted reactive hyperemic responses to brief periods of coronary artery occlusion, and reduced vasodilation in response to adenosine, when the most severe impairment in coronary reserve occurs in the subendocardium. During exercise, in the hypertrophied and failing heart, the normal coronary vasodilator response is also blunted. Although endocardial/epicardial blood flow ratios are depressed in congestive heart failure under baseline conditions, the endocardial/epicardial ratio decreases further with stress, e.g., during either adenosine or reactive hyperemia. These data suggest that one mechanism of failure of the severely hypertrophied heart may involve inadequate coronary perfusion to the subendocardium.