Experimental study
Regional myocardial volume alterations induced by brief repeated coronary occlusion in conscious dogs

https://doi.org/10.1016/0735-1097(88)90475-5Get rights and content
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Abstract

The purpose of this study was to evaluate whether brief repeated coronary occlusions induce changes in regional myocardial geometry at rest. Five conscious dogs were instrumented for the measurement of subendocardial segment length and transmural wall thickness in the ischemic area, subendocardial segment length in the normally perfused area, coronary flow and left ventricular pressure. After recovery from surgery, 180 (mean) 2 min coronary occlusions were given over a period of 20 days. The heart rate at rest, left ventricular peak systolic and end-diastolic pressures and peak positive first derivative of left ventricular pressure (dP/dt) remained unchanged throughout the experiment.

In the normal area, the end-diastolic segment length at rest did not change significantly. By contrast, in the ischemic area, at 14 days after the initiation of repeated coronary occlusion, the end-diastolic regional crosssectional area (product of segment length and wall thickness) at rest had increased by 9.7% (p < 0.05); thereafter it decreased to 6.5% (p < 0.05) above the value at rest before repeated occlusion despite an additional 6 days of coronary occlusions. At 10 days after the Interruption of repeated occlusion, this value had regressed to 4.3% (p = NS) above control. These findings suggest the occurrence of regional myocardial hypertrophy confined to the ischemic area in response to the periodic ischemic stimulus.

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This study was supported by Grant HL 32800 from the National Heart, Lung, and Blood Institute, National Institutes of Health. Bethesda, Maryland.