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Functional infarct expansion, left ventricular dilation and isovolumic relaxation time after coronary occlusion: a
P M Mehta1, K J Alker, R A Kloner
1Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan.
Insights
Early administration of angiotensin-converting enzyme inhibition, like captopril, can reverse left ventricular dilation and reduce infarct expansion after myocardial infarction. This intervention improves early diastolic function in dogs following coronary occlusion.
Area of Science:
- Cardiology
- Pharmacology
- Cardiovascular Physiology
Background:
- Left ventricular dilation and infarct expansion post-myocardial infarction (MI) are linked to increased patient morbidity and mortality.
- Early intervention strategies are crucial for mitigating adverse cardiac remodeling after acute coronary events.
Purpose of the Study:
- To investigate the efficacy of angiotensin-converting enzyme (ACE) inhibition in reversing early left ventricular dilation after acute myocardial infarction.
- To assess the impact of ACE inhibition on diastolic properties of the left ventricle in the acute phase following coronary occlusion.
Main Methods:
- A study involving 20 dogs subjected to 3 hours of coronary occlusion.
- Two-dimensional echocardiography was used to monitor left ventricular dilation and infarct expansion.
- Early diastolic isovolumic relaxation time was measured to assess diastolic function.
Main Results:
- Captopril treatment significantly reduced end-diastolic area 3 hours after occlusion compared to the 30-minute post-occlusion measurement.
- ACE inhibition with captopril mitigated functional infarct expansion.
- While both groups showed worsened diastolic function, captopril's effect on dilation and expansion was notable.
Conclusions:
- Early ACE inhibition can reverse acute left ventricular dilation following myocardial infarction in a canine model.
- Captopril demonstrates a beneficial effect in reducing infarct expansion and improving early diastolic function parameters.
- These findings suggest a potential therapeutic window for ACE inhibitors in the acute management of myocardial infarction to prevent adverse remodeling.
Abstract:
Left ventricular dilation and infarct expansion after acute myocardial infarction are associated with an increased morbidity and mortality. The purpose of this study was to determine whether angiotensin-converting enzyme inhibition could reverse left ventricular dilation and improve the diastolic properties of the left ventricle very early after coronary occlusion. The acute time course of left ventricular dilation and infarct expansion (as determined by two-dimensional echocardiography) and early diastolic isovolumic relaxation time were studied in 20 dogs subjected to 3 h of coronary occlusion. End-diastolic area before occlusion was 8.4 +/- 0.5 and 8.9 +/- 0.7 cm2 (p = NS) in the captopril- and the saline-treated group, respectively. At 30 min after occlusion (pretreatment), end-diastolic area increased to 12.6 +/- 0.8 cm2 in the captopril-treated group (p less than 0.01) and 11.3 +/- 0.9 cm2 (p less than 0.05) in the saline-treated group. Three hours after occlusion and after captopril treatment, end-diastolic area decreased to 9.4 +/- 0.6 cm2 (p less than 0.05 versus 30 min after occlusion), whereas it was unchanged in the saline-treated group. Functional infarct expansion (as assessed by end-systolic anterior to posterior endocardial segment length ratio) occurred early after occlusion, and captopril reduced this expansion. Pretreatment values for early diastolic isovolumic relaxation time increased from 29.1 +/- 2.4 to 50.5 +/- 2.9 ms in captopril-treated dogs (p less than 0.01) and from 34.3 +/- 3.4 to 46.9 +/- 2.7 ms in saline-treated dogs (p less than 0.01) after coronary occlusion, implying a worsening of diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)