907-107 Collateral Flow Influences the Myocardial Collagen Content Early After Acute Myocardial Infarction

• Published in: Journal of the American College of Cardiology 1995-02, Vol.25 (2), p.59A-59A
• Main Authors: Gonçalves, Lino, Pacheco, Maria, Silvéira, Maria, Botelho, Maria, Santos, Ana, Sousa, Pedro, Cabrita, Silverio, Beja, Matos, de Lima, João J. Pedroso, Providência, Luís A.
• Format: Article
• Language: English
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/0735-1097(95)91699-X

Collateral flow, even when developed after acute myocardial infarction (AMI), prevents the progressive left ventricular dilation and remodeling after AMI. independent of infarct size reduction. The mechanisms underlying this situation are unknown. The purpose of this study was to examine the hypothesis that collateral flow influences the collagen volume fraction in the necrotic area. We studied ten mongrel dogs with AMI. The dogs were sacrificed five days later. The hearts were arrested in diastole, perfusion fixed, and sliced. Sections from each slice were taken from the center of the infarct zone, and stained with hematoxylin and eosin or picrosírius red. Collagen analysis was performed using polarized light microscopy. Using a random sampling morphometric technique, the relative density of collagen, was calculated. To confirm the results from morphometry fresh transmural myocardial tissue samples were also taken from the center of the infarct zone, and processed for measurement of hydroxiproline content (μg/mg dry tissue weight). Myocardial blood flow was measured with 99mTc labeled microspheres(10μLm). Collagen deposition was analyzed in relation to baseline variables including the anatomic area at risk, necrosis, collateral blood flow and hemodynamic determinants of myocardial metabolic demand (heart rate, blood pressure, rate pressure product). Stepwise multivariate regression analysis showed that only collateral blood flow contributed to the model predicting an increase in myocardial collagen content (r2=0.89) P =0.01. In conclusion, we found that after a myocardial infarction a rich collateral flow to the necrotic area is associated with an increase in the collagen content. This is probably one of the reasons why after AMI, collateral flow has a positive influence on ventricular remodeling, independent of infarct size reduction. [Display omitted]