Article

The size of myocardial infarction after experimental coronary artery ligation.

Zeitschrift für Kreislaufforschung 09/1969; 58(8):904-9.
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    ABSTRACT: This study was designed to measure early sequential changes in blood flow to ischemic regions after acute coronary occlusion and to determine the relationship between blood flow and the extent of subsequent myocardial infarction. Initial studies were carried out on five dogs which verified using radioisotope-labeled microspheres, 7-10 mum in diameter, to measure changes in blood flow in small myocardial regions after acute coronary artery occlusions. Studies then were carried out on 11 awake dogs chronically prepared with dwelling catheters in the aorta and left atrium and occluders on the left circumflex coronary artery. Microspheres were injected via the left atrial catheter 45 seconds and 2, 6, and 24 hours after complete circumflex coronary occlusion. Six days later myocardial blood flow and the extent of histological infarction were determined for multiple samples from four transmural layers of the entire ischemic zone. Average blood flow to the circumflex region was 0.25 +/- 0.03 (SE), 0.39 +/- 0.05, and 0.53 +/- 0.07 ml/min per g at 45 seconds, and 2, 6, and 24 hours, respectively. When samples from each transmuarl layer were grouped according to increasing ranges of blood flow, the extent of infarction in each layer was inversely related to blood flow. When samples in the same range of blood flow were compared, the extent of infarction in endocardial samples exceeded that in epicardial samples. These data indicate that the relationship between a given measurement of regional blood flow after acute coronary occlusion and the extent of subsequent myocardial infarction varies in different transmural layers and is a function of the time after occlusion that blood flow is measured.
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    ABSTRACT: The left anterior descending coronary artery was proximally ligated in 50 anesthetized dogs. These animals were subdivided into groups studied for infarct size following 45, 90, 120, 240 and 360 minutes of occlusion. Reflow was established after these occlusion times, the animals were allowed to recover and infarct size was determined either by conventional histology or by enzyme-macrohistochemistry. These animals were compared with a group of dogs studied 48 hrs after occlusion without reperfusion. We found that histologic and macrohistochemical infarct size determinations produced identical results. —About 75% of the area-at-risk undergo recrosis following permanent occlusion. Similar infarct sizes were obtained 4 and 6 hours after occlusion. After 90 minutes of occlusion 60% of the area-at-risk are irreversibly damaged. Necrosis begins in the central subendocardial zone, spreads first towards the borders of perfusion and extends toward the subepicardium. 90 minutes after occlusion subendocardial necrosis is complete. This implies that interventions aimed at reducing infarct size should aim at salvaging as much subepicardial muscle as possible. Infarct size as compared to the area-at-risk is larger in apical regions as compared to more basal regions.Der R. interventricularis anterior wurde in 40 Hundeherzen proximal ligiert und nach 45, 90, 120, 240 und 360 Minuten wiederdurchblutet (je eine Gruppe pro Zeitintervall). Zwei Tage nach dem Eingriff wurden die Tiere gettet, die Infarktgre wurde histologisch oder makrohistochemisch (p-NBT) bestimmt und mit der Gre des Perfusionsgebietes der verschlossenen Arterie verglichen. Diese Gruppen wurden verglichen mit Infarktgren nach permanentem Verschlu (48 Studen). Etwa 75% des Perfusionsgebietes sind nach 48 Stunden infarziert. hnlich groe Infarkte wurden nach 4- und 6stndigem Verschlu gefunden.Nach 90mintigem Verschlu waren 60% der Perfusionszone bzw. 80% der endgltigen Infarktgre erreicht. Die Nekrose beginnt im Zentrum des betroffenen Subendokards und breitet sich bis an die Rnder des Perfusionsgebietes aus und schreitet in Richtung Subepikard fort. Die Infarktgre verglichen mit der Perfusionszone der verschlossenen Arterie ist in apikalen Abschnitten grer als in den basalen.
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