The Relation between the Location of Coronary Occlusions and the Occurrence of Shock in Acute Myocardial Infarction

Abstract

T HE mortality rate of shock associated with acute myocardial infarction remains high despite a variety of therapeutic approaches.' The relative importance of reduced cardiac output and reflex factors in the pathogenesis of this grave condition requires clarification if more satisfactory therapeutic measures are to be developed." 2 Support for a reflex mechanism may be found in experimental coronary artery embolization in dogs.3 Microspheres that lodged in the right angle branches of the main stem coronary arteries produced shock, whereas larger or smaller emboli did not. These observations, supported by hemodynamic data, suggested a reflex mechanism with receptors in the right angle branches, which interfered with an adequate compensatory rise in peripheral resistance.The reflex hypothesis has not been verified in man, however. Hemodynamic data or angiographic studies are sparse because of the hazard in performing these studies on precariously ill patients. The present study, utilizing postmortem coronary angiograms, correlates the location of coronary artery occlusions and the occurrence of shock in acute myocardial infarction. MethodMore than 500 postmortem examinations of patients who died of acute myocardial infarction at the Beth Israel Hospital between 1938 and 1955 were reviewed. All had been studied by the coronary injection and dissection

Results of a general hospital coronary care service.

“…Asystole was resistant to pacing on the four occasions that this was attempted. At necropsy the area of infarction was extremely large, though previous detailed pathological studies have shown no close correlation between shock and massive infarction (Rosenberg and Malach, 1960;Kurland et al, 1965). If there is such a correlation it would greatly diminish the chances of therapeutic advance in this direction.…”

Significance of coronary arterial thrombus in transmural acute myocardial infarction. A study of 54 necropsy patients.

“…Others believe that coronary thrombi follow the AMI, resulting from the slowed flow (in the coronary artery) produced by the infarct itself. [5][6][7][8][9][10][11][12][13][14][15][17][18][19][20] This view is based primarily on the absence of coronary thrombi in a significant percentage of patients with fatal transmural AMI,4-10, 13, 14, 18 their absence in patients with fatal coronary events other than transmural AMI (sudden coronary death,15' 34 3 subendocardial infarcts'4 and angina pectoris36), their increased frequency in patients with relatively longer durations of survival after AMI,5' 10 and their high frequency in patients with severe congestive heart failure or cardiogenic shock with AMI.1" 12,37,38 However, surprisingly little detailed information is available on the status of a coronary artery containing a thrombus in patients with fatal AMI.…”

Influence of scar on left ventricular performance at the onset of myocardial ischemia: shock versus heart failure

“…Previous experience in the normal dog has indicated that the initial episode of myocardial ischemia after obstruction of a single main branch of the left coronary near its origin is not associated with substantial hemodynamic abnormality (2,3) unless the left main coronary artery (4) or multiple small branches are occluded (5). Thus, experimental models employing a previously normal myocardium have required embolization of multiple coronary arteries to produce hypotension (6), which does not closely parallel the usual vascular abnormalities associated with clinical myocardial infarction (7). Further, there is evidence in man suggesting that cardiac decompensation or shock during myocardial ischemia is usually associated with previous abnormality of the myocardium (8,9).…”