Abnormal Ventricular Function
Segmental ventricular dysfunction associated with acute myocardial infarction (AMI) is the most common form of acute ventricular failure. Pump failure is the most common cause of death in patients with acute myocardial infarction who do not succumb to fatal arrhythmias. Detailed pathologic studies reveal that 37–70% of the left ventricular surface is infarcted in patients hospitalized in coronary care units with shock as the presumed cause of death . The volume of infarcted tissue, rather than its location, determine ventricular function and the ability of the heart to pump adequate amounts of blood to the peripheral circulation. Most patients dying with coronary shock have extremely severe coronary artery disease with extensive involvement of the left coronary artery. In one study, 68% of patients dying with cardiogenic shock had three vessel disease compared to 35% dying with severe heart failure; 80% of both groups had more than 75% occlusion of the left anterior descending coronary artery . Patients dying from AMI without shock, in one study, exhibited well-demarcated infarct zones that comprised less than 30% of the left ventricle while those dying with shock had a ragged edge and contained many damaged cells, suggesting continuation of the ischemic process. These patients and those dying with shock in the absence of AMI had scattered islands of necrosis in both ventricles . These studies allow a general understanding of the pathogenesis of coronary atherosclerosis and its consequences: angina, unstable angina, acute myocardial infarction, chronic congestive heart failure and shock.
KeywordsAcute Myocardial Infarction Infarct Size Acute Myocardial Infarction Cardiogenic Shock Coronary Blood Flow
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