No abstract

No abstract

An extensive histopathological study was carried out on the hearts of 108 patients with electrocardiographically proven acute myocardial infarction dying after admission to a coronary care unit. The occluded or the narrowest segments of the coronary arteries were examined at intervals of 100 mu using serial sections. Serial sectioning is important in such a study because the pathology of the lumen can vary considerably within a 2 to 3 mm segment. A high incidence (80.3%) of thrombus formation corresponding to the site of infarction was observed. These thrombi occluded the vessel lumen, were usually found proximally in the coronary arteries, and were associated with a ruptured atheromatous plaque in 90.8 per cent of cases. It is postulated that an increase of intraplaque pressure resulting from a honeycomb-like accumulation of foam cells, cholesterol clefts, and blood infiltration through the injured endothelial cells is the cause of rupture of the atheromatous plaque. This rupture into the vessel lumen may precede, and be responsible for, formation of thrombus and the onset of acute myocardial infarction.

No abstract

All patients were studied by cineangiography. Nineteen patients (54.3%) had no significant stenosis of a coronary artery. Sixteen patients (45.7%) were found to have stenosis of more than 50% in one of the major coronary arteries. In nine of the latter, the site of stenosis corresponded with the site of ST elevation on the ECG. These patients all had single vessel disease with good perfusion distal to the stenosis. All of these nine patients underwent an aortocoronary bypass procedure. The site of the stenosis in the other seven patients did not correspond to the site of STsegment elevation on their ECGs and these patients were not treated surgically. Medical TreatmentGlycerol trinitrate (0.3-0.6 mg sublingually) was administered to all patients during an attack. The drug resolved the chest pain, ST-segment elevation disappeared, and arrhythmias were abolished. However, due to its short action and the tendency for attacks to occur in the early morning, the preparation is not useful in preventing attacks.Isosorbide dinitrate (30-120 mg daily) also resolved the chest pain, and if a patient was kept on medication with doses every two hours, even during the sleeping hours, the patient seemed to remain free of symptoms.But routine administration of the drug in this way is not practical. In addition, the efficacy of the drug in patients whose attacks occur only once a month is difficult to assess. However, all patients were kept on 33 Downloaded from http://ahajournals.org by on April 30, 2019