Natural history of contractile abnormalities after acute myocardial infarction in man: severity and response to nitroglycerin as a function of time

The natural history of contraction abnormalities and their response after acute myocardial infarction in man were studied using radionuclide angiography. Sixteen patients were studied before and after sublingual nitroglycerin within 24 hours, 5-7 days and 4-6 weeks after the onset of chest pain. Within 24 hours, central chord shortening in the zone of infarction was reduced to 13.1 +/- 9.8%, but improved 27.2 +/- 18.4% (p less than 0.001) after nitroglycerin. After 5-7 days, central chord shortening improved similarly, but less markedly, from 12.9 +/- 9.2% to 24.4 +/- 13.2% (p less than 0.001). After nitroglycerin 4--6 weeks after the acute myocardial infarction, the central chord showed no response to nitroglycerin; it was 13.9 +/- 10.9% before and 13.4 +/- 2.5% after nitroglycerin. Changes in the lateral chords paralleled changes in the central chords in the three studies. Nonischemic zone improvement after nitroglycerin in all three studies. Global ejection fraction improved and end-diastolic and end-systolic volumes decreased in all three studies after nitroglycerin. These data indicate that after acute myocardial infarction, there is a significant reduction in hemiaxis shortening in the central and lateral chords that remains essentially unchanged over 4-6 weeks. However, the asynergic ischemic area improves considerably after nitroglycerin within 24 hours and 5-7 days, but fails to improve after 6 weeks.

Effect of progressive pressure reduction with nitroprusside on acute myocardial infarction in humans. Determination of optimal afterload

The effect of nitroprusside-induced progressive systemic pressure reduction on segmental function in patients with acute myocardial infarction is unclear. In 15 patients control radionuclide angiograms were obtained at control within 24 hours of the onset of chest pain and during the administration of intravenous nitroprusside. The initial study showed a significant reduction in hemiaxial shortening in the zone of myocardial infarction. With nitroprusside, systolic pressure was decreased from a mean of 133 mm Hg to an intermediate pressure of 116 mm Hg (p less than 0.001). At this pressure central chord hemiaxial shortening increased in eight of 15 zones with an average increase from 10.1% to 27.8% (p less than 0.006). After further reduction in pressure to 87.1 mm Hg, an additional five of the seven remaining zones of acute infarction improved. However, of the eight zones that improved initially, four deteriorated at the lowest pressure. Similar changes were seen in the lateral chords. Thus, afterload reduction can improve hemiaxial shortening of the infarct zone. However, the degree of reduction in systemic pressure must be individualized to avoid adverse effects of an excessive decrease in perfusion pressure.

Oral carcinoma in the first three decades of life

No abstract available.