Showing papers by "Eugene Braunwald published in 1990"

Ventricular remodeling after myocardial infarction. Experimental observations and clinical implications.

Abstract: An acute myocardial infarction, particularly one that is large and transmural, can produce alterations in the topography of both the infarcted and noninfarcted regions of the ventricle. This remodeling can importantly affect the function of the ventricle and the prognosis for survival. In the early period, infarct expansion has been recognized by echocardiography as a lengthening of the noncontractile region. The noninfarcted region also undergoes an important lengthening that is consistent with a secondary volume-overload hypertrophy and that can be progressive. The extent of ventricular enlargement after infarction is related to the magnitude of the initial damage to the myocardium and, although an increase in cavity size tends to restore stroke volume despite a persistently depressed ejection fraction, ventricular dilation has been associated with a reduction in survival. The process of ventricular enlargement can be influenced by three interdependent factors, that is, infarct size, infarct healing, and ventricular wall stresses. A most effective way to prevent or minimize the increase in ventricular size after infarction and the consequent adverse effect on prognosis is to limit the initial insult. Acute reperfusion therapy has been consistently shown to result in a reduction in ventricular volume. The reestablishment of blood flow to the infarcted region, even beyond the time frame for myocyte salvage, has beneficial effects in attenuating ventricular enlargement. The process of scarification can be interfered with during the acute infarct period by the administration of glucocorticosteroids and nonsteroidal antiinflammatory agents, which result in thinner infarcts and greater degrees of infarct expansion. Modification of distending or deforming forces can importantly influence ventricular enlargement. Even short-term augmentations in afterload have deleterious long-term effects on ventricular topography. Conversely, judicious use of nitroglycerin seems to be associated with an attenuation of infarct expansion and long-term improvement in clinical outcome. Long-term therapy with an angiotensin converting enzyme inhibitor can favorably alter the loading conditions on the left ventricle and reduce progressive ventricular enlargement as demonstrated in both experimental and clinical studies. With the former therapy, this attenuation of ventricular enlargement was associated with a prolongation in survival. The long-term clinical consequences of long-term angiotensin converting enzyme inhibitor therapy after myocardial infarction is currently being evaluated. Although studies directed at attenuating left ventricular remodeling after infarction are in the early stages, it does seem that this will be an important area in which future research might improve long-term outcome after infarction.

Comparison of coronary and myocardial morphologic findings in patients with and without thrombolytic therapy during fatal first acute myocardial infarction

Abstract: The hearts of 61 patients (39 men aged 64 +/- 11 years) who died from 5 hours to 42 days (median 3 days) after a fatal first acute myocardial infarction without having undergone percutaneous transluminal coronary angioplasty or coronary bypass surgery were studied to compare clinical and cardiac morphologic features of patients receiving thrombolytic therapy with tissue-plasminogen activator (t-PA) to those not receiving thrombolytic therapy. Comparison of findings in the 23 patients who received t-PA intravenously 3 +/- 1 hours after onset of symptoms, with the 38 patients who did not, showed similar baseline characteristics with respect to: age, gender, history of hypertension; location of the infarct; heart weight; severity and numbers of coronary arteries narrowed; and frequencies of plaque rupture, plaque hemorrhage and coronary thrombi. Among the patients receiving t-PA, however, there was a greater frequency of platelet-rich (fibrin-poor) thrombi in the infarct-related coronary arteries (6 of 11 vs 4 of 25 thrombi; p = 0.02), more nonocclusive than occlusive thrombi (6 of 11 vs 4 of 25 thrombi; p = 0.02), and a lower frequency of myocardial rupture (left ventricular free wall or ventricular septum) (5 of 23 [22%] vs 18 of 38 [46%]; p = 0.045).

Optimizing thrombolytic therapy of acute myocardial infarction.

Abstract: M ajor advances in medicine rarely burst upon the scene fully developed and immediately applicable to a large majority of the potential beneficiaries. More commonly, after the initial studies in which the clinical value of a new discovery is demonstrated, there is a period during which the precise indications are established and \"tooling up\" occurs. For example, following the development of the coronary care unit, coronary artery bypass grafting, and percutaneous transluminal coronary angioplasty, it took several years to work out the precise clinical indications for the use of each of these modalities, for the training of personnel, and for the manufacture of the equipment necessary for widespread application. Thrombolytic therapy of acute myocardial infarction has now reached the stage at which the clinical value of the technique for many patients has been clearly established and is no longer in dispute,12 and it is now undergoing clinical application. However, making this form of treatment available to all or nearly all patients with myocardial infarction who can benefit from it is now an important challenge.

Cardiac morphologic findings in patients with acute myocardial infarction treated with recombinant tissue plasminogen activator.

Abstract: The hearts of 52 patients (aged 61 +/- 11 years, 34 men) who participated in the Thrombolysis in Myocardial Infarction (TIMI) Study and died from 5 hours to 260 days (median 2.7 days) after onset of chest pain were studied. One heart became available at cardiac transplantation. Of the 52 patients, 38 received recombinant tissue plasminogen activator (rt-PA) not followed by percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG). Eight had PTCA, and 6 had CABG. The infarcts were hemorrhagic by gross inspection (with histologic confirmation) in 23 patients, nonhemorrhagic in 20, not visible grossly in 2 and, in 7, there was no myocardial necrosis by either gross or histologic examination.(ABSTRACT TRUNCATED AT 250 WORDS)