The feasibility of double-labeling of acute myocardial infarcts with 113mIn-EDTMP [ethylenediaminetetra(methylene phosphonic acid)] and 99mTc-EDTMP was evaluated. The in vitro distributions of these tracers in acute myocardial infarcts in dogs and their selectivities for infarcted versus noninfarcted myocardium were compared. Both tracers concentrated in acutely infarcted myocardium, and there was excellent correlation between their uptakes (r = 0.88). They also provided complete separation between infarcted and uninfarcted tissue, as checked by histology. Accordingly, these agents show promise for the multiple-labeling of acute myocardial infarcts in experiments to determine the natural course of myocardial infarction and the efficacy of therapy aimed at limiting infarct size. In addition, 113mIn-EDTMP may be useful for serial scintigraphy during the early phase of acute myocardial infarction when the damage may be, at least to some extent, reversible.
The hemodynamic effects of esmolol were evaluated in 12 male patients at rest (mean age, 51 +/- 10 years) undergoing routine cardiac catheterization. Hemodynamic measurements were obtained during baseline (prior to esmolol), at steady state (during an intravenous infusion of esmolol 300 micrograms/kg/min), and at 30 minutes after stopping esmolol (postinfusion). Esmolol produced hemodynamic effects similar to the effects of other beta blockers. Significant reductions in rate-pressure product (mean decrease, 15%), cardiac index (mean decrease, 17%), stroke volume index (mean decrease, 13%), left ventricular stroke work index (mean decrease, 20%), and left ventricular ejection fraction (mean decrease, 18%) were observed. In contrast to other beta blockers, all hemodynamic effects of esmolol had returned to baseline values within 30 minutes after the infusion stopped. One patient exhibited hypotension during the esmolol infusion; this episode resolved without sequelae after discontinuation of esmolol. In summary, the effects of esmolol at rest on hemodynamic parameters and left ventricular function are similar to other beta-adrenergic blocking agents. Due to its ultrashort half-life, esmolol can be administered safely in critically ill patients whose disease status makes treatment with currently available beta blockers risky.
The Valsalva maneuver was evaluated by echocardiography in three groups: A) 10 normal volunteers, B) 10 patients with no history of heart failure and normal ejection fractions, and C) 10 patients with heart failure and depressed ejection fractions. Groups A and B had a significant fall in left ventricular internal dimensions and calculated stroke volume by end strain which returned rapidly to baseline in recovery without significant overshoot. Arterial pressure showed a signoidal strain pattern with a normal overshoot in early recovery in all group B patients. In group C ventricular dimensions did not diminish during strain; arterial pressures showed a "square wave" pressure elevation during strain without an overshoot in recovery. Echocardiography allows a new approach to evaluate further the left ventricular response to the Valsalva maneuver. Patients with severely depressed ejection fractions, unlike those with normal ventricular function, are unable to alter stroke output in response to acutely increased intrathoracic pressure. A square wave pressure response is a likely consequence of a fixed stroke output during the strain maneuver.
Fifteen infants and children with the diagnosis of anomalous left coronary artery from the pulmonary trunk have been encountered at the Children's Hospital Medical Center, Boston, Massachusetts from 1958 to 1973. After thorough clinical and laboratory evaluation, they have been treated by anticongestive measures. Nine patients have had ligation of the anomalous left coronary artery at its entrance into the pulmonary artery; one patient has undergone coronary bypass surgery. The lelctrocardiogram proved to be the most helpful diagnostic clinical laboratory test, Vectorcardiograms are valuable not only in diagnosis but also in the follow-up of the patients from the prognostic point of view. The most sensitive tool for the definitive diagnosis is an aortic rool angiogram; we have no false negatives or false positives with this method. The twelve patients with complete cardiac catheterization data could be divided into three groups, according to the pressure and magnitude of the left-to-right shunt at the pulmonary level. All patients with an appreciable le?T-TO-RIGHT SHUNT SURVIVED. Patients in whom no left-to-right shunt could be demonstrated by angiography died. Half of the patients with only small left-to-right shunt survived; The results of surgical and medical treatment, were identical within the three groups. Medical management in infancy, according to coronary care principles, with definitive surgical correction at a later age, is the preferred treatment. Ligation of the anomalous left coronary artery is recommended in severely symptomatic infants with documented left-to-right shunt at the pulmonary artery level, who do not respond to medical management.
