Protective effects of slow channel calcium antagonists on noradrenaline induced myocardial necrosis.

Catecholamine excess results in two distinct forms of coagulative myocytolysis, apparently due to increased membrane permeability followed by a large influx of calcium. To determine if three slow channel calcium antagonists, verapamil, nifedipine, and diltiazem, could reduce the calcium overload and prevent the development of noradrenaline induced acute myocardial contraction band lesions, 48 adult mongrel dogs in eight groups (n = 6) were continuously infused with saline alone, noradrenaline alone (4 micrograms X kg-1 X min-1), nifedipine (1 microgram X kg-1 X min-1), or other calcium blockers (10 micrograms X kg-1 X min-1) with saline or noradrenaline. After 15 minutes of pretreatment with a calcium antagonist, the antagonists were simultaneously infused with either saline or noradrenaline for 60 minutes. Nifedipine increased heart rate to the same degree as noradrenaline alone, whereas verapamil and diltiazem significantly suppressed the noradrenaline induced increases in heart rate. All three calcium antagonists reduced the increases in blood pressure and frequency of ventricular arrhythmias seen with noradrenaline alone. Only nifedipine produced a moderate increase in contractility (dP/dtmax) within 5 min and a pronounced synergistic increase when combined with noradrenaline. The effect of the other antagonists with noradrenaline was no different than the effect with noradrenaline alone. Contraction band lesions in the hearts of dogs in the saline and saline plus calcium antagonist groups were rare. The group receiving noradrenaline alone showed large numbers of the two predominant lesions: small paradiscal contraction band lesions and large holocytic contraction band lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation of mild idiopathic polyhydramnios to perinatal outcome.

The relation between clinically obvious polyhydramnios and poor perinatal outcome has been described. Much less is known about mild, unexplained polyhydramnios, which usually is initially suggested by sonographic examination late in gestation. The purpose of the present investigation was to relate mild idiopathic polyhydramnios to perinatal outcome. Mild polyhydramnios was defined sonographically as an amniotic fluid index of 24.1-39.9 during fetal biophysical testing. All subjects had singleton gestations not complicated by conditions known to predispose to polyhydramnios. We diagnosed mild polyhydramnios in 97 of 1177 patients (8.2%) undergoing fetal testing at 26-42 gestational weeks. Premature delivery, intrapartum complications, and neonatal depression were no more frequent in the pregnancies complicated by mild, unexplained polyhydramnios than in a comparable control group with normal fluid volume. The mild polyhydramnios group showed a significantly higher incidence of birth weight greater than 4000 g than did the control group (18.6 versus 8.6%; P less than .05). We conclude that mild idiopathic polyhydramnios in late gestation is relatively common. Except for a higher incidence of large for gestational age fetuses, this condition by itself is not associated with an increased risk of adverse perinatal outcomes.