Intravenous terbutaline, 0.3 mg/kg/min for 30 minutes followed by 0.15 mg/min for 60 minutes, was studied in nine patients with severe heart failure due to documented coronary artery disease. Hemodynamic and myocardial metabolic effects were measured during terbutaline infusion. Cardiac index and stroke index increased, whereas mean pulmonary artery wedge pressure and pulmonary vascular resistance decreased significantly. No significant alterations in aortic oxygen content, coronary sinus oxygen content, myocardial oxygen extraction, and myocardial lactate extraction were observed during terbutaline infusion. No patient developed angina or electrocardiographic changes suggestive of ischemia. These results indicate that intravenous terbutaline infusion, at the dosage employed, produces beneficial hemodynamic effects without a deterioration of myocardial metabolism in patients with heart failure due to coronary artery disease.
Acute intravenous and short-term oral mexiletine therapy was effective in suppressing the arrhythmia in six of eight patients with recurrent ventricular tachycardia. Five of the six patients who were placed on maintenance therapy remained asymptomatic during a mean follow-up of 15 months. The study shows that the acute and short-term suppression of ventricular tachycardia by mexiletine can be a useful predictor of its long-term efficacy.
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