Severe left ventricular outflow obstruction often is associated with diastolic left ventricular myocardial dysfunction and tachycardia despite successful initial treatment. The authors have used esmolol to lower heart rate in this setting for successful weaning of patients from ventilation in postoperative recovery. Their limited experience supports the beneficial effect of continuous esmolol administration on infants with persistent tachycardia and severe left ventricular diastolic dysfunction in postoperative cardiac intensive care.