Rapid sinus tachycardia. Differentiation from supraventricular tachycardia.

Current pediatric literature suggests that in sinus tachycardia the heart rate rarely exceeds 200 beats per minute. Three infants had heart rates of 240 to 270 beats per minute in whom the diagnosis was sinus tachycardia. We report these cases and offer diagnostic and therapeutic suggestions for the clinician who encounters an infant with a heart rate between 200 and 300 beats per minute.