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Figure 1 Segment of 24-h Holter electrocardiogram recording from a 24-year-old male basketball player with history of frequent palpitations. (Top) Asymptomatic 10-beat burst of nonsustained ventricular tachycardia (shortest R-R interval, 300 ms). Intervals between the initial beat and subsequent ectopic beats gradually shorten as the rate of discharge of the ectopic focus increases. The electrophysiologic study with programmed ventricular stimulation was normal. (Bottom) Hourly profile of premature ventricular depolarizations (PVDs) over 24 h. There is a total of 12,186 PVDs during a 24 h period largely without significant differences between the morning and evening. Only during a training session (at 3 PM) was there a distinctly reduced number of PVDs (200/h).