[Fast heart rate after a ventricular premature beat--what is the mechanism?].

A 61-year-old patient with sinus node disease and intermittent AV block presented with palpitations and the feeling of an intermittent fast heart beat. A 24 h Holter recording documented repetitive fast heart rates starting after a premature ventricular beat. This case underlines that sometimes profound knowledge of the implanted pacemaker system is necessary to optimize device therapy.