Figure 4.

Effect of verapamil in familial CPVT. The ECG shows maximal treadmill exercise tests before (top) and after intravenous injection of 10 mg of verapamil (bottom) in a 33 year old woman with familial CPVT. This patient received no drug treatment during the control state. Top: control state, 25 beats of CPVT were induced at 1 min 24 s after the start of the exercise. Bottom: after injection of verapamil, the endurance time was prolonged and five beats of CPVT were induced. Note the left bundle branch block and the inferior axis type premature ventricular conduction which is the trigger of this polymorphic ventricular contraction.