The EKG in the patient treated with calcium channel blockers

Electrocardiographic Findings

 * 1) In patients with sinus node disease, verapamil and diltiazem may cause severe bradycardia and even sinus arrest.
 * 2) Effect on rate depends on the balance between the effect on the conduction system and a reflex increase in the heart rate due to vasodilation.
 * 3) Diltiazem and verapamil may prolong the PR interval, nifedipine has no effect.
 * 4) No effect on the QRS or the QTc