[Calcium channel antagonists and arrhythmias].

Ca channel antagonists (CCA) including verapamil and diltiazem work as antiarrhythmic drugs. Because CCA suppresses conduction through atrio-ventricular (AV) node, it is effective on both AV reciprocating tachycardia (AVRT) and AV nodal reentrant tachycardia (AVNRT). It is also useful to reduce ventricular response during atrial fibrillation/flutter. Idiopathic left ventricular tachycardia (VT) with a right bundle-branch block configuration and superior axis is sensitive to verapamil, and thus called as verapamil-sensitive VT. A caution should be needed to prevent adverse effects based on cardio-depressive effects of CCA.