[Long-term drug therapy of arrhythmias (with special reference to ventricular tachyarrhythmias].

Sudden death and its consequences in patients with coronary artery disease have stimulated research in this field. In the light of the literature an attempt is made to outline the present state of diagnosis and especially longterm medical treatment in ventricular arrhythmias. New morphological electrocardiographic criteria for differentiation between supraventricular and ventricular tachycardias are mentioned. It seems to be the general opinion that ventricular arrhythmias in persons with otherwise normal cardiac findings have a good prognosis and do not need drug therapy. Drug therapy of ventricular arrhythmias in patients with cardiac disease sets out to lower the incidence of sudden death and should be used only for dangerous arrhythmias (ventricular premature beats of Lown classes 3 to 5) and in patients with significant heart disease. Toxic factors and arrhythmogenic properties and other side effects of the antiarrhythmic drugs should be considered. The subdivision of these drugs into classes I to IV according to their effect on the action potential fo the isolated muscle fiber of the heart is briefly reviewed. Standard doses and important side effects of drugs generally used in the treatment of ventricular arrhythmias are given. Drug testing with invasive cardiac stimulation is complicated and expensive and is performed in a few specialized centers only. Oral drug testing with monitoring of the drug effect by ambulatory electrocardiography and measurement of blood levels usually permits the correct choice of an antiarrhythmic drug. For practical use a somewhat simplified method of oral drug testing is proposed in which rhythm strips replace the ambulatory ECG. This modification does not sufficiently allow for the spontaneous variability of ventricular ectopy, but will probably permit some guidance of the antiarrhythmic therapy. It is obvious that the practical application of the new concepts in the management of ventricular arrhythmias is difficult. Finally, the therapy of supraventricular tachyarrhythmias is briefly summarized.