[Genesis, pathophysiology and clinical aspects of cardiac arrhythmias. Characterization of the risk patient].

Extrasystoles and both supraventricular and ventricular tachycardias may occur as a complication of almost any underlying cardiac disease and many extracardiac causes; on the other hand, also a patient without any detectable structural heart disease may present with these arrhythmias. Refined mapping techniques of the intracardiac conduction process have let to important new informations about the pathophysiology of sustained tachycardias (focal impulse formation, macro-reentry) with practical consequences, for example when ablation of these arrhythmias by radiofrequency catheter ablation is considered. Cardiac arrhythmias may lead to both typical and atypical symptoms. Finally, the patient at risk of sudden cardiac death is characterized. One needs to differentiate patients who have survived a life-threatening event of ventricular tachycardia or have been successfully resuscitated from cardiac arrest (both situations usually need life-long antiarrhythmic interventions for secondary prophylaxis) from patients who also are at high risk, however, are asymptomatic until now. For the latter population, symptoms due to extrasystoles or assessment of the severity of ventricular ectopic beats by the Lown classification are of minor importance; most emphasis in this regard, however, must be placed on the type and severity of underlying cardiac disease.