Last 40 years of growing knowledge of the mechanisms of cardiac arrhythmias has unambiguously demonstrated therapeutic superiority of non-pharmacological treatment over antiarrhythmic drugs, which are in these days rather used in acute phase or moderate forms of tachyarrhythmias. Diagnosis of bradyarrhythmias relies mainly on bradycardia symptoms, bradycardia detection on the surface ECG and their mutual time correlation. Electrophysiological study stands aloof in these cases. Permanent cardiac stimulation dominates unequivocally in the therapy of bradyarrhythmias. Electrophysiological study has taken a unique place in the tachycardia therapy, since it allows inducing reproducibly tachyarrhythmia and by means of its mapping to determine its course. Thus, a completely new, „intracardiac“ view on the arrhythmia mechanism has evolved and considerably weakened the diagnostic importance of the surface ECG. Radiofrequency catheter ablations represent a rapidly evolving causal therapeutic modality of tachyarrhythmias, especially in the absence of structural heart disease. Significantly decreased left ventricular ejection fraction combined with tachycardia symptoms should raise suspicion of life threatening ventricular arrhythmias, which are nowadays successfully treated by implantation of a cardioverter-defibrillator.

        Key words: cardiac arrhythmias, diagnosis, therapy.