[Diagnosis of syncopes in suspected arrhythmias].

Several mechanisms lead to attacks with unsuspected sudden and intermittent loss of consciousness. A major cause for such syncopes are arrhythmias. Only in rare cases it is possible to register an ECG during a typical attack despite many newer methods as long-term ECG (LT-ECG), exercise stress test and electrophysiologic investigations. LT-ECG does not record the ECG only during symptomatic periods (syncopes, dizziness, palpitations etc), but also registers asymptomatic AR, which can be precursors of SY. Carotid sinus massage is a valuable tool for the detection of a cardio-inhibitory Carotid-Sinus-Syndrome, which can be treated with PM-implantation. Exercise stress testing induces ventricular arrhythmias, which also indicates AR as underlying cause for SY. Using the invasive electrophysiologic investigation methods the importance measuring supraventricular parameters (SNRT, SA-, AH-interval) or parameters of the AV-nodal conduction (AH-, HV-interval) decreased in contrast to the ventricular stimulation techniques. With these invasive procedures ventricular tachycardias, ventricular flutter or fibrillation can be induced in selected patients, which indicates also a possible arrhythmogenic substrate for SY. In a suspected arrhythmogenic genesis of SY it has to be recommended to perform LT-ECG, carotid sinus massage, exercise stress testing and -- in selected patients -- electrophysiological investigations in addition to the routine-ECG to exclude or confirm arrhythmias as possible substrate for SY.