[Syncope as a cardiologic problem]

Syncope is a frequent clinical event. It is mainly caused by a suddenly reduced cerebral blood flow. There are two reasons for sudden cerebral underperfusion: cardiogenic - associated with cardiac disorders and neurocardiogenic - resulting from a sudden fall of arterial blood pressure due to impaired autoregulation of the circulation. Cardiogenic syncopes prevail in cardiac diseases associated with impaired blood flow and cardiac arrhythmias. They develop in aortic stenosis, hypertrophic cardiomyopathy, atrial myxoma, myocardial infarction, pulmonary embolism, cardiac tamponade. Cardiac arrhythmias associated with syncope include ventricular tachycardia, supraventricular tachycardia in the preexcitation syndrome, sinus bradycardia, II degrees and III degrees atrioventricular block, atrial fibrillation with rapid ventricular response. The prognostic value and pathomechanisms loss of consciousness in these disease states have been discussed. Neurocardiogenic syncopes include vasovagal syncope, carotid sinus syndrome, orthostatic hypotension, event-induced syncope. It is frequently difficult to establish the reason for syncope. Physical examination and a history should be taken first followed by noninvasive studies such as standard ECG, exercise testing, carotid sinus compression, Holter monitoring, tilt testing, signal-averaged ECG. Noninvasive diagnosis helps establish the cause of syncope in 53-62% of cases and is indispensable before proceeding to electrophysiological testing. Such testing should be limited to patients with organic heart disease, in whom previous examinations did not reveal the etiology of loss of consciousness.