[Bradycardia-induced syncope].
Bradyarrhythmias are the cause of syncope in 3 to 10% of cases. Marked bradycardia or asystole can be due to impaired function of the sinus node (sick sinus syndrome), high degree AV block or neurocardiogenic disorders (carotid sinus syndrome, vasovagal syncope). A precise history, ECG and 24-h. Holter recordings are the most helpful tools in diagnosis of bradyarrhythmia-induced syncope. An association between symptoms and documented ECG is essential for proper diagnosis. Sometimes an event-recorder may be helpful for this purpose. If a patient has normal physical examination, ECG, Holter, stress test, tilt-table test and echocardiography, no further electrophysiological investigation is needed. If the noninvasive tests show pathologic results that do not clearly explain the cause of syncope (sinus bradycardia, first-degree AV block, fascicular block, structural heart disease), then electrophysiological studies are recommended, which will also rule out ventricular tachyarrythmias in the differential diagnosis. If all diagnostic tests in a patient with syncope are normal, the prognosis is fairly good despite 30% recurrence rate. Treatment for symptomatic bradyarrhythmias is implantation of a pacemaker. The selection of an appropriate pacemaker system is very important. Dual-chamber systems (DDD) provide physiological stimulation by maintaining AV synchrony; thus, they should be preferred whenever possible.
Wyss
E
E
Abteilung Kardiologie, Universitätsspital, Zürich.
Candinas
R
R
D001919:Bradycardia / Q000150:complications* / Q000209:etiology / Q000503:physiopathology; D015716:Electrocardiography, Ambulatory; D006327:Heart Block / Q000150:complications / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D010138:Pacemaker, Artificial; D013575:Syncope / Q000209:etiology* / Q000503:physiopathology