CHAPTER 26 Syncope
Syncope is a transient loss of consciousness due to global cerebral hypoperfusion characterized by rapid onset, short duration, and spontaneous complete recovery. The starting point for evaluation of syncope is the ‘initial evaluation’, which consists of history, physical examination, standard electrocardiogram and (if appropriate) echocardiogram, orthostatic challenge, and carotid sinus massage. The initial evaluation has two objectives: to assess the specific risk for the patient (death, severe adverse events, or recurrence of syncope) and to identify the specific cause of the faint in order to address an effective mechanism-specific treatment.Differentiating true syncope from other ‘non-syncopal’ conditions associated with real or apparent transient loss of consciousness is generally the first diagnostic challenge and influences the subsequent diagnostic strategy. Patients at high short-term risk require immediate hospitalization or early intensive evaluation. Others should be evaluated mostly as out-patients or day cases, and preferably referred to a specialized syncope facility (so-called ‘syncope unit’) if available. In the less severe forms, no further investigation is usually necessary and patients can be educated and reassured on the benign nature of their symptom.
The strategy of evaluation varies according to the severity and frequency of the episodes and to the presence or absence of heart disease. In general, the absence of suspected or certain heart disease excludes a cardiac cause of syncope. Conversely, the presence of heart disease at the initial evaluation is a strong predictor of a cardiac cause of syncope, but its specificity is low because about half of patients with heart disease have a non-cardiac cause of syncope. Determining the mechanism of syncope is a prerequisite to developing an effective mechanism-specific treatment. Most patients with syncope require only reassurance and education regarding the nature of the disease and the avoidance of triggering events.
Chapter 28)
