Syncope is a common clinical problem characterized by transient, spontaneously self-terminating loss of consciousness with complete and prompt recovery; the cause is insufficiency of cerebral oxygen/nutrient supply most often due to a transient fall of systemic arterial pressure to levels below those tolerated by cerebrovascular autoregulation. Careful and thorough evaluation of the cause of syncope is warranted in all patients. Determining that certain individuals are at "low mortality risk" is inadequate; syncope, although often benign from a mortality perspective, tends to recur, is associated with risk of physical injury, diminishes quality-of-life, and might lead to restriction from employment or avocation. However, the diagnostic evaluation and treatment of syncope is challenging for many reasons. First, syncope is only 1 of many causes of transient loss of consciousness. Second, the patient's symptoms are fleeting, and the patient is generally fully recovered when seen in the clinic; only infrequently are there helpful physical findings. Third, spontaneous events are often unwitnessed by medical professionals; consequently, the medical history of symptom events is usually a "second-hand" or "third-hand" story. Finally, there is often an excessive sense of diagnostic "urgency" that tends to result in a rush to undertake multiple poorly considered "diagnostic" testing procedures; a deliberate approach based on initial risk stratification is more likely to reap the dual rewards of a correct diagnosis and initiation of effective treatment in a cost-effective manner.
- cardiac arrhythmias