The duration of unconsciousness is brief, rarely lasting longer than several minutes. Because of the abrupt onset, traumatic injury is common. Spontaneous movements during syncope often cause confusion and misdiagnosis. Cerebral hypoperfusion from any cause, including ventricular tachycardia, may produce one or more clonic jerks of the extremities. Historical information regarding the patient's condition after awakening is frequently overlooked but may be very helpful.
Patients typically recover quickly from ventricular tachycardia- mediated syncope.
Postictal confusion lasting longer than five minutes suggests a grand mal rather than an arrhythmic event. Similarly, persistent residual malaise, nausea, and weakness are characteristic of a faint produced by the vasodepressor syndrome rather than arrhythmic syncope. Ventricular tachycardia of sufficient rate or duration to produce loss of consciousness is rare in patients with normal ventricular function. Thus, patients in whom ventricular arrhythmias are identified after a syncopal episode must be thoroughly evaluated for structural heart disease. The presence of severe left ventricular dysfunction in these patients is associated with an ominous prognosis.