![]() ![]() Symptoms consistent with vasovagal syncope and most predictive of the diagnosis include visual blurring, sweating, nausea, warmth, light-headedness and fatigue. ![]() Most patients can be diagnosed by careful history taking, 12 examination and electrocardiography. ![]() However, other stimuli may be operative in “situational” syncope (eg, in response to venepuncture, pain or emotion). Vasovagal syncope is classically provoked by prolonged standing or sitting. Excess venous pooling and abnormal vasodilation while standing, thus reducing venous return to the heart, is the most commonly accepted explanation. The mechanism remains a matter of controversy. It is characterised physiologically by sudden hypotension and varying degrees of bradycardia ( Box 3). Vasovagal syncope is a common and clinically challenging disorder widely recognised in the lay community as a faint or “blackout”. The diagnosis and treatment of this patient group is the major focus of our clinical update. Most of these patients have a disorder of postural circulatory control ( Box 2), the mechanism of which is poorly understood. However, the majority of patients fall into the non-cardiac syncope category - the most challenging form of syncope to investigate and manage. Patients with cardiac syncope have the highest mortality rate and need prompt evaluation. Syncope can be classified into three categories: cardiac syncope, non-cardiac syncope and syncope of undetermined cause ( Box 1). The quote above illustrates a commonly held view that most causes of syncope are potentially lethal and that, once these are excluded, there is no further need for diagnostic evaluation. 5 - 7 Recurrent syncope can have a major impact on quality of life, with devastating psychosocial consequences similar to those associated with other chronic diseases. 3, 4 Morbidity, even from “benign” causes of syncope, is profound: 70% of people experiencing recurrent syncope suffer impairment to activities of daily living, 6% suffer fractures, 64% restrict their driving and 39% change employment. Syncope has a lifetime cumulative incidence of 35% 2 and accounts for 1%–2% of all emergency department visits. It is due to a transient reduction in cerebral blood flow, is frequently related to posture, and is the most common cause of transient loss of consciousness. S yncope is a transient and abrupt loss of consciousness and postural tone that is generally followed by rapid recovery without the need for a major intervention. ![]() The only difference between syncope and sudden death is that in one you wake up. Most patients can be managed in an outpatient setting, and hospital admission or emergency department assessment is rarely warranted. Treatment is challenging and compounded by a lack of evidence. In difficult cases, analysis of sympathetic nervous system and circulatory responses during head-up tilting can aid diagnosis. With a detailed history, examination, blood pressure assessment and electrocardiography, most disorders of circulatory control can be diagnosed. Recurrent unexplained postural syncope is most often due to one of the five disorders of circulatory control: vasovagal syncope, postural tachycardia syndrome, chronic autonomic failure, initial orthostatic hypotension, or persistently low supine systolic blood pressure.įailure to identify the underlying cause of postural syncope can result in ongoing morbidity, impaired quality of life and high health care costs. It is the commonest cause of recurrent transient loss of consciousness. Postural syncope is a transient loss of consciousness secondary to a reduction in cerebral blood flow and is typically precipitated by standing. Statistics, epidemiology and research design. ![]()
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