An approach to the clinical assessment and management of syncope in adults

Abstract

Syncope, defined as a brief loss of consciousness due to an abrupt fall in cerebral perfusion, remains a frequent reason for medical
presentation. The goals of the clinical assessment of a patient with syncope are twofold: (i) to identify the precise cause in order to implement
a mechanism-specific and effective therapeutic strategy; and (ii) to quantify the risk to the patient, which depends on the underlying disease,
rather than the mechanism of the syncope. Hence, a structured approach to the patient with syncope is required. History-taking remains the
most important aspect of the clinical assessment. The classification of syncope is based on the underlying pathophysiological mechanism
causing the event, and includes cardiac, orthostatic and reflex (neurally mediated) mechanisms. Reflex syncope can be categorised into
vasovagal syncope (from emotional or orthostatic stress), situational syncope (due to specific situational stressors), carotid sinus syncope
(from pressure on the carotid sinus, e.g. shaving or a tight collar), and atypical reflex syncope (episodes of syncope or reflex syncope that
cannot be attributed to a specific trigger or syncope with an atypical presentation). Cardiovascular causes of syncope may be structural
(mechanical) or electrical. Orthostatic hypotension is caused by an abnormal drop in systolic blood pressure upon standing, and is defined as
a decrease of >20 mmHg in systolic blood pressure or a reflex tachycardia of >20 beats/minute within 3 minutes of standing. The main causes of
orthostatic hypotension are autonomic nervous system failure and hypovolaemia. Patients with life-threatening causes of syncope should be
managed urgently and appropriately. In patients with reflex or orthostatic syncope it is important to address any exacerbating medication
and provide general measures to increase blood pressure, such as physical counter-pressure manoeuvres. Where heart disease is found to be
the cause of the syncope, a specialist opinion is warranted and where possible the problem should be corrected. It is important to remember
that in any patient presenting with syncope the main objectives of management are to prolong survival, limit physical injuries and prevent
recurrences. This can only be done if a patient is appropriately assessed at presentation, investigated as clinically indicated, and subsequently
referred to a cardiologist for appropriate management.