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Syncope and palpitations 

Syncope and palpitations

Chapter:
Syncope and palpitations
Author(s):

K. Rajappan

, A.C. Rankin

, A.D. McGavigan

, and S.M. Cobbe

DOI:
10.1093/med/9780199204854.003.160202_update_001

Update:

Classification and investigation of orthostatic hypotension

Updated on 27 Nov 2014. The previous version of this content can be found here.
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date: 27 April 2017

Syncope is a transient episode of loss of consciousness (T-LOC) due to cerebral hypoperfusion. Its causes can be subdivided on the basis of pathophysiology, including (1) neurally mediated—or reflex—syncope; (2) orthostatic hypotension; (3) cardiac causes; and (4) cerebrovascular or psychogenic causes.

Neurocardiogenic syncope, or simple faint, is the commonest cause and is benign, but it is always important to exclude or establish the diagnosis of cardiac syncope, because this has an adverse prognosis that may be improved with appropriate treatment. Cardiac arrhythmia should be considered in all patients who have syncope associated with any of the following: (1) exertion, chest pain, or palpitations; (2) a past medical history of heart disease; (3) abnormal cardiovascular findings on examination; (4) an abnormal ECG; and (5) a family history of sudden cardiac death in people younger than 40 years old or with an inherited cardiac condition.

Initial assessment of the patient with syncope by clinical history, examination, and 12-lead ECG will indicate a probable diagnosis in most patients and guide further investigation (if required). Documentation of cardiac rhythm during syncope is extremely useful, especially if it is associated with palpitations, but this is usually difficult to obtain because of the intermittent and typically infrequent nature of the symptom. External or implanted loop-recorders, which can store the rhythm before, during, and after an episode, are increasingly used when the diagnosis remains unclear. In patients with structural heart disease in whom arrhythmia is suspected, programmed electrical stimulation of the ventricles may induce sustained monomorphic ventricular tachycardia: this is a relatively specific response, shows that the patient is at risk of recurrent ventricular arrhythmia, and makes an arrhythmic origin of syncope likely, but the diagnostic yield of electrophysiological testing is low in patients with a structurally normal heart.

Palpitation is the awareness of one’s heart beating—it may be due to an awareness of an abnormal cardiac rhythm, or an abnormal awareness of normal rhythm. It is most commonly due to premature beats (ectopics) and is benign. Correlation between symptoms and cardiac rhythm is the initial aim of investigations in patients presenting with palpitations.

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