The Approach to the Patient with Syncope

The Approach to the Patient with Syncope

Emad F. Aziz

Eyal Herzog

Syncope is a syndrome consisting of a relatively short period of temporary and self-limited loss of consciousness caused by transient diminution of blood flow to the brain.1,2 The term derives from the Greek word synkoptein, which means “to cut short,”3 and is used to classify a common clinical problem. The incidence of self-reported syncope is 6.2 per 1,000 person-years in the Framingham study with a cumulative incidence of 3% to 6% over 10 years.4,5 In selected patient populations, the lifetime prevalence of syncope could reach almost 50%. In the United States, 1 to 2 million patients are evaluated for syncope annually accounting for 3% to 5% of emergency department visits and 1% to 6% of urgent hospital admissions.6

Several guidelines have been published for the diagnostic approach to patients with syncope; however, they do not apply to every clinical situation encountered.7,8 The European Societies of Cardiology9 and the American College of Cardiology10 have published detailed documents specifying a classification of the principle causes of syncope (Table 18.1). However, given the vast differential diagnosis and the potential variation of required therapies for patients presenting with syncope and owing to the lack of consensus guidelines, there was a need for a structured approach for the management of these patients. To address this issue, we developed a standardized pathway that is comprehensive, yet simple, and provides guidelines for the management of all patients presenting with a complaint of syncope11 (Figure 18.1).


The initial assessment of a patient with syncope (Table 18.2) includes a meticulous and comprehensive medical history, incorporating eyewitness accounts that can help determining the cause of syncope.7 Important questions to be asked in assessing patients with syncope are listed in Table 18.3. Orthostatic hypotension and autonomic dysfunction are identified by measuring blood pressure and pulse rate in the upper and lower extremities in both the supine and the upright positions. A 12-lead ECG and basic laboratory tests including a basic metabolic panel and a complete blood cell count should be performed in all patients with syncope.


We use the acronym of SELF-1, which reflects the four criteria that should be met in order for an event to be considered true syncope.

These criteria include:

S—Short period, Self-limited, Spontaneous recovery

E—Early rapid onset

L—Loss of consciousness—transient

F—Full recovery, Fall

Patients who do not lose consciousness are defined as “not true syncope.”


The following are certain disorders causing true syncope with a transient loss of consciousness:

  • Reflex syncope: Neurally mediated reflex syndrome12 in absence of structural heart disease. It refers to a reflex that, when triggered, gives rise to vasodilatation and bradycardia. These triggers include fear, pain, instrumentation, blood phobias, prolonged standing, crowded warm places, nausea, vomiting, and abdominal pain.

  • Orthostatic hypotension syncope: In orthostatic hypotension syncope, syncope occurs with assumption of upright position. It can occur after starting a medication that can lead to hypotension, or it can be due to an autonomic neuropathy.13 Volume depletion is an important cause of orthostatic hypotension.

  • Cardiovascular disease: Structural heart disease can cause syncope when circulatory demands overwhelm the impaired ability of the heart to increase its output. Cardiac arrhythmia can cause a decrease in cardiac output, which usually occurs irrespective of circulatory demands.


One of the main dilemmas faced by emergency department physicians is whether to admit patients to the hospital or to refer them for an outpatient evaluation. Many risk assessment scores have been developed. These includes the San Francisco Syncope Rule,14 the Osservatorio Epidemiologico della Sincope nel Lazio,15 and the Evaluation of Guidelines in Syncope Study.16 In all of these risk scores, there is a consensus to admit patients with abnormal ECG, hypotension, heart failure, and anemia. In our standardized SELF pathway,11 we use the SELF-2 criteria to evaluate the need for admission.

TABLE 18.1 Classification of the Principle Causes of Syncope



Mediated by emotional distress: fear, pain, instrumentation, blood phobia

Mediated by orthostatic stress


Cough, sneeze

Gastrointestinal stimulation (swallow, defecation, visceral pain)

Micturition (postmicturition)



Carotid sinus syncope


Primary autonomic failure:

Pure autonomic failure, Parkinson disease with autonomic failure, dementia

Secondary autonomic failure:

Diabetes, amyloidosis, uremia, spinal cord injuries

Drug-induced orthostatic hypotension:

Alcohol, vasodilators, diuretics, phenothiazine, antidepressants

Volume depletion:

Hemorrhage, diarrhea, vomiting


Arrhythmia as primary cause:


Sinus node dysfunction (including bradycardia/tachycardia syndrome)

AV conduction system disease

Implanted device malfunction



Ventricular (idiopathic, secondary to structural heart disease or to channelopathies)

Drug-induced bradycardia and tachyarrhythmias

Structural disease:

Cardiac: cardiac valvular disease, acute MI/ischemia

Hypertrophic cardiomyopathy, cardiac masses (atrial myxoma, tumors)

Pericardial disease/tamponade, congenital anomalies of coronary arteries, prosthetic valves dysfunction

Others: pulmonary embolus, acute aortic dissection, pulmonary hypertension

Adapted from Brignole M, Alboni P, Benditt D, et al. Task force on syncope, European Society of Cardiology. Part 1. The initial evaluation of patients with syncope. Europace. 2001;3(4):253-260.

These criteria include:

S—Structural heart disease

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May 27, 2016 | Posted by in CARDIAC SURGERY | Comments Off on The Approach to the Patient with Syncope
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