Syncope

BASICS

DESCRIPTION

Transient loss of consciousness characterized by unresponsiveness, loss of postural tone, and spontaneous recovery; usually caused by cerebral hypoxemia
System(s) affected: cardiovascular, nervous

EPIDEMIOLOGY

Incidence

Up to 20% of adults will have ≥1 episode by age 75 years; 15% of children <18 years of age
Accounts for 1 " 6% of hospital admissions and ~3% of emergency room visits
Annually prevalence of fainting spells resulting in medical evaluation was 9.5/1,000 inhabitants (1).

Prevalence
In institutionalized elderly (>75 years of age) is 6%

ETIOLOGY AND PATHOPHYSIOLOGY

In some cases, vagal response leads to decreased heart rate.
Systemic hypotension secondary to decreased cardiac output and/or systemic vasodilation leads to a drop in cerebral perfusion and resulting loss of consciousness.
Cardiac (obstruction to outflow)
- Aortic stenosis
- Hypertrophic cardiomyopathy
- Pulmonary embolus
Cardiac arrhythmias
- Sustained ventricular tachycardia (VT)
- Supraventricular tachycardia (SVT) (atrial fibrillation, atrial flutter, reentrant SVT)
- 2nd- and 3rd-degree AV block
- Sick sinus syndrome
Noncardiac
- Reflex-mediated vasovagal (neurocardiogenic/neurally mediated), situational (micturition, defecation, cough, hair combing)
- Orthostatic hypotension
- Drug induced
- Neurologic: seizures; transient ischemic attack (can in theory cause syncope but presentation usually markedly clinically different from pure syncope)
- Carotid sinus hypersensitivity
- Psychogenic

Genetics
Specific cardiomyopathies and arrhythmias may be familial (i.e., long QT syndrome, catecholaminergic polymorphic VT, Brugada syndrome, hypertrophic cardiomyopathy).

RISK FACTORS

Heart disease
Dehydration
Drugs
- Antihypertensives
- Vasodilators (including calcium channel blockers, ACE inhibitors, and nitrates)
- Phenothiazines
- Antidepressants
- Antiarrhythmics
- Diuretics

GENERAL PREVENTION

See "Risk Factors. "

COMMONLY ASSOCIATED CONDITIONS

See "Etiology. "

DIAGNOSIS

HISTORY

Careful history, physical exam, and an ECG are more important than other investigations in determining the diagnosis (2)[A]. Syncope associated with physical exertion suggests a potential cardiac etiology.
Make sure that the patient or witness (if present) is not talking about vertigo (i.e., sense of rotary motion, spinning, and whirling), seizure, or causes of fall without loss of consciousness.
Even after careful evaluation, including diagnostic procedures and special tests, the cause will be found in only 50 " 60% of the patients.
Onset of syncope is usually rapid, and recovery is spontaneous, rapid, and complete. Duration of episodes are typically brief (<60 seconds). The presence of underlying cardiac or neurologic conditions provides the key to diagnosis.
Ask for family history of long QT syndrome, hypertrophic cardiomyopathy, or unexplained sudden cardiac death in young family members.

PHYSICAL EXAM

BP and pulse, both lying and standing
Check for cardiac murmur or focal neurologic abnormality.

DIFFERENTIAL DIAGNOSIS

Drop attacks
Coma
Vertigo
Seizure disorder

DIAGNOSTIC TESTS & INTERPRETATION

History and physical examination should guide laboratory testing.
Initial Tests (lab, imaging)
Consider (not all indicated in all individuals) the following:

CBC
Electrolytes, BUN, creatinine, glucose (rarely helpful: <2% have hyponatremia, hypocalcemia, hypoglycemia, or renal failure causing seizures)
Cardiac enzymes (only if history suggestive of cardiac ischemia)
D-dimer (for pulmonary embolism workup)
hCG
Lung scan or helical CT scan of thorax if history and physical exam suggest pulmonary embolism (PE)

Follow-Up Tests & Special Considerations

If history and physical suggest ischemic, valvular, or congenital heart disease (3)
- ECG (3)[A]
- Exercise stress test (if syncope with exertion) (3)[C]
- Echocardiogram (3)[B]
- Cardiac catheterization
If CNS disease suspected (3)[C]
- EEG
- Head CT scan
- Head MRI/MRA when vascular cause is suspected
- Do not order these tests without hints of CNS disease on history or physical exam.
ECG monitoring, either in hospital or ambulatory (Holter) (3)[C]
- Useful in 4 " 15% of patients
- Should be done in patients with heart disease or recurrent syncope
- Arrhythmias frequently documented but not always associated with syncope
Electrophysiologic studies (3,4)[C]
- Have been positive in 18 " 75% of patients
- Induction of VT and dysfunction of His-Purkinje system are the two most common abnormalities.
- Should be done in patients with heart disease and recurrent syncope, although they may not show whether arrhythmia noted or induced during study is cause of syncope
Carotid hypersensitivity evaluation (3,4)[C]
- Carotid hypersensitivity should be considered in patients with syncope during head turning, especially while wearing tight collars, and with neck tumors and neck scars.
- The technique is not standardized; one side at a time is compressed gently for 20 seconds with constant monitoring of pulse and BP/ECG.
- Atropine should be readily available.
Tilt-table testing ± isoproterenol infusion (3)[B],(4)[C]
- Provocative test for vasovagal syncope
- Perform if cardiac causes have been excluded; role in workup of patients with syncope of unknown origin
- Protocol is not standardized but has been reported positive (symptomatic hypotension and bradycardia) in 26 " 87% of patients; also positive in up to 45% of control subjects.
Psychiatric evaluation (3)[C]: Anxiety, depression, and alcohol and drug abuse can be associated with syncope.

Diagnostic Procedures/Other
Patient-activated implantable loop recorders can record 4 to 5 minutes of retrograde ECG rhythm. Helpful in selective patients with recurrent syncope, with yield of 32 " 80% (3,4)[B].
Test Interpretation
Depends on etiology and presence of underlying cardiac or neurologic conditions

TREATMENT

Maintaining good hydration status and normal salt intake are initial therapy. Educate patients of the premonitory signs of syncope (5)[B].

GENERAL MEASURES

Elderly patients without previously recognized heart disease should be admitted if the physician thinks that the cause of syncope is likely cardiac.
Patients without heart disease, especially young patients (age <60 years), can be worked up safely as outpatients.
Prescribe antiarrhythmics for documented arrhythmias occurring simultaneously with syncope or symptoms of presyncope. Asymptomatic arrhythmias do not necessarily require treatment.
The decision to treat patients on basis of arrhythmias or conduction abnormalities provoked or detected during EPS is even more problematic: Does the arrhythmia or conduction abnormality have anything to do with the patient 's symptoms?
Most would treat patients with provoked sustained VT with an antiarrhythmic drug that suppressed arrhythmia during study.
Rationale for such treatment: Recurrent syncope is less frequent in patients with positive EPS who are treated than it is in those who have negative EPS.

MEDICATION

First Line

Geared toward specific underlying cardiac or neurologic abnormalities
In cases of recurrent vasovagal/neurocardiogenic/neurally mediated syncope (6)[B]
- α-Adrenergic agonists (midodrine)
- Mineralocorticoids (fludrocortisone)
- ²-Adrenergic blockers

Second Line

SSRIs (paroxetine, sertraline, fluoxetine)
Vagolytics (disopyramide)

ISSUES FOR REFERRAL

When cardiac or neurologic etiologies are suspected, obtain appropriate consultation, as indicated.

ADDITIONAL THERAPIES

For vasovagal/neurocardiogenic/neurally mediated syncope

Counterpressure maneuvers, orthostatic training, and exercise have improved vasovagal symptoms and recurrence (3,5)[C].
Head-up tilt sleeping (3)[C]
Abdominal binders and/or support stockings (3)[C]

SURGERY/OTHER PROCEDURES

Implantable cardioverter-defibrillator (ICD) placement for patients with cardiac conditions with high risk of sudden death and/or recurrent syncope on medications (i.e., long QT syndrome, catecholaminergic polymorphic VT, hypertrophic cardiomyopathy) (3)[B]
Many recommend pacemaker implantation in patients with the following:
- 2nd- (Mobitz type II) and 3rd-degree heart block
- HV intervals >100 ms
- Pacing-induced infranodal block
- Sinus node recovery time ≥3 seconds

INPATIENT CONSIDERATIONS

Admission Criteria/Initial Stabilization
Patients with benign etiologies of syncope with negative ED workups are associated with benign outcomes, even in the presence of other risk factors (7)[B].
Patients with suspected cardiac or neurologic cause for syncope should be admitted to the hospital for evaluation.

Support ABCs.
Stabilize heart rate and BP, typically with IV fluids.

IV Fluids
Use isotonic crystalloid fluids for fluid resuscitation, if needed.
Nursing
Close monitoring of BP and heart rate during initial presentation
Discharge Criteria

Attainment of hemodynamic stability
Satisfactory completion of workup for etiology
Adequate control of specific arrhythmia or seizure, if present

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

Frequent follow-up visits for patients with cardiac causes of syncope, especially patients on antiarrhythmics
Patients with an unknown cause of syncope rarely (5%) are diagnosed during the follow-up.

DIET

No specific diet unless the patient has heart disease
Increased fluid and salt intake to maintain intravascular volume in cases of recurrent vasovagal syncope

PATIENT EDUCATION

Reassure the patient that most cardiac causes of syncope can be treated, and patients with noncardiac causes do well, even if the cause of syncope is never discovered.
Physical counterpressure maneuvers can prevent recurrences of vasovagal syncope.
Physician and patient should carefully consider whether the patient should continue to drive while syncope is being evaluated. Physicians should be aware of pertinent laws in their own states.

PROGNOSIS

Cumulative mortality at 2 years
- Low: young patients (<60 years of age) with noncardiac or unknown cause of syncope
- Intermediate: older patients (>60 years of age) with noncardiac or unknown cause of syncope
- High: patients with cardiac cause of syncope
Independent predictors of poor short-term outcomes (8,9)[B]
- Abnormal ECG
- Shortness of breath
- Systolic BP <90 mm Hg
- Hematocrit <30%
- Congestive heart failure

COMPLICATIONS

Trauma from falling
Death (see "Prognosis " )

REFERENCES

11 Malasana G, Brignole M, Daccarett M, et al. The prevalence and cost of the faint and fall problem in the state of Utah. Pacing Clin Electrophysiol. 2011;34(3):278 " 283.22 Kessler C, Tristano JM, De Lorenzo R. The emergency department approach to syncope: evidence-based guidelines and prediction rules. Emerg Med Clin North Am. 2010;28(3):487 " 500.33 Moya A, Sutton R, Ammirati F, et al. Guidelines for the diagnosis and management of syncope (version 2009). Eur Heart J. 2009;30(21):2631 " 2671.44 Brignole M, Hamdan MH. New concepts in the assessment of syncope. J Am Coll Cardiol. 2012;59(18):1583 " 1591.55 Romme JJ, Reitsma JB, Go-Sch Άn IK, et al. Prospective evaluation of non-pharmacological treatment in vasovagal syncope. Europace. 2010;12(4):567 " 573.66 Kuriachan V, Sheldon RS, Platonov M. Evidence-based treatment for vasovagal syncope. Heart Rhythm. 2008;5(11):1609 " 1614.77 Grossman SA, Fischer C, Kancharla A, et al. Can benign etiologies predict benign outcomes in high-risk syncope patients? J Emerg Med. 2011;40(5):592 " 597.88 Quinn JV, Stiell IG, McDermott DA, et al. Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes. Ann Emerg Med. 2004;43(2):224 " 232.99 Saccilotto RT, Nickel CH, Bucher HC, et al. San Francisco Syncope Rule to predict short-term serious outcomes: a systematic review. CMAJ. 2011;183(15):E1116 " E1126.

ADDITIONAL READING

Parry SW, Tan MP. An approach to the evaluation and management of syncope in adults. BMJ. 2010;340:c880.
Reed MJ, Newby DE, Coull AJ, et al. The ROSE (risk stratification of syncope in the emergency department) study. J Am Coll Cardiol. 2010;55(8):713 " 721.
Strickberger SA, Benson DW, Biaggioni I, et al. AHA/ACCF scientific statement on the evaluation of syncope: from the American Heart Association Councils on Clinical Cardiology, Cardiovascular Nursing, Cardiovascular Disease in the Young, and Stroke, and the Quality of Care and Outcomes Research Interdisciplinary Working Group; and the American College of Cardiology Foundation in Collaboration with the Heart Rhythm Society. J Am Coll Cardiol. 2006;47(2):473 " 484.
Puppala VK, Dickinson O, Benditt DG. Syncope: classification and risk stratification. J Cardiol. 2014;63(3):171 " 177.
Sheldon RS, Grubb BPII, Olshansky B, et al. 2015 Heart Rhythm Society expert consensus statement on the diagnosis and treatment of postural tachycardia syndrome, inappropriate sinus tachycardia, and vasovagal syncope. Heart Rhythm. 2015;12(6):e41 " e63.

CODES

ICD10

R55 Syncope and collapse

ICD9

780.2 Syncope and collapse

SNOMED

271594007 Syncope (disorder)
398665005 Vasovagal syncope (disorder)
58077008 Hypotensive syncope
234167006 Situational syncope

CLINICAL PEARLS

A careful history and physical exam are key to a diagnosis.
Use the ECG/event-recorder to evaluate for cardiac conditions.
True neurologic causes of syncope are very rare; by far, cardiac causes are more common.
<2% of cases are caused by hyponatremia, hypocalcemia, hypoglycemia, or renal failure causing seizures.

Home

Erectile Dysfunction

Doctor123.org