Syncope

Today we discussed an approach to syncope. Some important points:

Definition:
Abrupt loss of consciousness followed by rapid, complete recovery

Is it syncope?


All of dizziness, presyncope, drop attacks, and vertigo do not involve loss of consciousness.

Sz vs. syncope: features before, during, and after event:

1) Pre- aura in sz vs. pain, exercise, micturition, defecation, stress usually syncope
2) During- rhythmic movements, >5 min event suggest sz; sweating, nausea suggest syncope
3) Post- disorientation to event, slow to return to consciousness, Todd's paralysis suggest sz. Completely normal post-event suggests syncope.

Differential

1) Cardiac-
Arrhythmic: brady (blocks), tachy (VT, SVT).
Non-arrhythmic: HOCM, AoS. Less common: myxoma, pulm HTN, tamponade, massive MI, MS, Aortic dissection

2) Non-cardiac-
Neurocardiogenic (i.e. 'vasovagal'), neurological (carotid sinus hypersensitivity, subclavian steal, bilat carotid stenosis, posterior TIAs, migraine) orthostatic, psychogenic.
Metabolic: (hypoglycemia, hypoxia, hyperventilation)
"situational" (micturition, defecation)
menstrual

Prognosis

The presence of heart disease is the most important prognostic factor
Cardiac cause- 1 year mortality 18-33%
Non-cardiac cause 0-12%
Unknown cause 6%
NB- the high mortality from cardiac cause is driven by underlying cardiovascular disease, not arrhythmia per se. Data from 1980's.

Evaluation:

Initial: history, physical, orthostatic BP, ECG. If no confirmed or suspected cause, these pts fall under "unexplained" category. If suspected cause, confirm with appropriate testing.

Unexplained: Consider 2D echo, stress testing. If normal, neurally mediated syncope is likely. Consider tilt table testing for neurocardiogenic syncope if recurrent episodes.

Structural heart disease, abnormal ECG: Holter, EP study, loop recorder

Outpatient vs. inpatient management:
Admit when rapid evaluation is necessary because of concern about serious arrhythmia, sudden death, newly diagnosed serious cardiac disease. Pts with facial trauma, bleeding, PE, severe orthostatic hypotension should be admitted.

Reference:

Click here for good review of syncope from Circulation