Syncope

Question 1

What causes syncope?

Answer 1

A lack of blood flow or vital nutrient delivery to both cerebral cortices or to the brainstem RAS for 10 to 15 seconds will lead to loss of consciousness and postural tone.

A reduction of cerebral perfusion by 35% or complete disruption for 5 to 10 seconds will cause symptoms.

Question 2

What rate of mortality is associated with syncope?

Answer 2

Syncope in the setting of heart disease carries a 100% increase in the rate of death, 50% increase in the setting of a neurologic cause, and 30% in the setting of an unknown cause of syncope.

Question 3

What are the etiologies of syncope?

Answer 3

Cardiac (cardiomyopathy, valves, ischemia, arrythmias, pulmonary vasculature problems, infections)

Neurologic (TIA, subclav steal, migraine, seizures)

Neural/Reflex (vasovagal, situational, carotid sinus synd)

Orthostatic

Psychiatric

Drugs

Breath holding spells

Question 4

What is the most concerning part of cardiogenic syncope?

What are the two main categories of cardiogenic syncope?

Answer 4

Cardiogenic syncope carries a 6-month mortality rate of 10%.

Cardiogenic syncope is caused by either a non-perfusing rhythm or an obstruction/inhibition of forward cardiac output.

Question 5

Describe the mechanism of structual cardiogenic syncope.

Answer 5

Most occurs in the setting of exertion, vasodilation or heat stress. Anything that lowers SVR. A fixed CO is not able to compensate in this case, which drops BP delivery to the brain.

Ex. Ao stenosis, HOCM, myocardial dyskinesis, Pulm HTN and PE.

Drugs that cause vasodilation should be considered.

Question 6

Describe the mechanism of dysrhytmia related syncope.

Answer 6

The effect of the arrhythmia is related to the autonomic response to it, and the degree of cerebrovascular atherosclerotic disease. There is typically no prodromal symptoms. The patient collapses suddenly.

Dysrhythmias are more likely to occur in the setting of underlying structural heart disease, or electrolyte abnormalities. Other possibilities include genetic causes such as Brugada, Long QT, and catechol-assoc. polymorphic VT.

Question 7

What findings of a syncope work-up may predict outpatient morbidity and mortality?

Answer 7

Significant predictors of adverse events (primarily arrhythmia) included (1) a history of CHF, (2) an abnormal ECG (a rhythm other than sinus, including those on rhythm strips or monitoring, conduction delays, or new changes, as minimal as first-degree atrioventricular block, or any morphologic changes to the QRS complex or ST segment that could not be proven to be old by prior tracings), (3) a hematocrit of <30, (4) a com- plaint of shortness of breath, and (5) a systolic blood pressure of <90 mm Hg in the ED.

Question 8

What are follow-up options for syncope?

Answer 8

Question 9

Syncope in the setting of exertion or a systolic murmur should raise the possibility of…

What are the classical symptoms?

Answer 9

Aortic Stenosis

Late peaking systolic murmur at the right second intercostal space, radiating to the carotids, a single or paradoxically split S2, an S4 gallop, and a diminished carotid pulse with a delayed upstroke (pulsus parvus et tardus)

Question 10

Syncope in a person with a systolic ejection murmur heard best at the lower left sternal border is concerning for what?

What is the disposition in this person?

Answer 10

HOCM

They should be admitted for workup of HOCM, including holter, tilt table testing, and stress testing.