Syncope

Question 1

General definition of syncope

Answer 1

transient loss of consciousness and postural tone

Question 2

General underlying cause of all syncope

Answer 2

global cerebral hypofusion

Question 3

Time course of syncope

Answer 3

Onset is rapid, duration brief, and recovery spontaneous and complete

Question 4

Epidemiology of syncope

Answer 4

Lifetime incidence 35%
F > M
More after 70 yo

Question 5

Pathophysiology of syncope

Answer 5

Decrease venous return -> diminished CO and BP -> baroreceptors in carotid sinus and AA provoke reflex -> increased sympathetic and decreased vagal -> peripheral vasoconstriction to promote venous return and CO -> failure results in hypoperfusion, occurs at 50mmHg -> cessation of blood flow for 6-8 sec results LOC

Question 6

Categories of syncope

Answer 6

1) Neurally mediated - reflex, transient change in hemostatic reflexes
2) Neurogenic orthostatic hypotension - autonomic, chronically impaired homeostatic reflexes
3) Cardiogenic - cardiac conditions cause a decrease in CO

Question 7

Initial eval of all syncope patients

Answer 7

History: Witnesses, precipitating events, associated sx, and medical Hx

PE: cardio/neurologic exam, vital signs (orthostatic)

ECG if any cardiac suspicion

identifies cause in 50%
helps risk stratify the remainder

Question 8

Usual labs to dx syncope

Answer 8

CBC, BMP, UA

Question 9

RF for adverse outcomes of syncope

Answer 9

• Abnormal ECG
• H/O heart disease
• Systolic <30
• Older age
• FHX sudden cardiac death

Question 10

How to treat syncope patients with high-risk criteria

Answer 10

admit for eval and cardiac monitoring

Question 11

Cause of neurally mediated syncope

Answer 11

transient change in autonomic efferent activity

• increased parasympathetic excitation = bradycardia
• increased sympathetic inhibition = vasodilation

MUST HAVE INTACT AUNTONOMIC NS

Question 12

Which syncope is benign, usually associated with known trigger

Answer 12

neurally mediated

Question 13

Subtypes of NMS

Answer 13

1) vasovagal syncope (common faint)

2) situational reflex syncope (triggers include fear, intense emotion, unpleasant sight/odor)

Question 14

Tx for NMS

Answer 14

Reassurance, avoid provocative stimuli, IV fluids prn

Question 15

Prodromal sx of syncope

Answer 15

Caused by autonomic activation -> diaphoresis, pallor, palpitations, nausea, hyperventilation

Question 16

orthostatic hypotension

Answer 16

reduction of at least 20 systolic or 10 diastolic within 3 min of standing

Question 17

2 classifications of orthostatic hypotension

Answer 17

Volume depletion

Neurogenic (Autonomic)

Question 18

Volume depletion orthostatic hypotension

Answer 18

• Occurs within 15 secs of standing
• Mismatch between CO and PVR
• Compensatory increase in HR
• Supine Hypertension uncommon
• Caused by volume depletion, vasodilatation, or decreased CO

Question 19

Neurogenic/Autonomic orthostatic hypo

Answer 19

• Occurs within 3 mins of standing
• Sympathetic vasoconstrictor (autonomic) failure
• Usually NO compensatory increase in HR
• Supine Hypertension common
• Caused by central neurodegenerative disorders and peripheral neuropathies

Question 20

predisposing factors of NOH

Answer 20

Postprandial, elderly

Question 21

Presyncope symptoms

Answer 21

• Commonly in neurogenic orthostatic hypotension
• Caused by hypoperfusion/ischemia of various structures
• dizziness, lightheadedness, weakness, fatigue, and visual/auditory disturbances, headache, cognitive slowing

Question 22

Dx studies for NOH

Answer 22

• Tilt table test
• HR (parasympathetic) and BP (sympathetic) response to Valsalva
• Thermoregulatory sweat response (sympathetic cholinergic)

Question 23

Tx of NOH

Answer 23

• Remove reversible causes
• Patient education: staged moves from supine to upright, isometric counter measures, raising head of bed, warn about hypotension after meals
• Optimize intravascular volume with fluid and salt intake

Question 24

Which type get prodromal symptoms?

Answer 24

neurally mediated syncope (vasovagal)

Question 25

Which type get presyncope sx?

Answer 25

neurogenic orthostatic hypotension

Question 26

Central neurodegenerative disorders that cause orthostatic hypotension

Answer 26

Alzheimer’s, Lewy Bodies disorders (Parkinson’s, dementia), stroke

Question 27

Peripheral neurodegenerative diseases that cause orthostatic hypotension

Answer 27

DM, amyloidosis, spinal cord injury