S7C56 - Syncope

Question 1

Pathophys

Answer 1

• lack of blood flow to both cortices or brainstem for 10-15secs will lead to LOC and loss of postural tone
• commonly d/t drop in cardiac output
• vasospasm also a possible rare cause

Question 2

Etiology of syncope

Answer 2

• vasovagal 21%
• cardiac 10%
• orthostatic 9%
• meds 7%
• seizure 5%
• neurologic 4%
• unknown 37%

Question 3

Mortality and syncope

Answer 3

• heart disease + syncope = 2x mortality rate
• neurological cause + syncope = 50% more likely to die
• unknown cause + syncoep = 30% increased risk of death

Question 4

Cardiac causes of syncope

Answer 4

• Structural: valvular, Ao stenoiss, tricuspid stenosis, MS, cardiomyopathy, pulm HTN, congential dz, myxoma, pericardial dz, ao dissection, PE, myocardial ischemia, myocardial infarction
• Dysrhythmia: brady, stokes-adam attack, sinus node dz, 2nd/3rd heart block, pacemaker malfunction, tachydysrhythmia, VT, VF, torsades, SVT, a fib/flutter

Question 5

Neuro cause of syncope

Answer 5

• vasovagal
• situational - cough, micturition, defecation, swallow, neuralgia
• carotid sinus syndrome
• orthostatic HoTN
• psychiatric
• neurologic - TIA, subclavian steal, migraine
• meds
• breath holding

Question 6

HOCM

Answer 6

• hypertrophic cardiomyopathy

- asymmetric LV hypertrophy

Question 7

Vasovagal syncope

Answer 7

• inappropriate vasodilatation, bradycardia or both as a result of inappropriate vagal/sympathetic tone
• sensation of warmth and lightheadedness with sweating and nausea
• orthostatic HoTN will not have sweating and nausea

Question 8

Orthostatic Hypotension

Answer 8

• usually occurs w/in 3 mins of standing (may be more delayed)
• insufficient autonomic response to sudden decrease in BP upon standing
• take BP 5 mins after lying down, then 1 and 3 mins after standing
• > 20 drop in systolic is abnormal

Question 9

Neurologic syncope

Answer 9

• ischemia to the brainstem can cause decrease in blood flow to the reticular activating system and cause sudden brief episodes of LOC
• usually assoc with diploplia, vertigo, nausea

Question 10

Subclavian steal

Answer 10

• abnormal narrowing of the subclavian artery proximal to the origin of the vertebral artery
• exercise of the ipsilateral arm causes blood to be shunted from the vertebrobasilar system to the subclavian artery supplying the arm muscles
• more common on the Left

Question 11

Investigations

Answer 11

• ECG: heart block, QT, rate, brugada, delta wave
• lab: Hb, beta HCG,
• carotid massage, orthostatic BP
• cardiac and neuro exam
• BP both arms
• echo for valvular dz
• tilt table testing