Syncope

Question 1

What is Syncope?

Answer 1

Transient loss of consciousness due to hypoperfusion of the brain (regardless of the cause)

“like dying, but you wake up”

Question 2

What is the direct effect of vagal nerve stimulation on the CV system?

Answer 2

• Decreased HR
• No effect on force of contraction of LV
• No effect on PVR

Question 3

The (SNS/PNS) directly innervates the heart itself, the (SNS/PNS) does not.

Answer 3

SNS

PNS

Question 4

How do you treat vasovagal syncope?

Answer 4

• Increase volume status (also mineralocorticoid drugs)
• alpha 1 agonist: midodrine
• Fludrocortisone not as effective
• Possible beta blocker (strange)
  
  • Block triggering event (intense sympathetic discharge) to prevent event from occuring
• Pacemaker

Question 5

What are some ways to diagnose vasovagal syncope?

Answer 5

• ECG
• Echocardiogram
• Tilt-table test
• Holter monitor
• Implantable loop recorder

Question 6

young atheletes

LVH

outflow tract obstruction

Answer 6

hypertrophic cardiomyopathy

Question 7

How is HCM diagnosed?

Answer 7

• Classic murmur
  
  • Harsh systolic murmur at apex & lower LSB
  • Increases from squatting to standing
  • Passive leg elevation decreases murmur
• Echocardiogram
  
  • LV wall thickening
  • Septal hypertrophy

Question 8

What are the 4 phases of the ventricular myocyte AP?

Answer 8

• Phase 0 - I_Na
• Phase 1 - I_TO
• Phase 2 (Plateau Phase)
  
  • I_Ca-L, I_NaCa, I_Kr, I_Ks
• Phase 3 (Repolarization Phase)
  
  • I_Kr, I_KsI_K1, I_K-ACh/ATP
• Phase 4 (Resting State)
  
  • I_K1, I_K-ACh/ATP
  • I_f (funny current, SA node, pacemaker)

Question 9

How does prolonged QT lead to TdP?

Answer 9

• Prolonged QT leading to early after depolarization
• Early after depolarization breaking threshold & leading to ectopic beat (TdP)
• Sustained trigger activity

Question 10

In long QT what happens to each of these?

• I_Ks
• I_Kr
• I_K1
• I_Na
• I_Ca-L

Answer 10

• I_Ks decrease
• I_Kr decrease
• I_K1 decrease
• I_Na increase
• I_Ca-L increase

Question 11

________ prolongs the QT interval, but is rarely associated with TdP.

Answer 11

Amiodarone

Question 12

What medications cause acquired long QT?

Answer 12

• Anti-arrhythmics
  
  • Class 1: Quinidine, Procainamide
  • Class 3: sotalol, amiodarone, dofetilide
• Anti-depressants
• Anti-psychotics
• Antibiotics/Antifungals