Syncope

Question 1

Define Syncope

Answer 1

• Sudden loss of consciousness and postural tone
• Not due to epileptic seizure or trauma
• Spontaneous recovery

Question 2

What is the pathophysiology of Syncope

Answer 2

• LOC due to cerebral dysfunction
• Occurs in either both cortical hemispheres or in ascending retiular activating system
• Different from seizure b/c seizure depletes NT causing prolonged confusion: Post-ictal

Question 3

What cardiovascular electrical instabilities lead to syncope

Answer 3

• Ventricular tachycardia: should be suspected in anyone w/ history of MI b/c scar tissue creates re-entry circuit
• Catecholamine associated tachycardia: during exercise or stress
• Pro-arrhythmic congenital abnormalities: Long QT & HCM
  
  • Occur during exercise
• Sudden sinus node arrest causes cardiac arrest and syncope
  
  • Sick sinus syndrome and complete AV block

Question 4

Direct Mechanical Obstruction of Flow to the Brain

Answer 4

• PE

- Atrial myxoma

Question 5

Mechanical obstruction leading to indirect arrhythmia

Answer 5

-Aortic stenosis

Question 6

Mechanical obstructions causing syncope and chest pain

Answer 6

• aortic stenosis
• HCM
• Subvalvular stenosis

Question 7

Syncope with long history of hypertension

Answer 7

-Mechanical obstruction due to concentric left ventricular hypertrophy

Question 8

Syncope with dehydration or afterload reducing drugs

Answer 8

• Underfilling of ventricle

- pump priming failure

Question 9

Causes of neurally mediated syncope

Answer 9

• Interaction between brainstem and heart/vasculature
• Decreased HR and vascular tone
• Vaso-vagal faint: nausea, weakness, flush, pallor
  
  • Due to cortical input, dehydration, or venous pooling
  • Decreased venous return stimulates mechanoreceptors to stimulate C fibers up NTS
  • Increased parasympathetics and Decreased sympathetics
• Drug induced: nitroglycerine, diuretics, alpha blockers
• Orthostatic
• Post-micturation

Question 10

Less common non-cardiovascular causes of syncope

Answer 10

• Rare temporal lobe seizure w/o post-ictal confusion

- Conversion syncope: psychiatric condition

Question 11

Lab tests needed

Answer 11

• ECG: shows ischemia, heart block, MI, Ventricular preexcitation, Long QT, or ventricular hypertrophy
• Echocardiogram shows structural causes