Arrhythmia

The arrhythmia section provides High Yield information discerning different types of arrhythmias needed for USMLE Steps 1, 2, 3, and residency.

AV Block

1st degree AV block

• EKG shows a slow rate with contact PR interval >0.2s
  
• Pt is asymptomatic
  
• Treatment None

2nd Degree Block (Mobitz type 1)

• EKG shows a slow rate with PR interval progressively lengthens until a QRS is stopped
  
• Pt is asymptomatic or has palpitations
  
• Treatment None

2nd Degree AV Block (Mobitz type 2)

• EKG shows a slow rate, and QRS beats are intermittently dropped, without PR prolongation
  
• Pt is asymptomatic or has palpitations
  
• Treatment is a pacemaker

3rd Degree AV Block

• EKG shows a slow rate, and dissociation between the P’s and the QRS’s
  
• Pt is very symptomatic and often syncopal
  
• Treatment is pacemaker

Atrial Fibrillation

• EKG shows a fast rate with irregularly irregular rhythm with a narrow QRS
  
• No P waves
  
• HR is usually <150
  
• Aflutter will have a sawtooth appearance
• Treatment:
  • meds then shock
  • A Fib with CHF:
    • Digoxin and Amioderone
  • A Fib without CHF:
    • BB and CCB

CHADS₂ Score for Atrial Fibrillation Stroke Risk

• CHADS2:
  • CHF 1 point
    
  • HTN 1 point
    
  • Age >75 1 point
    
  • DM 1 point
    
  • Stroke (prior) 2 points
    
• Treatment:
  • 0 = ASA
    
  • 1 = ASA or anticoagulation
    
  • 2+ = Anticoagulation

Atrial Flutter

• EKG shows a sawtooth appearance
  
• No P waves
  
• HR is usually <150
• Treatment:
  • meds then shock

Sinus Bradycardia

• EKG shows regular slow rate
  
• Tx only if patient is sxs with atropine

Supraventricular tachycardia

• EKG shows a fast rate with regular rhythm with a narrow QRS
  
• Tx with Adenosine (6mg-12mg-12mg)
  
• Shock
  
• No P waves
  
• HR will be >150

Torsades de Pointes

• EKG shows a fast rate with a widened QRS and changing amplitude
  
• Tx with Magnesium
  
• Shockable

Ventricular Tachycardia