Arrhythmia

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

Atrioventricular 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

CHA2DS2-VASc Score for Atrial Fibrillation Stroke Risk

• CHA2-DS2-VaSc:
  
  • Congestive heart failure: 1 point
  • Hypertension: 1 point
  • Age ≥75: 2 points
  • Diabetes: 1 point
  • Stroke: 2 points
  • Vascular disease: 1 point
  • Age 65–74: 1 point
  • Sex: Female 1 point
• Score:
  • The score ranges from 0 to 9 points. 
  • A score of 0 in men or 1 in women is classified as low risk
  • 1 in men or 2 in women as intermediate risk
  • ≥2 in men or ≥3 in women as high risk
• 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