• look at the rhythm strip, best at II
• Approach to counting HR:
  • Regular: count # of square between 2 QRS complex
  • Irregular: count # of peaks in 10s, x 6

Normal Sinus rhythm

• Site of origination: coming from sinus (I, II, aVF +, biphasic V1)

  

• P:QRS → 1:1 ratio

• Rate: 60-100 bpm

• PR (120 - 200 ms)

Abnormal - Full DDx

Site of origination:

• Ectopic atrial beats: → always followed by an additional QRS
  • 1 early P value - PAC (premature atrial contraction) ECG
  • Sinus + 1 PAC - Atrial Bigeminy ECG
  • Sinus + many PAC - MAT (multifocal atrial tachycardia) ECG
  • chaos - AF - Atrial Fibrillation ECG
• AV node
  • No p-wave: Junctional beat ECG
• Ectopic ventricular beats: → widened QRS
  • 1 - PVC (premature ventricular contraction) ECG
  • Sinus + 1 PVC - Ventricular Bigeminy
  • Sinus + many PVC - Multifocal PVC

Rate:

• Too slow (< 60 bpm): ↓Bradycardia
  • AV Blocks ECG, !Hypercalcemia - ↑Ca (> 2.5) → PR prolongation
• Too fast (> 100 bmp): ↑ Tachycardia (>150)
  • regularly regular (all Narrow QRS)
  • regularly irregular
  • Irregularly irregular

A:V ratio

• 1:1
  • The
  • SVT
• P > QRS
  • Atrial Flutter ECG
  • AF - Atrial Fibrillation ECG
  • 2° Mobitz type I AV Block (Wenckebach)
  • 2° Mobitz type II AV Block
  • 3° (complete) AV Block
• QRS > P
  • VT: Monomorphic VT ECG, !pVT