ECG

Introduction

Electrocardiogram (ECG) is a way of reading electrical movement of the heart. Elecrtrical impulse started from Sinoatrial node (SA node) causing atrial contraction. Move to Atrioventricular node (AV node), Bundle of His then Bundle Branch and end at Purkinje fiber in which cause ventricular contraction. In this blog, i will present a systematic approch to reading an ECG. Knowledge and illustration from this blog was extracted from The Ecg Workbook (Angela Rowlands, Andrew Sargent) and The ECG Made Easy 8th edition.

Flow of reading.

1. Rhythm strip
2. Limb lead
3. Chest lead
4. Infraction
5. Bundle branch block
6. Chamber enlargment

Rhythm Strip

Rhythm strip is the Lead ll in the ECG Normal sinus rhythm

Rate

• Normal: 60 - 100 bpm
• Arrhythmia: Tachycardia > 100, Bradycardia < 60
• Calculate peak R wave in 6 seconds / 30 large box

Rhythm

• Normal: regular rhythm / equal distant between peak R wave
• Abnormal: Regullarly irregular, Irregullarly irregular

P wave

• Normal: present, < 120 milisec
• Abnormal: absent / inverted / prolong / P-mitral / P-pulmonale

QRS complex

• Normal: narrow, < 120 milisec
• Abnormal: broad / prolong

PR interval

• Normal: 120 - 200 milisec
• Abnormal: < 120 milisec / > mili200 sec

P:QRS ratio

• Normal: 1:1
• Abnormal: 1:0 / 3:1 / others

Arrhythmia

• Sinus origin / physiological
  • Complete visualization of PQRST complex with normal morphology
  • Sinus tachycardia / sinus bradycardia
• Artial fibrillation
  • Most common cardia arrthythmia
  • ECG finding: tachycardia, irregular irregular, absent P wave, narrow QRS ~150 bpm irregular irregular, no discrete P wave, narrow QRS, N/A PR, N/A P:QRS, (irregular irregular tachycardia with no discrete P wave and narrow QRS) *Atrial Fibrilation
• Artial flutter
  • ECG finding: tachycardia, broad multi P wave / F wave, P:QRS ratio is 2:1 / 3:1, narrow QRS ~100bpm regular, broad multi P wave / F wave / saw tooth, narrow QRS, N/A PR, P:QRS 3:1, (saw tooth appearance with P:QRS ratio of 3:1) *Atrial flutter
• Supraventricular tachycardia *AV node origin
  • ECG finding: tachycardia, absent P wave, narrow QRS ~150bpm regular, absent P wave, narrow QRS, N/A PR, N/A P:QRS (tachycardia with narrow QRS) *supraventricular tachycardia
• Ventricular tachycardia *Ventricular node origin
  • ECG finding: tachycardia, absent P wave, broad QRS ~150bpm regular, absent P wave, broad QRS, n/a PR, n/a P:QRS, (tachycardia with broad QRS) *ventricular tachycardia
• Ventricular fibrillaton
  • ECG finding: no P wave, no QRS, biazzare activity no rate and rhythm, no P wave, no QRS, n/a PR, n/a P:QRS