Baby Steps to ECG

Dr Saqib MahmudMRCP(UK), MRCPS(Glasg), MRCGP

Electrical Conducting system

ECG LEADS

leads representing regions

Anatomic region of heart & associated coronary artery

• Inferior MI----------------RCA

• Antero-septal MI---------LAD

• Antero-lateral MI---------Circumflex

• Posterior MI--------------RCA

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• Inferior leads-------------II, III, aVF

• Antero-septal leads------V1,V2,V3&V4

• Antero-lateral leads------I,aVL,V2-V6

Normal ECG

PR interval0.12s-0.2s(not>1 large sq)

QRS duration0.12s(not>3 small squares)

PQRST

ST segmentisoelectric

T upright

ECG reporting-systematic approach

1. Rate

2. Rhythm & P waves

3. Conduction intervals

4. Axis

5. QRS complexes-narrow, wide, bizarre

6. ST segments-elevation or depression

7. T waves-inverted, upright, peaked

How to calculate heart rate

Relationship b/w R-R interval (large squares)& heart rate

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R-R interval (large squares) heart rate• 1 300• 2 150• 3 100• 4 75• 5 60• 6 50

QRS nomenclature

Axis

Cardiac axis• Normal axis-’’ double thumbs

up’’(I&III+)

• RAD--- I –ve, III +ve• LAD--- I +ve, III –ve• ---------------------------------------------• RAD-(causes): normal in children, R

vent hypertrophy, PE, ASD/ VSD, antero-lateral MI

• LAD-inferior MI, WpW, emphysema, conduction defects

Bundle branch block

• RBBB

1. Tall R wave V1

2. QRS>0.12sec

3. RsR-V1

• LBBB

1. QS-V1,V2

2. QRS>0.12

LBBB

RBBB+LAD

Atrial flutter & fibrillation

• Atrial flutter1. Saw tooth appearance2. Rapid & regular rhythm• Atrial fibrillation1. No P waves or bizarre P waves2. Always irregular rhythm3. Can be slow or rate controlled

ACS classification

Heart block• 1st degree HB-prolonged PR>0.2secCauses-increased vagal tone, IHD, Rh fever, dig

toxicity, electrolyte imbalance,myocarditis

• 2nd degree HB-1. Mobitz type 1 or wenckebeck-

progressively increased PR,non conducted beat,short PR (causes-inf MI, athelete, drugs-Ca & beta blockers,digoxin)

2. Mobitz type 2-(2:1) fixed PR, one P wave not folowed by QRS-(causes-degenerative disease of conducting system, anteroseptal MI-may herald CHB)

CHB or 3rd degree HB• Atrial contraction normal-no beats

conducted to ventricles• Ventricles excited by slow escape

rhythm• ECG-no relationship b/w P waves and

Q waves• Bizarre or wide QRS complexes• Causes-degenerative fibrosis of

bundle of his, MI, drugs eg betablockers, digoxin

wpw

hyperkalaemia

P-pulmonale

SI,QIII,TIII-RV strain

Thank you Presentation

on

Peripheral vascular diseaseNext time if you are

interested