making sense of the ecg

ByDr Saqib Mahmud

MRCP(UK) MRCP(London) MRCGP

Rate – normal, tachycardia or bradycardia Rhythm – sinus or irregular P waves present (II & V1 best leads to assess) PR interval QRS complexes & axis- widened QRS, Q

waves, buddle branch block, voltage criteria for LVH

ST segments – isoelectric, depression or elevation

T waves – N, peaked or inverted

What was the indication? age Symptoms-CP, palpitations, sob, syncope,

dizziness Haemodynamically stable? Clinical signs- HF, poor peripheral perfusion Pre-morbid Hx-HTN, IHD, DM, CKD Medications- b-blockers, diltiazem etc Consider repeating for interval change Compare with previous ECG if available

LVH – sum of S in V1 & R in V5 or V6 >35 RBBB – tall R in V1, QRS >0.12sec, R’sR

pattern LBBB - QS-V1,V2, QRS>0.12 Axis - Axis leads-I&III or I&aVF, Normal axis-

“double thumbs up’’(I&III+), RAD I –ve, III +ve, LAD I +ve, III –ve

Inferior leads-------------II, III, aVF Antero-septal leads------V1,V2,V3&V4 Antero-lateral leads------I,aVL,V5,V6 Heart rate calculation-(rhythm regular) count the no of large

squares b/w 2 consecutive QRS & divide into 300.HR=300/? Irregular – count no QRS in 30 large squares X 10

RBBB LBBB

Thumbs up! Normal axis

RAD LAD

Sinus bradycardia Sick sinus syndrome 2nd or 3rd degree/CHB Escape rhythms- form of safety net to

maintain heart beat if impulse generation fails or blocked

Negatively chronotropic drugs – beta-blockers(don’t forget eye drops!), Ca antagonist; diltiazem, verapamil, digoxin

Dizziness Syncope Recurrent falls in elderly Fatigue Breathlessness CP Palpitations O/E-look for hypotension, signs of HF & poor

perfusion Relevant Investigations – U&Es , TFTs

Narrow complex (<3 small squares) Broad complex (>3 small squares)

Narrow complex tachycardias always supraventricular in origin

Narrow complex tachycardias:o Sinus tachycardiao Atrial fibrillationo Atrial fluttero AV nodal re-entrant tachycardia

Occurs if normal electrical impulses are abnormally or aberrantly conducted to the ventricles causing delay in ventricular activation & widening of QRS complex

VTTorsades de pointesAccelerated idioventricular rhythmSVT with aberrant conduction

Tachycardia causing hemodynamic disturbance requires urgent Rx

Evidence of hemodynamic disturbance;HypotensionCardiac failurePoor peripheral perfusion Investigations FBC U&Es TFTs BNP

Sinus bradycardia Sinus tachycardia

Hypothermia Hypothyroidism B-blockade Raised ICP Obstructive jaundice Uraemia Increased vagal tone Ischemia Structural SA node

disease

Thyrotoxicosis Any cause of

adrenergic stimulation including pain

Hypovolaemia Anaemia Pregnancy Fever Myocarditis drugs;theophylines,salbut

amol, vasodilator antihypertensives

Is it regular or irregular?Regular rhythmsSinus rhythm- P waves precedes every QRS

complex with consistent PR intervalNodal or junctional rhythm- no P wave

preceding QRS complex but narrow regular complexes

Atrial flutter-saw tooth appearance, rapid & regular with a rate about 150bpm(2:1 block)

SVT, AVNRT-if high rate 150-220bpm

Sinus arrhythmia-P wave precedes QRS with constant PR interval but irregular

Thank you