Working with ECGs

Working with ECGs Dr Cynthia Lim Dr Dean Pritchard FACEMs, Emergency Department The Northern Hospital

ECG 123s • Measurement of electrical flow across the heart using electrodes placed on the chest and limbs • Deviation of electrical flow from normal pathways indicates cardiac anomaly or cardiac disease

The Leads • Limb Leads • aVR – Right arm • aVL – Left arm • aVF – Left leg • Vectors • Flow of +ve current • I – R arm  L arm • II – R arm  L leg • III – L arm  L leg

The Leads • Chest leads • V1 • V2 • V3 • V4 • V5 • V6

Axis Look at leads I and avF If in left quadrant then look at lead II

Successive approximation method

ECG Morphology

Pick the Problem… NORMAL ECG

ECG of 2 year old – normal or abnormal? Higher rate, Partial RBBB pattern, Dominant R V1, R axis deviation

Chest Pain

The Barn Door… Acute anterior ST elevation myocardial infarction

The Barn door Acute inferior ST elevation myocardial infarction

What about this? Septolateral Non-ST Elevation Myocardial Infarction

And this? Acute Pericarditis

ACS – STEMI • Any ST dep except V1 or aVR (allowed in acute pericarditis) • ST elevation III > II • Horizontal or convex up ST elevation • New Q waves

ACS – acute pericarditis • PR dep multiple leads • Only reliably seen viral • transient • Low voltage and tachycardia = large pericardial effusion • Friction rub • Use T-P as baseline (not P-P interval) • If in doubt serial ECGs

T-wave Changes • T-wave inversions • STEMI – After the appearance of ST changes • NSTEMI – After a period of hyperacute T-wave changes • May persist for months or permanently

Working with ECGs