working with ecgs

Working with ECGs

Dr Cynthia LimDr 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

Look at leads I and avF

If in left quadrant then look at lead II

Axis

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