FACEMs, Emergency Department 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 Vectors 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 What do each of the waves mean? P, QRS, ST segment, T wave, U wave Whats are the normal durations of each segment? PR, QRS, QT

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