The following headings and prompts can be used as template for ECG-based exam questions.
ECG type and recording
- 12 lead vs rhythm strip, rate (normal 25 mm/s)
- Calibration (5mm wide, 10mm high = 1mV)
- Unusual leads – right, posterior, lead grouping format
- normal 60 – 100/min
- tachy/bradycardia (SA node) vs –arrhythmia (not SA node)
- method: 300/RR interval (large squares) or number of QRS complexes x 6 (if 25mm/s)
- Pattern – regular/ regularly irregular/ irregularly irregular
- Seven step approach to rhythm analysis
- Quick look test (Lead I and aVF)
- Three Lead Analysis (Lead I, Lead II, aVF)
- Isoelectric Lead Analysis
- Super SAM the axis Man
- Present? (esp check II and V1)
- Amplitude + duration: normal <3mm high and wide (LAE/RAE/Biatrial)
- Contour: normal — inverted aVR, biphasic V1, upright I,II, aVF, V2-V6
- Duration 0.12-0.2s normal/ short/ long/ varying
- Heart blocks:
- PR depression
- Normal: <25%R in I, aVL, AVF, V456
- Pathological: V23 > 0.02s, other >0.03s + >1mm deep
- Transition: normal V34, early: R>S in V1/2
- Poor R Wave Progression: R <3mm V3
- Duration: 60-110msec normal/ wide; R wave peak time
- Amplitude: normal/ large voltage/ low voltage/ alternans
- Morphology: notched/ RBBB/ LBBB
- Displacement: elevation/ depression (J point vs TP interval)
- Contour: horizontal /upsloping / downsloping
- Amplitude: normal <2/3 R/ peaked/ inversion/ alternans
- Duration: normal 390-450 or 460msec / long/ short/ QT dispersion
- Method, 3+ QRS in 3+ leads, QTc formulae, caveats
- Normal 10% T or <1.5mm/ prominent/ inversion/ alternans
Lethal – do not miss!
- Ischaemia – STE criteria and DDX/ Sgarbossa/ reciprocal change/ Wellens/ aVR
- Quick BRAD Walk Home! Lethal causes of syncope:
- Pulmonary Embolus
- Electrolytes: hyperK, hypoK, hypoCa, hyperCa, hypoMg
- Toxicology: TCAs, digoxin
Other tricks and traps
- Dextrocardia, Lead reversals
- Artifacts – tremor artifact
- Pacing spikes – pacemaker malfunction: failure to sense/ capture/ output?
- Leave space to put this at the start of the answer
- Unifying diagnosis, DDx, life threats
- Wiesbauer F, Kühn P. ECG Yellow Belt online course: Become an ECG expert. Medmastery
- Wiesbauer F, Kühn P. ECG Blue Belt online course: Learn to diagnose any rhythm problem. Medmastery
- Rawshani A. Clinical ECG Interpretation ECG Waves
- Smith SW. Dr Smith’s ECG blog.
- Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
- Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
- Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
- Hampton J. The ECG Made Practical 7e, 2019
- Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography 1e, 2009
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
- Mattu A, Brady W. ECG’s for the Emergency Physician Part I 1e, 2003 and Part II
- Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004
- Smith SW. The ECG in Acute MI. 2002 [PDF]
LITFL Further Reading
- ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis – ECG interpretation in clinical context
- ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
- 100 ECG Quiz – Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS – the best of the rest
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.