ECG Exam Template

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

Rate

• 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)

Rhythm

• Pattern – regular/ regularly irregular/ irregularly irregular
• Seven step approach to rhythm analysis

Axis

• Normal QRS axis -30 to 90/ LAD/ RAD/ NW axis
• Rotation (clockwise/ anticlockwise)

Axis Methods:

• Quick look test (Lead I and aVF)
• Three Lead Analysis (Lead I, Lead II, aVF)
• Isoelectric Lead Analysis
• Super SAM the axis Man

P wave

• 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

PR interval + PR segment

• Duration 0.12-0.2s normal/ short/ long/ varying
• Heart blocks:
  • 1^st Degree, Wenkebach, Mobitz 2, Fixed Ratio, High Grade, CHB
• PR depression

Q wave

• Normal: <25%R in I, aVL, AVF, V456
• Pathological: V23 > 0.02s, other >0.03s + >1mm deep

R wave

• Transition: normal V34, early: R>S in V1/2
• Poor R Wave Progression: R <3mm V3

QRS complex

• Duration: 60-110msec normal/ wide; R wave peak time
• Amplitude: normal/ large voltage/ low voltage/ alternans
• Morphology: notched/ RBBB/ LBBB

ST Segment

• Displacement: elevation/ depression (J point vs TP interval)
• Contour: horizontal /upsloping / downsloping

T wave

• Amplitude: normal <2/3 R/ peaked/ inversion/ alternans

QT Interval

• Duration: normal 390-450 or 460msec / long/ short/ QT dispersion
• Method, 3+ QRS in 3+ leads, QTc formulae, caveats

U wave

• Normal 10% T or <1.5mm/ prominent/ inversion/ alternans

Additional waves

• DOE: Delta wave, Osborn wave, Epsilon Wave

Chamber hypertrophy

• Atrial – LAE, RAE, biatrial
• Ventricular – LVH, RVH, biventricular

Lethal – do not miss!

• Ischaemia – STE criteria and DDX/ Sgarbossa/ reciprocal change/ Wellens/ aVR
• Quick BRAD Walk Home! Lethal causes of syncope:
  • Long/short QT, Brugada, RV infarction, ARVD, DCM, WPW, HCM
• 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?

Synthesis

• Leave space to put this at the start of the answer
• Unifying diagnosis, DDx, life threats

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
• Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course: Become an ECG expert. Medmastery
• Kühn P, Houghton A. ECG Mastery: Black Belt Workshop. Advanced ECG interpretation. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.
• Wiesbauer F. Little Black Book of ECG Secrets. Medmastery PDF

Textbooks

• Zimmerman FH. ECG Core Curriculum. 2023
• Mattu A, Berberian J, Brady WJ. Emergency ECGs: Case-Based Review and Interpretations, 2022
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Hampton J, Adlam D. The ECG Made Practical 7e, 2019
• Kühn P, Lang C, Wiesbauer F. ECG Mastery: The Simplest Way to Learn the ECG. 2015
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004

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