Ecg Diagnosis on ECG Library – LITFL Basics

ECG Differential Diagnosis

Sun, 21 Dec 2025 00:00:00 +0000

Lists of differential diagnoses of specific ECG findings based on from ECGs for the Emergency Physician 1 and ECGs for the Emergency Physician 2

Atrial fibrillation with slow ventricular response

Severe AV nodal disease
Hypothermia
Medications: Digoxin toxicity, Calcium-channel blocker / beta-blocker toxicity

Tachydysrhythmias

Narrow-complex regular rhythm:

Narrow-complex irregular rhythm:

Wide-complex regular rhythm:

Ventricular tachycardia
Sinus tachycardia with aberrant conduction
SVT with aberrant conduction
Atrial flutter with aberrant conduction

Wide-complex irregular rhythm:

Atrial fibrillation with aberrant conduction (for example bundle branch block)
Atrial flutter with variable block and aberrant conduction
Multifocal atrial tachycardia with aberrant conduction
Atrial fibrillation with WPW
Polymorphic ventricular tachycardia / Torsades de Pointes

Leftward axis

Low voltage

Myxoedema
Large pericardial effusion
Large pleural effusion
End-stage dilated cardiomyopathy
Severe chronic obstructive pulmonary disease
Severe obesity
Infiltrative myocardial diseases (i.e. restrictive cardiomyopathy)
Constrictive pericarditis
Prior massive MI
Low gain settings on ECG machine

Increased QRS Duration

Hypothermia
Hyperkalaemia
WPW
Aberrant intraventricular conduction (for example bundle branch block)
Ventricular ectopy
Paced beats
Drugs, particularly those with sodium-channel blocking effects

Increased QT-interval (and QTc-interval)

*Hypokalemia — the actual QT-interval is normal; the QT-interval appears prolonged because of the presence of fusion of the T-wave with a U-wave (a “T-U fusion complex”)

Raised Intracranial Pressure

Tue, 14 Jan 2025 00:00:00 +0000

Characteristic ECG Abnormalities with Raised Intracranial Pressure

Widespread giant T-wave inversions (“cerebral T waves”)
QT prolongation
Bradycardia (the Cushing reflex – indicates imminent brainstem herniation)

Other possible ECG changes that may be seen:

ST segment elevation / depression — this may mimic myocardial ischaemia or pericarditis
Increased U wave amplitude
Other rhythm disturbances: sinus tachycardia, junctional rhythms, premature ventricular contractions, atrial fibrillation

In some cases, these ECG abnormalities may be associated with echocardiographic evidence of regional ventricular wall motion abnormality (so-called “neurogenic stunned myocardium”).

Left Axis Deviation (LAD)

Tue, 08 Oct 2024 00:00:00 +0000

Left Axis Deviation LAD

Left Axis Deviation = QRS axis less than -30°.

Normal Axis = QRS axis between -30° and +90°
Right Axis Deviation = QRS axis greater than +90°
Extreme Axis Deviation = QRS axis between -90° and 180° (AKA “Northwest Axis”)

Hexaxial Reference System

Hexaxial Reference System – relationship between QRS axis and frontal leads of the ECG.

How to recognise left axis deviation

Three Lead analysis

QRS is POSITIVE (dominant R wave) in Lead I
QRS is NEGATIVE (dominant S wave) in leads II, III and aVF

Pacemaker Rhythms – Normal Patterns

Tue, 08 Oct 2024 00:00:00 +0000

Pacemaker Components

1. Pulse generator

Power source
Battery
Control circuitry
Transmitter / Receiver
Reed Switch (Magnet activated switch)

2. Lead(s)

Single or multiple
Unipolar or bipolar

Pacemaker Classification

Pacemakers are classified by the nature of their pacing mode.
Classification follows pacemaker code developed by the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Group (BPEG).
The NASPE/BPEG Generic (NBG) Pacemaker Code was last revised in 2002, although many textbooks still use the previous version from 1987.
The code is expressed as a series of up to five letters.

NBG Pacemaker Code (2002)

De Winter T Wave

Thu, 22 Jun 2023 00:00:00 +0000

First reported by Dutch Professor of Cardiology, Robbert J. de Winter in 2008, the de Winter ECG pattern is an anterior STEMI equivalent that presents without obvious ST segment elevation. These patients are suffering occlusion myocardial infarction (OMI) and require immediate reperfusion therapy.

ECG Diagnostic Criteria

Tall, prominent, symmetrical T waves in the precordial leads
Upsloping ST segment depression > 1mm at the J point in the precordial leads
Absence of ST elevation in the precordial leads
Reciprocal ST segment elevation (0.5mm – 1mm) in aVR
Typical STEMI morphology may precede or follow the De Winter pattern

Developing Visual Expertise in ECG Interpretation

Sun, 21 Mar 2021 00:00:00 +0000

Evaluating the Differences in Approach to the ECG Between Experts and Novices

We know that emergency medicine attendings are generally faster and more accurate at ECG interpretation than residents and medical students. But how are they able to process this information so much quicker while maintaining accuracy? And can we use these strategies to help learners progress to their own ‘expert-like’ level?

Our study combined eye-tracking and interview data to come up with a few ways in which EM attendings look and think about ECGs differently than more novice learners.1