ECG Pro / ECG findings

ECG findings, and how to recognise them

48 findings · Written for learners

Every page below answers the same question in the same order: what the finding looks like on a 12-lead, how to work through the tracing to find it, and which other findings it is mistaken for. These are the 48 categories ECG Pro organises its casebook around — each one has real recordings behind it in the app.

Rhythm

Sinus Rhythm The baseline every other rhythm is judged against.
Sinus Tachycardia A normal rhythm running fast, almost always because of something else.
Sinus Bradycardia Sinus rhythm under 60 — normal in an athlete, ominous with symptoms.
Atrial Fibrillation (AF) Irregularly irregular, with no P waves anywhere.
Atrial Flutter Sawtooth atrial waves at about 300, conducted in a fixed ratio.
Supraventricular Tachycardia (SVT) Fast, regular, narrow, and with no P waves you can find.
Ventricular Tachycardia (VT) Wide, fast and regular — the rhythm you must not talk yourself out of.
Wandering Atrial Pacemaker (WAP) Three or more P wave shapes as the pacemaker site drifts.
Escape Rhythm A backup pacemaker taking over because the one above it failed.
Asystole No electrical activity — and the one rhythm you must verify before believing.
AF With Rapid Ventricular Response (AF RVR) Atrial fibrillation conducting fast enough to matter.

Ectopy

Premature Atrial Contraction (PAC) An early beat with a P wave that does not look like the others.
Premature Ventricular Contraction (PVC) Early, wide, bizarre, and with no P wave in front of it.
Bigeminy Every other beat is an ectopic — a repeating pair.
Trigeminy Every third beat is an ectopic.
Quadrigeminy Every fourth beat is an ectopic.
Fusion Beats Two wavefronts meeting, producing a hybrid complex.

Conduction

1st Degree AV Block A long PR interval, but nothing is dropped.
2nd Degree AV Block Some P waves conduct and some do not — the pattern tells you which type.
3rd Degree AV Block Atria and ventricles beating independently, with nothing getting through.
Right Bundle Branch Block (RBBB) Wide QRS with an RSR' in V1 — the "M" pattern.
Left Bundle Branch Block (LBBB) Wide QRS, broad R in V6, deep S in V1 — and it hides infarction.
Left Anterior Fascicular Block (LAFB) Marked left axis deviation with a normal QRS width.
Intraventricular Conduction Delay (IVCD) A wide QRS that fits neither bundle branch block pattern.
WPW Syndrome (WPW) Short PR and a delta wave — an accessory pathway bypassing the AV node.
Short PR Interval PR under 120 ms — check immediately for a delta wave.
Pacemaker Rhythm Pacing spikes, and a QRS shaped by where the lead sits.

Chamber size and axis

Left Ventricular Hypertrophy (LVH) Big voltages in the left-facing leads, often with strain.
Right Ventricular Hypertrophy (RVH) A dominant R wave in V1 with right axis deviation.
Left Atrial Enlargement (LAE) A broad notched P in lead II — "P mitrale".
Right Atrial Enlargement (RAE) A tall peaked P in lead II — "P pulmonale".
Left Axis Deviation (LAD) Lead I up, lead aVF down — the QRS vector points up and left.
Right Axis Deviation (RAD) Lead I down, lead aVF up — the QRS vector points down and right.
Poor R Wave Progression (PRWP) The R wave fails to grow across the chest leads.
Clockwise Rotation The R/S transition pushed late, towards V5 or V6.

Ischaemia and repolarisation

Myocardial Infarction (MI) ST elevation, then Q waves — and the leads tell you where.
ST Elevation Not always infarction — the shape and distribution decide.
ST Depression Ischaemia, strain, digoxin — or the mirror of something posterior.
T Wave Inversion Normal in some leads, ominous in others — the distribution decides.
Early Repolarization J point elevation with notching, in a young healthy person.
Long QT Syndrome (LQTS) A prolonged QTc, and the risk of torsades that comes with it.
U Wave The small deflection after the T — normal until it is prominent.
Alternans Beat-to-beat variation in amplitude — think pericardial effusion.
S1Q3T3 The classic pulmonary embolism pattern — famous, and usually absent.
Pulmonary Heart Disease The chronic right heart picture — low voltage, right axis, peaked P waves.
ST-T Change The commonest phrase on a real report, and the least specific.
T Wave Change Flat, peaked, biphasic — abnormal shape short of frank inversion.

Single-lead recordings

Apple Watch ECG One lead, thirty seconds, and a much narrower question than a 12-lead.

Knowing the criteria is the easy half. The hard half is calling it on a tracing you have never seen before.

Practise on real cases in ECG Pro