ECG examples

Every rhythm and finding Squiggler draws, as 60 worked examples — STEMI territories, blocks, tachyarrhythmias, arrest rhythms and the metabolic patterns — each one a synthetic tracing you can open and tune.

Acute coronary syndrome

• Inferior STEMI — Elevation in II, III and aVF with reciprocal depression in aVL.
• Anterior STEMI — Convex ST elevation across the anterior leads, with sinus tachycardia.
• Posterior MI — ST depression in V1–V3, with no elevation on the standard leads.
• Anterior MI with Q waves — Flattened ST with established Q waves in the anterior leads.
• Wellens type A — Biphasic T waves in V2–V3, with no elevation.
• de Winter T waves — Upsloping ST depression with tall symmetric T waves in the anterior leads.
• Lateral STEMI — ST elevation in I, aVL, V5 and V6.
• NSTEMI, ST depression — ST depression across the anterior leads, with no elevation.
• Wellens type B — Deep symmetric T inversion in V2-V3, pain-free.

Blocks & conduction

• AF, conversion pause, sinus — Fibrillation, a three-second pause, then slow sinus.
• Wenckebach (Mobitz I) — The PR lengthens across the cycle until one P fails to conduct.
• Mobitz II — A fixed PR with a dropped beat.
• 2:1 AV block — Every other P conducts. No PR sequence to read.
• Complete block, narrow escape — Third-degree block with a narrow junctional escape.
• High-grade block with escape — Occasional conducted P waves, with a junctional escape covering the pauses.
• Junctional escape over a slow sinus — Mostly junctional complexes, with the P waves marching on independently.
• WPW pre-excitation — Short PR with a delta wave.
• Left bundle branch block — Wide QRS in a left bundle branch pattern.
• Right bundle branch block — Wide QRS with rSR' in V1 and a slurred S in I and V6.
• First-degree AV block — Every P conducts, with a PR of 280 ms.
• Junctional rhythm — Narrow complexes with no P wave before them.

Tachyarrhythmias

• AF with rapid response — Irregularly irregular and fast, with no organised atrial activity.
• Flutter, variable block — Flutter waves with variable block; R–R intervals are multiples of the flutter interval.
• AF, rate-controlled — Irregularly irregular, with a controlled ventricular rate.
• Regularised AF — Irregular atria, regular ventricles: complete block with a junctional escape.
• SVT — Regular, narrow and fast, with no visible P wave.
• Monomorphic VT — Wide, regular, uniform complexes across twelve leads.
• Pre-excited AF — Irregular, fast and wide: AF down an accessory pathway.
• SVT (twelve-lead) — Regular and narrow, with no P wave to find.
• Ectopic atrial tachycardia — A regular narrow tachycardia with an abnormal P axis.

Arrest rhythms

• Torsades de pointes — Polymorphic VT, the axis twisting about the baseline.
• Ventricular fibrillation — No organised complexes; a chaotic baseline.
• Idioventricular / agonal — A slow, wide escape rhythm with no atrial activity.
• Asystole — No complexes and no organised activity.

Metabolic & inherited

• Hyperkalaemia — Peaked T waves with a widening QRS.
• Pericarditis — Widespread concave ST elevation.
• Brugada type 1 — Coved ST elevation in V1–V2.
• PE pattern (S1Q3T3) — S wave in I, Q wave and inverted T in III.
• Hypothermia (Osborn) — J waves at the end of every QRS, with bradycardia.
• LVH with strain — Voltage criteria with lateral repolarisation change.
• Digoxin effect — Sagging 'reverse tick' ST depression.
• Hypokalaemia — Flattened T waves with a U wave behind them.
• Long QT — A QTc of 520 ms.
• Brugada type 2 — Saddleback elevation in V1-V2.

Chambers, axis & voltage

• Right ventricular hypertrophy — Right axis with a dominant R wave in V1.
• Left axis deviation — The frontal axis at -45 degrees.
• P pulmonale — Tall peaked P waves in II.
• P mitrale — Broad notched P waves in II.
• Low voltage — Small complexes throughout, at under half the usual voltage.
• Electrical alternans — The QRS amplitude alternating from beat to beat.
• Poor R-wave progression — The precordial transition delayed to V5.

Normal & variants

• Normal twelve-lead — Sinus rhythm at 72, with normal intervals and axis.
• Early repolarisation — Concave ST elevation with J-point notching.
• Ventricular ectopics — Sinus rhythm interrupted by wide ventricular ectopics.
• Atrial ectopics — Early atrial beats, each conducted with a narrow QRS.

Pacing

• Atrial pacing — A pacing spike before each P wave, with a narrow QRS.
• Ventricular pacing — A spike before a wide, left-bundle-shaped QRS.
• AV-sequential pacing — A spike before the P and another before the QRS.

The recording itself

• Movement artifact — Bursts of movement across the baseline, the rhythm intact beneath.
• Mains interference — Fifty-hertz interference across every lead.

For education only; not for clinical use. Every tracing on this site is generated, not recorded: there is no patient and no protected health information.