EKG Rhythm Library — All Cardiac Rhythms

Browse 44 cardiac rhythms with ECG waveform analysis, clinical significance, and recognition criteria.

  • Normal Sinus Rhythm (NSR) — The baseline rhythm all others are measured against. Master NSR first — every abnormality is a departure from it.
  • Sinus Bradycardia (SB) — A sinus rhythm with a rate below 60 bpm. The SA node fires slower than normal, but every other part of the conduction sy
  • Sinus Tachycardia (ST) — A sinus rhythm with a rate above 100 bpm. The SA node fires faster than normal — usually because the body is asking it t
  • Sinus Arrhythmia — A normal sinus rhythm variant where the heart rate cyclically increases during inspiration and decreases during expirati
  • Sinus Pause — A transient failure of the SA node to fire, producing a pause in the cardiac rhythm typically lasting less than 3 second
  • Sinus Arrest — A prolonged failure of the SA node to generate impulses, producing extended pauses (>3 seconds) that often require a sub
  • Atrial Fibrillation (AFib) — The most common sustained arrhythmia worldwide. Characterized by an irregularly irregular rhythm, absence of P-waves, an
  • Atrial Flutter (AFL) — A rapid, organized atrial rhythm driven by a single re-entry circuit in the right atrium, producing sawtooth flutter wav
  • Atrial Tachycardia — A supraventricular tachycardia originating from an ectopic atrial focus outside the SA node, producing abnormal P waves
  • Supraventricular Tachycardia (SVT) — A rapid rhythm (150-250 bpm) originating above the ventricles, characterized by sudden onset and termination, where P-wa
  • Wandering Atrial Pacemaker (WAP) — An irregular rhythm with at least 3 distinct P-wave morphologies at a rate below 100 BPM, indicating the dominant pacema
  • Multifocal Atrial Tachycardia (MAT) — An irregular atrial tachycardia with at least 3 distinct P-wave morphologies at a rate exceeding 100 BPM, reflecting mul
  • Junctional Bradycardia — A severely slow junctional rhythm below 40 BPM. It shares junctional P-wave behavior with narrow QRS but carries higher
  • Junctional Escape Rhythm — A backup rhythm originating from the AV junction when the SA node fails, producing a regular narrow-complex bradycardia
  • Accelerated Junctional Rhythm — A junctional rhythm with enhanced automaticity at 60-100 BPM — faster than the inherent junctional rate but not tachycar
  • Junctional Tachycardia — A narrow-complex tachycardia originating from the AV junction at rates exceeding 100 BPM, driven by abnormally enhanced
  • First Degree AV Block — A conduction delay at the AV node where every P wave is conducted to the ventricles, but the PR interval is prolonged be
  • Second Degree AV Block Type I (Wenckebach) — Progressive PR interval prolongation with each successive beat until one P wave fails to conduct, producing a dropped QR
  • Second Degree AV Block Type II (Mobitz II) — Intermittent failure of AV conduction where beats drop suddenly without PR prolongation. The block is infranodal and car
  • Second Degree AV Block 2:1 — A fixed 2:1 AV conduction pattern where every other P wave is blocked. Cannot be classified as Type I or Type II from th
  • Third Degree AV Block (Complete Heart Block) — Complete failure of AV conduction — no atrial impulses reach the ventricles. The atria and ventricles beat independently
  • Third Degree AV Block (Ventricular Escape) — Complete heart block with a wide-QRS ventricular escape rhythm. The block is below the bundle bifurcation (infranodal),
  • Isorhythmic AV Dissociation — A benign form of AV dissociation where the sinus node and a junctional pacemaker fire at nearly the same rate. P waves d
  • Idioventricular Rhythm (IVR) — The heart's last-resort escape rhythm — ventricular pacemaker cells fire at their inherent rate of 20-40 BPM when both t
  • Accelerated Idioventricular Rhythm (AIVR) — A wide-complex ventricular rhythm at 50-100 BPM — faster than ventricular escape but slower than VT. Usually transient,
  • Ventricular Tachycardia (VT) — A life-threatening wide-complex tachycardia originating in the ventricles. Can be monomorphic or polymorphic.
  • Ventricular Fibrillation (VFib) — A chaotic, life-threatening cardiac arrest rhythm where the ventricles quiver without any effective contraction, resulti
  • Torsades de Pointes (Polymorphic VT) — A distinctive polymorphic ventricular tachycardia where the QRS complexes appear to twist around the baseline — amplitud
  • Asystole — The absence of all electrical activity in the heart. This is cardiac arrest — the heart has stopped generating any organ
  • Atrio-Ventricular Paced Rhythm (AV Sequential) — A rhythm where an artificial pacemaker stimulates both the atria and the ventricles in sequence, maintaining AV synchron
  • Atrial Paced Rhythm (AAI) — A pacemaker stimulates the atrium, and the impulse conducts normally through the AV node to produce a narrow QRS. Used w
  • Ventricular Paced Rhythm (VVI) — A pacemaker directly stimulates the ventricles, producing a wide QRS with LBBB morphology. The most recognizable paced r
  • VDD Paced Rhythm (Atrial Sensed, Ventricular Paced) — A pacing mode that senses native atrial activity and paces the ventricle after a programmed AV delay. Maintains AV synch
  • Biventricular Paced Rhythm (CRT) — Cardiac Resynchronization Therapy paces both ventricles simultaneously to restore synchronized contraction. The QRS has
  • Pacemaker Failure to Capture — A pacemaker malfunction where the pacing spike fires but fails to produce myocardial depolarization. Spikes are visible
  • Pacemaker Failure to Output — A pacemaker malfunction where the device does not fire when expected — the pacing spike itself is absent. The pacemaker
  • Pacemaker Undersensing (Failure to Sense) — A pacemaker malfunction where the device does not detect (sense) the heart’s native electrical activity. The pacemaker f
  • ST Elevation (STEMI Pattern) — Marked ST segment elevation above the baseline, indicating acute transmural myocardial injury — the full thickness of th
  • ST Depression (Ischemia) — ST segment depression below the baseline, indicating subendocardial ischemia — the inner layer of the heart wall is not
  • Wolff-Parkinson-White (WPW) — A pre-excitation syndrome where an accessory pathway (bundle of Kent) bypasses the AV node, producing the classic triad:
  • Right Bundle Branch Block (RBBB) — A conduction abnormality where the right bundle branch is blocked, forcing the right ventricle to depolarize via muscle-
  • Left Bundle Branch Block (LBBB) — A conduction abnormality where the left bundle branch is blocked, forcing the left ventricle to depolarize via slow musc
  • Premature Ventricular Contractions (PVCs) — Early beats originating from an ectopic focus in the ventricles. PVCs are wide, bizarre-looking QRS complexes that appea
  • Premature Atrial Contractions (PACs) — Early beats originating from an ectopic focus in the atria. PACs produce a P wave with abnormal morphology (different sh