Narrow QRS
Results:
Premature Atrial Complexes (PACs)
Key Points PACs are early atrial depolarizations from an ectopic focus that create a premature P wave with a different morphology and axis than the sinus P wave, usually followed…
Unstable Bradyarrhythmias
Key Points: Unstable bradyarrhythmias cause poor perfusion which can rapidly progress to shock, irreversible organ injury, or cardiac arrest. Priority: Do not treat the heart rate alone — treat clinical…
Unstable Tachyarrhythmias
Key Points: Intervene Immediately: Unstable tachyarrhythmias pose significant risk for rapid clinical deterioration that may lead to irreversible end-organ damage or cardiac arrest. Clinical Indicators of Instability: Altered Mental Status:…
Premature Junctional Complexes (PJCs)
Key Points PJCs are premature impulses from ectopic foci in or near the AV junction. ECG hallmark is a narrow premature beat with an absent or retrograde P wave. Retrograde…
Premature Complexes (PACs, PJCs, & PVCs) Overview
Key Points Premature complexes are early depolarizations arising from the atrium, AV junction, or ventricle which interrupt the expected sinus rhythm. Rapid classification by origin: look for a P wave…
Atrioventricular Nodal Reentry Tachycardia (AVNRT)
Key Points AVNRT is a paroxysmal, regular, usually narrow-complex SVT caused by a reentry circuit within or adjacent to the AV node. Dual-pathway physiology is typical. Bedside hallmark is a…
Atrioventricular Reciprocating Tachycardia (AVRT)
Key Points AVRT is a macroreentrant SVT that uses both the AV node and an accessory pathway. Orthodromic AVRT conducts down the AV node and up the pathway and is…
Atrioventricular Blocks (AVB): Comprehensive Summary
Key Points AV block specifically reflects delayed or failed impulse conduction from atria to ventricles. Classification of blocks depend on the location of conduction delay or block within the cardiac…
Narrow QRS Bradycardia: DDx
Key Point Narrow QRS bradycardias are often related to vagal tone or reversible causes, but not always benign. Certain AV blocks and conduction abnormalities may still carry significant risk, even…
Heart Rate & Rhythm Interpretation
Key Points Treat the patient, not just the number or rhythm. If the strip explains hypotension, ischemic chest pain, shock, altered mentation, or hypoxia, manage instability (cardioversion/pacing) before granular analysis….
Multifocal Atrial Tachycardia (MAT)
Key Points Definition: Multifocal Atrial Tachycardia (MAT) is a rare type of irregularly irregular supraventricular tachycardia (SVT) characterized by the presence of at least three or more different P wave…
Supraventricular Tachycardias (SVTs)
Key Points Definition: SVT refers to any tachyarrhythmia that originates above the ventricles (atria, AV node, or bundle of His). Most present as regular narrow-complex tachycardias, although aberrant conduction can…
Narrow & Irregular Tachycardia: DDx
Key Points Narrow irregular tachycardia = QRS <120 ms with variable R–R interval. The big three DDx: Atrial fibrillation (AF) with RVR, atrial flutter with variable block, multifocal atrial tachycardia…
Narrow & Regular Tachycardia: DDx
Key Points Narrow regular tachycardia = QRS <120 ms with a steady R–R interval. The big three DDx: sinus tachycardia, SVT (AVNRT/AVRT/junctional), and atrial flutter with fixed AV conduction (commonly…
Junctional Tachycardia
Key Points Origin: Junctional tachycardia is a rare type of paroxysmal supraventricular tachycardia (SVT) that originates from the AV node or the bundle of His. Mechanism: The arrhythmia is caused…
WPW with Orthodromic SVT
Key Points WPW syndrome is caused by congenital ventricular pre-excitation via an accessory pathway. The classic sinus rhythm pattern includes a short PR interval, delta wave, and a widened QRS,…
ECG Tags
- A-Z
- ACS-OMI
- Annual ECG Competition
- Approach
- Arrest
- Arrhythmia
- Artifact
- Attending
- AV Block
- aVL
- aVR
- Axis
- Board Review
- Bradyarrhythmia
- Chest Pain
- Clumped Beats
- Conduction
- Core
- Curriculum
- DDx
- Devices
- Documentation
- ECG Interpretation
- ECG Variant
- Education/Teaching
- Electrolytes
- Emergencies
- Emergent Cath Lab Activation
- EMS
- Guidelines
- Hub
- Hypercalcemia
- Hyperkalemia
- Hypermagnesemia
- Hypocalcemia
- Hypokalemia
- Hyponatremia
- Hypothermia
- Index
- Intervals
- Irregular
- Ischemia
- J Waves
- LBBB
- Lead Placement
- Metabolic
- Mimics
- Narrow QRS
- Occlusion MI
- OMI Pattern
- Osborn Waves
- P Wave
- Paced Rhythms
- Pacemaker/ICD
- Paramedics
- Pauses
- PE
- Pediatrics
- Pericardial
- Pericarditis
- PGY-1
- PGY-2
- PGY-3
- PGY-4
- Post-Cardiac Arrest
- Posterior MI
- PR
- Preexcitation
- Prolonged QT
- Pulmonary Embolism
- PVCs
- Q Wave
- QRS
- QT
- R Waves
- RAD
- RBBB
- Regular
- Reperfusion
- Rhythm
- S Waves
- Segments
- Seizure
- Serial ECGs
- Shock
- ST
- ST Elevation
- STEMI
- STEMI Equivalent
- Stroke
- Structural
- Students
- Syncope
- T Waves
- Tachyarrhythmia
- Tachycardia
- Tamponade
- Toxicology
- TP
- U Waves
- Unstable
- Ventricular Rhythms
- Ventricular Tachycardia
- Voltage
- Waveforms
- Wide QRS
© 2026 ECG Weekly. All rights reserved. | Terms of Use | Privacy Policy
Powered by the member(dev) platform
Loading...