ECG Interpretation
Results:
R Wave: Basics
Key Points Definition: The R wave is the first positive deflection of the QRS complex, reflecting early ventricular depolarization, predominantly of the left ventricle. Normal progression: Precordial R amplitude increases…
Preexcitation Syndromes
Key Points Terminology: WPW pattern = ECG evidence of pre-excitation without symptoms. WPW syndrome = pattern plus symptomatic tachyarrhythmia (e.g., AVRT, pre-excited AF). Mechanism: An atrioventricular accessory pathway (e.g., Kent;…
Waveforms, Segments, & Intervals: Basics
Key Points ECGs display voltage changes across the cardiac cycle, captured as waveforms, segments, and intervals. Waveforms represent depolarization or repolarization events. Segments are baseline connections between waveforms, usually representing…
TP Segment: Basics
Key Points Definition: The TP segment is the isoelectric interval from the end of the T wave to the start of the P wave. It reflects electrical diastole when the…
U Wave: Basics
Key Points Definition and origin: The U wave is a small deflection following the T wave, best seen in V2–V3. It likely reflects late ventricular repolarization or Purkinje repolarization. Normal…
T Wave: Basics
Key Points Definition: The T wave reflects ventricular repolarization. Measure amplitude from baseline to peak and identify the end of T to help define the QT interval. Normal appearance: Upright…
S Wave: Basics
Key Points Definition and measurement: The S wave is the first negative deflection after the R wave within the QRS. Measure depth in mm from baseline to nadir; width contributes…
P Wave: Basics
Key Points Definition and measurement: The P wave is atrial depolarization. Measure duration from initial deflection to return to baseline and amplitude from baseline to peak. Normal values: Duration <120…
Isoelectric Segment of the ECG
Key Points The reference for ST-segment shift is the J point relative to an isoelectric baseline. The two candidates for that baseline are the TP segment and the PR segment….
Wide QRS Complex: DDx
Key Points A QRS duration greater than 120 ms indicates abnormal ventricular depolarization. A wide QRS can signal conditions that range from benign to immediately life-threatening. Developing a focused differential…
Understanding ECG Artifacts
Key Points Artifacts = non-cardiac signals that distort or obscure true ECG. They come from the patient, leads/equipment, or the environment. Clues to artifact: lacks a physiologic pattern, varies beat-to-beat…
Regularly Irregular Rhythms: Basics
Key Points Definition: A regularly irregular rhythm occurs when the distance between R-R intervals or P-P intervals varies in a consistent, repeating pattern throughout the ECG tracing. Significance: Determining the…
Regular Rhythms: Basics
Key Points Rhythm Regularity: Regular rhythm is characterized by equal distances between consecutive P waves (P-P intervals) and QRS complexes (R-R intervals). Verify rhythms with calipers—don’t trust the machine interpretation…
Heart Rhythm: Basics
Key Points Don’t trust the ECG machines automated interpretation. Confirm the rhythm yourself. Start with the ventricles (R–R pattern), then the atria (P waves), then the AV relationship (PR behavior/P:QRS)….
Heart Rate: Basics
Key Points Never accept the machine’s rate blindly. Confirm it yourself as ECG computer interpretations are frequently inaccurate. Verify paper speed and gain first (default 25 mm/s, 10 mm/mV). Name…
Stepwise Approach to STAT ECGs
Key Points: Consistency Saves Lives: A standardized approach helps you avoid errors in chaotic environments. Many Methods Exist: Rate, rhythm, axis, intervals, voltage, ischemia, conduction — choose an order that…
Normal STAT ECG
Key Points Clinical Context: A single normal 12-lead ECG in the emergent setting does not exclude life-threatening conditions such as occlusion MI, PE, tamponade, tension pneumothorax, or aortic dissection. Serial…
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….
Right Axis Deviation: Basics
Key Points Definition: Right Axis Deviation (RAD) occurs when the QRS axis is > +90°, typically up to +180°. ECG Criteria: Negative QRS in Lead I Positive QRS in Lead…
Normal QRS Axis
Key Points Normal Axis Range: –30° to +90° Lead I: QRS complex is positive Lead aVF: QRS complex is positive → This combination confirms a normal QRS axis Frontal plane…
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
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