Basics & Fundamentals
Latest
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…
Delta Waves
Key Points Definition: A delta wave is the slurred upstroke at the start of the QRS, produced by early ventricular activation through an accessory pathway that bypasses the AV node….
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…
Inverted U waves
Key Points Definition: A negative deflection after the T wave (a true U wave) that is ≥0.5 mm deep in a lead where the T wave is upright. Why it…
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…
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…
Blocked Premature Atrial Complexes (PACs)
Key Points Definition: Blocked premature atrial complexes (PACs) are early ectopic atrial impulses not conducted to the ventricles, resulting in a visible P wave without a subsequent QRS complex. They…
Isorhythmic AV Dissociation
Key Points Definition: A type of AV dissociation in which sinus and escape rates are nearly identical, so P waves and QRS complexes appear to “track” each other while remaining unrelated….
Third-Degree AV Block (Complete Heart Block)
Key Points Definition: Third-degree AV block is complete failure of conduction from atria to ventricles, resulting in independent atrial and ventricular activity—known as AV dissociation. Hallmark Feature: No P waves…
High-Grade (Advanced) AV Block
Key Points Definition: A severe form of second-degree AV block with two or more consecutive non‑conducted P waves (for example 3:1, 4:1). Do not force a Mobitz label when multiple…
Atrial Septal Defect (ASD) & Crochetage Pattern
Key Points ASD Overview: Atrial septal defects are often detected and repaired in childhood, but uncorrected lesions may remain silent into early adulthood. Symptoms usually appear by age 30–40 and…
Irregularly Irregular Rhythms
Key Points Definition: An irregularly irregular rhythm occurs when the R-R intervals or P-P intervals vary with no consistent pattern, making the rhythm unpredictable and abnormal. Clinical Significance: Identifying an…
Regularly Irregular Rhythms
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 Rhythm
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…
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….
Free Content
Jump on our email list for free tips and insights delivered to your inbox monthly. No spam - just quick pearls and ECG education.
Categories
- No categories
© 2025 ECG Weekly. All rights reserved. | Terms of Use | Privacy Policy
Powered by the member(dev) platform
Loading...