Basics & Fundamentals
Latest
First-Degree AV Block
Key Points: First-degree AV block is defined by a PR interval greater than 200 ms with fixed 1:1 AV conduction and no dropped QRS complexes. It usually reflects delayed conduction,…
Second-Degree AV Block Type II (Mobitz II)
Key Points: Mobitz II is defined by sudden failure of AV conduction after at least 2 consecutive conducted beats with fixed PR intervals and no preceding PR prolongation. The block…
Atrial Flutter 2:1 Conduction
Key Points: Atrial flutter is a macro-reentrant atrial tachycardia, most commonly typical cavotricuspid isthmus-dependent right atrial flutter, with an atrial rate usually near 300 bpm. With 2:1 AV conduction, the…
Atrial Flutter
Key Points: Atrial flutter is a supraventricular tachyarrhythmia caused by a macro-reentrant circuit, most commonly typical cavotricuspid isthmus-dependent flutter in the right atrium. The atrial rate is usually about 250-350…
Flutter Waves (F waves): Basics
Key Points: Atrial flutter is a supraventricular tachyarrhythmia caused by a macro-reentrant circuit, most commonly typical cavotricuspid isthmus-dependent flutter in the right atrium. The atrial rate is usually about 250-350…
The Bix Rule (Unmasking Atrial Flutter)
Key Points: The Bix Rule is a bedside ECG clue for atrial flutter with 2:1 conduction. If an apparent “P wave” sits exactly halfway between 2 QRS complexes in a…
Advanced (High-Grade) AV Block
Key Points: Advanced or high-grade AV block is a severe second-degree AV block with 2 or more consecutive non-conducted P waves, such as 3:1 or 4:1 conduction. Do not force…
Appropriate Discordance
Key Points: Appropriate discordance refers to the expected secondary ST segment and T wave pattern seen with abnormal ventricular depolarization, especially LBBB and ventricular-paced rhythm. The ST segment and T…
QRS Morphology and ST-T Interpretation: Basics
Key Points: Read the QRS before you read the ST segment or T wave. Ventricular depolarization shapes repolarization. Narrow QRS usually reflects normal His-Purkinje conduction. Wide QRS suggests abnormal ventricular…
Preexcitation Syndromes: Overview
Key Points: Pre-excitation means an accessory pathway allows atrial impulses to reach the ventricle without traversing the AV node, producing early ventricular activation. A delta wave is the defining ECG…
Delta Waves: Basics
Key Points: Definition: A delta wave is a slurred upstroke at the very start of the QRS. It reflects early ventricular activation through an accessory pathway that bypasses the AV…
Short QT Syndrome
Key Points: Short QT Syndrome (SQTS) is a rare condition characterized by a shortened QT interval on the ECG, increasing the risk of atrial and ventricular arrhythmias, including sudden cardiac…
WPW Syndrome and Pseudo-MI Patterns
Key Points: WPW alters ventricular depolarization, producing secondary repolarization abnormalities that can mimic or mask myocardial infarction. ST-segment deviation in WPW is often non-ischemic, driven by abnormal activation via the…
WPW with Antidromic SVT (Antidromic AVRT)
Key Points: Antidromic AVRT is an AV re-entrant tachycardia that conducts antegrade down the accessory pathway and returns retrograde through the AV node (or another pathway), producing a regular wide-complex…
WPW with Orthodromic SVT (Orthodromic AVRT)
Key Points: Orthodromic AVRT is the most common tachyarrhythmia in WPW and presents as a regular narrow-complex SVT that is indistinguishable from AVNRT during the tachycardia. Mechanism: antegrade conduction down…
ECG Foundations: Vectors, Leads, & Activation
Key Points: An ECG records voltage differences over time. The ECG tracing is a plot where the horizontal axis is time and the vertical axis is voltage. Leads are viewpoints….
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…
Non-Thrombotic Causes of Acute Coronary Syndrome (ACS)
Key Points: ACS ≠ Always Thrombosis: While most ACS is due to plaque rupture with thrombus formation, several important non-thrombotic causes can produce identical ECG changes, troponin elevation, and symptoms….
Occlusion MI: STEMI Criteria & Beyond
Key Points: The ECG’s primary role in ACS is detecting acute coronary occlusion. Acute coronary occlusion myocardial infarction (OMI) is a time-critical diagnosis that requires immediate reperfusion. Time is myocardium….
QT Interval: Basics
Key Points: Definition: QT is measured from QRS onset to T-wave end. It reflects total ventricular depolarization plus repolarization. Use QTc: QT varies with heart rate. Interpret QTc, not the…
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
© 2026 ECG Weekly. All rights reserved. | Terms of Use | Privacy Policy
Powered by the member(dev) platform
Loading...