Approach
Results:
Three More ECG Pitfalls That Punish Anchoring Bias
A 51-year-old man with lung cancer presents with shortness of breath and tachycardia. The arrival ECG shows an S1Q3 pattern and seems to support a familiar diagnosis that would normally…
Four ECG Pitfalls That Punish Anchoring Bias
A 43-year-old woman with sharp left-sided chest pain and minimal cardiac risk factors has an initial ECG that is not diagnostic for STEMI. She looks stable, but one feature on…
Dr. Mattu’s 5 Favorite ECG Cases of 2025
A 68-year-old man presents after syncope with profound bradycardia. The ECG shows a very slow ventricular rate with high-grade AV block. The reflex move is to focus only on pacing,…
Stepwise Approach to STAT ECGs
Key Points: Consistency saves lives: Use a repeatable ECG routine to reduce misses in chaotic settings. Many valid methods exist. Pick an order that fits your acute-care workflow and do…
J Point: Basics
Key Points The J point is the junction where QRS ends and the ST segment begins. It is a location, not a waveform. ST deviation is judged at the J…
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…
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…
Wide & Regular Tachydysrhythmia DDx
Key Points Definition: Wide complex tachycardia (WCT) = QRS >120 ms with a steady R-R interval. This section focuses on regular WCT (RWCT). Wide & irregular rhythms are covered separately…
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…
Ischemia & Infarction Interpretation
Key Points: The ECG is the fastest bedside tool for detecting acute coronary occlusion and dynamic ischemia, often before troponin changes and sometimes before classic symptoms. Acute coronary syndromes are…
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…
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…
Heart Rate & Rhythm Interpretation
Key Points: Treat the patient, not just the number or rhythm. Start with a 10-second stability check. If the rhythm explains hypotension, shock, ischemic chest pain, altered mentation, or severe…
Wide & Irregular Tachycardia: DDx
Key Points Definition: QRS >120 ms with an irregular ventricular rate. Clinical Priority: Always first consider AF with accessory pathway (AF + WPW) and polymorphic VT (PMVT, including torsades) —…
STAT ECG 101: The Acute Care ECG Approach
Key Points Rapid, Non-Invasive, High-Yield Tool: The STAT ECG is the single best screening test in acute care medicine. It is inexpensive, minimally invasive, and immediately available. Within seconds, it…
QRS Axis Interpretation Basics
Key Points Definition: The QRS axis reflects the net direction of ventricular depolarization and is expressed in degrees on the frontal plane. Why It Matters: Axis assessment is a fast,…
Extreme Axis Deviation: Basics
Key Points Definition: Extreme axis deviation (aka “Northwest Axis”) occurs when the QRS axis is between –90° and ±180°. ECG Clue: QRS negative in Lead I QRS negative in Lead…
Indeterminate QRS Axis: Basics
Key Points Definition: An indeterminate QRS axis (also called “no man’s land”) occurs when the frontal QRS vector lies between –90° and ±180°, but no dominant direction is evident. ECG…
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…
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