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…
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…
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…
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…
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…
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) —…
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,…
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…
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…
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…
Top 3 Emergent Causes of New Rightward Axis Deviation: When you see new RAD in an adult, immediately consider life-threatening etiologies: Acute Right Heart Strain Pulmonary embolism until proven otherwise…