Basics & Fundamentals
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Early Reciprocal Changes (OMI Pattern)
Key Points ACS Dynamics: ACS is complex and dynamic, with occluded arteries potentially reperfusing and reoccluding at any time. ECG Pattern Recognition: Mastering ECG pattern recognition in ACS is crucial…
Occlusion MI: STEMI Criteria & Beyond
Key Points A STAT ECG is the most critical first test in patients with suspected acute coronary syndrome (ACS). It allows for early identification of acute coronary occlusion myocardial infarction…
Hyperkalemia
Key Points ECG as a Frontline Diagnostic Tool: Hyperkalemia often reveals itself on the ECG before lab confirmation. Early recognition of characteristic changes can be life-saving, especially in critically ill…
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…
Escape-Capture Bigeminy
Key Points Escape-capture bigeminy is a unique rhythm characterized by alternating escape beats and normally conducted sinus beats, resulting in a bigeminal (paired) rhythm pattern. It typically occurs in patients…
Modified Sgarbossa Criteria
Key Points Wide QRS Rhythms Can Mask OMI: Left bundle branch block (LBBB) and right ventricular (RV)-paced rhythms alter ventricular depolarization, producing expected secondary ST/T changes. However, acute occlusion MI…
Ventricular Escape Rhythms
Key Points Wide QRS Complex Rhythm: Ventricular escape rhythms (aka idioventricular rhythms) are characterized by a wide QRS duration (>120 ms), absent or dissociated P-waves, and a regular, slow ventricular…
Appropriate Discordance
Key Points Definition: Appropriate discordance is a normal repolarization pattern in which the ST segment and T wave are directed opposite to the main QRS vector. It reflects expected changes…
Junctional Escape Rhythms
Key Points Narrow QRS Complexes typically indicate junctional escape rhythms, originating near the AV node or proximal His-Purkinje system. These generally have a more favorable prognosis. Wide QRS Complexes suggest…
The Bix Rule (Unmasking Atrial Flutter)
Key Points The Bix Rule refers to a simple but powerful ECG clue: if you observe a consistent P wave located exactly halfway between two QRS complexes, suspect concealed atrial…
Sinus Tachycardia
Key Points Definition: Sinus tachycardia is a regular rhythm originating from the sinoatrial (SA) node, defined by a heart rate >100 bpm in adults or above age-adjusted norms in children….
Ashman Phenomenon
Key Points Definition: Ashman phenomenon is an aberrant intraventricular conduction pattern triggered by cycle-length variation. It is most often seen in atrial fibrillation but can appear in any supraventricular rhythm….
Sinoatrial Nodal Reentry Tachycardia (SANRT)
Key Points Mechanism: SANRT is a rare type of paroxysmal supraventricular tachycardia (SVT) that operates through a similar mechanism as AV nodal reentry tachycardia (AVNRT), with the reentry loop occurring…
Junctional Tachycardia
Key Points Origin: Junctional tachycardia is a rare type of paroxysmal supraventricular tachycardia (SVT) that originates from the AV node or the bundle of His. Mechanism: The arrhythmia is caused…
Atrial Tachycardia
Key Points: Definition: Atrial tachycardia is a supraventricular arrhythmia characterized by rapid atrial depolarizations from one or more ectopic foci outside the SA node. Atrial Rate: > 100 bpm, typically…
Trifascicular Block
Key Points Definition: Trifascicular block refers to ECG evidence of impaired conduction in all three fascicles of the ventricular conduction system: the right bundle branch (RBB), left anterior fascicle (LAF),…
Pseudo-Wellens Waves
Key Points Wellens Syndrome: A critical condition resulting from severe stenosis of the left anterior descending (LAD) coronary artery, characterized by specific ECG patterns known as Wellens waves. This is…
Sinus Node Dysfunction (Sick Sinus / Brady–Tachy Syndrome)
Key Points Spectrum, not one rhythm: Look for sinus brady, pauses, arrest, alternating atrial tachyarrhythmias (AF, flutter, ATach). Symptoms matter: Syncope, presyncope, fatigue usually come from cerebral/systemic hypoperfusion, especially after…
Wellens Waves
Key Points Significance: Wellens waves are T wave abnormalities (either biphasic or deeply inverted) in the mid-precordial leads (V2-V3, +/-V4-6) that are highly specific for critical obstruction of the left…
Right Atrial Enlargement (RAE)
Key Points Definition: Right atrial enlargement (RAE) is an increase in the size of the right atrium, typically resulting from chronic pressure or volume overload, commonly related to cardiac or…
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