Killer Differentials
Latest
Short QT Interval DDx
Key Points Short QT Interval: A QT interval is considered short when the corrected QT (QTc) interval is less than 350 ms. A short QT interval on the ECG can…
Narrow QRS Bradycardia DDx
Key Point Narrow QRS Bradycardias: These rhythms are more commonly associated with vagal stimulation or reversible causes, making them generally less severe than wide QRS bradycardias. Due to their better…
Left Bundle Branch Block (LBBB) DDx
Key Point Overview: Left bundle branch block (LBBB) is an intraventricular conduction delay that results from a block in the left bundle branch of the heart’s electrical conduction system. It…
Extreme Axis Deviation DDx
Key Points Definition: Extreme right axis deviation refers to the QRS axis being between -90° and 180°. Common Causes: Ventricular ectopy, dextrocardia, chronic lung disease (e.g., COPD), pulmonary hypertension, and…
Must-Know Differential Diagnoses (DDx)
Key Points About Using Differentials: Definition: Differential diagnosis involves systematically considering and ruling out multiple potential conditions that could explain a patient’s symptoms and ECG findings. Purpose: The goal is…
T Wave Inversion DDx
Key Points Ischemia Isn’t Everything: While T-wave inversions often raise concern for ischemia, many non-ischemic processes (e.g., pulmonary pathology, neurologic conditions, repolarization variants) can produce similar findings. Clinical Correlation: Always…
Bradycardia DDx
Key Points Common Offenders: Beta-blockers, calcium channel blockers, and digoxin often top the list of medication-induced bradycardia. High Vagal Tone or AV Block can arise from structural heart disease, ischemia,…
Abnormal P Wave Axis DDx
Key Points Normal Sinus Rhythm: In a normal rhythm, the sinus node initiates atrial depolarization, resulting in a P wave with a normal axis: upright in lead II, inverted in…
Diffuse ST Elevation DDx
Key Point ST-Segment Elevation (STE): It’s crucial to recognize that several conditions beyond STEMI can cause ST-segment elevation (STE) on an ECG. Identifying these differentials is vital to avoid misdiagnosis…
Low Voltage QRS DDx
Key Points Definition: Low voltage QRS complexes reflect decreased myocardial electrical amplitude on ECG. Sensitive Definition (Preferred): Limb leads (I + II + III) sum < 15 mm OR precordial…
Wide QRS Bradyarrhythmia DDx
Key Points Infranodal Block: Wide QRS bradycardias often indicate an infranodal block, typically involving the His-Purkinje system. These rhythms are more likely to be unstable and may necessitate urgent pacemaker…
Acute Chest Pain DDx
Key Point In patients presenting with acute chest pain, rapidly identifying life-threatening conditions is essential. Use a systematic ECG approach alongside clinical context to evaluate for high-risk diagnoses that require…
Prolonged QT Interval DDx
Key Points Definition: The QT interval reflects the time it takes for total ventricular depolarization and repolarization (Q wave onset to T wave end). Clinical Relevance: QT prolongation increases the…
ST Depression in V1-V4 DDx
Key Point ST segment depression in V1–V4 is often misattributed to anterior ischemia or NSTEMI. In patients with ACS symptoms, this pattern should first raise concern for isolated posterior occlusion…
Ventricular Tachycardia (VT) Mimics
Key Points Initial Assumption: Any wide (QRS >120 ms), regular tachycardia should be considered ventricular tachycardia (VT) until clearly proven otherwise. VT Characteristics: VT generally has a ventricular rate of…
Narrow & Irregular Tachycardia DDx
Key Points Definition: Narrow complex irregular tachycardia is characterized by a QRS duration <120 ms with an irregular rhythm. Primary rhythms include Atrial Fibrillation (AF) with Rapid Ventricular Response (RVR),…
Narrow & Regular Tachycardia DDx
Key Points Definition: Narrow complex regular tachycardia refers to a rhythm with a QRS duration <120 ms and a regular rhythm. Key rhythms include Sinus Tachycardia, Supraventricular Tachycardia (SVT), and…
Syncope DDx
Key Points Syncope and the ECG: Syncope is a transient loss of consciousness and postural tone, characterized by rapid onset, brief duration, and spontaneous recovery without medical intervention. Cardiac syncope…
Right Axis Deviation DDx
Top 3 emergent causes of new rightward axis to consider: When encountering a new rightward axis on an ECG, immediately consider the following life-threatening conditions: Acute Right Heart Strain /…
Wide & Regular Tachydysrhythmia DDx
Key Points Definition: Wide complex tachycardia (WCT) is defined by QRS duration >120 ms. The differentials are distinguished using the rhythm, regular wide complex rhythms (RWCT) are discussed here. 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
© 2025 ECG Weekly. All rights reserved. | Terms of Use | Privacy Policy
Powered by the member(dev) platform
Loading...