Basics & Fundamentals

Latest

Dextrocardia

Key Points Dextrocardia: A congenital condition where the heart is located on the right side of the chest. Situs Inversus Totalis: A complete reversal of thoracic and abdominal organs, including…

Persistent Juvenile T wave Pattern

Key Points Benign Variant: Persistent juvenile T waves (PJTW) represent a benign ECG finding and require no further evaluation in the absence of clinical symptoms or concerning findings. Typical Distribution:…

Lead Misplacement

Key Points Proper lead placement is critical to avoid misdiagnoses that can lead to unnecessary interventions and patient harm. Misplaced precordial leads (V1-V6) can mimic ischemia and cause false MI…

Left Posterior Fascicular Block (LPFB)

Key Points Anatomy of the Left Bundle Branch: The left bundle branch divides into two main fascicles: the left anterior fascicle (LAF) and the left posterior fascicle (LPF), both of…

Atrial Flutter with Variable Conduction

Key Points Mechanism: Typical atrial flutter arises from a large re-entry circuit in the right atrium. The atrial rate is usually near 300 beats per minute. ECG hallmark: Continuous “saw-tooth”…

QRS Voltage Basics

Key Points Definition: QRS voltage represents the amplitude (height) of the QRS complex on ECG, reflecting ventricular electrical activity during depolarization. High Voltage: Increased QRS voltage typically indicates ventricular hypertrophy—most…

Normal Cardiac Conduction

Key Points SA Node: Initiates electrical impulses; primary pacemaker (60–100 bpm). AV Node: Slows conduction to permit ventricular filling. Bundle of His: Transmits impulses from the AV node to ventricles;…

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…

Post-Cardiac Arrest ECGs

Key Points Coronary Occlusion After Shockable Arrest: ~30% of patients resuscitated from ventricular fibrillation (VF) arrest have an acute coronary occlusion and present with STEMI on ECG. Among patients without…

Second-Degree AV Block Type I
(Mobitz I/Wenckebach)

Key Points Definition: Progressive lengthening of the PR interval until one atrial impulse fails to conduct to the ventricles (a dropped QRS complex). Site of Block: Typically within the AV…

Second-Degree AV Block with 2:1 Conduction

Key Points Definition: A form of second-degree AV block in which every other atrial impulse is blocked, producing a 2:1 atrioventricular conduction ratio. Diagnostic Challenge: Differentiating between Mobitz I and…

Second-Degree AV Block, High-Grade
(“Advanced AV Block”)

Key Points Definition: A severe form of second-degree AV block—most often Mobitz II—characterized by multiple consecutive non-conducted P waves (e.g., 3:1 or 4:1 conduction). PR Intervals: Constant before conducted beats,…

First-Degree AV Block

Key Points Definition: PR interval prolongation (>200 ms) without dropped QRS complexes (consistent 1:1 P:QRS conduction). Mechanism: Usually results from slowed conduction within the AV node or the His-Purkinje system,…

Second-Degree AV Block Type II (Mobitz II)

Key Points Definition: Mobitz II is a type of second-degree AV block defined by sudden, intermittent failure of atrial impulses to conduct to the ventricles, without progressive PR interval lengthening…

Atrial Flutter

Key Points Definition: Atrial flutter is a common type of supraventricular tachycardia caused by a re-entry circuit within the right atrium. Atrial Rate: Typically around ~300 bpm, ranging from 240-360…

Flutter Waves (F waves)

Key Points Atrial Flutter Overview: Atrial flutter is a common type of supraventricular tachycardia caused by a re-entry circuit within the right atrium. Atrial Rate: The atrial rate in atrial…

Electrical Alternans

Key Points Classically associated with pericardial tamponade but seen in fewer than 30% of confirmed cases. Combination of low-voltage QRS + sinus tachycardia strongly suggests pericardial effusion/tamponade. Always perform rapid…

Pericardial Effusion

Key Point Always consider pericardial effusion in any patient with new low-voltage QRS complexes combined with sinus tachycardia. Prompt bedside ultrasound (POCUS) prevents diagnostic delays and potentially catastrophic outcomes. Classic…

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…

QT Interval Basics

Key Points Definition: The QT interval is a measure of the time from the beginning of the QRS complex to the end of the T wave. It reflects the total…

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
Loading...