AV Block
Results:
UMEM Cases, Part 3: When the Diagnosis Seems Clear and When It Is Not
A 71-year-old man presents with shortness of breath, and his ECG is initially read as a junctional rhythm. On later review, it is even mistaken for atrial fibrillation. But the…
Atrioventricular (AV) Block: Comprehensive Summary
Key Points: AV block refers specifically to delayed or failed conduction of impulses from the atria to the ventricles. AV block is classified by the ECG pattern of conduction: First-degree…
The Syncope ECG With Too Much P
A 68-year-old man has syncope, then has a second syncopal episode while lying still on a stretcher during evaluation at an outpatient clinic. He is sent emergently to the ED….
Isorhythmic AV Dissociation
Key Points: Isorhythmic AV dissociation is a form of AV dissociation in which the sinus rate and junctional or ventricular escape rate are nearly identical, making the P waves and…
Third-Degree AV Block (Complete Heart Block)
Key Points: Third-degree AV block is complete failure of atrial impulses to conduct to the ventricles. The defining ECG feature is AV dissociation with no conducted P waves. The atrial…
Second-Degree AV Block Type I (Mobitz I/Wenckebach)
Key Points: Mobitz I is defined by progressive PR prolongation until a single P wave fails to conduct, after which the cycle resets. The block is usually at the AV…
Second-Degree AV Block with 2:1 Conduction
Key Points: Second-degree AV block with 2:1 conduction means every other P wave conducts and every other P wave is blocked. A single ECG with 2:1 conduction usually cannot be…
First-Degree AV Block
Key Points: First-degree AV block is defined by a PR interval greater than 200 ms with fixed 1:1 AV conduction and no dropped QRS complexes. It usually reflects delayed conduction,…
Second-Degree AV Block Type II (Mobitz II)
Key Points: Mobitz II is defined by sudden failure of AV conduction after at least 2 consecutive conducted beats with fixed PR intervals and no preceding PR prolongation. The block…
Advanced (High-Grade) AV Block
Key Points: Advanced or high-grade AV block is a severe second-degree AV block with 2 or more consecutive non-conducted P waves, such as 3:1 or 4:1 conduction. Do not force…
Baltimore City EMS ECGs: Pitfalls and Mimics (Part 2)
A 54-year-old man presents to the emergency department by EMS with acute shortness of breath. A prehospital ECG triggers a STEMI alert based on the computer interpretation. The tracing shows…
Baltimore City EMS ECGs: Pitfalls and Mimics (Part 1)
A 68-year-old man is brought to the emergency department by EMS with acute chest discomfort. The following prehospital ECG was obtained and shows concave ST elevation across multiple leads. The…
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…
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,…
Grouped Beats: A Subtle AV Block Pitfall
An elderly patient is brought to the emergency department with acute stroke symptoms and the following routine 12-lead ECG is obtained during the patient’s stroke evaluation:
Bifascicular Block
Key Points Definition: Conduction block in any two of the three fascicles: right bundle branch (RBB), left anterior fascicle (LAF), or left posterior fascicle (LPF). High-Risk OMI Pattern: New RBBB…
Rhythm Interpretation: differential diagnoses for electrocardiographic polyuria in unstable bradycardias
An 88-year-old man is brought into the ED with lightheadedness and palpitations. The following ECG is obtained:
Bradyarrhythmias: differentiation of Mobitz and other atrioventricular (AV) blocks
An 83-year-old woman is brought into the ED with lightheadedness and is noted to be bradycardic. The following ECG is obtained:
Bifascicular blocks, BRASH syndrome, and so much more!
This week we will continue discussing 6 more interesting prehospital EMS ECGs. Let’s start with this 78-year-old woman with PMHx of HTN who called an ambulance for generalized weakness associated…
How to distingusish between left anterior vs. posterior fascicular blocks (LAFB vs. LPFB), hyperkalemia emergencies, and much more!
This week we will quickly review 6 interesting prehospital EMS ECGs. Let’s start with this 46-year-old man who called an ambulance for chest pain and was noted to be diaphoretic….
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