Conduction
Results:
Left Anterior Fascicular Block (LAFB)
Key Points: LAFB occurs when conduction through the left anterior fascicle is delayed or blocked. Ventricular activation travels preferentially down the left posterior fascicle, then spreads inferior-to-superior and rightward-to-leftward across…
Left Posterior Fascicular Block (LPFB)
Key Points: LPFB occurs when conduction through the left posterior fascicle is delayed or blocked. LV activation travels preferentially through the left anterior fascicle, then spreads superior-to-inferior and left-to-right toward…
Fascicular Ventricular Tachycardia (Idiopathic Left Fascicular VT)
Key Points Idiopathic reentrant VT arising within the left Purkinje system, most often the left posterior fascicle. Patients are usually young and lack structural heart disease. Signature ECG: RBBB-like morphology…
Beta-Blocker and Calcium Channel Blocker Toxicity
Key Point BBs and CCBs are widely prescribed but overdoses can cause life-threatening bradycardia, AV block, hypotension, and shock. Differentiating between them is important, but both require early recognition, aggressive…
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…
Bundle Branch Blocks
Key Points: Bundle branch blocks widen the QRS, usually to 120 ms or more, because ventricular depolarization is delayed through one of the main bundle branches. The two classic patterns…
Normal Sinus Rhythm
Key Points Definition: Normal sinus rhythm (NSR) refers to the heart’s rhythm when impulses originate from the sinoatrial (SA) node, the heart’s primary pacemaker. This rhythm suggests that electrical impulses…
Trifascicular Block
Key Points Definition: Trifascicular block describes ECG evidence of impaired conduction across all three fascicles: right bundle branch (RBB), left anterior fascicle (LAF), and left posterior fascicle (LPF). Common Usage:…
Unifasicular Block
Key Points Definition: Unifascicular block refers to conduction delay or interruption in a single fascicle of the ventricular conduction system: the right bundle branch (RBB), left anterior fascicle (LAF), or…
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…
Sodium Channel Blocker Toxicity
Key Points: Recognizing the Danger: Sodium channel blocker toxicity can present with a variety of ECG changes that are critical to recognize, especially in patients with altered mental status or…
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