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…
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…
Key Points Fewer P waves than QRS complexes: This means impulses are originating from below the atria (junctional, ventricular, or paced), or from ectopy interrupting sinus rhythm. Clinical relevance: In…
Key Points Absence of Sinus Rhythm: The lack of clear P waves before the QRS complexes suggests loss or dysfunction of sinus activity. Potential Causes: This pattern can result from…
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:…
Key Points Definition: SA exit block occurs when the sinus node generates impulses that are blocked before they can activate the right atrium, leading to dropped P waves on the…
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…
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…
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…