Electrocardiographic Abnormalities and Cardiac Disorders
Heart Block: Types (first-degree, second-degree, third-degree), pathophysiology, and management
Heart block is a cardiac conduction disorder affecting electrical signal transmission in the heart. It has three types: first-degree, second-degree, and third-degree, each with distinct features and treatment approaches.
Electrocardiographic Abnormalities and Cardiac Disorders
Heart Block: Types, Pathophysiology, and Management
Heart block is a condition in which electrical signals from the atria fail to properly reach the ventricles, leading to arrhythmias or slow heart rates. It can be classified into three main types:
Types of Heart Block
- First-degree heart block: Characterized by prolonged PR interval (>200ms), with every atrial impulse conducted to the ventricles.
- Second-degree heart block: Further divided into:
- Type I (Wenckebach): Progressive PR interval prolongation followed by a dropped beat.
- Type II: Sudden, unpredictable dropped beats without PR interval prolongation.
- Third-degree (complete) heart block: Atria and ventricles beat independently due to complete conduction failure.
Pathophysiology
Heart block occurs due to dysfunctional conduction at the atrioventricular (AV) node or below. Causes include ischemic heart disease, electrolyte imbalances, myocarditis, and degenerative changes in conduction pathways.
Management
- First-degree: Often benign, requiring no treatment unless symptomatic.
- Second-degree: Type I may require observation, while Type II often necessitates pacemaker implantation.
- Third-degree: Requires immediate intervention with a pacemaker to restore proper heart rhythm.
Conclusion
Recognizing the different types of heart block is crucial for proper management and prevention of serious complications like sudden cardiac arrest. Pacemaker therapy remains the primary intervention for high-degree blocks.
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Electrocardiographic Abnormalities and Cardiac Disorders
