Konduksjonsblokk

Konduksjonsblokk refers to a delay or complete interruption of electrical impulse conduction within the heart. This can occur in various parts of the heart's electrical system, most commonly in the atrioventricular (AV) node or within the His-Purkinje system.

There are different degrees of conduction block. First-degree block is characterized by a prolonged PR interval on an electrocardiogram (ECG), indicating a general slowing of conduction. Second-degree block involves some impulses failing to conduct, leading to dropped beats. Mobitz type I (Wenckebach) block typically occurs in the AV node and shows a progressive lengthening of the PR interval before a dropped beat. Mobitz type II block is usually found below the AV node and has a constant PR interval before a dropped beat, often indicating a more serious underlying condition. Third-degree, or complete heart block, means no impulses are conducted from the atria to the ventricles, resulting in independent atrial and ventricular rhythms.

Causes of conduction block are diverse and can include myocardial ischemia or infarction, inflammatory conditions, degenerative diseases of the cardiac conduction system, certain medications (like beta-blockers or calcium channel blockers), and congenital abnormalities. Symptoms can range from asymptomatic to dizziness, syncope (fainting), or shortness of breath, depending on the severity and rate of the ventricular response. Diagnosis is primarily made through ECG, which reveals characteristic patterns for each type of block. Treatment depends on the type and cause, with interventions ranging from observation for mild cases to pacemaker implantation for complete heart block or symptomatic Mobitz type II block.