AVknoopfalen

AVknoopfalen, or AV nodal failure, is a form of impaired conduction through the atrioventricular (AV) node that slows or blocks the transmission of impulses from the atria to the ventricles. It is part of the spectrum of AV-block disorders and can be temporary or persistent, depending on the underlying cause.

Causes and risk factors include age-related degeneration of the conduction system, ischemic heart disease or myocardial infarction affecting the AV node, myocarditis, and structural heart disease. Medications that slow AV conduction, such as beta-blockers, non-dihydropyridine calcium channel blockers (for example verapamil and diltiazem), and digoxin, can contribute. Electrolyte disturbances and inflammatory conditions can also play a role.

Clinical presentation varies. Many individuals are asymptomatic, discovered on routine ECG. When conduction is significantly impaired, symptoms may include dizziness, fatigue, syncope or near-syncope, and shortness of breath, especially with exertion. The severity and pattern of block determine urgency and treatment needs.

Diagnosis relies mainly on electrocardiography. First-degree AV block shows a prolonged PR interval with all atrial impulses conducted. Second-degree blocks include Mobitz type I (Wenckebach) and Mobitz type II, with varying patterns of dropped ventricular beats. Third-degree (complete) AV block shows no atrial impulses reaching the ventricles and often requires urgent assessment.

Treatment focuses on the underlying cause and symptom severity. Reversible factors (drug effects, electrolyte abnormalities) are addressed. Symptomatic or high-grade blocks may require temporary pacing, and persistent high-grade AV block typically necessitates a permanent pacemaker. Prognosis depends on the cause and the presence of symptoms or other heart disease.