Wenckebach phenomenon

Wenckebach Phenomenon is a type of second-degree atrioventricular block (AV block) in the heart. It is also known as Mobitz Type I or Wenckebach block. This condition is named after the Dutch physician Karel Frederik Wenckebach, who first described it in 1899.

Overview

The Wenckebach Phenomenon is characterized by a progressive lengthening of the PR interval on an electrocardiogram (ECG) until a ventricular beat is dropped, or completely fails to conduct. This pattern is typically seen in a repeating cycle, with the number of beats in each cycle varying from patient to patient.

Pathophysiology

In the Wenckebach Phenomenon, the delay in conduction occurs at the atrioventricular node (AV node). The AV node has a unique property known as decremental conduction, which means that the speed of conduction decreases as the rate of incoming signals increases. This property is what leads to the progressive PR interval prolongation and eventual dropped beat seen in Wenckebach Phenomenon.

Clinical Significance

The Wenckebach Phenomenon is usually a benign condition and often does not cause significant symptoms. However, it can sometimes be a sign of underlying heart disease, such as ischemic heart disease or myocarditis. In some cases, it may also be caused by certain medications, such as beta blockers or calcium channel blockers.

Diagnosis

The diagnosis of Wenckebach Phenomenon is typically made based on the characteristic pattern seen on an ECG. Other diagnostic tests, such as echocardiography, may be used to evaluate for underlying heart disease.

Treatment

Treatment for Wenckebach Phenomenon is usually not necessary unless the patient is symptomatic or the condition is caused by an underlying disease or medication. In these cases, treatment would be directed at the underlying cause.