Mobitz Type II AV Block

Mobitz Type II AV Block is a heart condition that affects the electrical signals controlling the heartbeat. It involves the atrioventricular (AV) node, which normally helps coordinate the timing between the upper and lower chambers of the heart. In this condition, some electrical signals fail to pass through the AV node, causing missed heartbeats or pauses. This can lead to symptoms like dizziness, fainting, or feeling very tired because the heart is not pumping blood effectively. The condition affects the cardiac conduction system, which is essential for maintaining a steady and coordinated heartbeat. It is more serious than some other types of heart block because it can suddenly progress to a complete heart block, which is life-threatening. Understanding this condition helps explain why the heart sometimes beats irregularly or too slowly.

Mobitz Type II AV Block is a type of second-degree atrioventricular block characterized by intermittent failure of conduction of atrial impulses to the ventricles without progressive prolongation of the PR interval. The block typically occurs below the AV node, often in the His-Purkinje system, and is usually caused by structural damage such as fibrosis, ischemia, or infarction of the conduction pathways. This block results in sudden dropped QRS complexes on the electrocardiogram (ECG) without preceding PR interval changes. It is clinically significant because it often leads to bradycardia, decreased cardiac output, and can progress unpredictably to complete heart block, increasing the risk of syncope and sudden cardiac death. Unlike Mobitz Type I, Mobitz Type II is less likely to be benign and often requires urgent intervention. It is commonly associated with underlying heart disease such as myocardial infarction or cardiomyopathy.