What is First-Degree Atrioventricular (AV) Block?

First-degree atrioventricular (AV) block is a relatively common cardiac condition. It is commonly believed that first-degree AV block does not cause severe harm to the body. But what exactly is first-degree AV block?

What is First-Degree Atrioventricular Block?

First-degree AV block refers to a prolonged conduction time between the atria and ventricles. Under normal circumstances, the electrical impulse travels from the atria to the ventricles in approximately 120–200 milliseconds (ms). If the conduction time exceeds 200 ms, it is defined as AV block. However, careful analysis is required: if the conduction time is consistently prolonged by more than 20 ms in every cardiac cycle—and this delay remains fixed—it is diagnosed as first-degree AV block. In other words, although conduction is delayed, there is no significant variation or intermittent failure of conduction—this characteristic pattern is reflected on the electrocardiogram (ECG) as first-degree AV block.

Patients with first-degree AV block typically do not require pharmacological treatment. However, it is essential to actively investigate potential underlying causes—such as medications that slow heart rate (e.g., beta-blockers, calcium channel blockers), electrolyte imbalances (e.g., hyperkalemia), or myocardial ischemia. Addressing the underlying cause may lead to resolution of the AV block. Close monitoring is also crucial, as first-degree AV block may coexist with—or progress to—second- or third-degree AV block, which are more serious conditions potentially requiring medication or even pacemaker implantation.

In daily life, prioritize adequate rest, avoid frequent late-night activity, and ensure sufficient sleep. Maintain a light, easily digestible diet, and minimize intake of greasy or spicy, irritating foods. We hope this information has been helpful to you!