Which type of atrioventricular block best describes this rhythm?
The Correct Answer and Explanation is :
Atrioventricular (AV) blocks are classified into three degrees based on the severity of conduction delay between the atria and ventricles:
- First-Degree AV Block: Characterized by a prolonged PR interval (>200 milliseconds) without any dropped beats. This indicates a delay in the electrical impulse from the atria to the ventricles but does not result in missed ventricular beats. It is often asymptomatic and typically does not require treatment.
- Second-Degree AV Block: Divided into two types:
- Type I (Mobitz I or Wenckebach): Features a progressive lengthening of the PR interval until a QRS complex is dropped. This pattern repeats cyclically. It is usually benign and may not necessitate intervention.
- Type II (Mobitz II): Involves a sudden failure of impulse conduction without prior PR interval prolongation, leading to dropped QRS complexes. This type is more concerning due to the risk of progression to complete heart block and often requires a pacemaker.
- Third-Degree AV Block (Complete Heart Block): Represents a complete dissociation between atrial and ventricular activity, with no impulses conducted from the atria to the ventricles. This results in atrial and ventricular rhythms that are independent of each other. It is a medical emergency and typically requires immediate intervention, such as pacemaker implantation.
Accurate identification of the type of AV block is crucial for determining the appropriate management and treatment plan. Electrocardiography (ECG) is the primary diagnostic tool used to assess the PR intervals, the relationship between P waves and QRS complexes, and the overall rhythm to classify the AV block accurately.
For a visual explanation and further details on AV blocks, you may find the following video helpful: