Modern Family Physician: Understanding and Managing Atrioventricular Block

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Overview

Modern Family Physician: Understanding and Managing Atrioventricular Block

Overview

Atrioventricular (AV) block is a condition where the electrical impulses that coordinate the heart's pumping action are delayed or blocked as they travel between the atria and the ventricles. This blog aims to provide a comprehensive overview of AV block, including its types, diagnosis, and treatment options.

Types of Atrioventricular Block

AV block can occur at various levels within the heart's conduction system:

• Sinoatrial (SA) Block: Occurs between the sinoatrial (SA) node and the atria.
• AV Node Block: Occurs between the atria and the ventricles.
• Intra-atrial Block: Occurs within the atria.
• Intra-ventricular Block: Occurs within the ventricles.

AV block is categorized based on the severity of the conduction delay:

• First-Degree: The PR interval is prolonged, but all impulses are still conducted.
• Second-Degree: Impulses are intermittently blocked. It is further divided into Mobitz I and Mobitz II blocks.
• Third-Degree (Complete): All impulses are blocked, and the atria and ventricles beat independently.

Diagnosis

The diagnosis of AV block is primarily based on clinical symptoms, physical examination, and electrocardiogram (ECG) findings:

• Symptoms: May range from asymptomatic to palpitations, fatigue, dizziness, syncope, angina, and heart failure.
• ECG Findings: PR intervals, QRS duration, and heart rates can provide key information. The presence of blocked P waves, irregular rhythms, and changes in the first heart sound can be indicative of AV block.

Treatment

The treatment of AV block is tailored to the underlying cause and the severity of symptoms:

• First-Degree and Mobitz I: No treatment is usually required unless the heart rate is too slow.
• Mobitz II and Third-Degree: May require pacing therapy, especially if symptoms are severe or if there is evidence of hemodynamic instability.
• Drugs: Medications like atropine and isoproterenol can be used to increase heart rate, but they may have limited efficacy and side effects.
• Pacing Therapy: Temporary or permanent pacemaker implantation is often the definitive treatment for severe cases.

Conclusion

Understanding AV block is crucial for family physicians, as it can range from asymptomatic to life-threatening. Proper diagnosis and timely intervention are essential to manage this condition effectively. If you suspect an AV block or experience symptoms such as palpitations, dizziness, or fainting, it is important to consult with a healthcare professional for a thorough evaluation and appropriate treatment.