In early disseminated Lyme disease, which cardiac conduction abnormality can occur?

In early disseminated Lyme disease, which cardiac conduction abnormality can occur?

• A. Atrial fibrillation
• B. AV block
• C. Sinus tachycardia
• D. Ventricular tachycardia

Answer: (B)

The key idea is that Lyme carditis often disrupts the heart’s electrical conduction, especially affecting the AV node. In early disseminated Lyme disease, inflammation from Borrelia burgdorferi can involve the AV conduction pathway, leading to varying degrees of AV block. Clinically this shows up as dizziness, near-syncope, or bradycardia, and an ECG may reveal a prolonged PR interval that can progress from first-degree block to higher-degree AV blocks. This pattern distinguishes it from other rhythm issues: atrial fibrillation is an atrial rhythm disturbance with irregular conduction rather than a block in the AV node; sinus tachycardia is a non-specific response to fever or inflammation and doesn’t reflect conduction system failure; ventricular tachycardia is a ventricular rhythm disorder not typically caused by Lyme carditis. Management focuses on antibiotics, and in cases of high-degree AV block or symptomatic bradycardia, temporary pacing may be needed while the infection is treated, with the block often improving as the patient recovers.

The key idea is that Lyme carditis often disrupts the heart’s electrical conduction, especially affecting the AV node. In early disseminated Lyme disease, inflammation from Borrelia burgdorferi can involve the AV conduction pathway, leading to varying degrees of AV block. Clinically this shows up as dizziness, near-syncope, or bradycardia, and an ECG may reveal a prolonged PR interval that can progress from first-degree block to higher-degree AV blocks. This pattern distinguishes it from other rhythm issues: atrial fibrillation is an atrial rhythm disturbance with irregular conduction rather than a block in the AV node; sinus tachycardia is a non-specific response to fever or inflammation and doesn’t reflect conduction system failure; ventricular tachycardia is a ventricular rhythm disorder not typically caused by Lyme carditis. Management focuses on antibiotics, and in cases of high-degree AV block or symptomatic bradycardia, temporary pacing may be needed while the infection is treated, with the block often improving as the patient recovers.