Overview
Second degree atrioventricular (AV) block involves intermittent failure of ventricular depolarization due to impaired AV nodal conduction, leading to dropped beats and potential hemodynamic instability depending on the degree and duration of block 1.Diagnosis
Electrocardiogram (ECG) findings: Presence of PR interval prolongation with intermittent non-conducted P waves (Mobitz Type I or Type II) 1.
Holter monitoring: Useful for prolonged observation in patients with intermittent symptoms 1.
Grading: Mobitz Type I (Wenckebach) vs. Mobitz Type II, with Type II often more concerning due to higher risk of progression to higher grade AV block 1.Management
First-line treatment: Observation in asymptomatic patients with stable rhythms 1.
Pacemaker implantation: Recommended for symptomatic patients or those with hemodynamic instability 1.
VDD pacing system: Single pass lead VDD system can be considered for patients with symptomatic AV block and intact sinus node function, offering advantages in atrial sensing and procedural efficiency 1.Special Populations
Elderly: No specific considerations mentioned beyond general management principles 1.Key Recommendations
Implant a pacemaker in symptomatic patients with second degree AV block to prevent progression and manage symptoms (Evidence: Moderate 1).
Consider a single pass VDD pacing system for patients with symptomatic second degree AV block and competent sinus node function, given its advantages in sensing and procedural benefits (Evidence: Weak 1).
Asymptomatic patients with stable rhythms may be managed with observation alone (Evidence: Expert opinion 1).References
1 Hassi M, Power K, Vlietstra R. Initial experience with single lead VDD system. Case study. The Journal of the Florida Medical Association 1993. link