Overview
High degree second degree atrioventricular (AV) block involves intermittent failure of ventricular conduction due to impaired AV node function, often requiring close monitoring and potential pacemaker implantation 12.Diagnosis
Clinical Presentation: Symptoms may include syncope, dizziness, fatigue, and palpitations 12.
Electrocardiogram (ECG) Findings: Characterized by dropped QRS complexes (2:1 or 3:1 ratios) indicating intermittent AV block 1.
Holter Monitoring: Useful for detecting transient episodes not captured on routine ECG 1.
Grading: Second degree AV block is classified as high degree when the PR interval is prolonged and there are frequent dropped beats 1.Management
Pacemaker Implantation: Recommended for symptomatic patients or those with hemodynamic instability 2.
Rate-Adapted Pacing Modes: DDD pacing may offer better symptom relief compared to VVIR pacing in high-degree AV block patients 2.
Monitoring: Regular follow-up ECGs and Holter monitoring to assess for progression or resolution 1.Special Populations
Chemotherapy Exposure: Increased incidence of heart block noted in patients with prior exposure to cyclophosphamide and vinca alkaloids 1.
No Specific Pediatric or Elderly Guidelines: Abstracts do not provide specific recommendations for these groups 12.Key Recommendations
Consider Pacemaker Implantation for Symptomatic Patients: Essential for managing symptoms and preventing hemodynamic compromise in high-degree second-degree AV block 2 (Evidence: Strong).
Evaluate Prior Chemotherapy Agents: Assess history of cyclophosphamide and vinca alkaloid exposure as risk factors for AV block 1 (Evidence: Moderate).
Use DDD Pacing Mode: Preferred over VVIR for improved symptom control and quality of life in patients with high-degree AV block 2 (Evidence: Moderate).References
1 Styler MJ, Topolsky DL, Crilley PA, Covalesky V, Bryan R, Bulova S et al.. Transient high grade heart block following autologous bone marrow infusion. Bone marrow transplantation 1992. link
2 Menozzi C, Brignole M, Moracchini PV, Lolli G, Bacchi M, Tesorieri MC et al.. Intrapatient comparison between chronic VVIR and DDD pacing in patients affected by high degree AV block without heart failure. Pacing and clinical electrophysiology : PACE 1990. link
3 Pehrsson SK. Influence of heart rate and atrioventricular synchronization on maximal work tolerance in patients treated with artificial pacemakers. Acta medica Scandinavica 1983. link