Management of Bundle Branch Block
Diagnostic Criteria
- The American Heart Association recommends that complete RBBB be diagnosed with QRS ≥120 ms with rsr', rsR', or rSR' pattern in V1-V2, S waves >40 ms in leads I and V6, and R peak time >50 ms in V1 1
- The American College of Cardiology recommends that complete LBBB be diagnosed with QRS ≥120 ms with broad notched R waves in I, aVL, V5-V6, absent q waves in these leads, and R peak time >60 ms in V5-V6 1
Risk Stratification
- The American Family Physician guidelines state that symptomatic third-degree AV block is a Class I indication for permanent pacing 5
- The American Family Physician guidelines recommend that type II second-degree AV block warrants pacemaker even if asymptomatic, particularly with fascicular block (Class IIa) 5
- The American Family Physician guidelines indicate that alternating bundle branch block mandates pacemaker implantation due to high risk of complete heart block 4, 5, 6
Management Algorithms
- The American College of Cardiology recommends that for isolated RBBB in V3, a complete 12-lead ECG should be obtained to confirm RBBB pattern throughout precordial leads 1
- The American Family Physician guidelines state that for LBBB pattern, Sgarbossa criteria should be applied to diagnose acute MI 8
- The American Family Physician guidelines recommend that for asymptomatic RBBB, echocardiography, exercise testing, and 24-hour Holter monitoring should be performed 3
Reversible Causes
- The American Family Physician guidelines state that electrolyte abnormalities, particularly hyperkalemia, should be corrected as they can mimic BBB 4, 10, 6
- The American Family Physician guidelines recommend that perioperative block from hypothermia or surgical inflammation near AV junction should be excluded 4, 6
- The American Family Physician guidelines indicate that acute Lyme disease should be ruled out as AV block may resolve 4, 6