Overview
Bifascicular block involves the disruption of two of the three main fascicles of the His-Purkinje system, commonly manifesting as right bundle branch block with left anterior hemiblock or left bundle branch block, often associated with an increased risk of progression to higher grade atrioventricular (AV) block.Diagnosis
Electrocardiogram (ECG) Findings: Identification of specific bundle branch block patterns (right bundle branch block with left anterior hemiblock or left bundle branch block) 15.
Pharmacological Stress Testing: Use of Class I antiarrhythmic agents like disopyramide, procainamide, and ajmaline to provoke AV block; disopyramide shows high sensitivity (75%-100%) and specificity (>90%) for predicting impending high-grade AV block 12.
Electrophysiological Studies: May help assess risk but have limited predictive value due to variable outcomes 45.Management
Antiarrhythmic Drugs: Disopyramide (2 mg/kg IV) can be used for acute stress testing but caution is advised due to potential induction of AV block 2.
Pacemaker Implantation: Considered for patients with recurrent syncope or high risk of progression to complete heart block, though prophylactic use in asymptomatic patients is debated 35.
Monitoring: Close monitoring in high-risk scenarios such as perioperative periods, especially in those with recent syncope or myocardial infarction 3.Special Populations
Perioperative Considerations: Asymptomatic patients with bifascicular block and prolonged PR interval do not require prophylactic pacemakers during general, spinal, or local anesthesia 3.
Comorbidities: No specific management adjustments noted for pediatrics or elderly populations within the provided abstracts; focus remains on risk stratification and symptomatic management 5.Key Recommendations
Perform pharmacological stress testing with disopyramide for high-risk patients with bifascicular block and suspected intermittent AV block to predict progression; sensitivity is high but specificity varies 12 (Evidence: Moderate).
Prophylactic pacemaker implantation is not routinely recommended for asymptomatic patients with bifascicular block, even with prolonged PR interval, during non-high-risk procedures 3 (Evidence: Strong).
Closely monitor patients with bifascicular block undergoing major surgeries, particularly those with recent syncope or myocardial infarction, for potential complications 3 (Evidence: Expert opinion).References
1 Englund A, Bergfeldt L, Rosenqvist M. Pharmacological stress testing of the His-Purkinje system in patients with bifascicular block. Pacing and clinical electrophysiology : PACE 1998. link
2 Bergfeldt L, Rosenqvist M, Vallin H, Edhag O. Disopyramide induced second and third degree atrioventricular block in patients with bifascicular block. An acute stress test to predict atrioventricular block progression. British heart journal 1985. link
3 Mikell FL, Weir EK, Chesler E. Perioperative risk of complete heart block in patients with bifascicular block and prolonged PR interval. Thorax 1981. link
4 McKenna WJ, Rowland E, Davies J, Krikler DM. Failure to predict development of atrioventricular block with electrophysiological testing supplemented by ajmaline. Pacing and clinical electrophysiology : PACE 1980. link
5 Dhingra RC, Wyndham C, Amat-y-Leon F, Denes P, Wu D, Sridhar S et al.. Incidence and site of atrioventricular block in patients with chronic bifascicular block. Circulation 1979. link