Trifascicular block

This code represents a severe form of cardiac conduction disturbance involving all three fascicles of the His-Purkinje system: the right bundle branch, the left anterior fascicle, and the left posterior fascicle. It indicates a significant impairment in the electrical pathway responsible for coordinating ventricular contraction, often leading to bradycardia or syncope.

Assign this code when documentation explicitly states "trifascicular block" or describes a complete block of all three fascicles. This diagnosis is typically made based on electrocardiogram (ECG) findings demonstrating a combination of right bundle branch block and bifascicular block (left anterior or posterior hemiblock).

• Do not confuse with bifascicular block (I45.2) or other less severe conduction defects.
• Ensure the medical record clearly specifies involvement of all three fascicles.
• Consider sequencing this code as a primary diagnosis if it is the reason for the encounter, or as a secondary diagnosis if it is a co-morbidity impacting patient care.