I44.4

ICD-10-CM Coding Rules

• I44.4

Approximate Synonyms

• Left anterior fascicular hemiblock heart rhythm)

• Left anterior hemiblock

Clinical Information

• An impairment of transmission of the cardiac electrical impulse along the fibers of the left anterior fascicle. In left anterior fascicular block lafb) the posteroinferior regions of the left ventricular endocardium are activated abnormally before the anterosuperior left ventricular area. After emerging from the posteroinferior division of the left bundle branch, the impulse first propagates in an inferior, rightward, and usually anterior direction for a short period of time. This orientation is responsible for the small q waves in leads 1 and avl and for the r waves in leads ii, iii, and avf.

• An impairment of transmission of the cardiac electrical impulse along the fibers of the left anterior fascicle. In left anterior fascicular block lafb) the posteroinferior regions of the left ventricular endocardium are activated abnormally before the anterosuperior left ventricular area. After emerging from the posteroinferior division of the left bundle branch, the impulse first propagates in an inferior, rightward, and usually anterior direction for a short period of time. This orientation is responsible for the small q waves in leads i and avl and for the r waves in leads ii, iii, and avf.

• An impairment of transmission of the cardiac electrical impulse along the fibers of the left anterior fascicle. It is characterized by all of the following: left-axis deviation with frontal qrs axis between -45 degrees and -90 degrees; q wave in lead avl; rs in inferior leads ; qrs duration is <120 ms.

Details

• I44.4 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.

• The 2023 edition of ICD-10-CM I44.4 became effective on October 1, 2022.

• This is the American ICD-10-CM version of I44.4 – other international versions of ICD-10 I44.4 may differ.