Source:http://linkedlifedata.com/resource/umls/id/C0264912
NCI: 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.,NCI: 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. (NCI)