<prompt> Normal axis of hea is?-30 to 9090 to 120120 to -3060 to - 60  <response>: -30 to 90 REF: Harrisons Internal Medicine 17th edition chapter 221 The heas electrical axis refers to the general direction of the heas depolarization wavefront or mean electrical vector in the frontal plane. With a healthy conducting system the cardiac axis is related to where the major muscle bulk of the hea lies. Normally this is the left ventricle with some contribution from the right ventricle. It is usually oriented in a right shoulder to left leg direction, which corresponds to the left inferior quadrant of the hexaxial reference system, although -30deg to 90deg is considered to be normal 