Final answer:
The left anterior descending artery (LAD) is most likely to be diseased when hypo-contractility of the distal ventricular septum and left ventricular apex is observed, as it supplies these areas with blood.
Step-by-step explanation:
If the distal ventricular septum and left ventricular apex are hypo-contractile, this suggests that the blood supply to these areas of the heart is compromised.
The coronary artery most likely to be diseased in causing hypocontractility in the distal ventricular septum and left ventricular apex is the left anterior descending artery (LAD). The LAD is a major branch of the left coronary artery that follows the anterior interventricular sulcus and supplies blood to the front of the left ventricle and the interventricular septum.
When the LAD is occluded, areas it supplies can become ischemic and hypo-contractile, which can be identified in an apical 4-chamber (4 ch) view during an echocardiogram.