Which leads should a therapist look at to monitor the left heart?

To monitor the left heart, the appropriate leads to focus on are V5 and V6. These leads are positioned over the left side of the chest and specifically correspond to the left ventricle's electrical activity. V5 is located at the anterior axillary line at the same horizontal level as V4, while V6 is positioned at the mid-axillary line. Together, they provide a comprehensive view of the electrical impulses originating from the left ventricle, making them ideal for assessing left heart function.

In contrast, the other options include combinations of leads that are either situated around the right side or do not adequately capture the electrical activity of the left ventricle. For example, V1 and V2 are primarily focused on the right side and the septal area, while V3 and V4 also incorporate anterior views but miss the lateral aspects that V5 and V6 cover effectively. By focusing on V5 and V6, therapists can better evaluate conditions associated with the left heart, such as left ventricular hypertrophy or ischemia.