Final answer:
The compensatory mechanisms employed by the body in heart failure include the ventricular walls becoming thicker, the atria becoming more contractile, and the heart enlarging. However, cardiac muscle contracting more vigorously is not a compensatory mechanism in heart failure.
Step-by-step explanation:
The compensatory mechanisms employed by the body in heart failure include the ventricular walls becoming thicker, the atria becoming more contractile, and the heart enlarging. However, one compensatory mechanism that is not employed by the body in heart failure is the cardiac muscle contracting more vigorously. Instead, heart failure causes a decrease in cardiac contractility.