Shortness of breath while lying flat, orthopnea, is a common finding of congestive heart failure associated with high fluid pressures behind the left ventricle.  Whereas standing tends to keep excess fluid in the extremities by gravity–lying down can allow this fluid to return to the central circulation including the lungs.  Surgically repairing a mitral and aortic valve may help with the reduction of pressure by pumping blood out of the lungs by the left ventricle, but paradoxically, especially when repairing a leaking mitral valve, previously present cardiac remodeling or hypertrophy may be unmasked by the removal of the “pop off” valve when the heart ejects blood.This impaired state will reduce the efficiency at which the blood pumps out of the ventricle. So, even though the valves have been repaired the ventricle itself may not be able to work as a proper pump to push the blood into the vascular system.

Even in the absence of heart failure, peripheral edema can be caused by obesity and stretched venous valves. Additionally, severe anemia contributes to the feeling of being short of breath due to lack of oxygen especially in combination with your father’s obesity.  At this time, if possible, your father may do best to take heart failure medication, correct his anemia, and lose weight.