This can eliminate it as an option for many men with heart conditions. The causes of libido loss are due mainly to serum binding of testosterone with age. This is true for both men and women. The causes of impotence are more varied and complicated.
Psychological factors play a major role for many men.
Organic causes can include a variety of drugs and alcohol. Blood pressure medications and antidepressants are particularly bad offenders. Impotence is also a consequence of diabetes or atherosclerosis. This tends to be a circulation problem. See the pages on diabetes and cardiovascular disease to learn how to deal with these conditions.