Drug or pharmacologic management of patients with cardiac allografls is an area of clinical cardiology that is quite different from most pharmacological management involved in caring for patients with cardiac disease. In transplant patients one is dealing with a heart that is not stunned, isehemic, infarcted, hypertrophied, dilated, or in any way weak or structurally abnormal. The patient has a perfectly healthy heart, usually chronologically younger than the patient, the only flaw of which is its antigenic dissimilarity from tissue of the patient. This dissimilarity, of course, leads to the need to suppress the normal immune response and make the patient at least relatively immunologically tolerant of his or her solid organ allograft. Problems inherent in the induction and maintenance ofimmnne tolerance in cardiac allograft patients are no different than those encountered in the more widely practiced field of renal transplantation. The major obvious difference is that of the more disastrous consequence of graft "loss" in cardiac transplant recipients since no cardiac equivalent of chronic hemodialysis exists to be resorted to. Thus, immunosuppressive regimens used in cardiac transplant programs tend to err (if they err) on the side of heavier suppression and accept the consequences of this choice.
KEY WORDS. cardiac transplant, drug management
H istorically, most clinically used immunosuppressive regimens have consisted of a combination of several agents used concurrently and sequentially. This multiple-drug approach continues to be considered the state of the art; the number of drugs and timing of their administration varies from institution to institution, but several general principles are commonly adhered to.
The first general principle is that immune reactivity and the tendency to graft rejection are highest early after graft implantation and decrease with time, although they likely never disappear entirely. Thus, most regimens employ the highest levels of immunosuppression immediately after surgery and decrease later, eventually settling on the lowest maintenance levels of suppression compatible with preventing recurrent graft rejection. The second general principle is reminiscent of that originated in oncology chemotherapy regimens, that of using low doses of several drugs without overlapping toxicities