heart transplant

Heart transplant:

The survival rate for those with advanced heart failure is much higher with transplantation than with therapy. One year survival is at eighty-five percent, and five year, sixty-five percent

The most common cause of death for those who have undergone the procedure is infection, and acute cases of rejection second

The process of orthotopic heart transplant involves cutting the heart just above the AV valves. The donor heart is then resected at the atria. The graft includes the sinuatrial node so that a pacemaker will not be needed

The donor heart is denervated and so is not influenced sympathetic or parasympathetic impulses. Also as a result, myocardial ischemia is a rare occurrence

To help prevent graft rejection, a high dose of corticosteroid and anti-thymocyte or monoclonal antibodies is given at the time of surgery. Later, azathiaprine and cyclosporine A are administered. Prednisone is used in addition to these two for long-term immunosuppression

cyclosporine A is a cyclic polypeptide. It is derived from a fungus by the name of Beauveria nivea. It reversibly inhibits the functions of lymphocytes in Go and G1 phases of mitosis. The primary target of cyclosporine A is the T-helper cells, but T-suppresser cells may be affected. The drug also inhibits lymphokine production and secretion, including interlukin 2. Cyclosporine dosage is determined by blood levels and renal function at one to two milligrams per kilogram per day in two doses. The possibly resulting toxicity is most often reversible by dose reduction, but toxicities such as hyperkalemia or hepatoxicity may remain
azathiaprine is derived from 6-mercaptopurine and suppresses cell mediated hypersensitities and changes antibody production. Renal function has little effect on the drug, since it is metabolized, for the most part, in the liver and erythrocytes (red blood cells), causing a dose dependent reduction in leukocyte (white blood cell) and thrombocyte (platelet) counts. The beginning dose is between three and five milligrams per kilogram per day. Maintenance is between one to three milligrams per kilogram per day
Almost all patients are given corticosteroids for immunosuppression, beginning as injected methylprednisone at five hundred milligrams, then changed to oral prednisone at about one milligram per kilogram. Long-term administration is most often five to ten milligrams daily, higher if there are signs of rejection

The most common post-transplant problems are graft rejection, infection and renal troubles

In severe cases, acute rejection will lead to myocardial dysfunction. Rejection occurs about twice a year for most patients, but most of these are minor cases. They are usually treated with immunosuppressants. Women are at a slightly higher risk of rejection, acute or otherwise

Most infections are bacterial, but some other causes may be fungal in nature, or cytomegalovirus (CMV)

Acute cell mediated rejection most often occurs within three months after transplant, decreasing in frequency over time. Symptoms may include low grade fever, fatigue, malaise and a decrease in any type of physical exertion. Indications of more severe rejection may be hemodynamic compromise and myocardial dysfunction. Immunosuppressant regimen may mask some or most of the rejection symptoms. Localized pain may also be dulled

Moderate to severe rejection may be identified by hypotension, tachycardia, quiet heart or distal cyanosis

Effects of azathiaprine are tested through bone marrow and cyclosporine A through renal function

Hemodynamic support in suspected rejection is provided with inotropic agents, like dobutamine