heart transplant


heart transplant
Procedure to remove a diseased heart and replace it with a healthy one from a legally dead donor.

The first was performed in 1967 by Christiaan Barnard. The diseased heart is removed (except for some atrial tissue to preserve nerve connections to the natural pacemaker). The new heart is put in place and connected to the recipient's blood vessels. Patients and donors are matched for tissue type, but the patient's immune system must still be suppressed to prevent rejection (see immunosuppression). A successful transplant can enable the recipient to have an active life for many years.

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▪ medical procedure
      medical procedure involving the removal of a diseased heart from a patient and its replacement with a healthy heart. Because of the immense complexity of the procedure and the difficulty of finding appropriate donors, heart transplants are performed only as a last resort in patients with end-stage heart failure or irreparable heart damage whose projected survival with their own heart is only a few weeks or months. In most cases, transplanted hearts are taken from persons who have suffered irreversible brain damage and have been declared legally dead but whose organs have been kept artificially viable for the purposes of transplant.

      The first heart transplant in an experimental model was performed by French surgeon Alexis Carrel (Carrel, Alexis) in 1905. American surgeon Norman Shumway (Shumway, Norman E.) achieved the first successful heart transplant in a dog in 1958. In 1967, South African surgeon Christiaan Barnard (Barnard, Christiaan) performed the first human heart transplant. His success was followed by attempts at many other medical centres, but lack of adequate therapy to combat immune rejection of the transplanted heart led most surgeons to abandon the procedure after the initial attempts. Barnard, Shumway, and some others, however, continued to perform heart transplants, and in the 1970s cyclosporine, a compound isolated from an earth fungus, was discovered to be a very effective drug for combating rejection. Cyclosporine brought about a rapid and successful increase in the number of heart transplant procedures. The survival rate at one year is now about 84 percent and at three years about 77 percent. Many heart transplant patients are able to lead productive lives for years after the procedure.

      Heart transplant actually occurs in several stages. First comes the selection and care of the transplant candidate. Patients with end-stage heart failure are acutely ill and require extraordinary support, often including mechanical circulatory assistance or the placement of devices that support the circulation. The second stage is the harvesting of the donor heart (frequently at a remote site) and timely implantation of the heart in the recipient. Both processes mount significant challenges. Current implantation procedure involves removal of the diseased heart except for some of the tissue from the atria (atrium), the two upper chambers of the heart. Leaving this tissue in place preserves nerve connections to the sinoatrial node, a patch of electroconductive tissue that regulates heartbeat. The replacement heart is removed from the donor and preserved in a cold salt solution. During implantation it is trimmed to fit and sutured into place, making all necessary vascular connections.

      The third stage of heart transplant is the postoperative period, which is directed toward providing adequate antirejection treatment with close monitoring to prevent rejection of the heart. Medical therapy “trains” the immune system to cope with a foreign heart, but patients require lifelong immune suppression. Indeed, a successful transplant is very demanding on the patient and requires close follow-up, especially during the first year, to decrease the risk of rejection and prevent infections associated with immune suppression. Partly for this reason, it is an extraordinary option for those who are very ill and have no other alternative. Heart transplant is not a cure for heart failure but is a new condition in which the recipient gains new life and functional capacity, though with the commitment to maintain lifelong medical treatment to prevent rejection and infection.

Guillermo Torre-Amione
 

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Universalium. 2010.