Heart Transplant Breakthrough -- Research Summary

BACKGROUND: Ever since Christiaan Barnard, M.D., performed the first heart transplant in Capetown, South Africa, in 1967, doctors have been searching for better ways to care for heart transplant patients after their surgery. A heart transplant is a delicate procedure reserved for patients who suffer from irreversible, life-threatening heart diseases like coronary artery disease and cardiomyopathy. During a heart transplant, doctors work together to remove a failing heart and replace it with a healthy heart from a recently deceased donor.

ORGAN REJECTION: One of the biggest problems heart transplant patients encounter in their post-operative state is organ rejection. Organ rejection occurs when a patient's immune system views the new heart as a threat and releases white blood cells to destroy it. Mario Deng, M.D., director of cardiovascular transplantation research at Columbia University in New York, says the risk of organ rejection is highest the first 12 months after surgery. He also says 3 percent to 5 percent of heart transplant patients experience moderate to severe rejection of the organ after the first year.

TRADITIONAL METHODS OF MONITORING ORGAN REJECTION: Because organ rejection can be fatal for some transplant patients, doctors have come to rely on endomyocardial biopsies to monitor a transplant patient's post-operative health and guide immunosuppressive therapy. Initially, biopsies are performed on a weekly basis. Once a patient becomes more stable, biopsies are generally performed once a month or once every three to six months for the remainder of the patient's life. A biopsy is a painful, highly invasive procedure that requires a doctor to route a catheter through a vein that leads to the right ventricle of a patient's heart. Once the catheter reaches the heart, doctors use the tiny pair of scissors attached to the end of the catheter to remove four to six pieces of tissue. After staining the tissue samples, doctors place them under a microscope to look for signs of organ rejection, like white blood cells or tissue damage. This procedure requires the patient to be anesthetized and can take anywhere from 15 minutes to 45 minutes. There are many risks associated with endomyocardial biopsies, including vein injury, lung injury, artery injury, arrhythmia, perforation of the heart, infection, scarring and even death. Biopsies of the human heart are often criticized because interpretation of results is highly subjective and variable. Endomyocardial biopsies are also considered late indicators of rejection since rejection can only be detected once cellular damage has already been done to the heart.

ALTERNATIVE METHODS OF MONITORING ORGAN REJECTION: In 2005, Dr. Deng developed a new, non-invasive procedure called the AlloMap test to help doctors monitor organ rejection in heart transplant patients. The test was created when Dr. Deng discovered white blood cells express different genes when they are rejecting or accepting a foreign tissue. The AlloMap test is a molecular blood test that assesses the absence or presence of acute rejection of the transplanted heart," says Dr. Deng. "With the AlloMap test now introduced into the United States health care system, routine biopsy has become more and more obsolete." The AlloMap test is virtually painless and risk-free. The testing begins when patients provide clinicians with a basic blood sample. Trained professionals analyze the blood sample and look for any gene activity in white blood cells that could indicate a potential for organ rejection. Unlike biopsies, AlloMap tests are objective, convenient, reproducible measures that serve as early indicators of organ rejection. They can also clarify the risk of organ rejection for patients with inconclusive results from biopsies. The AlloMap test can help physicians make more informed immunotherapy decisions for patients who may be at risk for organ rejection. The measure was originally designed for stable, asymptomatic heart transplant patients. "The patients are excited about this," says Dr. Deng. "They perceive this as a tremendous advance in their quality of life after heart transplantation without any compromise on the accuracy of the diagnostics."

This article was reported by Ivanhoe.com, which offers Medical Alerts by e-mail every day of the week. To subscribe, click on: http://www.ivanhoe.com/newsalert/.

If you would like more information, please contact:

New York-Presbyterian Hospital
(866) 697-6397
http://www.nyp.org