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Heart in a Box: An Advance in Cardiac Transplantation
by Reyna Jones
According to the Mayo Clinic, there are approximately 3,000 people in the United Stateswaiting to receive a heart transplant. Individuals needing a transplant are typically suffering from heart failure or are affected by other severe cardiac conditions, such as a congenital heart defect. When a donor heart becomes available, heart transplantation rapidly begins. After removing the heart from the donor, physicians have only four to six hours to retrieve, transport and begin surgically inserting the organ into a recipient before the donated heart becomes unviable. This narrow window of time in which the heart can remain outside of the body, called the “ischemic time,” is largely dependent upon the way in which the heart is stored after it is removed from the donor. The main method for preserving organs awaiting transplant is called “simple static cold storage;” essentially, the organ is sustained through a combination of preservation fluids and cooling. Although this technique works well enough and is relatively inexpensive, its efficacy is limited by time constraints and the availability of donor hearts. For example, due to the short preservation time, patients in need of heart surgery must live within four hours of the hospital from which they will receive their transplant. This means that it is impossible for people living outside of this radius to receive a donor heart. Additionally, elements such as recipient blood type, body size, severity of patient condition, infection and length of time that a patient has been awaiting a transplant play a sizable role in determining the compatibility and availability of donor hearts. Unfortunately, some donor organs go to waste because no patients residing within the four-hour radius of proximity are a match for the donor heart. The desperate need for new preservation methods that increase the longevity of donor hearts, making certain that they can be utilized by those most in need, paved the way for the development of a cardiac preservation system known as Heart in a Box.
Heart in a Box may just be the greatest technological breakthrough for heart transplantation in decades. Researchers have designed a portable heart storage and preservation system that moves about on a rolling cart. The Heart in a Box is different from the traditional simple static cold storage method, however, as it is uniquely able to keep the heart warm and beating outside of the body. No, it’s not science fiction! The cart carrying the heart contains a sterilized box for the organ, an oxygen tank, blood and perfusion chemical reservoirs and technology to monitor the heart during transport. The box, called the perfusion module, is sophisticated in that it can control the humidity and temperature of the heart as well as prevent contamination. A blood supply for the heart is taken from the donor, stored in a reservoir and continually processed to ensure that the blood is well oxygenated. This reservoir also contains a solution that functions to maintain and prevent inflammation of the organ. The blood is then pumped through the heart allowing it to continue beating as it is relocated for transplant surgery. The use of the donor blood in combination with the oxygen perfusion system allows the heart to remain in natural, physiological conditions as compared to the traditional use of preservation chemicals and ice. This technology can actually double the ischemic time of the donor heart to approximately 12 hours. This means that donor hearts can travel longer distances to get to patients in need, eliminating healthcare disparities related to proximity and patient accessibility.
Prior to the development of Heart in a Box, physicians were not able to evaluate the functionality of the donor heart before transplanting it into a patient because the heart was not active. Therefore, a transplant recipient had the possibility of receiving a diseased heart that may have gone undetected. The ingenuity of Heart in a Box exists not only in its unique preservation technique but in its ability to test the condition of the heart. The organ care system closely monitors the heart, providing physicians with critical information such as blood temperature, coronary flow, heart rate and aortic pressure. Therefore, physicians can use this information to ensure that they are giving a recipient a healthy heart. By increasing the quality of donor hearts, Heart in a Box has the potential to reduce healthcare system costs related to transplant complications and post-operative care.
Heart in a Box is currently being tested in clinical trials in the hopes of gaining FDA approval. Amazingly, it has already been approved and implemented in Europe and Australia. You may be wondering if organ care systems can be used for organs besides the heart. The answer is yes! The company that pioneered Heart in a Box has developed similar equipment to preserve lungs, kidneys, and livers. With organ care systems, “hearts beat, lungs breathe, kidneys produce urine, [and] livers produce bile.” Heart in a Box, along with other organ care systems, could start the next transplant revolution.