Friday, March 20, 2020

Prolonged Preservation of the Heart Prior to Trans Essays

Prolonged Preservation of the Heart Prior to Trans Essays Prolonged Preservation of the Heart Prior to Transplantation Biochemistry Prolonged Preservation of the Heart Prior to Transplantation Picture this. A man is involved in a severe car crash in Florida which has left him brain-dead with no hope for any kind of recovery. The majority of his vital organs are still functional and the man has designated that his organs be donated to a needy person upon his untimely death. Meanwhile, upon checking with the donor registry board, it is discovered that the best match for receiving the heart of the Florida man is a male in Oregon who is in desperate need of a heart transplant. Without the transplant, the man will most certainly die within 48 hours. The second man's tissues match up perfectly with the brain-dead man's in Florida. This seems like an excellent opportunity for a heart transplant. However, a transplant is currently not a viable option for the Oregon man since he is separated by such a vast geographic distance from the organ. Scientists and doctors are currently only able to keep a donor heart viable for four hours before the tissues become irreversibly damaged. Because of this preservation restriction, the donor heart is ultimately given to someone whose tissues do not match up as well, so there is a greatly increased chance for rejection of the organ by the recipient. As far as the man in Oregon goes, he will probably not receive a donor heart before his own expires. Currently, when a heart is being prepared for transplantation, it is simply submerged in an isotonic saline ice bath in an attempt to stop all metabolic activity of that heart. This cold submersion technique is adequate for only four hours. However, if the heart is perfused with the proper media, it can remain viable for up to 24 hours. The technique of perfusion is based on intrinsically simple principles. What occurs is a physician carefully excises the heart from the donor. He then accurately trims the vessels of the heart so they can be easily attached to the perfusion apparatus. After trimming, a cannula is inserted into the superior vena cava. Through this cannula, the preservation media can be pumped in. What if this scenario were different? What if doctors were able to preserve the donor heart and keep it viable outside the body for up to 24 hours instead of only four hours? If this were possible, the heart in Florida could have been transported across the country to Oregon where the perfect recipient waited. The biochemical composition of the preservation media for hearts during the transplant delay is drastically important for prolonging the viability of the organ. If a media can be developed that could preserve the heart for longer periods of time, many lives could be saved as a result. Another benefit of this increase in time is that it would allow doctors the time to better prepare themselves for the lengthy operation. The accidents that render people brain-dead often occur at night or in the early morning. Presently, as soon as a donor organ becomes available, doctors must immediately go to work at transplanting it. This extremely intricate and intense operation takes a long time to complete. If the transplanting doctor is exhausted from working a long day, the increase in duration would allow him enough time to get some much needed rest so he can perform the operation under the best possible circumstances. Experiments have been conducted that studied the effects of preserving excised hearts by adding several compounds to the media in which the organ is being stored. The most successful of these compounds are pyruvate and a pyruvate containing compound known as perfluoroperhydrophenanthrene-egg yolk phospholipid (APE-LM). It was determined that adding pyruvate to the media improved postpreservation cardiac function while adding glucose had little or no effect. To test the function of these two intermediates, rabbit hearts were excised and preserved for an average of 24.5 1 0.2 hours on a preservation apparatus before they were transplanted back into a recipient rabbit. While attached to the preservation apparatus, samples of the media output of the heart were taken every 2 hours and were assayed for their content. If the compound

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