Take a moment and think about your heart. None of that lovey-dovey crap, this muscle is all business, beating over 2.5 billion times in the average person’s life. It pumps blood an average of 12,000 miles per day, every day, for your entire life. And when it decides to stop, bad news ensues. That’s where the heart transplant comes into play. When all else fails and the heart cannot be saved, doctors don’t give up hope or just say sorry, they replace that bugger with a new one. The truly miraculous procedure of heart transplantation goes into the center of the body and replaces what was traditionally considered to be the most important organ.
Modern day heart transplants are normally conducted by donations from recently deceased or brain-dead donors. The heart is taken out of the donor and given a potassium chloride injection to stop the heart from beating. It is capable of surviving outside of the body for about 4-6 hours. In this last year in the United States, there were about 2300 successful heart transplants (3500 worldwide) while 800 U.S. patients died while waiting for a suitable donor. More than half of U.S. heart transplant patients are between 50 and 70 years old.
The road to successful heart transplants was a bit of a rocky one. The first heart transplant was conducted in 1964 when a monkey heart was placed in the chest of a dying man. This, of course, raised a great number of ethical considerations. Unfortunately, the man’s life was only prolonged for about 90 minutes, but the procedure set the stage for future operations between humans. The first intra-human operation was performed in 1967 with a heart from a brain-dead donor. The patient lived only 18 days before succumbing to pneumonia.
The procedure for a heart transplant is tricky at best. The body is opened with a cut through the sternum and the heart is exposed. A heart/lung machine is attached to the blood vessels leading in and out of the heart, which acts to pump and oxygenate the blood during the operation. After the patient is weaned off of the defective heart, it is literally cut out of the body, leaving only a little bit of the original heart behind. The part left behind contains the pulmonary veins and some heart tissue. The donor heart is trimmed to fit to the remaining tissue and is then sewed in place. The heart is restarted (and defibrillated if necessary) and the patient is removed from the heart/lung machine. At this point, the patient is surviving solely by their new heart. The patient is closed up with plenty of sutures and some metal wire to reconnect the sternum. NOVA Online has a very informative and slightly eerie interactive game that describes exactly how the procedure is conducted. Be sure to check it out if you never wish to forget how to replace a heart.
Overall, the transplant process is about 7 hours long and costs roughly $150,000. The patient is generally sent home as quickly as possible (about 1 to 2 weeks after the operation) to avoid contracting any diseases. Anti-rejection medication must be taken for the rest of the patient’s life or else they risk the body rejecting the new tissue and causing heart failure. Survival rates from the procedure are about 86% after the first year but drop to about 70% after five years among US citizens.
So, where can it go from here? Though any patient would prefer a 99% survival rate, the odds don’t seem all that bad for somebody who doesn’t have long to live otherwise. The majority of problems occur in the body rejecting the new tissue and attacking it. Current medication reduces the body’s ability to fight off the new tissue, but also makes the patient more vulnerable towards other infections. It is in these complications that much of the focus should be placed.
The end goal is to make the rejection issue a moot point by growing organs in the laboratory that are autologous. If the patient is given their own cells, then the body will not react negatively towards the transplant. Lifelong suppressant medication would not be necessary and the immune system would be able to fend off many of the diseases that can cause complications among heart transplant patients. Unfortunately, such an advancement is a long way off and the rejection problem is the issue to focus on in the near term.
It’s amazing to look back and see how far modern medicine has gone with the heart transplant. For over forty years, the procedure has progressed and transformed into what it is today. Ideally, it will continue to become more reliable and more accessible, but what modern medicine has created in the heart transplant is already astounding.