Top 6 Single-Organ Transplants

More than 500,000 organ transplants have been done in the U.S.

According to the United Network for Organ Sharing (UNOS), between January 1, 1988, and June 30, 2016, an estimated 669,556 organs were transplanted in the United States. Although these numbers are remarkably impressive, there simply aren’t enough organs available for those who need them. Currently, 120,139 people are in need of lifesaving organ transplantation.

Here are the six most common single-organ transplants in order of decreasing frequency. Single-organ transplants are specified because organ recipients often receive more than one organ at the same time. For example, the number of kidney/pancreas transplants (21,727) during the above-mentioned period is greater than the number of pancreas transplants alone (8,235).

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Number 1: Kidney

Blood vessels and kidneys, artwork
PASIEKA/Getty Images

The number of kidney transplants between January 1, 1988 and June 30, 2016, was 395,510

The kidneys are the most commonly transplanted organ. In 2011, there were 11,835 deceased-donor kidney transplants and 5772 living-donor transplants.

Kidney transplantation is used to treat people with end-stage renal disease, or kidney failure. Typically, such kidney failure is due to diabetes or severe hypertension. For the most part, kidney transplants are more successful than dialysis and improve lifestyle and increase life expectancy to a greater extent than does dialysis.

In the 1960s, the only immunosuppressive medications we had to combat rejection of organs were azathioprine and prednisone. Because we had fewer immunosuppressive medications during these early years of transplantation, kidneys procured from living donors were more likely to take than kidneys procured from deceased donors.

Today, we have a variety of medications to help suppress immune response in people who receive kidney transplantations. Specifically, these drugs suppress a variety of immune responses, including those caused by bacteria, fungi, and malignant tumors.

Agents used to suppress rejection are broadly classified as either induction agents or maintenance agents. Induction agents reduce the chance of acute rejection and are given at the time of transplant. In people receiving kidneys, these induction agents include antibodies that eliminate the use of either steroids or calcineurin inhibitors (cyclosporine and tacrolimus) and their associated toxicities.

Maintenance therapy helps prevent acute rejection and loss of the kidney. Typically, patients receive the following therapy: prednisone (steroids), a calcineurin inhibitor and an antimetabolite (think azithioprine or, more commonly, mycophenolate mofetil). Maintenance therapy is adjusted over time.

Thanks to improvements in immunosuppressive treatments, loss of transplanted kidneys due to acute rejection is uncommon. As of December 2012, the number of kidney recipients alive after five years, or five-year survival rate, was 83.4 percent for kidneys procured from deceased donors and 92 percent for kidneys procured from living donors.

Over time, however, the function of transplanted kidneys is vitiated by a poorly understood chronic process, involving interstitial fibrosis, tubular atrophy, vasculopathy, and glomerulopathy. Thus, average life expectancy for those receiving kidneys from living donors is 20 years and that for recipients of deceased donor organs is 14 years.

Living volunteer donors should be cleared of any serious medical conditions, and deceased donors shouldn’t have any types of disease that can be spread to the recipient, such as HIV, hepatitis or metastatic cancer.

Donors are matched with recipients using blood group antigens (think blood type) and antigens of the HLA major histocompatibility gene complex. Recipients of kidneys who are more closely matched by HLA types fare better than those with mismatched HLA types. Typically, first-degree relatives are more likely to express matching HLA transplantation antigens. In other words, a first-degree relative is more likely to provide a viable organ that will take better than a kidney from a deceased cadaver.

Kidney transplantation surgery is relatively noninvasive with the organ being placed on the inguinal fossa without need to breech the peritoneal cavity. If all goes smoothly, the kidney recipient can expect to be discharged from the hospital in excellent condition after five days.  

Kidneys procured from deceased donors can be kept for about 48 hours before transplant. This time gives health care personnel adequate time to type, cross-match, select and transport these organs.

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Number 2: Liver

The number of liver transplants between January 1, 1988, and June 30, 2016, was 143,856

 As with kidneys and kidney transplantation, livers can come from live donors. Deceased organ liver donations usually come from brain-dead donors who are younger than 60. The deceased donor must meet certain criteria, including no liver damage due to trauma or diseases like hepatitis.

Specialists match donors with recipients using ABO compatibility and size of the person. Interestingly in cases of emergency, a liver can be split (split liver) and provided to two child recipients. Also in cases of emergency or marked organ shortage, livers that are ABO-incompatible can be used. Unlike with kidney transplants, livers don’t need to be screened for HLA compatibility.

The liver is the only visceral organ to possess remarkable regenerative potential. In other words, the liver grows back. This regenerative potential is the reason why partial liver transplants are feasible. Once a portion or lobe of the liver is transplanted, it will regenerate.

With liver transplant, the more-sizeable right lobe is preferred to the left lobe. Furthermore, although partial liver transplants procured from living donors are performed, typically livers are procured from cadavers. In 2012, only 4 percent of liver organ transplants (246 procedures) were procured from living donors.

Liver transplantation is offered as a means of treatment once all other options have been exhausted. It is offered to people with severe and irreversible liver disease for which there are no further medical or surgical treatment options. For example, a person with advanced cirrhosis caused by hepatitis C or alcoholism may be a candidate for liver transplantation.

With liver transplantation, timing is very important. The person receiving the transplant must be ill enough to need the transplant but well enough to recover from the surgery.

Whole liver transplant, or orthotopic transplantation, is a major surgery and technically challenging--especially in people with portal hypertension of which cirrhosis is a common cause. The combination of portal hypertension and coagulopathy, or impaired blood clotting which results from the liver failure, can lead to much blood loss during surgery and large blood product transfusion requirements. Moreover, to remove the entire liver and then replace it requires first the dissection (cutting) and then anastomoses (joining) of several important blood vessels and other structures, such as the inferior vena cavae, portal vein, hepatic artery and bile duct.   

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Number 3: Heart

The number of heart transplants between January 1, 1988, and June 30, 2016, was 64,085

To replace a heart was once something dreamed up by science fiction writers … but we did it. It took more than 200 years for advances in both our understanding of immunology and improvements in surgery as well as suture technique and technology to open the door for heart transplant. In 1967, the first heart transplant was done in Cape Town, South Africa, by a surgeon named Dr. Christiaan Barnard.

Although technologically impressive, early heart transplants didn’t prolong survival in any substantial way. In fact, Barnard’s patient lived only 18 days after receiving a new heart. It would take improvements in immunosuppressive drugs and tissue typing to improve survival after heart surgery.

According to the U.S. Department of Health & Human Services, in 2012, the five-year survival rate, or number of people who were still alive five years after heart transplant, is 76.8 percent.

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Number 4: Lung

The umber of lung transplants between January 1, 1988, and June 30, 2016, was 32,224

Ever since 1985, more than 40,000 lung transplants have been performed worldwide. Lung transplantation is done in people with end-stage lung disease that isn’t cancerous (nonmalignant). Here are the top four indications for lung transplant:

Typically, lungs are procured from deceased donors with total brain failure (brain death). However, between 15 and 20 percent of such donors possess lungs suitable for transplant.

For most types of disease warranting lung transplant, either one or two lungs can be transplanted. With cystic fibrosis and other forms of bronchiectasis, however, both lungs need to be transplanted. Transplantation of both lungs is done to stop infection from spreading from native lung tissue to transplanted lung tissue. Even though one or two lungs can be transplanted to treat most types of disease, the transplantation of two lungs is typically preferred.

The right lung is divided into three lobes, and the left lung is divided into two lobes. Transplantation of a lobe procured from a living donor has been performed in the past but is now uncommon. Typically, such lobar transplantation was performed in teens and young adults with cystic fibrosis who would likely die while awaiting a bilateral (or double) lung transplant procured from a deceased donor, or cadaver.

Typically, quality of life improves markedly in those receiving lung transplants. The actual time a person lives with transplant varies according to which disease necessitated the transplant as well as age of the recipient—with younger recipients living longer—and transplantation procedure. In broad terms, many people who receive lung transplants live around 10 years before chronic rejection inevitably sets in.

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Number 5: Pancreas

The number of pancreas transplants between January 1, 1988, and June 30, 2016, was 8,235

The first pancreas transplant was performed by William Kelly and Richard Lillehei at the University of Minnesota in 1966. Ever since then, more than 25,000 pancreas transplants have been performed in the United States and more than 35,000 worldwide. Typically, pancreases are procured from deceased donors; however, although far less common, living donors can also be used.

Pancreas transplant is the definitive long-term treatment for people with insulin-dependent diabetes mellitus (type 1 diabetes mellitus). Such transplant can restore normal glucose homeostasis and metabolism as well as decrease the risk of long-term complications secondary to diabetes.

Of note, pancreas transplants are commonly compared with islet transplants, which are less invasive. Islet cells are clusters of cells in the pancreas that produce hormones, such as insulin and glucagon. Although islet transplants have improved significantly in recent years, pancreas transplants function better than islet transplants. Instead of competing procedures, it’s best to view pancreas and islet transplants as complementary procedures, which both can help the recipient in need. 

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Number 6: Intestine

The number of intestine transplants between January 1, 1988, and June 30, 2016, was  2,733

Transplantation of the intestine is a complex procedure. In recent years, this procedure has gained popularity in the treatment of short bowel syndrome, wherein people can’t absorb enough water, calories, protein, fat, vitamins, minerals and so forth. Typically, people who receive intestine transplants experience intestinal failure and require total parenteral nutrition (TPN), or intravenous nutrition.

Nearly 80 percent of people who receive an intestine transplant attain full function in the intestinal graft. Complications associated with this procedure include CMV infection, acute and chronic rejection, and post-transplant lymphoproliferative disease.

Sources

Azzi J, Milford EL, Sayegh MH, Chandraker A. Transplantation in the Treatment of Renal Failure. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015. 

Gruessner AC, Jie T, Papas K, Porubsky M, Rana A, Smith M, Yost SE, L. Dunn D, Gruessner RG. Transplantation. In: Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. eds. Schwartz's Principles of Surgery, 10e. New York, NY: McGraw-Hill; 2014. 

Tavakkoli A, Ashley SW, Zinner MJ. Small Intestine. In: Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. eds. Schwartz's Principles of Surgery, 10e. New York, NY: McGraw-Hill; 2014.

Transplants By Organ Type January 1, 1988 - June 30, 2016. United Network for Organ Sharing https://www.unos.org/data/

Trulock EP. Lung Transplantation. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015. 

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