Two hearts are better than one for toddler who undergoes historic operation

Surgeons at Lucile Packard Children's Hospital successfully place a second heart in the chest of a 22-month-old girl

Abdulaziz Alkhaldi, MD

Surgeons last month performed a heterotopic, or piggyback, heart transplant that involves connecting a donor’s heart to the patient’s heart, as shown in the diagram above. This was the first time the procedure was performed on a child in California.

Camila Gonzalez now has two hearts beating separate rhythms inside her tiny chest. At 22 months of age, she became the youngest child in the United States to receive a donor?s heart while also retaining her original one.

Bruce Reitz, MD, professor and chair of cardiothoracic surgery at the School of Medicine, connected a second heart to Camila?s on Sept. 16 at Lucile Packard Children?s Hospital.

The procedure ? called a heterotopic or ?piggyback? heart transplant ? was first developed by Christaan Barnard in 1971 in South Africa. But Camila is the first child to undergo such a procedure in California and only the ninth child to receive a second heart in the United States. In adults the procedure is rare as well. Out of the 1,200 adult heart transplants performed at Stanford Hospital, only one other involved the piggyback procedure.

According to Reitz, Camila?s surgery was a success. This week she will leave the hospital for a three-month stay at the nearby Ronald McDonald House. ?I think we?ve rejuvenated this procedure and shown that it can work in small children,? he said.

Double hearts are a good choice for patients whose heart problems cause extremely high blood pressure in the pulmonary artery ? the blood vessel that takes blood from the heart to the lungs. Such pressure often builds up in people with a weakened heart muscle, a condition known as cardiomyopathy.

In essence, the weakness in the left side of the heart ? which pumps blood to the body ? acts like a blockage in the system, causing blood pressure to rise in the lungs and from there back into the pulmonary artery and the right side of the heart. The right sides of these patients? hearts are enlarged because they have adapted to the excess pressure.

Such a problem generally can?t be solved by replacing the ailing heart with a donor heart because the new one can?t adapt quickly enough to handle the excess pressure built up in the lungs.

?Put a new heart in with that pressure and it will fail,? said Dan Bernstein, MD, co-director of the Children?s Heart Center and chief of pediatric cardiology at Packard Children?s Hospital. Bernstein has been caring for Camila since her surgery.

From 1997 to 2001, eight children received heterotopic heart transplants in the United States. Although five are alive today with their twin-hearts still working fine, the procedure had fallen out of favor because a heart-lung transplant is often appropriate for patients with conditions like Camila?s.

Reitz predicts, however, that Packard Hospital will perform more heterotopic heart transplants on kids in the future. ?Once every two years or so we might encounter a pediatric patient for whom heterotopic heart transplantation would be a good option,? he said.

The number of children who are good candidates for the procedure is still limited, said Bernstein. But the wait for heart-lung donors is usually longer than the wait for a heart, and long-term survival is better for heart transplants alone.

Last February, Camila was diagnosed with restrictive cardiomyopathy, meaning that her heart muscle was not only weakened but also stiff. Her heart muscle ? particularly on the left side ? couldn?t inflate properly when blood flowed into it from her lungs. As a result, the blood pressure in her lungs gradually built up over the period of about a year.

By the time of the surgery, the pressure in Camila?s lungs was five times normal levels, the right side of her heart was enlarged from trying to pump blood against so much pressure, and the left side continued to stiffen, making matters worse.

Camila initially had few symptoms to indicate how sick she was. ?That?s the concerning thing,? said Bernstein, the Alfred Woodley Salter and Mabel Smith Salter Professor in Pediatrics. ?Children with this restrictive cardiomyopathy can slip through the system without getting needed attention.? Left untreated the disease can lead to sudden death or extremely restricted breathing.

When Camila first came to Packard nine months ago, she had a hard time eating and breathing and wasn?t gaining weight. The cardiology team at Packard was able to stabilize her so that she could be fed and remain fairly active while waiting for transplant surgery.

?When she was presented as a possible candidate,? said Reitz, ?it was clear she couldn?t survive a traditional transplant. The new heart would not be prepared to pump at high enough pressure.?

In addition, said Bernstein, ?Camila was ideal for this surgery because the course of her disease wasn?t extremely long, so we believe there?s a good chance her lungs can remodel themselves back to normal.?

Reitz placed the second heart on the lung on the lower right side of Camila?s chest. ?The donor heart is rotated and flipped over a bit,? he said. ?It points off to the right in about the same way as a normal heart points off to the left.?

Adding a second heart is more difficult than traditional heart replacement because there are more complicated hookups, said Reitz, the Norman E. Shumway Professor in Cardiovascular Surgery. ?You have to open the heart four times in order to make all the connections,? he said. ?And it?s harder in kids because everything is a little more fragile in the smaller patient and more crowded.?

The important part is lining up the two left atria ? the upper chamber on the left side of each heart ? so they can be merged. ?That?s really the function of the recipient heart that needs replacing,? explained Reitz. ?If the left side of the donor heart works as it should, that allows the pulmonary pressure to come down.?

Four weeks after surgery, the blood pressure in Camila?s lungs has dropped to near-normal levels, said Bernstein. Although the two hearts are both working, each has its primary function. The oversized right side of Camila?s original heart pumps 90 percent of the blood to her lungs, while the donor heart?s left side pumps 90 percent of the blood to her body.

Over time, the right side of Camilla?s heart will return to a more normal size and will share its load more evenly with the right side of the donor heart.

Although they work and grow together, Camila?s two hearts beat at their own rhythms. The native heart, which is connected to Camila?s nervous system, responds more quickly to changes in Camila?s activity levels. On her electrocardiogram, Camila?s doctors can monitor both hearts at the same time because the peaks caused by each heart are easily distinguished.

Heterotopic heart transplantation carries potential complications. If insufficient blood flows through Camila?s own left ventricle ? the lower chamber on the left side ? clots could form there, said Reitz. But that doesn?t seem to be a problem for Camila. ?She does eject a little bit of blood from that left ventricle about every third beat,? he said.

Because the second heart compresses her right lung slightly, Bernstein noted, Camila might also be at risk of lung infections, an issue that will have to be watched in the years to come.

Other risks that Camila faces are no different from traditional heart transplant recipients ? including immune suppression problems and a chance of chronic rejection. Long-term, Camila can be expected to do as well as patients whose hearts have been replaced by a single heart, Bernstein said.

?In the last five to 10 years, there?s been a marked improvement in long-term survival,? Bernstein said. ?Of 17 heart transplants performed at Lucile Packard Children?s Hospital last year, there have been no early deaths. Many of our heart transplant patients are doing very well 10 or 25 years post-transplant. There?s no reason to think Camila won?t do the same.?