After historic procedure, University heart studies move ahead

Wednesday, September 9, 2015 - 5:51pm

In January, 24 year-old Stan Larkin left the University of Michigan Health System with a SynCardia temporary Total Artificial Heart. He’s now waiting for a heart transplant.

Many patients aren’t so lucky. According to UMHS doctors, there is much more research to be done before this technology is accessible to all patients— particularly children.

John Charpie, professor of pediatrics and director of pediatric cardiology at C.S. Mott Children’s Hospital, said there are three categories of devices doctors can choose from when treating a patient with a failing heart. The first device, extracorporeal membrane oxygenation, or ECMO, was pioneered at the University. ECMO is used to help a patient recover after an operation by distributing oxygen throughout the body until the heart can do so on its own. 

“ECMO is a form of artificial heart, and it is a technology that was invented here at Michigan by a gentleman named Bob Bartlett,” Charpie said. “We probably use it two or three times a month for children whose hearts do not start up after their operations.”

The second technology is the Total Artificial Heart, which Larkin received. Gabe Owens, assistant professor of pediatrics, said the mechanism replaces our body’s natural pumping system until the patient can either receive a transplant or decides on “destination therapy” — meaning the patient keeps the mechanism indefinitely — if they are not a transplant candidate.

The machine has tubing outside the body and pumps blood to organs that need it. This method is unique in that the patient’s biological heart is completely removed, Owens said.

The third category, Charpie said, is mechanical support devices. ECMO can fall under this category. These devices still leave the patient’s organic heart inside the body, but insert an additional device to help the heart do its job.

Owens emphasized the need for more research, especially for pediatric patients.

“In the pediatric world, there’s a lot of research going on to make these assist devices or Total Artificial Hearts amenable for people who are smaller,” Owens said. “The Pediatric Cardiac transplant waitlist has one of the highest mortality rates of any other solid organ because the babies are small, they are young kids. They don’t have as much time to wait.”

Owens also noted the need for research on revitalizing sub-par organs such as kidneys, so they can be used for transplants. This would alleviate some of the stress that comes from limited availability of organs from human donors for transplant. 

Charpie said due to lack of experience with artificial heart technology in pediatric patients, research needs to be done in many areas, including how to choose what anticoagulants, or blood thinners, to use for smaller patients. He cited a patient of his named Caden who passed away due to a stroke caused by blood complications.

“Being so early on in this experience, we as cardiologists and cardiac surgeons didn’t exactly know what the optimal anticoagulation regimens were for kids on the artificial heart,” he said. “All we have is experience in adults.”

Owens expressed similar concerns and said there is technology available to assist failing hearts, but that it often cannot be applied to his pediatric patients.

Even so, Charpie said there is hope. He and his colleagues are working on growing beating heart tissue from human and animal cells so that eventually patients can have their tissue used to build their own replacement heart. Through this alternative process, the patient’s body is unlikely to reject the new heart.

“We’re not on the edge of creating a heart that beats in a dish yet,” Charpie said. “But we are in growing parts of the heart and getting those to a point where they may be able to transplant them back to an animal model.”

In the past, the National Institute of Health has funded this research at the University. Now, according to Charpie, these grants are harder to receive. Charpie and other interested University doctors must look to foundations and philanthropy for most of their monetary support.

Owens said there is also progress in miniaturizing heart technology to cater to pediatric patients and hopes the NIH would fund this research.

“There have been great resources and opportunities through the National Institute of Health to fund both industry and academic centers to advance mechanical devices for the support of children,” Owens said. “I think that’s where the future needs to go.”