Transplant surgeons test ‘heart in a box’
A human heart lies encased in a plastic box. Still warm. Still beating. Still pumping blood. Completely disconnected from a human body.
To some, that seems the stuff of science fiction. But not to transplant surgeons.
They hope this “heart in a box” will be the solution that brings a second chance at life to people who have waited far too long for a heart.
Spectrum Health physicians are taking part in a U.S. study to determine whether the “heart in a box” technology can expand the number of donor hearts deemed healthy enough for transplant.
The purpose of the study is to determine whether the technology offers a key advantage—extra time, said Martin Strueber, MD, a cardiothoracic surgeon with the Richard DeVos Heart & Lung Transplant Program at Spectrum Health.
The device is designed to give surgeons several more hours to transplant a heart that remains warm and beating. Dr. Strueber and Asghar Khaghani, MD, FRCS, also a cardiothoracic surgeon, are involved in a clinical trial for the heart Organ Care System created by TransMedics.
Only 30 percent of the hearts donated qualify for transplant under the current system—in which doctors stop the heart, pack it in ice and transport it in a picnic cooler. Seven of every 10 hearts, about 5,000 a year, go unused.
One reason lies in the risks of deterioration once the heart stops. Using cold storage, surgeons typically have only about four hours to transplant it.
The time frame begins “the minute you put the clamp on the heart,” Dr. Strueber said. “You haven’t even taken it out. You just clamp the aorta. Then the clock starts.”
He ticked off all the steps that must occur next.
“You have to do the preservation procedure for the heart. You have to take it out. You have to pack it. You have to find your way out of the foreign operating room and change in between.
“You run to your car that takes you to the airport. You may get stuck in some security things. Then, you fly (back to Grand Rapids) with a private jet. You need to get everything out of the jet and into a car. You drive over here, unpack and run to the operating room.”
In the meantime, another team begins surgery on the recipient, to prepare the patient for transplant. Once the heart arrives, they transplant the heart into the recipient.
They remove the clamp. Blood flows into the coronary arteries. And that’s when the clock stops.
“The entire thing has to happen in four hours,” Dr. Strueber said.
That tight time frame means a transplant can depend on the fickle fate of weather.
A donor heart across the country might be a good match for a local patient. But before they accept it, the surgeons consult a pilot to see how quickly they can get back.
Their decision can hinge on tailwinds and headwinds. A snowstorm can be a deal breaker.
The study is examining whether the TransMedics transport module could keep a heart viable longer, the doctors said. It remains beating, supplied with warm, oxygen-rich blood. The module, about the size of a dishwasher, includes a monitoring system that allows doctors to track the heart’s health.
A feasibility trial involving 128 patients compared outcomes with the Organ Care System and cold storage. Patients fared equally well with both methods, said Marianne Sanders, vice president of global marketing for TransMedics.
The Expand Heart trial—now underway—involves surgeons at seven sites in the U.S., including the Richard DeVos Heart & Lung Transplant Program transplant program at the Fred and Lena Meijer Heart Center. It focuses on the system’s ability to preserve and assess hearts that would not meet current standards for transplants.
That could include those from donors over 50 that are a long distance from the hospital. A prolonged time of ischemia—when the heart is stopped—poses risks, especially to hearts in that age range.
It may also help assess the health of younger donor hearts that have suffered stress—during cardiopulmonary resuscitation, for example.
Surgeons hope having more information about the heart’s health will help them decide whether to implant it into a recipient, Dr. Strueber said. Ultimately, he hopes the TransMedics system will increase the number of hearts deemed suitable for transplant.
Transport by ferry
Although the system created by Massachusetts-based TransMedics is still under clinical investigation in the U.S., the two Spectrum Health surgeons have experience with the device—Dr. Strueber in Germany and Dr. Khaghani in the United Kingdom. The device received approval for clinical use in Europe in 2006.
Dr. Khaghani conducted the first dry run for the device in England on Dec. 8, 2003.
As a cardiothoracic surgeon with Royal Brompton & Harefield NHS Foundation Trust in London, he tested the system transporting a donor heart that could not be used for transplant.
He had to travel to the Isle of Wight to recover the heart. Fog hung so heavy that night he couldn’t go by helicopter, so he crossed to the island by car ferry.
At sunrise the next morning, he caught the first ferry back. The heart, packed in the perfusion module, remained in the ambulance below deck for the 20-minute crossing.
Dr. Khaghani and the surgical team sat in the near-empty lounge.
“We had the monitor there,” he said. “We were monitoring the heart beating inside the ambulance inside the ferry.”
Dr. Khaghani, who came to Spectrum Health in 2010 to lead its heart transplant program, said his former hospital in England now uses the TransMedics system to transport donor hearts.
It is hoped the device may prove even more useful in the U.S., he said, because of the size of the country. Donor and recipient may be separated by thousands of miles.
About 4,200 people wait on the national list for a new heart, including 122 in Michigan, according to the National Organ Procurement and Transplantation Network. Last year, nine Michigan patients died as they waited for a heart, and another eight became too sick for a transplant, Gift of Life Michigan reports.
“We want to get the waiting time down and get the transplants done,” Dr. Strueber said.
More hearts, more patients
The introduction of the ventricular assist device, a portable device that pumps blood for the heart, has improved survival rates for those awaiting transplant.
But that also means more people on the waiting list—and a longer wait for a heart.
“At some point, the advantages we are getting from the assist devices will go away,” Dr. Strueber said. “The next step needs to be some improvement in the availability of donor hearts.”
In Michigan, a push by Secretary of State Ruth Johnson has sparked an increase in the donor registry. Fifty-five percent of residents now are registered, up from 27 percent in 2011.
Spectrum Health’s surgeons perform about 20 heart transplants a year. If the donor pool expands, they could bring new hearts to more patients.
“Adding another 10 would be extremely good,” Dr. Khaghani said. “That is a really big jump. Even if you do another four or five, the service you are doing for patients would be a big success.”