• Article
  • October 24, 2019

New Blood Test for Heart Transplant Patients Reduces Invasive Procedures

Inspired by a patient, a clinical husband and wife duo create a new blood test.

By Evan Solochek

Mike Mitchell, M.D.,
and Aoy Tomita-Mitchell, Ph.D., developed a noninvasive blood test for heart transplant recipients.
Mike Mitchell, M.D., and Aoy Tomita-Mitchell, Ph.D., developed a noninvasive blood test for heart transplant recipients.

In the first year following a heart transplant, patients are tested for rejection up to a dozen times. Then they must undergo regular surveillance biopsies the rest of their lives. The traditional biopsy to test for transplant rejection is expensive, invasive and labor-intensive.

But a blood test developed by a husband and wife surgeon/scientist team, Mike Mitchell, M.D., pediatric cardiothoracic surgeon at the Herma Heart Institute at Children’s Wisconsin, and Aoy Tomita-Mitchell, Ph.D., professor of pediatric cardiothoracic surgery at the Medical College of Wisconsin and investigator for the Children’s Hospital of Wisconsin Research Institute, is changing that.

“For a patient who has just undergone a serious surgery—especially a child—undergoing additional invasive procedures countless more times can cause a great deal of physical and mental stress,” says Mitchell. “This blood test takes that strain away.”

With this test, the process starts with a blood draw. No invasive procedure. No anesthesia. No fasting for 12 hours and arriving at the hospital at dawn. No waiting around all day (or night) for results. The blood sample is shipped overnight to the TAI Diagnostics lab in Wauwatosa, Wisconsin. A test looks for how much donor DNA is present in the patient’s blood—a high level of donor DNA indicates rejection. Results are available within one business day.

The inspiration for the test can be traced back to Emma, who was born in 2010 with hypoplastic left heart syndrome (HLHS). When she was 9 months old, Emma was placed on the heart transplant list. After multiple HLHS surgeries, life began to stabilize, and she was discharged from the hospital.

Almost two years later, while Emma was undergoing a cardiac catheterization to evaluate her for a final HLHS surgery, Mitchell discovered the arteries and veins in her groin had collapsed. Without vascular access to her heart, doctors would not be able to perform biopsies to test for organ rejection when Emma ultimately received a transplant.

That also meant she was a high-risk candidate, and her transplant would be unlikely to be approved. Mitchell refused to accept that, and he and Tomita-Mitchell began work to develop the blood test.

Fortunately, Emma has not needed the blood test. After making progress, she was taken off the transplant list in 2017. But her family knows it’s a matter of when, not if. And knowing this test exists gives them peace of mind.

Evan Solochek is a writer at Children’s Wisconsin. Send questions or comments.