With Valentine’s Day around the corner, doctors at the University of Michigan Health System are looking to mend some broken hearts.
UMHS surgeons made history on Jan. 21 by performing a new surgery to repair thoracic aortic aneurysms, the cause of approximately 10,000 deaths in the United States each year according to the Centers for Disease Control. The procedure performed at the University Hospital involved the first-ever implantation of a new type of heart graft, the Gore TAG Thoracic Branch Endoprosthesis.
Cardiac Surgery Prof. Himanshu Patel, Radiology Prof. David Williams and Surgery Prof. Jon Eliason performed the first two surgeries with the newly approved device. The Gore TAG is unique in its ability to reach a portion of the heart that has generally been difficult to treat.
Heart grafts are a commonly used treatment for heart aneurysms, which occur when there is a weak spot in a blood vessel. The pressure from blood on such weak spots can cause them to bulge, which can eventually result in the vessel rupturing.
The aorta is the largest blood vessel in the body, so it is particularly dangerous for an aneurysm to occur in that area near the heart. An aortic rupture can result in massive internal bleeding, which is fatal without immediate treatment.
The aorta runs from the heart through the chest before descending to the abdomen. A thoracic aortic aneurysm is an aneurysm that affects the aorta in the thoracic, or chest, area. Patel said aneurysms near the arch of the aorta are much more difficult to treat than those near the abdomen or other areas.
“Aneurysms that encroach within the arch vessels are a little harder to treat because of the curvature of the aorta,” Patel said. “They come close to important blood vessels that supply important parts.”
To treat aneurysms, surgeons place stent grafts in the diseased area of the blood vessel. Stent grafts are small tubes supported by a metal mesh framework. The graft redirects blood flow so that it can pass the aneurysm without causing further injury to the area. Relieving the pressure on the vessel walls lessens the risk of rupture.
While stent grafts were used to treat aneurysms before the invention of the Gore TAG, Patel said former grafts were designed to treat straight sections of the aorta. Treating aneurysms in the aortic arch with these grafts required a complicated supplemental procedure.
“Usually when it encroaches on the left arm blood vessel, we made a cut in the neck, we did a bypass from the left brain blood vessel to the left arm blood vessel … and then put the stent graft across that area where the left arm blood vessel comes off,” Patel said.
Unlike former stent grafts, the Gore TAG has a branch that allows it to fit better into the aorta’s arch. Patel said this device was designed and manufactured specifically for this procedure. It allows for a much less invasive surgery than was previously possible, requiring only a small groin incision.
Although the Gore TAG stent graft is a step forward, it only has one branch. In contrast, the aorta branches into three different blood vessels. Patel said he hopes that there will soon be multiple branch stent grafts to better fit the shape of the aorta.
“The hope is that we’re going to a multiple branch system to treat more of the arched aorta,” Patel said.
UMHS is one of only six hospitals in the country with access to the Gore TAG. The others are University of Pittsburgh, the Mayo Clinic, Dartmouth College, The University of Pennsylvania and Stanford University. The Gore TAG is also undergoing a feasibility study through the FDA. Patel said the device has been successfully implanted in animals and was determined ready for human use.
“What the FDA allows is a small number of patients to be enrolled in the study, to see how this device interacts with human beings,” Patel said. “If it looks like it works pretty well, then what they’ll do is they’ll allow for a bigger trial, to see if it can be approved for use in the U.S.”
Patel said UMHS was the first hospital to perform the surgery because they had the first willing patients. The surgery was a success on both of the first two patients, who were discharged from the hospital within a week of having the surgery. Now that UMHS has shown that the Gore TAG works, it is likely that it will be approved for wider use.
“They were very brave people,” Patel said. “Because they were brave enough to participate in this trial, we hope that this type of device will succeed and be available to other patients so that we can treat them perhaps in a better way.”