Minimal Effort
Physicians expert in minimally invasive surgery techniques replace an aneurysm's threat of sudden rupture with peace of mind for the patient.
All Carolyn Goubert had to hear was the word “aneurysm,” and she knew intimately what it meant.
When doctors spotted the bulging area in Goubert’s aorta in 2001 while
she was undergoing some unrelated imaging scans, the Newport Beach native
understood its potential danger. After all, her mother had died of a brain
aneurysm. Her father had five aneurysms, in various parts of his body. And
her niece had been stricken by one, as well.
“The possibility of my aneurysm rupturing was in the back of my mind,” says Goubert, a 65-year-old grandmother of eight. “You can’t live your life thinking about it all the time, but you do always know it’s there.”
So after four years of seeing her aneurysm gradually grow bigger, while under the watchful eyes of her USC physicians, Goubert opted to take the plunge and undergo a new surgical procedure that could stop the potential ticking time bomb in her chest. In June 2005, she found herself in a USC University Hospital operating room, slowly drifting into an anesthesia-induced sleep. Goubert had a simple hope—that when she awoke from her surgery, the aneurysm’s threat of sudden rupture would be a distant memory, replaced by peace of mind.
Repair expertise
More than a dozen physicians and technicians are packed into USC University Hospital’s dedicated endovascular surgical suite, eager to see the first minimally invasive repair of a thoracic aortic aneurysm in Southern California.
Not only will Goubert have her aneurysm defused, she will have it done in a pioneering way: Surgeons at the Keck School of Medicine of USC will repair her aneurysm without having to open her chest or cut her aorta.
The surgeons will install the Gore TAG endoprosthesis, a high-tech device that pops open like a sleeve inside the aorta and acts like a scaffold to relieve the pressure on the vulnerable aneurysm before it can burst. The newly approved TAG endoprosthesis can be navigated into place through endovascular techniques: Surgeons access a large artery by making small incisions in the groin, then thread the compressed device through arteries up to the aorta, where they carefully install their payload.
It is a critical procedure—one that Douglas B. Hood, M.D., assistant professor of surgery at the Keck School, does not take lightly.
As Hood explains, the aorta is the largest artery and carries oxygen-rich blood from the heart to the rest of the body. Shaped much like the curved handle and long stem of a cane, and about the width of a garden hose, the aorta rises from the heart and then descends through the chest and abdomen before forking in two to serve both legs.
Over a lifetime, layers of the aorta’s wall may become damaged and weakened, creating a bulging area called an aneurysm. The heart’s constant pumping of blood may push on this faulty area, causing it to dangerously distend and grow more vulnerable. Sometimes the inner layers of the artery split or crack, too—what physicians call a dissection.
“It’s not known for certain why they develop, but alterations in the amount of collagen and elastin in the artery wall can play a part,” Hood says. “It seems that risk can be inherited, and it may be linked to other inflammatory conditions.”
Most aortic aneurysms arise in the abdomen—what physicians call an abdominal aortic aneurysm.
But aneurysms can arise in the chest, too. Called thoracic aortic aneurysms, these are hidden behind the chest wall and often go undetected. “Most of the time, they are asymptomatic—until they rupture,” says Fred A. Weaver, M.D., professor of surgery at the Keck School and chief of the vascular surgery division. When they rupture, most patients die before they can reach the hospital.
Fortunately, though, imaging is helping to find many of these aneurysms before a crisis hits.
“We’re seeing more of these cases being found early, before they rupture, because the aneurysms can be seen on scans, such as chest X-rays, that are done routinely for other medical issues,” Weaver says.
In Goubert’s case, a radiologist at Hoag Memorial Hospital Presbyterian in Newport Beach found the aneurysm while Goubert was undergoing a computed tomography, or CT, scan for a hypertension-related kidney problem. She was referred to cardiovascular surgeons at USC, who are widely known for their expertise in aortic repair.
The surgeons are part of the Aortic Center at USC, an alliance of vascular and cardiothoracic surgeons who have crossed traditional boundaries and joined forces to find the best solutions to patients’ unique aortic problems. Patients are referred to the Aortic Center both from nearby cities and far-away states.
Robbin G. Cohen, M.D., associate professor of cardiothoracic surgery at the Keck School, co-directs the Aortic Center with Hood, who is a vascular surgeon. “We now have the opportunity to redesign our surgical approach to aortic aneurysms and dissections to create safer and less-invasive operations for these serious problems,” Cohen says. “The comprehensive nature of our Aortic Center is unique to Southern California.”
The careful observation and customized game plan extolled by the Aortic Center are important in the appropriate treatment of an aneurysm, physicians say.
When doctors find an aneurysm in a patient, they usually start with a conservative approach, monitoring the patient until the aneurysm grows big enough that the risk of rupture outweighs the risks involved in surgery. For abdominal aneurysms, the threshold is usually about 5 centimeters (cm) across; for thoracic aneurysms, surgeons wait until they approach 6 cm across.
Like all surgeries, aortic repair poses certain risks that patients and surgeons have to carefully consider. To fix the aneurysm, surgeons have traditionally had to use a procedure in which they make a long incision across the abdomen or chest. They temporarily clamp the aorta to cut off blood flow, then cut into the aorta to remove the aneurysm, and finally suture in a graft.
When the aneurysm lies in the chest—above the diaphragm—the operation is especially challenging, since it involves a thoracotomy: opening the chest and separating the muscles from the ribs. That requires a large incision and significant recovery time for the patient. It also requires great expertise on the part of the surgical team, because restricting blood flow to the important vessels of the spinal cord and renal system poses the risk of paralysis and kidney problems.
Over the last decade, though, vascular surgeons have developed less invasive alternative methods to treat abdominal aortic aneurysms, using synthetic, sleeve-like stent grafts introduced through small groin incisions. For the past five years, USC vascular surgeons have used these specialized, high-tech devices in more than 50 percent of patients with abdominal aortic aneurysms, avoiding open surgery.
Now it was time for Goubert and her USC surgeons to usher in a new era—and bring similar devices to patients with thoracic aneurysms.
Aorta entry
Hood and Weaver stand next to Goubert, who is already under anesthesia and rests comfortably on the surgical table. At their side, Curtis Prejean Jr., M.D., assistant professor of cardiothoracic surgery at the Keck School, tugs at his surgical cap while nurses, anesthesiologists and technologists prepare for the surgery.
“This is a big moment,” Weaver says.
Hood nods, the excitement visible behind his surgical glasses. “We’ve been planning this for a long time,” he says.
The surgeons make incisions in Goubert’s hips—a small puncture in one and a larger incision in the other—creating entryways into the iliac arteries. The arteries serve as sort of freeway on-ramps where the surgeons can enter the vascular system and thread several feet of guide wire toward the aorta. Surgeons usually prefer to introduce catheters and wires through the femoral arteries, but in small patients such as Goubert, surgeons must use the iliac arteries instead.
After a technologist takes an X-ray image of Goubert’s aorta—visible on a television monitor beside the operating table—the surgeons carefully insert a plastic tube into her artery.
Then they prepare their key payload: a TAG aortic endoprosthesis, compressed and densely packed into a tube no wider than a pinky finger. They thread it on a catheter through the tube and into the artery, painstakingly nudging the device up toward her chest.
“Looks good,” Hood says, staring at the monitor beside him. The device is in its target area, ready for unfurling.
Hood’s fingers grip a thin thread that is still attached to the endoprosthesis like a tail. With a swift yank, he pulls the string—and springs open the device inside the aorta, much like a parachute.
Goubert’s device is a 15 cm-long fabric sleeve made of a slick, thin plastic called polytetrafluoroethylene. It features accordion-like ridges that allow it to bend and follow the curves of the aorta. The sleeve measures 3.1 cm across.
Lining the circumference of the sleeve and holding the sleeve open are kinked wires made of nitinol, an initially soft metal alloy that stiffens when heated to body temperature.
When deployed, the device carries blood flow through the aorta and diverts it from the vulnerable parts of the artery wall, while withstanding the forces created by pumping blood.
After the device is installed, the surgeons position another catheter within the endoprosthesis. On its tip, Hood points out, are three deflated rubbery balloons. With a slight push, the surgeons inflate the balloons, which open up to form a three-dimensional, three-leaf clover shape inside the endoprosthesis. The balloons push on the sides of the device, ensuring it is snugly in place within the aorta. Then the surgeons deflate the balloons and remove the catheter, and Goubert is ready to have her incisions closed.
Designed for life
Made by the same company that came up with breathable Gore-Tex fabric for clothing, the endoprostheses come in different lengths and widths, and surgeons can use as many as three at a time when a patient has several aneurysms.
The devices are too new to have data on their long-term outcome. But similar devices have proved reliable for abdominal aortic aneurysms, and studies done before the federal government approved the TAG device’s use are encouraging.
“We’re optimistic about what this procedure means for patients: less loss of blood, a shorter hospital stay and quicker recovery time,” Hood says.
In the studies, patients receiving the device through minimally invasive surgery had lower rates of paraplegia, lower risk of death during the procedure, and significantly less blood loss than what was seen in patients receiving open surgeries. A two-year follow-up revealed fewer deaths related to aneurysms in the TAG group. Hospital stays dropped from a typical 10 days down to three, and patients were able to return to normal activities more quickly as well.
Goubert can vouch for the surgery. She stayed in the hospital for six days, longer than expected, but not because of trouble with the surgery; rather, she was anemic after the procedure and physicians had to make sure she was healthy before she was discharged. And the operation left only small scars from the entry incisions rather than the long scar she would have had across her chest if she had the traditional surgery.
“I am definitely relieved that I had it done,” Goubert says. “It was worth it, and I recommend it to anyone who needs it.”
Not all patients are good candidates for the minimally invasive surgery, surgeons caution. Sometimes aneurysms are located in areas near branching arteries or near the heart, making it tough to reliably place the TAG device. Those patients may still benefit from the traditional open surgery. USC surgeons are experts in both forms of treatment.
“For patients who are appropriate candidates for this procedure, this is a valuable option,” Hood says. “We’re very excited about it.”
For more information about the Aortic Center at the Keck School of Medicine of USC, call 1-800-USC-CARE (1-800-872-2273).
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