A new procedure is being used to treat thoracoabdominal aortic aneurysms.
If you must have major surgery, the best news you can get is to learn that it can be a minimally invasive one. That means tiny—or no—incisions, far less pain, and a speedy recovery instead of a more dramatic procedure that requires surgeons to open up your body. This is exactly the news most Yale patients are getting after being diagnosed with a thoracoabdominal aneurysm (TAAA), a weakening of the walls of the aorta in both the chest and the abdomen. TAAA is the most complex and deadliest type of aneurysm.
So far, only a handful of centers in the United States treat TAAAs with minimally invasive surgery, and Yale is one of just a few places to pioneer a unique approach.
“In a major way, endovascular surgery for TAAAs is the last frontier in surgery for aortic aneurysm,” says Naiem Nassiri, MD, a vascular surgeon who introduced the new approach at Yale and has performed a dozen of the procedures in less than a year. “It has completely revolutionized how we care for patients with a complex thoracoabdominal aneurysm. It also means that, for the most part, there is no longer a need for most aneurysm patients to undergo massive surgeries.”
Dr. Nassiri collaborates on all TAAA surgeries with cardiothoracic surgeon Prashanth Vallabhajosyula, MD, director of the Aortic Institute, which is part of the Yale New Haven Health Heart & Vascular Center. The unique platform used at Yale is the Unitary Manifold—a modular, physician-assembled, branched stent-graft system invented by Patrick Kelly, MD, of Sanford Health in South Dakota. The Yale Medicine surgeons say that using this particular stent-graft platform and combining their two different skill sets—cardiothoracic and vascular—have contributed to a strong record of successful outcomes.
Dr. Nassiri and Dr. Vallabhajosyula answered questions about the procedure and how minimally invasive approaches are transforming aneurysm care.
What is a thoracoabdominal aneurysm, and why is it so difficult to treat?
Aortic aneurysm disease is the 12th leading cause of death in the U.S. An aneurysm can develop anywhere along the aorta—the body’s major blood vessel, which carries blood from the heart down through the chest into the abdomen and all of the organs. While most aortic aneurysms occur in either the chest or the abdomen, a TAAA occurs in both areas and therefore requires more extensive surgery in both places.
“The entire aorta can get aneurysmal, meaning it becomes weakened, dilated, and enlarged,” Dr. Vallabhajosyula says. There isn’t solid data to show how frequently it occurs, but when it does, it is complex and often lethal, he adds.
Surgeons repair TAAAs when they reach 5.5-6.0 cm (2 inches, more or less) in diameter because of the risk of rupture. There are other reasons surgery might also be needed, including genetic predisposition, rapid growth, tears in the aorta, unexpected configurations of the aneurysm, and the onset of symptoms.
But TAAAs, like other aneurysms, often don’t have symptoms until there is an imminent risk of rupture (and death). For this reason, most people don’t know they have one unless it is identified during imaging for another condition. And they don’t seek medical attention until it becomes an emergency, with sudden, severe chest and back pain.
What is unique about the new surgery for a thoracoabdominal aneurysm?
Minimally invasive surgeries for aortic aneurysms are endovascular, meaning they are performed from within the arteries. Surgeons use wires and catheters—thin tubes used for engaging various blood vessels and their respective branches—as well as X-ray and/or ultrasound guidance to deliver stent-grafts to the disease site.
Stent-grafts are metal mesh networks of various configurations with fabric sewn onto them. Placed inside an aneurysmal aorta, they can block blood flow from reaching and pressurizing the aneurysm, thereby eliminating blood flow within the aneurysm sac, causing it to “clot off.” This prevents the aneurysm from expanding further, and, in some cases, it can shrink completely.
Because of the areas it affects, a TAAA calls for a complex stent-graft system that can be deployed across an area of the aorta with branches supplying critical organs, including the liver, intestines, and kidneys. The aorta at these locations cannot be treated with a simple stent-graft—it would cut off the blood supply to these critical organs. Instead, the stent-grafts have to cover the aortic aneurysm and maintain blood flow to these vital branches.
The Unitary Manifold is the stent-graft configuration used at Yale Medicine, and the technique is called Endovascular Debranched Aortic Repair (EDAR). It currently has a “Breakthrough Device” designation through a Food and Drug Administration (FDA) program that provides timely access to certain new medical devices by speeding up their development, assessment, and review.
The Unitary Manifold system has a unique design. There is a stent to cover the weakened aorta, which can be used alone or in combination with other aortic stent-grafts. Sewn to the stent are four branches that allow blood to flow to critical abdominal organs, including the kidneys, intestines, stomach, liver, spleen, and pancreas.
The device cuts off blood flow to the aortic aneurysm while maintaining blood flow into those four vessels, Dr. Vallabhajosyula explains.
How is the endovascular surgery for aneurysm performed?
The operation involves only two needle punctures in the groin. The physician-assembled Unitary Manifold is compressed into a tube and delivered through those punctures via a guidewire that is threaded up through the femoral artery and into the aorta, where it will be deployed and its four branches flowered open.
Another small incision is then made in the underarm through which surgeons insert, thread, and deliver individual endovascular bypass grafts to the Unitary Manifold’s four branches, supplying blood to the abdominal organs.
How is the endovascular approach different than an open operation?
The new operation is a dramatic improvement for patients, explains Dr. Vallabhajosyula.
The biggest change is in the reduced trauma to the body. An open thoracoabdominal aortic aneurysm repair involves cutting open body cavities; manipulating the lungs and diaphragm muscle; mobilizing, or moving aside, the kidneys and intestines; placing clamps on the aorta; cutting it open; sewing a synthetic graft to replace it, and sewing individual bypasses to individual organs. It is done through an incision that goes from the side of the back, across the ribcage, and down to the navel; it can require cutting open the diaphragm muscle and even removing ribs.
Traditional open TAAAs have a high rate of complications, including paraplegia and death. With this procedure, “patients would require days, weeks, or even months in the hospital,” Dr. Nassiri says. “They would be in the intensive care unit [ICU] for an extended time, have significantly more blood loss, and a propensity for organ injuries.”
Patients who survived the operation would describe feeling “like they were hit by a bus,” he says, and never fully regain their quality of life.
Why do cardiac and vascular surgeons work together on this endovascular procedure?
Many studies have shown that a multidisciplinary approach makes a difference in patient outcomes, Dr. Vallabhajosyula explains. “I believe it’s crucial,” he says. Even with the advantages of an endovascular approach, the collaboration provides TAAA patients with a stronger safety net, he adds.
“These aneurysms are so complex, and we both think about every single detail of the planning of the procedure,” Dr. Vallabhajosyula says. “It automatically gives patients two minds—two experts—working together.”
What is the benefit of using the Unitary Manifold stent?
Similar stent systems are being investigated for TAAAs, but the Unitary Manifold has the advantage of being able to mold to different anatomies. Other systems access the four vessels differently, using holes, for instance. Their designs are limited in their ability to fit the different anatomies patients have—to the point where many are not able to have surgery using those platforms.
The Unitary Manifold is more straightforward. “It does not require customization, which would take between three or four weeks—or beyond—to prepare, and it does not require strict anatomic criteria. Therefore, it is much broader and more flexible,” Dr. Nassiri says.
Another benefit is that the device makes it possible to “stage” this major surgery, meaning the surgeon can stop at a given point, if necessary, and continue at a later date without having to redo work, Dr. Vallabhajosyula explains.
This is a crucial benefit as doctors might want to stop the surgery to reduce the risk of paraplegia, a major concern with the open operation. “We do continuous monitoring of the brain and spinal cord,” he says. “If at any point we see any concerns, we might want to stop and give the patient time to build collateral blood supply.”
“In addition, the Unitary Manifold platform can be used for other conditions, such as aortic dissections and tears, and to treat patients who had previous open or endovascular aortic repairs that didn’t work or failed over time,” Dr. Nassiri says.
Is the endovascular procedure better for patients with other health issues?
For those with medical issues other than aortic disease, minimally invasive surgery may be their best option—in fact, it may be the only one. “With the aging population, for example, a large subgroup of people in their 60s, 70s, and 80s require a complex repair, but they would never survive an open surgery. So, they have been told nothing can be done for them, and they need to seek hospice and comfort measures,” Dr. Nassiri says. The endovascular approach might be a solution for those in this group, he adds.
Open surgery is also too high-risk for people with chronic lung problems due to smoking, or those with poor kidney function or a weak heart. “With this endovascular platform, we're able to take care of these patients with much less strain on the body,” Dr. Vallabhajosyula says.
Patients who have the open aortic operation may need a breathing tube for days and weeks. In some cases, the breathing tube never comes out, he explains. In contrast, many of those who have the endovascular procedure have the tube removed while they are still on the operating table.
Quality of life is also immensely better, Dr. Nassiri adds. Most patients may only stay one or two days in the ICU for monitoring. “Many are ready to go home within 72 hours after the operation,” Dr. Nassiri says.
How is the surgery transforming aneurysm care in general?
Endovascular surgery for TAAAs isn’t available everywhere, but Yale Medicine surgeons expect that, over time, more colleagues around the country will learn the technique. These procedures, however, are best performed at large-volume, tertiary referral centers that have access to collaborative, multidisciplinary infrastructures such as the one at the Aortic Institute at Yale, explains Dr. Nassiri.
“Endovascular procedures and newer-generation endografts have, in a very significant way, replaced open aortic surgery in my practice,” Dr. Nassiri says. “In my experience, patients no longer need to undergo such massive surgeries.”
“It’s a game-changer,” says Dr. Vallabhajosyula. “Time will tell us more about long-term outcomes, but right now, looking at it from the perspective of treating high-risk, sick patients who may have no alternatives other than palliative care, you can imagine what this option means to them.”