Shahab Toursavadhoki, MD, Expert in Vascular and Aortic Surgery at University of Maryland School of Medicine, talks about an innovative and minimally invasive surgery to treat aneurysms.
How does an aortic aneurysm develop and what kind of problems might it cause?
TOURSAVADKOHI: The aorta connects the heart to the rest of the body and has branches that lead down to your body. If you have high blood pressure, the aorta will be under even higher pressure than it’s designed to tolerate. Over time, as you age, that pressure ultimately weakens the wall and aorta starts bulging. As this happens, it poses risk of rupture. As you can imagine, rupture of a high-pressure pipe, inside your body can be very deadly.
When you have that bulging aneurysm, what are the treatments?
TOURSAVADKOHI: The problem with bulging of the aorta is that the aorta doesn’t have pain fibers. So many people don’t even know that they have an aneurysm, and their life is in danger. It is really a silent assassin in some terms. The way it is discovered is that your primary doctor feels a large pulsating mass during abdominal examination. This will save your life. You could be having imaging for different reasons, and they find you have a large aneurysm of the aorta. There is also a nationwide screening program for patients older than 65, where they get free ultrasounds that scan their aorta to see if it is large, and the treatment can start from there. Rarely we get patients who come in with rupture. It’s more partial rupture where they come in with severe pain and bleeding. We must rush them to the operating room and sometimes they survive and sometimes they don’t. As you see, it’s a very deadly problem when it ruptures. Most patients don’t make it through the rupture process.
Before the TAMBE, which I know is a device that you’re still working on, what was the gold standard for how surgeons treated aortic aneurysms?
TOURSAVADKOHI: The traditional treatment, which started since 1955, was an open surgery. This technique has evolved and become better and better, but still requires a large incision. Now, if you are talking about an extensive aneurysm that involves the entire aorta, then you could imagine an incision that runs through the entire body starting from the chest all the way to the abdomen and pelvic. This way we can create exposure of the entire aorta and then replace the entire aorta with all of its branches. We are talking about several hours of surgery, several liters of blood loss, and significant morbidity and mortality related to the surgery in that extent. This is quoted as the largest surgery that you can perform in a human being. There is no other surgery in that magnitude that you can perform.
That leads me to TAMBE. Can you tell me what it is?
TOURSAVADKOHI: TAMBE is an abbreviation for Thoracoabdominal Multi Branch Endoprosthesis. It implies that we are capable to perform the same extent of surgery inside the artery without making any incision in the body. With current technology, we can get inside the artery from different ports and have a device that is modular. This means that the device goes in pieces inside you and the whole assembly of the device is under fluoroscopy without opening the body.
Walk me through the process where the device is implanted in pieces and then assembled inside the body?
TOURSAVADKOHI: The device, when put all together, is very long with multiple branches. The problem with endovascular surgery is that access ports are small, and you must squeeze this very large device inside the body. So, the device is broken to small pieces so you can put it in and then each opened like an umbrella inside the artery. It’s like you’re assembling a Lego house inside the body without opening the body. How do you do it? You put small pieces inside and do the assembly inside. It’s a very sophisticated way of doing surgery.
Describe for me how you put it together? Are you assembling it through catheters while using a camera?
TOURSAVADKOHI: We use mainly fluoroscopy to visualize the device pieces and sometimes we utilize Intra Vascular Ultrasound, or IVUS. We have two modes of imaging that would guide us to exactly what location these grafts are in relation to the body and to the other devices. The ports are multiple because you need multiple hands to do the assembly inside.
Where are the ports and where are the catheters going in through?
TOURSAVADKOHI: It goes through the groins because they are large arteries and larger pieces can go through, and then also the upper body arteries, called axillary or brachial artery, and we sometimes use both upper extremity arteries and advance these pieces toward the aneurysm.
You said you need multiple hands. How large is the team of surgeons?
TOURSAVADKOHI: There are at least two surgeons, Vascular and cardiac, because one needs to work from the groin and the other needs to work from the top. Sometimes we have more than two surgeons, They are there to help with imaging and other stuff. So, it truly is teamwork.
Once you have the TAMBE inside and assembled, can you explain how you fix the aneurysm?
TOURSAVADKOHI: The traditional idea of fixing something life threatening was to cut it out and replace it with something good. That requires an incision. If you have an artery that is large, instead of taking it out, you can take the pressure out of the wall by creating another piping within this large aneurysm. This means the aneurysm doesn’t have pressure anymore and becomes soft and collapses, just like a balloon expelling air.
So, the aneurysm stays inside? It isn’t tied off?
TOURSAVADKOHI: No. It collapses and shrinks around the piping that you have created inside the artery because the blood pressure is not going to be affecting the wall of the aneurysm. So, the tension is taken off the wall. The stentgrafts are permanent and they are bio compatible. These are materials that we’ve been using for decades. They are polymers that the body tolerates, are very strong, and stay with the patient forever.
What’s the benefit to being able to operate this way for surgeons and patients?
TOURSAVADKOHI: Aneurysms affects older patients. We rarely see aneurysms in young age. So, since majority of patients are elderly avoiding a large incision and mobilizing them quick and fast would be the biggest benefit for this operation. That essentially translates to less morbidity and less mortality related to surgery.
In terms of where you are in this clinical trial, is the device still being modified?
TOURSAVADKOHI: Correct. There are multiple centers that are helping to collect data that we need to know to understand the longevity of the repair. However, we are very confident about this trial’s effectiveness. We know it is very effective at preventing rupture in our patient population, but don’t know how long it’s going to last, how effective it is in several years post-surgery is what we are watching at this point.
Is there an endpoint for collecting that information? When does it end?
TOURSAVADKOHI: Five years is the duration of the study. But this study will go forward as we watch these patients’ age. We don’t have large published data yet, but based on our experience and other centers, there is a success rate of over 95 percent.
Is there anything that you would like to add for people to know either about aortic aneurysm or TAMBE?
TOURSAVADKOHI: I love my job because we are walking on the cutting edge of technology. We are going to improve things for the future. I’m very optimistic and I believe most diseases that we have today, that don’t have good treatment, like cancers and aneurysm, in the future, we will look back and say these diseases are gone or we have effectively treated them.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
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