Aortic Aneurysms: Endovascular Stent Grafting – Part 1
Guest: Dr. John Ikonomidis – Cardiothoracic Surgery
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I am Dr. Linda Austin. I am interviewing, today, Dr. John Ikonomidis who is Associate Professor of Cardiothoracic Surgery and director of the Heart Transplant service here at the Medical University of South Carolina.
Dr. Ikonomidis, let’s talk about an area of specialty for you, endovascular stenting for aortic aneurysms. First of all, let’s start with the basics. What, exactly, is an aortic aneurysm?
Dr. John Ikonomidis: An aortic aneurysm is a localized dilation of the aorta, which is the large blood vessel that supplies arterial blood to the entire body. The aorta starts at the base of the heart. It is basically a large tube from which all other arteries branch. Probably the most common disease process, the most common disease in the aorta, is when it starts to expand in size.
Dr. Linda Austin: So, kind if kind of balloons out, in other words?
Dr. John Ikonomidis: It starts to balloon out. If it balloons out to approximately the size of maybe a tennis ball or a small orange, it can be associated with the aorta bursting.
Dr. Linda Austin: Now, I understand this can be hard, often times, to diagnose. Are there warning symptoms of an aneurysm or is it possible to have an aneurysm, a ballooning out, without even knowing that you have it?
Dr. John Ikonomidis: The vast majority of the time, aneurysms have no symptoms whatsoever. Most of them are picked up as part of a physical examination in which a chest x-ray is done and something unusual about the aorta is identified. Or, people come into the emergency department for evaluation of colds or they have developed a cough and they feel sick and they are coughing up colored sputum. Subsequently, during the course of the evaluation, they have a chest x-ray in which something abnormal is noted about the x-ray and ultimately those patients go to a CT scan, a CAT scan, and the CAT scan identifies the aneurysm.
Dr. Linda Austin: But, you mentioned that some people, such as those with family history, or smokers, may be at particular risk for that. So, is there a population where there are characteristics of folks who ought to get screened, ought to get checked for it?
Dr. John Ikonomidis: The answer to your question is, there is. The problem is that we do not have a screening modality that is inexpensive, sensitive and specific. A good screening tool has to be able to pick up all cases of disease that exist but be able to eliminate or rule out those cases that do not exist. In the year 2008, probably the best screening test is a CAT scan, but CAT scans are very expensive. So, to perform screening CAT scans on a very large population of people is unreasonable because it would cost too much money.
What we really need is some kind of a test that will pick up a lot of aneurysms and eliminate those people that do not have aneurysms that is relatively inexpensive. Probably the best way we have to go with that is some sort of blood test. The idea with a blood test is that if we can identify a particular marker, some compound that is released by aneurysms which goes into the bloodstream, and it can be measured by a relatively inexpensive blood test, it would be an excellent screening test. At the present time, that biomarker, if you will, does not exist and we are in the process, in the laboratory, of trying to identify some of those candidate compounds to test.
That is a long way of answering your question, which is we do not have a good screening tool at the present time.
Dr. Linda Austin: So, let’s talk now, let’s turn to your area, for this podcast anyway, which is the endovascular stenting of aneurysms. Those are pretty big words. Endovascular means, what?
Dr. John Ikonomidis: Endovascular means from within the inside of the blood vessel.
Dr. Linda Austin: And, a stent is, what? It is a word that people hear a lot without knowing what it is.
Dr. John Ikonomidis: A stent is essentially a piece of metal, like a piece of chicken wire that is fashioned into a tube. It is put inside of a blood vessel and expanded open and it maintains the integrity, it provides structural support to the blood vessel from the inside.
Dr. Linda Austin: Sort of like a scaffolding, I guess?
Dr. John Ikonomidis: It is like a scaffold, absolutely right.
Dr. Linda Austin: So, walk us through then. Let’s imagine that someone comes in, let’s say for pneumonia and an aneurysm is picked up on x-ray. You then have to make a decision if that person is a good candidate for stenting versus, let’s say, an open surgical procedure, versus just watchful waiting. How do you make that decision?
Dr. John Ikonomidis: It starts out with a patient. Fore example. older patients who have many other disease processes, like patients who have been smoking for a long time that have lung disease, who might not be able to tolerate the surgery from the standpoint that surgery for these aneurysms involves having to open the chest and close it again, which dramatically changes the ability to breath afterwards. Patients who have significant heart disease, patients who have significant kidney disease, all of which can be affected by a very large operation, such as an open surgical repair, might do better with endovascular stent grafting which is a much less invasive procedure.
All of that having been said, other important factors to consider are, age. Younger individuals would probably be more likely to do well with open surgery since we do not know what the long-term results of stent grafting are quite yet. There are important anatomical considerations. What I mean by that is the location and characteristics of the aneurysm are very important. In order to effectively land a stent graft, there has to be a normal size piece of aorta on one side of the aneurysm and the other that the stent graft would be able to bridge across. There has to be appropriate access. In other words, we put a very large introducer that contains a stent graft into an artery. You have to be able to find an artery that is of appropriate size to do that without damaging the artery. Some patients simply do not have that. Or, alternatively, some patients have so much disease in those arteries that it is too dangerous to do that.
So, consideration for stent grafting involves consideration of the patient, characteristics of the aneurysm and the mode of access, how we are actually going to get into the arterial tree to advance the stent graft up to where the aneurysm is and actually deploy it. It is important to remember that what is happening with endovascular stent grafting is that we are putting a device in the inside of the aorta and then we are springing it open to exclude the aneurysm from the inside.
Dr. Linda Austin: Dr. Ikonomidis, I want to go on with this topic. Let’s do it in a second podcast though. We will talk about the actual procedure then. Thank you so much.
Dr. John Ikonomidis: Sure.
If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection: (843) 792-1414.