Aortic Dissection

Dr. Charles Roberts discusses what an Aortic Dissection is, what occurs when you have one, possible treatment methods, and much more.
Aortic Dissection
Featured Speaker:
Charles Roberts, MD
Dr. Charles Roberts, Chief of Cardiovascular Services, Chair of Cardiac Surgery and Medical Director of Cardiovascular Education for Baylor University Medical Center in Dallas and on the medical staff at Baylor Scott & White Heart and Vascular Hospital – Dallas.  Dr. Roberts is board certified and specializes in cardiac, vascular and thoracic surgery. His clinical expertise includes valvular heart disease, coronary artery disease, aortic conditions, and carotid and peripheral arterial disease. After receiving a medical degree from Emory University in Atlanta, Dr. Roberts completed his internship at Barnes-Jewish Hospital in St. Louis, MO. He went on to complete a residency in surgery at the Medical University of South Carolina in Charleston and a residency in cardiothoracic surgery at the University of North Carolina in Chapel Hill. He received his fellowship training in cardiac surgery at the Royal Brompton Hospital in London. Dr. Roberts has led multiple clinical trials and published numerous articles related to his field. He regularly presents at national and international conferences. Prior to relocating to Dallas, Dr. Roberts served as Clinical Professor of Surgery at Medical University of South Carolina in Charleston. In addition, he is an active member of the American College of Surgeons, the Society of Thoracic Surgeons and the American Osler Society. Dr. Roberts is active in the American Heart Association.
Transcription:
Aortic Dissection

Caitlin Whyte: Welcome back to HeartSpeak, the podcast from Baylor Scott and White Heart and Vascular Hospital. I'm your host, Caitlin Whyte. Today, we welcoming Dr. Charles Roberts on the show. He is the Chief of Cardiovascular Services, Chair of Cardiac Surgery and Medical Director of Cardiovascular Education for Baylor University Medical Center in Dallas. Dr. Roberts is board-certified and specializes in cardiac, vascular and thoracic surgery and is here to talk about aortic dissection. Now doctor, what happens when aortic dissection occurs?

Dr. Charles Roberts: Well, aortic dissection means a tear in the main artery. The main artery is called the aorta. And what happens is the wall of the aorta tears. And then it creates a flap all down the aorta in the wall. And so with aortic dissection, there's usually what they call an entrance tear and that's where the tear begins. And then it separates the wall going all the way down.

And so the medical term for that event is called an aortic dissection, tear in the main artery. And it's really a major cardiovascular event, if not the most violent cardiovascular event that happens in adulthood. It's more fatal than a heart attack. And it's very difficult to treat. The treatment of aortic dissection is usually concentrated in medical centers that treat it a lot for good reasons.

Caitlin Whyte: Now, we've had a vascular surgeon on as a guest on HeartSpeak, explaining aortic aneurysms. Can you tell us about the difference between the two?

Dr. Charles Roberts: Yes. An aneurysm just means enlargement. It means the artery is bigger. In general, the definition is 50% bigger than it ought to be. And then it's called an aneurysm. We often don't like to use that word because it's alarming. And so we often try to say dilation, your artery is dilated. And we'd like to follow it every year with a CAT scan. That seems a more humane way to describe the condition. But aneurysm simply means the artery is enlarged.

Now dissection is different. Dissection means that a tear has occurred in the wall of the artery and it's created a flap. And what happens is the artery, whereas before it had one channel, now it's got two channels. It has what we call our true channel and a false channel because the wall has split. And the problem with a dissection is that the false channel, usually the outer channel, can rupture outward.

So dissection and aneurysm are fundamentally different. Now, you can have a dissected aorta that's enlarged. And so people will sometimes mix the terms and say, "Well, it's an aneurysm." But in fact, they're basically two different conditions. Aneurysms just grow outward over time, whereas dissection is a sudden event and it's a ripping of the wall, usually from high blood pressure. That's the main cause.

Virtually, everybody that has a tear in the aorta that experiences an aortic dissection has high blood pressure. And if they don't know they have high blood pressure, they usually would have high blood pressure when they're in the emergency room. Almost everybody that comes in to an emergency room with an aortic dissection has a blood pressure over 140. That is to say the top number is above 140. So the way to prevent an aortic dissection is keep your blood pressure normal. Keep the top number under 140. That's the best preventive medicine.

But those two conditions, they can get confused a little bit, dissection and aneurysm, but they're basically two different conditions.

Caitlin Whyte: So focusing back on aortic dissections, there are two distinct types, type A and type B. Tell us about each of those.

Dr. Charles Roberts: Yes. Well, the aorta, as I said, is the main artery that arises from the heart and it goes up toward the head. And that's called the ascending, it rises up toward the head, the ascending aorta. And then it takes a turn and we call that the arch. And then, it goes down the back and we call that the descending aorta. So there's the ascending and then the arch and then the descending. And the descending goes all the way down to the pelvis and then it divides into the two iliac arteries, the right and the left, which go to the legs. And that descending aorta, which is long, there's a chest portion and the belly portion or a thoracic portion and an abdominal portion.

Now, if the dissection involves the ascending aorta, which is to say the aorta rising from the heart, then it's called a type A. And if the dissection strictly involves the descending aorta going down, then it's called a type B. And both dissections are very dangerous. They're both major events and they both have a rather high mortality, which is to say that the death rate of a dissection is rather high compared to other cardiovascular events. For a type A, it's about 20% and for a type B, it's around 15%. So both conditions are very lethal. You know, in a heart attack today, the risk is under 5%, so you see the difference.

Treating these aortic dissections is also a much higher risk affair even in the operating room. For example, when we treat an ascending, aortic dissection or a type A, it's generally an emergency. We take the patient right to the operating room and we replace the ascending aorta with the tube. It's like a polyester tube. It's called Dacron. And that operation, it's about a 20% mortality doing that operation. Now, if you compare that to a bypass surgery, bypass surgery is under 2%. So it's 10 times the risk of a bypass surgery treating a type A aortic dissection, which is another reason that it's very sensible when somebody has a type A dissection to often transfer the patient to a center that does a lot of them because doing that operation very sporadically, say twice a year, is very challenging for a surgeon. The surgeon may be a superb surgeon, but if you only treat that condition twice a year, it has so many complexities that, you know, the risk is higher.

Now, a type B is often treated with a stent and that can be a little less impactual on the patient. The stent is often deployed through the artery in the groin and passed up into the descending aorta and opened.

But the risk of both of those dissections is still very high. And one of the main reasons is, well, they can rupture, but all the branches of the body, the main artery branches of the body come off the aorta. So when you have a rip in that aortic wall and it travels from the heart, the first part of the aorta all the way down into the pelvis, it can shear off the branches.

And so, you know, there are branches going to the head, you can have a stroke. There are branches going to the arms, you can lose blood flow to an arm. There are branches going to the intestines and you can lose blood flow to the intestines. You can lose blood flow to the kidneys. You can lose blood flow to the legs. And that's called malperfusion. When the perfusion to an organ or limb is interrupted, we call that malperfusion. And we see that a lot when patients come in with aortic dissection. And that's one of the first things we look at is do you have any pain in your legs, in your belly? Can you move all extremities, follow commands? We try to make sure, you know, by our examination and history that malperfusion has not occurred.

Now, the main test we get to make the diagnosis of aortic dissection is a CT scan and we get a CT scan of the chest, abdomen and pelvis on everybody and try to determine, you know, whether it's a type A or type B, which branches are compromised. That's the first and best test to determine how to proceed when somebody comes in with an aortic dissection.

Caitlin Whyte: Just how common is either types?

Dr. Charles Roberts: Well, they're much less common than say coronary artery disease, which is atherosclerosis, which is blockage. Now, blockage is the number one cause of death in the Western world. And that's a cholesterol disease. This is different. This is on a lower scale.

Now, patients have high blood pressure, but patients that ultimately get aortic dissection are relatively few in number compared to the vast majority of patients that have high blood pressure, let's say. So you would have to ask the question, "Well, why does one person get a dissection and another person doesn't and they both have high blood pressure?"

Well, there are probably some variables that we're still exploring. Sometimes people have a family history of aortic problems, either aneurysm or dissection. And that's a big red flag for us. If somebody in your family has had a dissection and we're aware of, let's say, a dilated aorta in you, then we follow that very carefully with CAT scans and keep your blood pressure under control.

Other people are born with an abnormal aortic valve. There are four valves in the heart and the one at the base of the aorta is called the aortic valve. And sometimes people are born with, instead of three leaflets, two leaflets. That's called a bicuspid aortic valve. And those patients are at higher risk for dissection. The aorta can be abnormal under a microscope when you look at it in patients with bicuspid aortic valve, two cuspid aortic valve. So that's another group that's a little higher risk for dissection.

And then there's a third group of patients that have something called a connective tissue disorder. It's people with conditions like Marfan syndrome. There's another one, Ehlers-Danlos syndrome. And these are people that have the collagen, that sort of soft tissue skeleton of the body is a little abnormal and the aorta is abnormal. It's not as tough. And these patients are at higher risk for dissection.

Marfan syndrome patients in particular always have aortic problems. So we follow those patients very carefully. And if those aortas in patients with Marfan syndrome become too dilated, we replace them and we replace the aorta because it's at such risk for dissection.

So there are some groups of patients that seem to be predisposed to aortic dissection. But fundamentally, aortic dissection is a blood pressure disease. There are really two main sort of fatal events that people can get with high blood pressure. And one of them is a stroke, a hemorrhagic stroke, where the blood pressure is so high that a stroke occurs. That happened to President Franklin Roosevelt. He was living with a blood pressure of 240 and he had a hemorrhagic stroke.

But the other condition that people with very high blood pressure get is aortic dissection. Because the pounding of that aorta with the pressure from the heart is just so hard that it rips the aorta. We see it sometimes in young people that have uncontrolled blood pressure. They come into the emergency room. Their pressure's 220, you know, high numbers like that. So it's basically a blood pressure disease, but several groups seem to be predisposed to aortic dissection as well.

Caitlin Whyte: With that, are there any signs and symptoms that someone can look out for?

Dr. Charles Roberts: Unfortunately, it's sort of a violent instant event and it's very similar to a heart attack. People use the expression, you know, they feel a pain in their back, a sudden pain in their back, a ripping feeling and it can be in their chest or their abdomen. And it's kind of sudden, and they know something's happened and sometimes that just, you know, keels them over. They know a big event has happened. And a lot of times they think it's a heart attack and then go to the hospital, and lo and behold, it's not a heart attack, it's a dissection.

And emergency rooms are very keen on identifying the heart attack, but they're also increasingly aware of the possibility of an aortic dissection. So they'll get a CT scan. If they have any concerns about aortic dissection, they'll send you right for a CT scan. But the aortic dissection, because of all the branches that come off of the aorta, it can cause sudden right leg pain. Let's say the artery to the right leg gets sheared off. Or it can cause left leg pain or it could cause belly pain because your bowels is suddenly cut off from blood supply. And it can even cause a stroke. That carotid artery is going to the brain get cut off from blood supply because of the tear. A dissection can present as a stroke.

But the worst presentation of all is when the dissection occurs and simply ruptures and then it's over. And particularly a type A, which means the ascending aorta, if that ruptures, well, it ruptures into the sac. There's a sac around the heart and the ascending aorta, it includes both, both the heart and the ascending aorta. There's a sort of sac around it and it's called the pericardial sac.

And if the aorta ruptures, if the ascending aorta ruptures, it fills the sac with blood and so it's a fairly instant death. And that's why when somebody has a dissection involving the ascending aorta, we go right away and replace that ascending aorta, because our great fear is that the aorta within the sac will rupture and fill the sac with blood and then the heart won't move.

So that's why a type A aortic dissection, that is the say, an aortic dissection involving the ascending aorta is always considered an emergency. Go right to the operating room and replace the ascending aorta.

Caitlin Whyte: Well, that leads me to my next question. Tell us about the surgical repair process.

Dr. Charles Roberts: Well, the surgical repair, you know, it's done at all hours. It depends on when the patient arrives. Generally, it's an emergency. And for a type A, ascending aorta, the patient goes to the operating room and gets general anesthesia. And it's done through the front of the chest, just like a coronary bypass. You open the front of the breastbone and then you have to use the heart-lung machine, which is used on 95% of heart operations.

And the heart-lung machine, you put two cannulas in and it allows you to divert the blood so you can stop the heart. And in a type A dissection, you not only stop the heart, but you generally cool the body down and literally stop the circulation for a period of time. And the reason you have to do that is because that ascending aorta at the top of it, where the arch is, the blood vessels go to the brain. So you somehow have to replace that part of the aorta, but you can't just put clamps on those arteries to the brain because the patient would have strokes. So you have to cool the body down and literally stop the circulation, turn off the pump, no circulation and then sew in, we call them grafts, sew in the tube, the polyester tubes and the limbs to the branches to the brain.

Now, we've made some modifications of those procedures. We now continuously give blood to the brain, usually through a separate graft, so that the brain is continually bathed in blood, but the rest of the body is not, the rest of the body has no circulation for a period of time and that's called circulatory arrest. But we do continually feed the brain blood to avoid, you know, a stroke during the procedure. But it's generally a big procedure. It generally lasts five to six hours.

In contrast, a typical coronary bypass lasts two and a half to three hours, so you see the difference. When you have to cool the body and then rewarm the body and replace the ascending aorta and branches to the brain, sometimes it can be a long procedure.

Caitlin Whyte: Well, once it is fixed, what is the potential for reoccurrence of this or occurrence in another location?

Dr. Charles Roberts: Any part that's replaced with a graft or any part that has a stent in it is generally safe. It's those other parts. For example, if you have an aortic dissection that starts at the beginning in the ascending and goes all the way down the descending to the iliac arteries going to the legs, the surgery would only involve replacing the ascending. So the rest of the aorta, we just allow to heal, but it requires follow-up. In other words, we let it heal, but then you come back in three months and we do a CAT scan and see what things look like. And then come back every year and do CAT scans and make sure that the rest of the aorta is healing well.

Sometimes it dilates over time and that's where that word aneurysm can be used. Sometimes it just means it enlarges. So sometimes down the line, an aortic dissection that has healed may require an additional procedure like a stent. And so we follow all patients that have had aortic dissection. We follow them at the aortic center and study them with CAT scans over time, usually at a minimum of once a year. And we make sure that that aorta is not enlarging too much or causing a problem with a branch. So that's why we use the word surveillance. Surveillance is very important after an aortic dissection. And we have our clinic, for example, every Monday afternoon, we have our aortic clinic. Patients get a CT scan in the morning and then come see us in the afternoon.

Caitlin Whyte: And wrapping up here. What is the recovery process like for this surgery?

Dr. Charles Roberts: Most heart surgeries or major vascular surgeries take two months to recover. Now, generally it's about a week in the hospital and then home. If it's a type A, which is the bigger operation, you know, that's the emergency one and that's the one involving the heart-lung machine and circulatory arrest, you know, that's a six-hour operation and it's usually, you know, three or four days in the ICU and three or four days in a regular room and then home.

But if it's a type B and they get a stent, it can usually be a shorter hospital stay, maybe five days. But usually, during this hospital stay, we're trying to get the blood pressure under control. So often the patients come in and their blood pressures are too high. So we have to get medicines adjusted to get blood pressures under control, and some people need two or three blood pressure medicines to do that. And we almost always consult a blood pressure specialist to help us during the hospital stay. But generally seven to 10 days, the patient's home. And then it's really about two months from the day of surgery that healing is required.

But once the two months have passed, most people can go about their daily activities and, you know, return to work and these kinds of things. Aortic dissection is not meant to disable one for life. It can be treated and the treatments can be very effective and, you know, allow people to get back to a good quality of life. It's just that surveillance is necessary from then on and blood pressure control.

Caitlin Whyte: Wonderful. Well, that's Dr. Charles Roberts, Chief of Cardiovascular Services, Chair of Cardiac Surgery and Medical Director of Cardiovascular Education for Baylor University Medical Center in Dallas. And he is on the medical staff at Baylor Scott and White Heart and Vascular Hospital, Dallas.

To reach the aortic center for more information, call (214) 820-4876. That's (214) 820-4876. To find a specialist on the medical staff at Baylor Scott and White Heart and Vascular Hospital in Dallas and Fort Worth, please visit BSWHealth.com/heartDFW, or call 1-844-BSW-DOCS. That second number is 1-844-BSW-DOCS.

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