Gabriel Velazquez, MD, assistant professor of Vascular and Endovascular Surgery at Wake Forest School of Medicine, discusses aortic aneurysms and aortic dissections, two of the most common aortic pathologies. She also describes the pathophysiology and epidemiology of these conditions, risk factors, how they present, treatment options and outcomes.
GABRIELA VELAZQUEZ: Well, we're going to talk about aortic disease and most of the common things that we see in terms of the abdominal aorta and the thoracic aorta, and what are the things that we like to identify ahead of time or promptly in order to initiate therapy to help patients in general. So we're going to talk, again, about abdominal aortic aneurysms, thoracoabdominal aneurysms, and aortic dissections, which are the most common conditions, and we will address each of them separately. Just so that you know, these patients share a lot of the PAD risk factors. This is all the patients that we've been talking about today. So a lot of our patients today will have diabetes, hypertension, chronic kidney disease, congestive heart failure, coronary heart disease, so we all share the same kind of patients. So this is something to take in consideration as to what are going to be their options in terms of treatment. In terms of our overview, we're just going to go through definition, pathophysiology, epidemiology, and risk factors, as well as natural history of aneurysms and dissections-- how did they present, and how we currently treatment, and what are the options. So fortunately now, we have many options for any kind of patient at this time, which now allows more and more patients being treated. The definition of an aneurysm is a focal dilatation of the normal aorta, in this case, which is going to be an increase of one and a half size of the vessel itself, or greater than 3 centimeters for the abdominal aorta. We call true aneurysms those that include the three vessels of the artery, which will be the intima, media, and adventitia, and also the false aneurysms, which only have either one or none of the three layers. This is called-- this also will be maybe pseudoaneurysms and so forth. There are several factors that contribute to aneurysm formation, which are in this table. Will be inflammation and degradation of elastin and collagen, which will be the main proteins and enzymes related to aneurysm formation, as well as mural thrombus creation and apoptosis. All of those things are going to promote aneurysm formation. And the most common site of this irritation of the aorta will be infrarenal aorta. The reason for that is because this area has the least content of elastin, which-- and collagen-- which will protect us, in some way, from developing aneurysms. But that's the reason why. So why do we care about aneurysms? Well, 4% to 5% of Americans that are greater than 65 years old have aneurysms. That doesn't mean they have to be treated. However, we have to be aware of that and that we know that aneurysms happen to grow, and it is common to have aneurysms as we get older. But again, that doesn't mean that all of them need to be treated, and that's why we're going to go over things. Over 100,000 cases will be diagnosed every year. The reason for that is nowadays patients that go to the ER will get, with belly pain or back pain, they usually will get a CT scan. So we have a ton of patients that show up to our clinic basically with the incidental findings, which is a good thing some ways, because now it's allowing us to identify more and more patients that can be treated in a prompt time and without having to surveille them for a long time and so forth. So that's a good thing. Also as we talked about, most of these patients are going to have aneurysms in the abdominal aorta, and the least are going to be thoracic, iliac, or thoracoabdominal. In terms of the variable rates, it's more-- are more common in men. And again, as we get older, the percent more commonly-- If you are greater than 65 years old, chances are you'll have some sort of aneurysmal degeneration in some of your arteries. And basically, those that are greater than 5 centimeters will be mostly present in men. What are the major risk factors for aneurysm formation? One would be age, most importantly-- nowadays, obviously someone that is greater than 65. However, now in the "Welcome to Medicare" surveillance, we have now abdominal aneurysm survey, which of those patients that have any kind of history of smoking and that are greater than 50 years old will require one of these if they have had ever smoked. Also tobacco. This is the main thing that we know contributes aneurysm formation, and the only thing that we know that will in some way-- not prevent, but-- not regress, but maybe slow down the aneurysm growth. Smoking is such a big risk factor for almost anything cardiovascular, but in terms of aneurysm formation, this is known to be one of the most important risk factors for developing them. Other risk factors are family history. As you know, a lot of the patients that, for example, will be younger and will have aunts or cousins or brothers, siblings overall, that have had aneurysm formations or aneurysm repair, those are the patients that we have to pay more attention to. And even if they are young, if they have had significant familial history of aneurysms, I will encourage you to get an ultrasound and an aneurysm survey to make sure that they have not developed it at a young age. Hypercholesterolemia and hypertension as well are some of the main risk factors, and for some reason it's also most common in the white race. What aneurysms do? They grow. So we know that. So once you have an aneurysm, they're going to grow. However, we still haven't figured out exactly how to determine the growth of rate-- sorry, the rate of growth. So basically, we know that aneurysms in general will grow from 0.2 to 0.6 millimeters a year, and those will be maybe considered normal. However, it will be that one year it will grow only 1 millimeter, and for the next year will grow 3 millimeters, and then one year won't grow at all. So that's why we surveille them. That's why when they get to a specific size-- and we'll talk about that-- we look at them, because we don't know how fast or how slow they're going to grow. They will grow eventually, but how much each year we don't know. So it's variable. So how do they present? So aneurysms can be asymptomatic, and this is why we have a lot of patients that present with ruptured aneurysms, because they don't know they have it and they've probably lived with them all their lives, and suddenly they have belly pain or back pain and present with rupture. However, yeah, there's a ton of people that have aneurysms and never have a problem with it. They may have even like 8 centimeter aneurysms and not even know that they have one. Exam is really not reliable. A lot of the times when we have very skinny patients, you are able to palpate their aorta. So sometimes you may be like oh, I feel like maybe they have a pulsatile mass, or it may not be it. If you're really skinny, you'll be able to feel your aorta. So it's somewhat unreliable. Again, when we find them as incidental findings, very common to do that, with more and more CT scans getting done in the emergency department. And as we talked about, those with-- that had "Welcome to Medicare" physicals get-- nowadays get ultrasounds surveillance for aneurysms, which are very important. One of the things for us to remember is the best screening for aneurysms is ultrasounds. There's no need to get a CT scan right away if not needed. So if you have any suspicion but they're not having any-- they have family history, but they don't have any symptoms and you think that they may have an aneurysm, an ultrasound is enough. So you need the ultrasound. It is close to 5 centimeters in, you can get a CT scan, but if they have a small aneurysm, there's no reason to get it unless you're looking for something else. As we talked about, the natural history of aneurysms are they grow. There's really no medical therapy to prevent or slow the growth or prevent the development of it, except for in some way prevention would be smoking. But besides that, there's really nothing else. Often, 12% of these patients will present ruptured, and a lot of the patients that present with ruptured aneurysms are in big trouble. Not a lot of them make it, especially if they have a free rupture and they're-- if they are not in a hospital, they will not survive. Mortality could be up to 77% if they present with rupture to the hospital, if they have a contained rupture. However, if they present with a free rupture outside the hospital, up to 95% of these patients don't make it. It is the tenth leading cause of death in the US, so once we acknowledge them, we just have to have all this information and share it with the patient so that we know what the natural history of this is. So this is a picture of a CAT scan with contrast. You can see the opacification of the aorta here and a little bit of like an outpouching of the aorta with all these casings around it, which is a retroperitoneal hematoma. This is a contained rupture, so these are the patients that if we get them on time, if they're presenting with belly pain and back pain, these are the patients that we could potentially help and save their lives. However, if they present like this-- again, you can see also the aorta, but the contrast is also going all the way into their retroperitoneum, not just a hematoma, but it's just like a free rupture-- these are the patients that most likely won't make it. Even if they survive the operation itself, they likely will not make it through the hospitalization. So what's the risk of rupture? The rupture depends on the size. And this is very important, because this is why we particularly fix aneurysms that are 5 and 1/2 and above in order to fix them. We do not, in general, fix small aneurysms unless we think they're symptomatic or infected aneurysms in general. But this is why the size of the aneurysm matters a lot, because the bigger the aneurysm it is, the bigger risk of rupture the have. So we know that those aneurysms that are less than 5 centimeters have a less than 3% chance of rupture. So if you think about the risk of rupture versus the risk of surgery, even nowadays with endovascular therapy, your risk of having significant morbidity and mortality having surgery will be 3% to 5%. So if you put those things in consideration, that's why we don't fix those aneurysms. However, once we get to the 5 and 1/2 to 6 centimeter size, that risk of rupture goes up to 10% from those that have 6 centimeters, and so on. So obviously the ones that are greater than 7 centimeters will have a higher than 20% to 40% chance of rupture a year. So how we diagnose it, we talked about that. The ultrasound, this is a great place to start. We also like getting CAT scans with contrast. As you know, a lot of our patients will have chronic kidney disease and they cannot get IV contrast, so that's the reason why sometimes we'll get magnetic resonance with contrast as well, or without contrast, but they're opacified to the arteries itself. So that's the way we get it. And here's just a picture of a 3D reconstruction of an infrarenal abdominal aneurysm, and how we look at them as well when we take them to the operating room to fix them endovascularly, while the picture on the right would be the fluoroscopy picture. So what are the treatment options in terms of what to repair? We have two options, which are the endovascular and open, and we'll go over them briefly. But the indications for repair will be those that present ruptured, of course, those aneurysms that are symptomatic. The ones that have this weird belly pain that we can't explain with other things, and by that I mean they could have had gall bladder problems or like a UTI or anything like that. Those that present with back pain and then they have an aneurysm, or those that you push in their aneurysm and it hurts when you push it in. So those we can see they're symptomatic aneurysms, and those are the only ones that we would try to fix. Obviously, those that are greater than 5 and a half centimeters and those that are growing fast. So let's just say if I had an aneurysm that was 5 centimeters in September and when I see them back six months later for surveillance and it's 5.5 already, obviously you will be there. But those that are consistently growing fast will be the ones that you will like to fix sooner rather than later. We do not fix small aneurysms because they really don't make a difference in terms of rupture. There were two main studies, the UK study and the ADAM trial based on the VA, that basically showed that if you-- we treated small aneurysms, less than 5 centimeters, there's really no advantage in survival and mortality. So that's why we don't do them. So this is all very well studied, and that's one of the reasons why we're really strict to when to fix them when they are asymptomatic. So we talked about the endovascular repairs and how technology has brought a lot and we have a ton of options. But this is one of the best things we have. It's called an EVAR, endovascular repair of abdominal aneurysm. It's done either under general, regional, or local anesthesia, which would allow more patients that have a lot of comorbidities to undergo this procedure if they are not allowed to get general anesthesia, for example. This procedure usually lasts about a half-- one hour, an hour and a half, and with minimal blood loss. It can be percutaneous, just like if you were going to do a cath or with small cutdowns in the femoral arteries. Most of these patients don't need to go to the ICU, and if everything goes well, they go home the day after. So everyone really likes doing this, and if you give the patient the option, they'll be like, sure. I mean, I'd rather do this. So the science behind the EVAR is to create a zone of seal for this aneurysm. So you have a proximal seal zone and a distal seal zone that basically would prevent the blood flow to go into the aneurysm and prevent it to grow. So that's the concept behind it. However, as wonderful as EVAR is, there's always-- also have risk and complications, and patients that are undergoing endovascular repair had a higher rate of reintervention compared to open repair. And this is just an example of what we do. This is, on your left, that's how it looks in a fluoroscopy, and a 3D reconstruction on the right after repair. You can see the aneurysm on the left side, a fusiform aneurysm, and the right one is fixed after the endograft has been placed. So the open repair, we've been doing it for a long time, of course, and mortality can vary and be as high as 8%. And we try to select these patients very well, and there's some patients that will not be candidates for EVAR. That's the other thing, that not everyone can have an endovascular repair Their anatomy is not suitable for it. So for those patients that are not in good shape and that they don't have good anatomy for an EVAR will undergo open repair. And obviously, the more comorbidities you have, the higher risk of morbidity or mortality you will have. These patients do better if they're in a high-volume center or experienced surgeons that they are used to treat, not just for the surgery itself, but also with a multi-disciplinary team and call it pre-operative care, anesthesia, and the post-operative care in the ICU, who are used to take care of these patients, that's where they do better. So this is just a picture of the aneurysm. We do a midline incision. It's a pretty long incision. And basically, once we have the aneurysm resected, we replace that with a Dacron, usually, graft. You will see that in your corner right in the bottom, and that's how it looks afterwards. So when we talk about what's the difference between one and the other and does one do better than the other, when I first was learning all this, I figured that obviously the endovascular repair will be better for the patient, right, because it's just one day in the hospital and they don't have as much comorbidities related to the open surgery and so forth. But it comes after the fact that, long term, there's no difference between one or the other. 30 day mortality and morbidity is a little different. However, long-term survival and long-term morbidity is the same for open or endovascular repair. And again, that has to do with the fact that endovascular repair has a higher rate of reintervention just because of the fact that you can have endoleaks or other kinds of situations that you will have to take care of, so that's the thing. And we've had a lot of studies. We did two in 2005. We didn't believe that. We did it again in 2009. We didn't believe that. And we did it again in 2011, and all of them showed the same, virtually no difference. As I told you earlier, technology has advanced a lot. And nowadays, even with those patients that have very challenging and not only that cannot have straightforward EVAR, now we have what we call fenestrated devices, and that has allowed us to take care of a lot of patients that have iliac aneurysms that we were not able to treat endovascularly before, and also those patients that have thoracoabdominal aneurysms. This is a iliac branch device. Which means that if you have an iliac aneurysm that is involving the hypogastrical internal iliac artery, usually we'll have to cover it and sacrifice that blood flow, but with these devices we can actually put another stent into that internal iliac and seal the iliac aneurysm but also preserve the internal iliac flow. This is another example of fenestrated grafts. These are the ones that we use to treat now thoracoabdominal aneurysms. Well, they will have fenestrations below those metal barbs, that will be the proximal fixation. And those holes will be basically lined up with the visceral vessels called the celiac arteries, superior mesenteric, and the renals, and we'll have little stents going that way. So it's pretty amazing technology. Those are the ones that we use for those thoracoabdominal aneurysms. We have five kinds, and this all depends on their location and involvement within the thoracic and the visceral aorta. This is a minimally invasive approach to thoracoabdominal aneurysms. So as you can imagine, whenever you talk to the patients about this, they're like, I would rather not have that. And obviously we now are very careful in picking who's going to have this kind of surgery, but for those that have prohibitive open surgery risks, they can be considered now sometimes to have a fenestrated endograft, which I think is a great thing. Again, these are all this. I told you the fenestrated grafts, they have these little holes into the graft that will be aligned and lined up with the visceral vessels-- renals, viscerals, and so forth. And you can basically seal the aneurysm with all these and the fabric with it. Again, even when it sounds like it's easy, it's not. It's still plenty hours in the operating room, and even when it's just two little incisions in the groin or percutaneous, it's still patient is in the operating room for a few hours to fix this, and as well they have a high risk of complications. So in summary in terms of aneurysms, those patients that are indicated for repair, the ones that have a 5 and 1/2 aneurysm or if they are symptomatic, ultrasound surveillance is adequate for small aneurysms and no need to be getting CT scans on aneurysms of 3 or 4 centimeters, in general. Once they get close to five, I think it's reasonable to do so, and I will definitely consult with a vascular surgeon in order to determine which will be the best test. As we talked about options for repair will be endovascular and open. This will depend on the patient's anatomy, how good shape they are, and what are the options that they will have in terms of their physique in general. And advancing technologies here are now allowing us to take care of these patients. Even when they were getting before huge dark abdominal incisions, now we can fix them endovascularly, have more options for them. So in terms of aortic dissection, this is characterized by the separation of the aortic wall layers and the extraluminal blood that usually enters the aortic wall through an intimal tear. So basically, you will have two lumens. You will have a false and a true lumen. This is going to have a septum that is going to separate the lumens and there will be multiple re-entry sites. The key point for dissection in terms of the histology, you think about cystic medial necrosis when you do your certification test and all that. That's the main thing to remember. It's pretty uncommon. However, it does present and we do have to have a high suspicion in order to catch them in time and help these patients. So the key to survival in these patients will be to detect them on time and prompt treatment. We have two kinds of classifications. Will be the DeBakey classification and the Stanford. I always like using the Stanford because I think it's easier and basically it does refer-- it does talk to us about the involvement of the aortic wall. So for those patients that have any kind of involvement of the ascending aorta will always be Stanford A, and those that have only descending aorta will be Stanford B. And this is very important in terms of the treatment and how to recognize both. It's more common in men, and it's more common in men for those that have ascending aneurysms. Those patients that have chronic hypertension or have hypertension crisis will be the ones that will present with this. And those that have connective tissue disorders such as Marfan, coarctation, or Ehlers-Danlos will be the ones that will present with dissections. Also risk factors will be those patients that have bicuspid aortic valves. So just to touch briefly on Marfan's syndrome, which would be of the most common collagen disorders that we see. That will be hereditary connective tissue disorder, and it's autosomal dominant. And basically, the defect is in the fibrillin-1. This is not very common, but when-- in our hospital, we have a lot of patients that come with this disease, and we end up treating them. It's just to sort of recognize that it's not just a heart and aorta problem. They can have other things that they need to have a multidisciplinary team taking care of these patients. So when we see dissections, the main thing they're going to come with pain. They're going to talk about sharp, ripping pain, tearing pain, and it will be abrupt. Usually it does not radiate to the neck or shoulders such as when someone will have an MI. However, this is why sometimes the detection of dissections tends to be delayed, because we think of most common things, like MIs or having a PE or so forth. So that's why sometimes we can miss them. So the location may reflect the distribution of the dissection. And hypertension, they'll be-- most of the times, they'll be hypertensive. Very important to rule out other things, obviously, but have always dissection in the back of your mind. The problem with dissections, they can be pretty fatal since they can send you into acute aortic regurgitation, and those can present with an acute diastolic murmur. They can be in shock, and as well as obstruction of branch arteries such as malperfusion. So it could be a pretty bad thing. Obviously, clinical suspicion is most important. Make sure that we do a good physical exam and chest x-ray, EKG, to rule out any other cardiovascular event. Most importantly, we have to identify if they are ascending or descending. CT, nano, MRI, echocardiogram will be the main and safest things to diagnose this. And nowadays in almost every hospital we have these really available, so it allows us to identify them right away. Again, this is just a CAT scan. You can see the dissection flat there. And it goes all the way down, and the aorta pretty much looks like it's going to fall apart. And if you had to look at it open and do surgery on this open, the aorta's pretty friable and really looks like that, like it's going to fall apart. So institution of treatment is the main thing in order to have good outcomes for these patients. Most importantly, blood pressure control every time for our cardiothoracic holds, the vascular people as well. All these patients get placed on selected beta blockers in order to reduce their blood pressure. And then they may require an afterload reduction as well, and at that time you can use hydralazine or nitroprusside. But in general, we'll start with selected beta blockers and obviously pain control. This is the one thing that I would like you to remember-- for those patients that are presenting with ascending aortic dissection, this is a true emergency. Those patients need to be referred to the cardiothoracic surgeon right away. If these patients don't get treated, they will die. And this is different from those that present with descending dissections. The reason for that is because some of these descending dissections tend to be, I don't want to say more benign, but we could have more time to get to them if they need an operation or not, rather than the ones that have ascending aortic dissection. Outcomes, they're not that great. 20% mortality rate within initial 30 days for those that have descending aortic dissections, and up to 35% will develop degenerative aneurysms. So those that have chronic dissections have to be followed long term so that they don't develop significant aneurysms that need to be fixed later on. So they main thing for dissections is to understand the difference between dissection and rupture. Think of it in patients with hypertension and tearing, non-radiating chest pain, and the difference between the ascending and descending in terms of the treatment. So I'll be happy to answer any questions if you have any.
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