Thoracoabdominal aortic aneurysms (TAAA) result from continuous dilation of the descending thoracic aorta extending into the abdominal aorta. Degradation of the structural proteins that form the medial layer of the aorta, like collagen and elastin, causes degeneration and weakening of the aortic wall.1 Symptoms often occur after the aneurysmal diameter is greater than 5 cm; the most common initial symptoms may be vague pain in the back, chest, flank, or abdomen. It may be confused with angina, aortic dissection, or degenerative disease of the spine. Hoarseness of voice due to stretching of the left recurrent laryngeal nerve can occur. Occasionally, TAAA presents as a pulsatile abdominal mass.2 TAAAs are asymptomatic in 95% of cases, meaning most TAAAs remain undetected unless incidentally discovered.3 Herein, we describe the case of a patient who was initially treated for fluid overload as an outpatient, but a TAAA was ultimately discovered and she was treated via an endovascular approach.
An 83-year-old female with a past medical history of heart failure with preserved ejection fraction, atrial fibrillation, hypertension, and emphysema, and a chronic smoker, presented to the emergency department with bilateral lower extremity swelling for 3 days. The patient was treated in the emergency department with intravenous diuretics and sent home after symptomatic improvement. After discharge from the hospital, she was seen by her primary care physician, where she was found to have persistent swelling in both her lower extremities accompanied by intermittent shortness of breath. She then underwent a lower extremity venous duplex as there was a suspicion of deep venous thrombosis and a possible question of pulmonary embolism. The venous duplex was negative, and a chest x-ray (Figure 1) was done, which showed right mid and lower lung opacities and minimal right-sided pleural effusion, cardiomegaly, and an overall widened mediastinum. Considering her chronic smoking history and recent shortness of breath, the patient underwent computed tomography (CT) thorax imaging (Figures 2-3) that showed mild cardiomegaly and a 9.5 x 8 cm descending thoracic aneurysm requiring further evaluation with a contrast-enhanced scan. At that point, it was determined that the patient would require repair of the aneurysm, for which she was referred to a tertiary care center. On examination, vitals were temperature 98.7˚ F, blood pressure 126/89 mmHg, pulse rate 76-80/minute, and a respiratory rate of 16-18 breaths/minute saturating at 95% on 3 liters of oxygen via a nasal cannula, which was her baseline requirement. Coarse crackles were heard over the right mid to lower lung zones and there was 1+ bilateral lower extremity pitting edema up to the shin. Further evaluation with a CT angiogram of the chest, abdomen, and pelvis (Figures 4-5) also showed a thoracoabdominal aortic aneurysm type 3. Subsequently, the patient received medical management for her chronic obstructive pulmonary disease (COPD) for optimization from a pulmonary standpoint and also underwent a left heart catheterization for preoperative evaluation that was normal (Figures 6-8). She was taken to the operating room for total endovascular aortic repair (TEVAR) with stent grafting of the TAAA. Given the risk of spinal cord ischemia (SCI) due to anticipated long thoracic aortic segment coverage, we planned for the patient to receive a spinal drain pre-procedurally. She also underwent general endotracheal intubation without any complications. Bilateral common femoral arteries (CFA) were accessed under ultrasound guidance at a compressible point above the femoral head proximal to the femoral bifurcation, confirmed on fluoroscopy. A 5 French (Fr) diagnostic sheath was placed in both CFAs. Left brachial artery cutdown was performed for the purpose of delivery of the endograft. Two Perclose (Abbott Vascular) devices were placed in the right CFA to accommodate a 25 Fr stent graft, and a pigtail catheter was placed in the left CFA and a diagnostic aortogram was performed that showed findings similar to the CT angiogram: extensive mural thrombus and a type 3 TAAA. A 44/40 mm tapered Bolton Relay (Terumo Aortic) thoracic stent graft (middle segment) was delivered several centimeters proximal to the celiac artery (CA) and distal to the left subclavian artery. Then a 46/150 mm thoracic stent graft (proximal segment) was landed just distal to the left subclavian artery. At that point, a 5 Fr diagnostic sheath was placed in the left brachial artery to gain access down the descending thoracic aorta. It was upsized to an 8 Fr x 90 mm Shuttle sheath (Cook Medical) that was positioned above the CA. The CA was cannulated using a long angled Glidecath (Terumo) and an angled Glidewire (Terumo), which was then exchanged for a Rosen wire (Cook Medical) and the sheath was advanced into the ostium of the CA. A 7 x 79 mm Gore Viabahn VBX balloon expandable endoprosthesis (VBX Stent Graft, Gore Medical) was deployed into the CA approximately 2 cm distal to the ostium. An additional celiac stent was landed inside the previous one to create a snorkel with the CA. The final thoracic piece was advanced, which was the distal seal to screen a sandwich snorkel with the celiac artery. A 42 x 100 mm stent graft was landed just proximal to the superior mesenteric artery (SMA). The entire CA snorkel was protected with a 7 mm long balloon and an angioplasty of the stent graft at the overlap sites was performed with a Reliant stent graft balloon catheter (Medtronic). Final balloon angioplasty of the distal right CA was performed with a 9 mm short Mustang balloon (Boston Scientific). The diagnostic aortogram from the left groin pigtail catheter showed no evidence of type 1 or type 3 endoleaks, no gutter leaks, and a patent filing celiac artery snorkel (Figures 9-10). At that point, all devices were removed, the left brachial artery was primarily closed, and a 6/7 MynxGrip vascular closure device (Cordis, A Cardinal Health company) was deployed to the left CFA. The patient tolerated the procedure well and was monitored postoperatively in the intensive care unit before being moved to the floor.
Crawford first classified TAAA based on preoperative angiography or extent of repair. In 1986, Crawford described the first TAAA classification scheme based on the anatomic extent of the aneurysm (Figure 11). Type I involves most of the descending thoracic aorta from the origin of the left subclavian to the suprarenal abdominal aorta. Type II is the most extensive, extending from the subclavian to the aortoiliac bifurcation. Type III involves the distal thoracic aorta to the aortoiliac bifurcation. Type IV TAAAs are limited to the abdominal aorta below the diaphragm. Safi’s group modified this scheme by adding Type V, which extends from the distal thoracic aorta, including the celiac and superior mesenteric origins, but not the renal arteries (Figure 11). Crawford’s definition uses T6 as a boundary between group II and group III aneurysms because this is the rib that was commonly removed during repair, and thus provided a radiographic marker of the level of disease. Thoracoabdominal aneurysm describes an aneurysm involving both the thoracic and abdominal aorta, as well as their visceral branches: the CA, SMA, and renal arteries. The most common is a Crawford type III TAAA with lesions at the distal area of the aorta (below the T6 section) and the entire abdominal aorta.5 The natural history of aortic aneurysms is dissection or rupture. Hypertension worsens wall tension by increasing the diameter of the aorta (Law of Laplace).6 TAAA diameter is the strongest predictor of rupture, and while the growth rate is non-linear and unpredictable, the rupture rate accelerates as aneurysms grow.7 Both female sex and the presence of (COPD) have been associated with increased risk of rupture, as in our patient. While female sex has been associated with delayed time to aneurysm formation, the absolute risk of rupture is increased in size-for-size match cohorts. COPD has been associated with a 3.6-fold higher risk of rupture. Longitudinal studies have shown that for every 1 cm growth over 5 cm, the risk of rupture doubles.8 The potential advantages of endovascular grafting over open operation include the absence of a thoracotomy incision, and the need for partial or total extracorporeal circulatory support and clamping of the aorta, as well as lower hospital morbidity rates and shorter length of hospital stay. Endovascular grafting may be of particular value in patients with significant comorbid conditions (older age, substantial cardiac, pulmonary, and renal dysfunction) who would be considered poor or non candidates for open surgery.9 Initial enthusiasm for TEVAR was low due to the fear of spinal cord ischemia resulting from the exclusion of intercostal and lumbar arteries, but these fears have waned with the progression of successful endovascular treatment of juxtarenal abdominal aortic aneurysms. When treating TAAA with an endograft, the use of a simple fenestration is not adequate. Unlike fenestrated grafts where a hole in the graft suffices, in more complex aneurysms such as TAAA, the branch arteries arise from the aneurysm. In this scenario, blood flow must be carried from the endograft, across the aneurysm, and to the target vessel, without extravasation into the aneurysm.10 Another popular option for branch vessel preservation during complex aneurysm repair is to use parallel endograft. Two recent publications summarized early results with a parallel endograft.11 These papers included mostly juxtarenal pathologies, but did demonstrate a technical success rate of 98.9%. Additionally, they found a 97.8% patency rate at a mean follow-up interval of 9 months. While these techniques (ie, the so-called “chimney” or “snorkel” technique) have been more commonly used for juxtarenal pathologies, the concept can be applied to TAAAs by utilizing a standard endograft as the landing zone for the parallel endograft. This configuration has been referred to as the “sandwich” technique. The technique has been championed by Lobato and Camacho-Lobato, who recently reported a large series of such cases that included 13 elective and two emergent TAAA repairs.12 The big advantage of a parallel endograft is that it is completely modular, providing an off-the-shelf option for almost any anatomy, without the need for device modification. Another advantage is that the branch vessels are cannulated before deployment of the aortic endoprosthesis. This advantage can be quite important in three situations. The first is in tortuous anatomy, where the alignment of a fenestration or side branch to the target vessel can be difficult. The second is in small lumens, such as dissections, in which the aortic device may remain partially compressed. The third is when there is a significant thrombus in the perivisceral aorta, placing the patient at risk for atheroembolization during deployment of the aortic endoprosthesis. A disadvantage of a parallel endograft, however, is the imperfect seal inherent to the technique. The side-by-side configuration leads to gutters along the parallel endograft, which can result in endoleaks and continued pressurization of the sac. Although the gutters can be eliminated by oversizing the aortic stent so that it wraps around the branch stent, in reality, endografts are not designed to deploy in such a manner. This approach also led to significant infoldings, leaving the authors to recommend 30% oversizing and an acceptance of larger gutters.13 Complications commonly encountered in open surgery for TAAA are also seen in TEVAR. Symptoms attributable to spinal cord ischemia are observed in 4 to 7% of cases, but appear more common in patients where a long extent of the thoracic aorta is treated. The incidence of SCI in endovascular surgery is not statistically different compared with open repair, although intercostal arteries are not reimplanted.14 A larger risk of spinal cord ischemia is associated with the previous aortic repair, as this is a surrogate indicator of a larger extent of disease, despite the extent covered in the index operation. Most centers agree that adjunctive measures, such as spinal cord drainage during and after the procedure, likely have some benefit for spinal cord protection, although this has not been specifically studied. Despite being widely used for several years, TEVAR remains challenging, particularly the revascularization of the abdominal aortic visceral branches. The parallel stent graft technique is relatively easy, but the incidence of endoleaks and stent occlusion is high because of the gutter between the stents.15 Fenestrated and branched EVAR might overcome the latter shortcomings by maintaining the original anatomical structure and blood supply of visceral arteries, without the development of a gutter.
Talking With the Operators
A discussion with Internal Medicine Resident Monarch Shah, MD1, Cardiothoracic Surgeon Anthony Lemaire, MD, FACS2, and Interventional Cardiologist Pratik Patel, MD, FACC3.
Can you describe how you work together and your hopes for the structural heart intervention program at Robert Wood Johnson University Hospital?
Dr. Patel: The collaboration between interventional cardiology, the cardiothoracic surgery program, and the vascular surgery program has been ongoing for over seven years in our structural heart program. With the advent of transcatheter aortic valve replacement (TAVR), we had to collaborate under Centers for Medicare and Medicaid (CMS) guidelines. Both the cardiothoracic surgeon and the cardiologist needed to do the procedures together. Now, still collaborating, we are branching out to more complex procedures, such as peripheral vascular procedures, and most recently, endovascular procedures involving aortic dissections and aortic aneurysms. Initially, we were doing more in-person reviewing of CT scans and planning for the valve replacement. Now, the technology is such that we can work independently and virtually.
We are rarely required to be physically present to discuss the coordination of care, making it much easier to share imaging and patient information.
Dr. Lemaire: We started off with TAVRs, but have now branched out to mitral valve clips, tricuspid valve clips, and thoracic endovascular aortic repair (TEVAR). We are able to do TEVARs together in all stages, from the preoperative portion, to the procedure, and then for post-operative management. Talking virtually has actually made our workflow a lot easier.
Did you anticipate early on how your program’s procedural reach might expand over time?
Dr. Lemaire: Honestly, I never imagined it being as successful as it has been, nor that we would be branching out to these other procedures. When TAVR started, it was very intimidating for everyone, I think, at least initially. As people got more facile with it, we began to see how we could branch out and started thinking about other options. I absolutely love the collaboration, because it’s nice to see a person in a different field tackle the same problem and learn how they do it. I’ve learned so much from Pratik and from the vascular attendings.
Dr. Patel: Exactly. This natural evolution is occurring very rapidly. The collaborative spirit has been great. I don’t know if it was Anthony or one of the other surgeons who joked, our closest friends now are the cardiologists and who would have thought something like that would happen? It hasn’t become territorial; it has become a spirit of working together. With these complex TEVARs and TAVRs, it requires all three disciplines to be present and working together. But this collaboration is not entirely new. With complex peripheral procedures, I have worked with the vascular surgeons where they would either back me up or we would work together for a solution. Now with complex vascular procedures, it requires all three of us to, in some capacity, work together. It has been such a positive environment for everyone.
Dr. Shah: We are not far away from a day where there might be an extra year or even an additional rotation for cardiologists to work amongst the cardiothoracic surgeons and become involved in these multidisciplinary cases. It is exciting to see.
Dr. Lemaire: I can only imagine our involvement is going to continue to grow. First of all, the results have been successful and I hope our collaboration continues in such a way that no one feels threatened by the other specialty. Our reach will continue to grow into other areas, because what drives this kind of patient care is the outcomes. With a widely successful structural heart program, most of these patients are only staying overnight. They are coming in the day of their procedure, and then, especially with the TAVRs, about 80% of our patients leave the hospital the next day. With these other complex vascular procedures, we are hoping it translates the same way: a minimally invasive procedure, a good outcome, and a safe discharge within a very few days.
Could you talk about some of the challenges that were present in this case?
Dr. Shah: Certainly. The diagnosis of these patients visually is very difficult. Our female patient also had a history of COPD. COPD patients tend to have worse outcomes in terms of thoracic aneurysms, which not only don’t have many symptoms, but tend not to be caught early on very often. So she was a challenging patient not only to diagnose, but also to treat.
Dr. Lemaire: Her comorbidities became challenging. Chronic pulmonary disease always plays a role, not only when you are preparing for the procedure, but also postoperative in terms of recovery. I would say one of the limiting factors was her inability to mobilize afterwards per her COPD. That was challenging, but the actual procedure was also very challenging.
Why was this patient chosen for an endovascular repair?
Dr. Lemaire: One of the reasons an endovascular approach was beneficial was her age and her frailty, and frankly, we thought she would recover a lot faster from an endovascular approach, as opposed to doing a thoracotomy. We know patients will do better if you can use a minimally invasive versus an open approach, and her age and comorbidities really pushed us toward doing a minimally-based approach.
Dr. Patel: Yes, her two biggest risk factors were female sex and age. I precluded an open repair. She also told us, flat out, “You don’t operate on me. If you can avoid it, please avoid it.” She presented for a different reason, for heart failure. Her thoracic aortic aneurysm was found more or less incidentally, but it was such a big aneurysm and the risk of rupture was so high that we couldn’t ignore it. Once it becomes really symptomatic, then there is nothing that can be done. There are plenty of data showing that older, frail COPD patients have a hard time in terms of post-operative complications and then they just can’t get off the vent.
The procedure itself looked like there were some specific techniques that needed to be used around the placement of the stent graft.
Dr. Lemaire: The challenge of this patient was that the aneurysm involved the descending thoracic aorta, but also involved the aorta of the abdomen, sitting close to the vessels providing blood to the intestines. In order to tackle such a large aneurysm and preserve the blood flow to the intestines, it took a lot of planning. It is important to point out the significance and importance of the vascular surgery team in coordinating this work. Essentially, it was a two-part goal. We stented the entire aneurysm that was involved with the descending thoracic aorta, and also the abdominal aorta above the blood vessels going to the intestines. We also made sure that in addition to excluding the aneurysm, that there was reliable blood flow to the vessels going to the intestines. It would be of no benefit to the patient if we excluded the aneurysm, but blood flow going into the intestines was compromised, because that could be lethal. By doing this snorkeling procedure, we made sure there was stent going into the celiac artery and that this artery supplying blood flow to the intestines was patent.
Was this a time-sensitive procedure?
Dr. Lemaire: It was not an emergency, but it was definitely urgent. A 9-centimeter aneurysm is not something that you want to get any larger, so we wouldn’t have sent her home. Classically, you want to fix a thoracic aortic aneurysm when it is greater than 6.5 centimeters.
Dr. Shah: I agree that this patient couldn’t go home until her aneurysm was taken care of. The size of the aortic aneurysm matters, because of the risk of rupture, as well as location. The data are not as robust with only using medications such as beta blockers to control blood pressure in order to decrease the distributing force, what we call dp/dt force. Medication alone would not have been adequate treatment in this case.
Were there any particular benefits from the specific devices that were chosen?
Dr. Lemaire: The parallel endograft technique — the snorkeling technique — allows off-the-shelf equipment use. There are cases where the vascular surgeons have to incorporate 3D modeling in order to individualize the device for the patient. It then becomes a time factor, because the surgeons have the company individually manufacture a fenestrated stent. In our case, use of the parallel endograft technique means you can incorporate whatever you have on the shelf for a very reasonable outcome.
Dr. Patel: The choice of balloons and different stent grafts were based on the size of the aneurysm and experience of the vascular surgeon, Dr. William Beckerman, as this is his area of expertise. The technique was also based on what Dr. Beckerman thought would be the most lasting and successful.
How has the patient fared?
Dr. Patel: I just saw her about two to three weeks ago and she is doing well. She did quit smoking. All her incisions were minimally invasive. The left brachial was the only one that was a surgical cut down, but the two groins were percutaneous. She was happy with having just three small bandages afterwards and the incisions are healing well.
Any final thoughts?
Dr. Patel: It is important to emphasize the critical role played by vascular surgery. We want to acknowledge Dr. William Beckerman and his team for their hard work in getting this case done successfully.
Disclosures: The authors report no conflicts of interest regarding the content herein.
The authors can be contacted via Monarch Shah, MD, at email@example.com
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