Authors

• Maja Strozzi — University of Zagreb School of Medicine, University Hospital Centre Zagreb, Zagreb, Croatia — ORCID: 0000-0003-4596-8261

Abstract

Thoracic EndoVascular Aortic Repair (TEVAR) was initially developed for occlusion procedures in treatment of diseases of the descending aorta, but its use was soon expanded to a whole spectrum of pathologies of this aortic segment, including dissection and traumatic ruptures. Surgical treatment of degenerative aneurysms of the descending aorta has a very high mortality and morbidity, so TEVAR leads to significantly improved outcomes for these patients. This is the reason the University Hospital Centre (UHC) Zagreb introduced the use of this procedure in the Department of Cardiovascular Diseases. Despite difficulties, TEVAR was used to treat the most at-risk patients with aneurysms, type B dissection, and traumatic rupture of the descending aorta. Long-term results of the treatment of 24 patients were acceptable, with a mortality of 8.3% and common complications (type I and II endoleaks in 12.5%; infection in 4.1%; proximal dissection propagation in 4.1%) which were resolved with an additional intervention or surgical procedure. In the future we expect much more rapid development of this method in UHC Zagreb and in Croatia in general once the Croatian Health Insurance Fund has arranged financing for the device.

Keywords

thoracic aorta, endovascular procedure, stent grafting, aneurysm, dissection, vascular approach

DOI

Full Text

## INTRODUCTION More than 20 years have passed since the first report of using stent grafting to treat an aneurysm in the thoracic aorta in a patient with high surgical risk (1). This procedure, known as TEVAR (Thoracic EndoVascular Aortic Repair) was soon shown to be efficient and safe, with lower morbidity and mortality rates than surgical intervention. Today, thoracic stent grafts are commercially available, and studies have shown the superiority of this technique compared with surgery: mortality 2.1% compared with 11.7%, spinal cord ischemia 3% vs. 14%, and several times less common respiratory and renal insufficiency (2). Soon after being introduced as an aneurysm treatment, stent grafts started being used in cases of aortic dissection type B (3). In comparison with conservative treatments, this method had better five-year survival rates (6.9% vs. 19.3%) (4). As any new method, there were new complications associated with it. Perioperatively, they were mostly associated with the vascular approach, and in the long term because of incomplete exclusion of the aneurism or dissection, which can result in disease progression. Consequently, long-term follow-up is recommended after TEVAR procedures. The number of these procedures being performed worldwide has grown dramatically over the last twenty years, and has now practically replaced, whenever possible, the surgical approach for diseases of the descending aorta due to constant improvements to the implantation technique and the device itself (5). ## INDICATIONS AND CONTRAINDICATIONS The ideal patient for thoracic stent grafting would have the following characteristics: - An aneurysm, not a dissection, - The possibility of implanting the stent graft distally from the left subclavian artery, without covering it if possible, - The possibility of implanting proximally from the celiac trunk, - Good vascular access, - The presence of an adequate proximal and distal “neck” for implantation in “healthy” tissue, and - No thrombi and minimal presence of calcium. The procedure is usually performed on patients less ideally suited to it, affecting the chances of success and complications. TEVAR, initially developed to treat degenerative and later dissection of the descending aorta as well, is now indicated for a wide spectrum of aortic pathologies, especially in extensive traumatic injuries where this method has shown itself to be much less invasive and risky (6, 7). Although it is sometimes also used in patients with mycotic aneurysms and in patients with systemic connective tissue disease (Marfan syndrome), these patients were not included in randomized studies, and it is widely accepted that TEVAR is not appropriate in such cases due to expected complications (8). Patients with peripheral vascular diseases or inadequate vascular approach are not suited to the procedure, nor are cases in which aneurysm exclusion would occlude important (cerebral) arteries. ## TECHNIQUE The intervention is planned using multislice computed tomography (MSCT) angiography, which is a key diagnostic tool for diagnosis and monitoring of these patients. The radius of the femoral artery needs to be determined (usually the vascular approach), and exact measurements of the proximal and distal “neck” are conducted, which determine the dimensions of the device. The procedure is usually conducted under general anesthesia in a radiology angiography theater. A standard percutaneous procedure is used to introduce a catheter into the ascending aorta for angiographic monitoring, and a stent graft is then introduced either using a percutaneous procedure with later use of a vascular vascular occlusion device, or, or after surgical preparation of the chosen vascular approach. The stent graft pre-attached to a release system, is than introduced over a very hard leading wire, carefully positioned, and released (Figure 1). In some cases, especially for occluded aneurysms, the release of the graft can be followed with a balloon dilatation to achieve better apposition. This should be avoided in cases of dissection. Figure 1. A) Angiographic presentation of descending aortic aneurysm. B) Stent-graft positioning before deployment (red arrow). C) Partially deployed stent-graft (yellow arrow –proximal stent-graft end, red arrow – aneurysm steel feeling with contrast in the distal, non-expanded end of the stent-graft). D) Complete aneurysm occlusion, left subclavian and partially left carotid artery covered with the uncovered part of the stent (green arrow). ## COMPLICATIONS The abovementioned complications most commonly include damage to the peripheral vasculature due to the large dimensions of the device (14%), neurological complication such as ischemic stroke (4%), paraparesis/paraplegia (3%), and even death (2%) (8). Incomplete exclusion of the aneurysm, i.e. endoleaks, can be a problem as well and are divided into 4 types depending on the point of origin: - Type I denotes leaks at the proximal or distal end of the graft (Figure 2),Figure 2"Endoleak" type I, arrow indicate contrast feeling of the aneurysm after occlusion with stent-graft. - Type II appears in cases of retrograde hemorrhage from small blood vessels covered by the graft, - Type III appears when several grafts are implanted, at the point of their overlap, - Type IV is rare and is caused by porousness of the graft. Leaks can appear early or later during the follow-up. They affect further progression of the aneurysm and should therefore be resolved with an endovascular procedure, if possible, or with a surgical intervention (9). ## STARTING THE TEVAR PROGRAM IN THE UNIVERSITY HOSPITAL CENTRE ZAGREB Internationally, TEVAR procedures are generally performed by vascular surgeons and interventional radiologists, but cardiologists as well. In the University Hospital Centre (UHC) Zagreb we started using this method in the Department of Cardiovascular Diseases, for the following reasons: patients suitable for the procedure are referred to us, and we are expected to treat their complex health issues; their surgical mortality is high, and as interventionists dealing with a high volume of patients we had the resources and skills required, especially since no one else wanted to treat these patients. The first intervention was performed on October 18, 2004, with the help of the proctor (Prof Josip Mašković, MD) on a young patient with posttraumatic aneurysm of the descending aorta. We faced a number of problems over the next 10 years. Notably, we had difficulties organizing the team, despite the willingness of colleagues from other fields (in addition to the personnel of the Laboratory for Interventional Cardiology, a team of anesthesiologists and surgeons are needed as well) and a non-existent budget for such procedures, which meant that we could perform the procedures only intermittently using the budget for coronary interventions. During the first years, our premises and equipment were completely inadequate for this type of procedures. As cardiologists, we struggled with MSCT image analysis. A lack of interest from all administration groups of the UHC Zagreb for support and improvement in the method was evident in in that period, likely due to the procedure not being subsidized by the Croatian Health Insurance Fund. During this period, we tried to draw attention to the fact that the high price of the graft at 55 000 HRK is insignificant compared with the prices of surgery that are several times larger, even for the most optimistic outcomes with no complications, which are very rare with these types of surgeries. ## RESULTS Over a period of ten years, 26 stent grafts were implanted into the thoracic aorta of 24 patients in the Zagreb Clinical Hospital Center. The most common indication for the procedure was dissection type B (11 patients), and the other cases included 5 patients with posttraumatic aneurysm, 3 patients with atherosclerotic aneurysm in the thoracic aorta, and 5 patients with acute traumatic dissection at the usual site. Considering the low number of procedures over a large amount of time, and as a result of inadequate resources, the learning curve was very long; despite these problems the results were good, with expected frequency and type of complications. Perioperative complications. The procedure was not successful in one of the patients due to problems in the introduction of the graft due to significant calcification in the area of the abdominal aorta and the peripheral arteries. A patient experienced a complication after percutaneous closure of the vascular approach, which was surgically resolved. This was the only vascular complication we experienced. The most significant complication was a migration of the graft during the procedure, which was resolved with an additional device. Early complications. One patient experienced retrograde dissection in the ascending aorta. The patient experienced no significant issues, and the diagnosis was made during the first MSCT follow-up within 48 hours of the successful procedure. The patient was successfully transported and underwent surgery abroad (the cardiosurgical team in our hospital refused the referral due to the lack of experience in such procedures). None of our patients presented with paraparesis, paraplegia, or cerebral incidents. Late complications and long-term results. One patient developed graft infection, which was successfully resolved by a surgical procedure abroad (graft extraction and homograft implantation). Two patients died during follow-up, one a year after the procedure during anesthesia before an unrelated cardiosurgical procedure. It is impossible to rule out an aortic rupure as the cause (described in the autopsy, possible as the result of excessive pressure during reanimation). The other patient died four years after the procedure as a result of a malignant disease (Figure 3). Figure 3. Number of patients according to indication, early and late complication and mortality. ## LEAKS One patient experienced a type I periinterventional leak, which was resolved with an additional stent graft. In a single female patient, a very large type II leak remained after the procedure, which was resolved with an Amplazer occluder in the left subclavian artery (Figure 4). The most significant problem appeared in a single female patient after intervention for acute dissection type B. We tried to resolve a minor leak after the procedure using a coil, but the leak increased, and a large aneurysm developed. The leak was a combination of type I and II, and the only treatment solution was a complex hybrid procedure including a large surgical intervention in the proximal part of the aneurysm and an additional distal endovascular procedure (Figure 5). Figure 4. A) Thoracic aorta aneurysm including left subclavian artery. B) After stent-graft deployment, continued contrast feeling of the aneurysm from the dilated subclavian artery (Type II «endoleak»). C) and D) Before and after occlusion of subclavian artery with the «occluder» (amplazer device pointed with yellow arrow). Figure 5. MSCT aortography of a patient with progression of aneurysm 9 years after procedure, caused by «endoleaks» type I and II. ## TEVAR IN TRAUMATIC DISSECTION During the past four years, TEVAR procedures have been conducted in five polytraumatized patients (ages 31-55). In all cases the causes of the traumas were traffic accidents, and ruptures in the aorta were found during computerized tomography imaging. All the procedures were successful, with no early or late complications, as expected (Figure 6). In these life-threatening cases, survival after a successful TEVAR procedure depends primarily on the other injuries. All the patients recovered in our cases. Figure 6. A) Aortography presenting traumatic transection of aorta on typical location. B) After stent-graft deployment. ## CONCLUSION The motivation for this short overview of the results of the TEVAR program in UHC Zagreb was twofold: The first is the fact that it has been 10 years since we started performing the procedure, which is fairly early compared with the emergence of this method worldwide, coupled with the fact that, despite many difficulties and a lack of support, we managed to keep the program running, albeit at a minimal level. In the meantime, the number of TEVAR procedures has grown much faster in areas where the teams have been supported by those with the resources to do so. The second reason is the encouraging fact that this method has finally been recognized by the Croatian Health Insurance Fund as an established procedure for the treatment of diseases of the descending aorta, with much less risk involved than the very complex and more costly surgical procedures, and that TEVAR is now being routinely performed in several institutions in Croatia by cardiologists, radiologists, or vascular surgeons.

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