Current Endovascular Treatment of Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAA) may now be treated by endovascular Several FDA-approved clinical trials are currently in progress with a variety of.
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Table 2 shows the average diameter of the aneurysm and the characteristics of the proximal neck and the aortoiliac bifurcation. The tri-modular pattern of the stent graft was used in all cases.

Introduction

It was necessary to use unilateral extensions in five Stent graft repositioning was performed in three cases In one case it was necessary to convert to an open surgical approach. In three cases There were no cases of pelvic or intestinal ischemia, erectile dysfunction, or buttock claudication at follow-up.

The complication rate was Perioperative infection occurred in one case 6. This was an operative site infection that was treated with the use of systemic antibiotics without clinical repercussions for the patient Table 3. Perioperative mortality was 6. Despite conversion to an open surgery, one patient died because the bilateral renal arteries were occluded due to stent body migration during the operation.

The total endoleak rate was The perioperative reintervention rate was One patient with a type Ia endoleak was treated during the operation by insufflating the compliant balloon in the proximal neck, which led to resolution of the endoleak. A type III endoleak, which is caused by inappropriate sealing of the anchoring zone of the iliac legs, was treated in the same way.

Endovascular treatment of abdominal aortic aneurysms

A type II endoleak, with branches filling the aneurysm sac, was observed in one case on postoperative angio-tomography. Additional interventions due to an increase in the size of the aneurysm sac were not necessary. Two reinterventions to treat a type Ib endoleak and the endoleak of the stent graft iliac leg were necessary; iliac leg extensions were used after surgery.

Endovascular treatment of abdominal aortic aneurysms is a less invasive alternative compared to open surgery, and it is indicated for high-risk patients and for those with appropriate anatomy. Not all patients can undergo endovascular treatment, and unfavourable anatomy is the main limitation to using this technique. These limitations must be evaluated individually, taking into account the team's experience, the characteristics observed on computed tomography, and the stent graft used. The most important anatomic features that determine endovascular treatment are the tortuosity of the aorta and the diameter, the length of the proximal neck fixation area for the stent graft , and the access to the iliac-femoral segment.

Secondary factors include angulation of the aorta proximal neck and iliac arteries, calcification, and the presence of mural thrombus in the proximal neck. Despite the advantages of using stent grafts with suprarenal fixation for complex abdominal aortic aneurysms, it is still necessary to wait for long-term follow-up in order to document the incidence of embolization or renal occlusion. The Anaconda TM stent graft is a device that uses infra-renal fixation and consists of a ring design that provides more flexibility and radial strength to adapt to landing necks with unfavourable anatomy.

The easy manoeuvring of the delivery system and the hydrophilic coating facilitate navigation through tortuous iliac vessels. The repositionable deployment system enables position correction in the aortic neck. The catheterization system with the contralateral leg facilitates the procedure in patients with pronounced aortoiliac angulations. These features make the stent graft more attractive for the treatment of more complex infra-renal abdominal aortic aneurysms.

In a comparative study using aortic stent grafts in humans aimed at evaluating iliac and aortic fixation, Melas et al. The improved proximal fixation is due to the presence of four pairs of hooks and the nitinol coating, which provides greater radial strength and an improved proximal seal.

The present study analysed consecutive patients; 16 had complex abdominal aortic aneurysms. Despite anatomic difficulties, technical success was achieved in In one patient it was not possible to position and release the stent graft at the appropriate site, and surgical conversion was necessary. In this case, the degree of aortic tortuosity and calcification of the access arteries were underestimated.

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Brazilian authors have published a study with patients with abdominal aortic aneurysm undergoing endovascular repair, with a technical success rate of In a study published by Perdikides et al. The mean angulation of the aneurysms of these patients was 62 degrees, the length of the proximal neck ranged from 18 mm to 30 mm, and the average angulation of the aortoiliac bifurcation was 59 degrees. In the population of this study, an initial endoleak was observed in Of these, types Ia and III were resolved during the procedure by insufflating the balloon in the proximal neck in the case of the type Ia endoleak and by using the same technique in the iliac leg connection in the case of the type III endoleak.

These endoleaks were considered primary endoleaks in this study, since post-dilation with a compliant balloon was not recommended during the initial procedure and was only performed in the case of an endoleak during the aneurysm repair. Angio-tomography performed one month after the procedure confirmed that there was no endoleak in these cases. The remaining two cases of type Ib endoleak were successfully treated with an extension of the iliac leg during the postoperative period, leading to a reintervention rate of In a study performed by Freyrie et al. All endoleaks showed favourable aortic anatomy.

In the present study, the mortality rate within 30 days of the procedure was 6. A patient died during conversion to an open surgery due to occlusion of the renal arteries provoked by stent body migration during the procedure. In a Brazilian study, Palma et al. The EVAR 1 study 4 showed a 4.

Brazilian authors showed a less significant decrease in the perioperative mortality rate of 6. Some of them are inversely proportional to the length of the aneurysm neck, that is, the smaller the aneurysm neck, the harder it is to position the endovascular device. At the same time, the greater the number of comorbidities, the greater the risk of intra- and postoperative complications.

The DREAM study, 13 which compared operative mortality and complications after surgical treatment and endovascular treatment, concluded that endovascular treatment is more appropriate due to the lower mortality rate, the type of complications, and due to the significant reduction in systemic complications. In this study, the total complication rate was Intraoperative bleeding at the surgical site occurred in two cases two in the inguinal region, in which surgical intervention was not necessary and peripheral embolization occurred in two cases one case treated with embolectomy during surgery and the other case, a microembolism, treated with conservative management.

These were the most frequent complications. Occlusion of an iliac leg was also observed. This was due to the presence of a calcified plaque close to the iliac extension, which led to thrombosis seven days after the surgery. The occlusion was successfully treated with a crossover femoro-femoral graft. Limitations of the study. The limitations of this study were the small sample size and the short follow-up, which limited the conclusions and the possibility of comparing the results with more comprehensive studies.

In this study, the second-generation stent graft with a dual-ring design was effective in the treatment of complex infra-renal abdominal aortic aneurysms. Studies with a greater number of patients and with medium-and long-term follow-up may define its applicability. The authors declare no conflicts of interest. Resection of aneurysm of abdominal aorta: Transfemoral intraluminal graft implantation for abdominal aortic aneurysms. Eur J Endovasc Surg. Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm EVAR trial 1 , day operative mortality results: The advantages of Anaconda endograft for AAA.

J Cardiovasc Surg Torino. Endovascular aneurysm repair and outcome in patients unfit for open repair of abdominal aortic aneurysm EVAR trial 2: Incidence and risk factors of late rupture, conversion, and death after endovascular repair of infrarenal aortic aneurysms: The care of patients with an abdominal aorticaneurysm: In all patients the procedure was carried out by femoral artery dissection in a catheterization laboratory.

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There was no need to convert to open repair. There were no operative or postoperative deaths. Two other patients needed femoro-femoral bypasses, one at the same time as the endovascular procedure and the other one 24 hours later because of lower limb ischemia. The endovascular treatment of AAAs represents a new less invasive alternative to conventional surgery, especially for high risk patients. Further prospective and randomized studies to evaluate the long term outcomes are needed.

Excellent results in the short and medium-terms can be obtained by multidisciplinary teams in our country. Interest in the development of minimally invasive techniques for surgery has grown very much over the last few years. The s presented a technological revolution in the treatment of aortic diseases. In , Parodi et al. The conventional surgical treatment of AAAs requires laparotomy and replacement of the abdominal aorta by a prosthesis. With endovascular treatment, laparotomy is avoided and, by incisions in inguinal area, the endoprosthesis may be implanted in a less invasive procedure.

The endoprosthesis is retrogradely directed along a guide-wire through the common femoral artery, via the iliac arteries to the abdominal aorta. Once correctly positioned, it is immediately released below the renal arteries. Blood loss is much less than conventional surgery, the aorta does not need to be clamped and patient recovery is faster [2, 3]. Careful selection of patients based on reliable imaging methods including computed tomography CT must always be employed, taking into consideration several factors and a rigid protocol of measurements Figure 1.

Several prospective and randomized studies are being conduced in order to compare the conventional with endovascular technique. Two already published studies, the EVAR 1 [2] and the DREAM [3] trials show a trend of lower surgical mortality rates, even in low risk patients, offering a viable alternative with less morbidity than conventional surgery. Another point of discussion is which professional should perform the procedure, as there is overlapping among interventionist cardiology, interventionist radiology, vascular surgery and cardiovascular surgery.

The learning curve of surgeons to perform procedures by catheter is sometimes long.

Endovascular treatment of abdominal aortic aneurysms.

In our institution, we have set up a team with interventionist cardiologist, vascular radiologist, anesthetist with experience in aortic surgery and cardiovascular surgeons. The objective of this work is to present the facts and the short and medium-term results of endovascular procedures for AAAs performed by this multidisciplinary team, coordinated by a cardiovascular surgeon. Of the 42 patients, 17 were cases of aneurysms or thoracic aortic dissections and 25 of abdominal aortic aneurysms AAAs ; this latter group is the series studied in the current work.

All patients signed written informed consent forms. Three brands of endoprostheses were utilized: In total twenty-four bifurcated and one straight endoprostheses were implanted. The criterion for the surgical indication of AAAs was a diameter greater than 5 cm. Most of the patients presented with some contraindications for conventional surgery and others, after an explanation of the therapeutic choices, opted for endovascular treatment.

All patients were submitted to tomography in the preoperative period, for careful selection using the following criteria: Additionally, all patients observed the postoperative follow-up protocol, which included computed tomography in the first month, at six months and thereafter each 12 months if there was no evidence of endoleaks.

All patients were submitted to the procedure of femoral artery dissection in the hemodynamics laboratory, with anesthesia to the rachidian nerve. No patient needed conversion to laparotomy and the mean hospital stay was 4 days range from 2 to 7 days. The patients stayed during one night in the heart intensive care unit and in the following morning were transferred to the wards. There were no deaths in the trans- and post-operative periods. For one of these patients it was in the same procedure due to dissection of a plaque and occlusion of iliac artery and for the other, it was 24 hours after, due to ischemia of the lower limb caused by iliac artery occlusion.

Both patients evolved without ischemic sequels. All patients are alive after a follow-up time of between 2 and 27 months.


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One patient presented with a type I endoleak; he was successfully submitted to another endovascular intervention with the placement of three extensions one proximal and two distal one year after the initial procedure. Another patient presented with a type II endoleak, with a slight retrograde filling via the lumbar arteries; the patient is being accompanied by means of serial tomographies, but has not shown any increase in the aneurysm. All patients are being submitted to periodical evaluations by computed tomography, with the first evaluation one month after the procedure then after 6 months and thereafter once per year.

Not all patients with AAAs with indications for intervention are candidates for endovascular procedures and, in reality the adequate selection of patients is the most important factor for success in treatment []. The main criterion of selection relates to the anatomy of the aortic, iliac and femoral system 5. Computed tomography is currently considered the best examination for the evaluation of patients with AAAs in order to study the possibility of endovascular repair []. The images are achieved with iodated contrast and performed with 2- and 3-dimentional reconstruction with all the necessary measurements.

It is also the preferential method and the most reliable for the post-implant follow-up and to identify endoleaks Figures 3 and 4. In respect to the materials, several have been tested, but most endoprostheses are currently manufactured from metallic alloys nitinol or stainless steel and covered with fabric PTFE or polyester.

Endovascular Repair for Aortic Aneurysms

Endoprostheses have been designed to be delivered in the arterial system utilizing guide-wires and delivery systems so that they can be introduced via the femoral and iliac arteries without causing injury. Ideally, the material must be strong enough to avoid deterioration with time and at the same time, sufficiently thin and supple to go into delivery catheters.

Most are self-expanding and are anchored to the aorta by outward force. They may be placed using a balloon; some apparatuses have hooks or clamps for anchoring in order to reduce the possibility of migration. Some endoprostheses have a small uncovered proximal segment, called the free-flow section, which is to anchor the stent over the renal arteries, increasing the length of contact with the proximal aorta in AAAs with short necks [8].

At hospital release, the patients need to be accompanied with periodical imaging methods [2, 4, 6, ]. Computed tomography CT should be performed 30 days and again 6 months after the procedure and thereafter one time per year. Aortic Doppler echocardiography may be performed in this period and, if there is any suspicion of endoleak, computed tomography is required. When there is no possibility of performing computed tomography allergy to the contrast or renal insufficiency , magnetic nuclear resonance must be used. We must be aware about the possibility of the migration of stents, occlusion of branches and endoleaks.

Endoleaks, which are the most frequent complication of this procedure [4], are classified in four types: