Fixation of infrarenal aortic stent-grafts using laparoscopic banding -- an experimental study in pigs

Aortic Banding to Treat Simultaneously a Type Ia Endoleak and Aortic Neck Rupture during Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Type Ia endoleak due to inadequate seal at the proximal end of the endograft is not infrequent during the initial operation. However, repeated attempts at balloon inflation or over-dilatation of the balloon can produce high axial pressures and can lead to aortic neck rupture with hemodynamic instability.

METHODS

The purpose of the paper is to present a useful technique for simultaneously treating a type Ia endoleak and aortic neck rupture during endovascular abdominal aortic aneurysm repair.

RESULTS

The technique for treating a type Ia endoleak has been described, but it was used for the first time to treat simultaneously a type Ia endoleak and rupture of the aortic neck with active bleeding during endovascular abdominal aortic aneurysm repair. After laparotomy, the left renal vein was ligated and a proximal control was achieved with placement of a vascular clamp above the renal arteries. Effective external banding of the infrarenal neck was performed with two 10-mm polyester Dacron limbs tied in the same fashion, close to one another, and parallel just below the renal arteries. We describe the steps of the surgical technique in detail and we analyze crucial issues associated with the technique.

CONCLUSIONS

In this paper, we presented a useful technique for simultaneously treating a type Ia endoleak and aortic neck rupture during endovascular abdominal aortic aneurysm repair. Effective external banding of the infrarenal neck led to control of the hemorrhage and exclusion of the blood flow in the aneurysm sac.

Laparo- and thoracoscopic aortic aneurysm neck optimization and treatment of potential endoleaks type IA and II in a porcine model

Background

Endovascular repair of aortic aneurysms has a higher incidence of late complications, and open conversion (OC) associated with high mortality may be required. As alternatives to OCs, we propose minimal invasive laparo-/thoracoscopic approaches, either to control endoleaks after endovascular repair, or to convert non-endovascular treatable cases due to a hostile neck anatomy by inserting a peri-aortic PTFE collar before endovascular repair. Such interventions may reduce complications and the necessity for OCs in the future.

Methods

In twelve pigs, were 10 had infra-/juxtrarenal AAAs, externally placed collars/aneuwraps around the proximal AAA neck and just below the left subclavian artery and division of the aortic side branches were carried out laparo-and thoracoscopically.

Results

For the laparoscopic and thoracoscopic procedures respectively, mean operative time was 143 ± 41 min and 86 ± 51 min and a mean of 2.6 and 2.25 aortic side branches were ligated/divided. For both procedures, the last half in the series were carried out significantly faster (p < 0.05) indicating a learning curve. Blood loss was minimal and no procedure related complications were seen.

Conclusion

Using these minimal invasive endoscopic approaches, it seems feasible to externally band aneurysm necks and ligate aortic side branches in a pig model. These procedures could potentially be considered as alternatives to OCs in controlling endoleaks and in improving the safety of endovascular interventions. As endoscopic aortic surgery is challenging a learning curve is expected. Practicing the described procedures using this model, can be used as a learning tool prior to similar interventions on humans.

•

Laparo-/thoracoscopic approaches for treating endoleaks can be simulated in a pig model.

•

Laparo-/thoracoscopic approaches to optimize a challenging aortic aneurysm neck can be simulated in a pig model.

•

Endoscopic aortic surgery is challenging and a learning curve must be expected.

•

A pig model with aortic aneurysm can be used as a realistic surgical learning tool before human application.

A standardized aortic aneurysm model for the assessment of endovascular stent-graft technology

Reliable models of aortic aneurysms are required to test endovascular stent-graft technology prior to human use. We describe the creation of a standardized prosthetic aneurysm in an ovine model to assess endovascular technology. In an adult ovine model under general anesthesia, a polyester sphere measuring 6 cm across was sutured onto the infrarenal aorta following aortotomy. Two weeks later an endovascular stent-graft was deployed in the aorta. Exclusion was confirmed on monthly ultrasound duplex and during angiography at three months and under terminal anesthesia at six months. Autopsy along with histology of the specimen were then performed. A total of 10 sheep underwent aneurysm implantation. Nine received a straight tube endovascular stent-graft (Lombard Medical, Abingdon, Oxon, UK) and seven completed the study. Five prosthetic aneurysms shrank during serial imaging with duplex ultrasound and angiography. However, two remained the same size. One of these had a type I endoleak whereas the other had endotension (type I endoleak confirmed at autopsy). This animal model provides a reliable and reproducible method of creating prosthetic aneurysms for assessing endovascular stent-grafts. It was possible to assess aneurysm exclusion non-invasively using duplex ultrasound. Aneurysms effectively excluded from the circulation shrank whereas those with an endoleak did not.

A novel alternative to open conversion for type 1 endoleak resulting in ruptured aneurysm

In this article, a novel technique for the treatment of ruptured abdominal aortic aneurysm secondary to proximal type 1 endoleak as a result of progressive neck dilatation after endovascular aneurysm repair is reported. A 74-year-old man with multiple comorbidities including severe ischemic heart disease, congestive cardiac failure, and chronic renal failure presented with a ruptured abdominal aortic aneurysm. He had an infrarenal endovascular aneurysm repair performed in 1999 and had subsequently developed a proximal type 1 endoleak. At open laparotomy, the placement of 4 nylon ties around the infrarenal aneurysm neck to refashion a seal and exclude the sac from systemic pressurization effectively treated the rupture. In the high-risk patient, ruptured proximal type 1 endoleak can be successfully treated with external banding avoiding the potential morbidity seen with the aortic clamping and blood loss of open conversion.

Development of endovascular stent-grafts

The very first experiences in the early 1990s with endovascular aortic stent-grafts were associated with significant numbers of complications including an inability to deploy the stent-graft, conversion to open surgery, and aneurysm rupture. By the mid-1990s, improved home-made and commercially available stent-grafts started to appear. These devices could be successfully deployed in the aorta, achieving aneurysm exclusion with low morbidity and mortality. However, follow-up results raised concerns about the longer-term durability. Gradually, too, these problems have been addressed such that, in the recent UK multi-centre randomized controlled trial of endovascular versus open aneurysm repair, aneurysm-related mortality was 3 per cent less in the endovascular group four years following surgery. Currently the indications for aortic stent-grafts are being expanded. It is now possible to maintain perfusion successfully in aortic side branches and to treat aneurysms that would have once been thought untreatable. This review paper reviews the main developments in endovascular stent-grafting and the major role played by medical engineering and technology.

Funnel technique for first-line endovascular treatment of an abdominal aortic aneurysm with an ectatic proximal neck

PURPOSE

To describe a novel endovascular technique for proximal stent-graft fixation in an abdominal aortic aneurysm (AAA) with an ectatic aortic neck.

CASE REPORT

An 84-year-old man with multiple comorbidities and an asymptomatic 7-cm infrarenal AAA with a 38-mm aortic neck diameter was treated with a 3-component Talent-LPS stent-graft system. After the left internal iliac artery was embolized with coils, a 34 x 16 x 170-mm Talent bifurcated stent-graft was placed in the lower part of the AAA. A 44-mm-diameter, 90-mm-long free-flow thoracic tube endograft (6-mm oversizing) was delivered to the proximal neck through the bifurcated device and deployed with at least 30 mm of overlap, leaving more than 40 mm extending into the infrarenal aorta to ensure expansion to its nominal diameter as well as an adequate seal. An iliac extension was deployed into the left external iliac artery, and 2 sequential iliac extensions were inserted from the bifurcated stent-graft limb to the right common iliac artery in a bell-bottom configuration. Serial computed tomographic angiograms at up to 18 months have documented the intact 3-component stent-graft, with no endoleak or migration and no increase in aneurysm sac diameter.

CONCLUSION

This case illustrates the feasibility of placing a straight thoracic endograft as a proximal extension of a bifurcated aortic endograft into a dilated proximal aortic neck. This endograft configuration appears secure and effective, with no type I endoleak or migration over a midterm follow-up.

Surgical corrections of endovascular aneurysms: repair complications

The authors describe their experience with the use of 21 open surgical corrections after endovascular abdominal aneurysm repair, reporting the frequency, type and outcome of these procedures in their group of 165 patients treated during a 10-year period.

Laparoscopic aortic reinforcement and endovascular graft placement in swine: a new external wrap

OBJECTIVE

To evaluate the feasibility, safety, and histological response of laparoscopic external aortic wrap implantation in conjunction with an endovascular stent/stent-graft placement in the infrarenal aorta in a porcine model.

METHODS

Seven swine underwent laparoscopic retroperitoneal placement of a custom-made Dacron fabric wrap placed around the infrarenal aorta to create a landing zone for an endovascularly placed aortic stent/stent-graft.

RESULTS

Technical success was achieved in all animals without any major complications. Follow-up ranged from 1 to 4 weeks. At necropsy, the external wraps were well incorporated into the adventitia, and the stents/stent-grafts were well incorporated into the intima. Small patches of medial necrosis of the aortic wall were observed in one animal in the stent model and in two animals in the stent-graft model. There was no transmural necrosis observed. CONCLUSIONS This adjunct technique, an external wrap around the infrarenal aorta combined with endovascular grafting, is feasible and deserves further studies into how it may be used to facilitate endovascular repair of aortic aneurysms.

CLINICAL RELEVANCE

We hypothesize that our new device could provide capability of altering the proximal neck morphology of abdominal aortic aneurysm and reinforcement to the aortic wall. This, in turn, could improve eligibility for endovascular aneurysm repair and prevent or treat type I endoleak and graft migration. Future investigations will involve evaluation of the long-term effect of the external aortic wrap on the integrity of the aortic wall in an animal model and testing the clinical usefulness of this new technique.

Banding in aortic stent-graft fixation in EVAR

The authors describe the method of surgical aortic banding for better stent-graft fixation in cases of problematic aortic neck in the endovascular infrarenal aneurysms repair.

Long-term renal function following endovascular aneurysm repair with infrarenal and suprarenal aortic stent-grafts

PURPOSE

To determine in a retrospective analysis the incidence of renal impairment (RI) following endovascular repair (EVR) of abdominal aortic aneurysm (AAA), to assess the morbidity and mortality in endograft patients with preoperative RI, and to examine the impact of suprarenal stent-grafts on renal function.

METHODS

From March 1994 to October 2001, 315 AAA patients (289 men; mean age 72.4+/-7.0 years) undergoing EVR were entered prospectively into a vascular registry. The patients received either an in-house custom-made stent-graft or one of several commercially made devices implanted with infrarenal or suprarenal fixation. Renal function was monitored by serum creatinine measurements prior to discharge and at 3, 6, and 12 months and annually thereafter. Preoperative RI was defined as a serum creatinine >130 micro mol/L and/or long-term dialysis. Postoperative RI referred to a >20% increase in the serum creatinine over baseline. Additional deterioration of renal function in patients with preoperative RI was referred to as postoperatively worsened RI.

RESULTS

Of the 315 patients treated, 220 (69.8%) were considered high risk (ruptured AAA or ASA grade III or IV). Sixty-nine (21.9%) patients had preoperative RI (6 [1.9%] on preoperative dialysis). A suprarenal stent-graft was used in 169 (53.7%) patients and infrarenal stent-graft in the remaining 146 (46.3%). The mean follow-up was 30.1+/-22.7 months. Postoperative RI occurred in 53 (16.8%) patients (24 [7.6%] transient, 29 [9.2%] persistent). Patients with preoperative RI had a significantly higher incidence of postoperatively worsened RI (37.7% versus 11.0%, p<0.0001) and a higher mortality related to RI (7.2% versus 1.6%, p=0.02). Suprarenal fixation had no influence on the incidence of RI, on perioperative mortality, or on mortality related to RI. The only significant predictive factor of postoperative RI was preoperative RI (risk ratio 5.09, 95% CI 2.38 to 10.87, p=0.0001).

CONCLUSIONS

Endovascular AAA repair may lead to persistent postoperative RI in nearly 10% of cases, especially in patients with preoperative RI. Suprarenal stent-graft fixation does not seem to have any deleterious effect on renal function. Further long-term studies are required to confirm the innocuous nature of transrenal stent placement.

Adjunctive procedures for the treatment of proximal type I endoleak: the role of peri-aortic ligatures and Palmaz stenting

PURPOSE

To investigate the feasibility, efficacy, and long-term effects of peri-aortic ligatures and Palmaz stenting used to treat proximal type I endoleak after endovascular repair (EVR) of abdominal aortic aneurysm (AAA).

METHODS

An 8-year single-center experience with proximal type I endoleak was reviewed; the records of the 55 identified cases were examined to ascertain the methods of treatment used. Among these, all 22 patients who were treated with peri-aortic ligatures and Palmaz stenting were segregated for analysis.

RESULTS

The 22 patients (14 men; mean age 74.6 years, range 66-85) with proximal type I endoleak (18 early, 4 late) selected for analysis underwent 23 secondary procedures: 15 involving peri-aortic ligatures and 8 Palmaz stent implantations. Of the 18 early endoleaks, 11 were treated intraoperatively and 7 were observed. Ten (45%) patients died within 30 days of endoleak treatment: 8 had early endoleaks. Five of the 10 deaths occurred in patients successfully treated with peri-aortic ligatures (3/10) or Palmaz stenting (2/7). The 12 (54%) surviving patients suffered no aneurysm-related deaths or secondary endoleaks over a median follow-up of 20 months (range 4-75).

CONCLUSIONS

Endoleak is an important mode of failure after endovascular repair. Peri-aortic ligatures and Palmaz stenting are feasible techniques for the treatment of proximal endoleak; however, the perioperative mortality of peri-aortic ligatures was higher when compared with other less invasive techniques. In contrast to other therapeutic options, these methods are more effective in the short and medium term.