Abdominal Aortic Aneurysms: Experience with the Ivancev-Malmö Endovascular System for Aortomonoiliac Stent-Grafts

Mortality Rates following Endovascular Repair of Abdominal Aortic Aneurysms

Purpose:

To present the perioperative and late mortality following endovascular repair (EVR) of abdominal aortic aneurysms (AAAs).

Methods:

Data were collected prospectively on 221 patients undergoing AAA EVR over a 4-year period (median 5-month follow-up). Patients were classified preoperatively as high risk with at least 1 of these features: serum creatinine > 150 μmol/L, ischemic heart disease or poor left ventricular function, respiratory function < 50% of predicted normal, ruptured or symptomatic AAA, contraindication to or failed open repair, and age > 80 years.

Results:

One hundred forty (63.3%) patients were classified as high risk, the most common criterion being cardiac disease (n = 96, 68.6%). There were 25 (11.3%) deaths in the 30-day perioperative period, 22 (15.7%) in the high-risk group compared to 3 (3.7%) in the acceptable-risk group (p = 0.02). The most common causes of perioperative death were multisystem organ failure and myocardial infarction. A further 21 (9.5%) late deaths occurred, 16 (11.4%) in the high-risk group and 5 (6.2%) in the acceptable-risk group (p > 0.1).

Conclusions:

The mortality of patients at acceptable risk undergoing EVR compares with the best published series for conventional open AAA repair. The perioperative and late mortality in the high-risk patients are substantially higher.

Percutaneous Modular Stent-Grafts in the Treatment of Abdominal Aortic Aneurysms

Purpose:

To describe a newly designed bifurcated modular stent-graft and assess the feasibility and safety of its use in the treatment of abdominal aortic aneurysms (AAA).

Methods:

Thirteen patients (10 men; mean age 61.2±16 years, range 57–78) with AAAs underwent treatment with a bifurcated stent-graft consisting of 4 components: an unsupported bifurcated stent-graft, an inner bare stent, and 2 stent-grafts. The system was placed sequentially through a percutaneously introduced 12-F sheath; the preloaded bifurcated main body of the stent-graft was deployed first, followed by the inner bare stent and individual stent-graft limbs through separate 10-F sheaths. Spiral computed tomography (CT) was performed before treatment and at 1 week, 3 months, and then at 6-month intervals.

Results:

The stent-grafts were successfully deployed in all patients, although 3 types of procedure-related adverse events occurred: left limb kinking in 1, postimplantation syndrome (fever, leukocytosis, and decreased platelet count) in 5, and a small access site arteriovenous fistula in 1. Postprocedural angiography and 1-week follow-up CT scanning did not identify any endoleaks. At a mean 9.2±4.6-month follow-up, all devices were intact, with complete exclusion of the aneurysms and no endoleaks.

Conclusions:

This newly designed bifurcated modular stent-graft appears to be effective for percutaneous AAA repair; further investigation is warranted.

Abdominal Aortic Aneurysm Morphology in Candidates for Endovascular Repair Evaluated with Spiral Computed Tomography and Digital Subtraction Angiography

Purpose:

To analyze the morphology of abdominal aortic aneurysms (AAAs) and to study the usefulness of spiral computed tomography (CT) versus digital subtraction angiography (DSA) in the evaluation of patients for endovascular repair.

Methods:

Of 133 AAA patients (120 men, mean age 67 years, range 52 to 84) evaluated preoperatively with CT imaging, 77 endograft candidates (68 men) were also assessed with intra-arterial DSA. Arterial parameters were measured on axial CT scans and angiographic films for comparison.

Results:

Mean maximum AAA diameter was 58 ± 11 mm (range 39 to 95). Aneurysmal neck diameter was consistently smaller on DSA than on CT (20.7 ± 3.6 mm versus 23.0 ± 3.5 mm, p < 0.0001). The distance from the most distal renal artery to the aortic bifurcation was longer on angiography than on CT (mean difference 10.0 mm, p < 0.0001). There was a positive correlation between the maximum AAA diameter and the AAA length (r = 0.49, p < 0.0001) and an inverse relationship between the neck length and the neck diameter (r = −0.36, p < 0.0001). No correlation was found between the maximum AAA diameter and maximum iliac diameter, angulation, or length.

Conclusions:

AAA anatomy varies widely and independently of the aneurysm size. Therefore, the maximum size of the aneurysm is a poor predictor of whether or not an aneurysm is suitable for endovascular repair. The discrepancy between angiographic and axial CT measurements suggests that neither alone is sufficient as a preoperative imaging technique when evaluating a patient for an endovascular graft procedure.

Endovascular Repair of Abdominal Aortic Aneurysm Using the EVT Device: Limited Increased Utilization with Availability of a Bifurcated Graft

Purpose:

To determine if the availability of a bifurcated graft would increase the percentage of patients eligible for endovascular repair of abdominal aortic aneurysms (AAAs).

Methods:

One hundred eighty-five consecutive patients were evaluated prospectively for endovascular AAA repair at a university referral center. Data were collected on eligibility for tube or bifurcated endovascular grafts, reasons for exclusion, aneurysm morphology, and the interventions performed.

Results:

Forty-six (25%) patients were eligible for endovascular treatment using the first-generation Endovascular Technologies (EVT) system: 19 (10%) for a tube graft and 27 (15%) for a bifurcated device. An unsuitable proximal neck was the reason for exclusion in 48% of patients (excess diameter in 27%, inadequate length in 21%). Unsuitable iliac configuration was present in 41% of those excluded; 29% of the common iliac arteries were enlarged or aneurysmal, while 12% were small or tortuous.

Conclusions:

Although a bifurcated graft more than doubles the eligibility of AAA patients for endovascular repair, the configuration of the proximal neck and iliac disease excluded the majority of AAA patients from endovascular therapy using the first generation EVT device.

Endovascular AAA Exclusion: Will Stents with Hooks and Barbs Prevent Stent-Graft Migration?

Purpose:

To investigate if stents with hooks and barbs will improve stent-graft fixation in the abdominal aorta.

Methods:

Sixteen- to 24-mm-diameter Dacron grafts were deployed inside cadaveric aortas. The grafts were anchored by stents as in endovascular abdominal aortic aneurysm repair. One hundred thirty-seven stent-graft deployments were carried out with modified self-expanding Z-stents with (A) no hooks and barbs (n = 75), (B) 4 5-mm-long hooks and barbs (n = 39), (C) 8 10-mm-long, strengthened hooks and barbs (n = 19), or (D) hooks only (n = 4). Increasing longitudinal traction was applied to determine the displacement force needed to extract the stent-grafts. The radial force of the stents was measured and correlated to the displacement force.

Results:

The median (interquartile range) displacement force needed to extract grafts anchored by stent A was 2.5 N (2.0 to 3.4), stent B 7.8 N (7.4 to 10.8), and stent C 22.5 N (17.1 to 27.9), p < 0.001. Both hooks and barbs added anchoring strength. During traction, the weaker barbs were distorted or caused intimal tears. The stronger barbs engaged the entire aortic wall. The radial force of the stents had no impact on fixation, while aortic calcification and graft oversizing had marginal effects.

Conclusions:

Stent barbs and hooks increased the fixation of stent-grafts tenfold, while the radial force of stents had no impact. These data may prove important in future endograft development to prevent stent-graft migration after aneurysm exclusion.

Use of Proximal Aortic Cuffs as an Adjunctive Procedure during Endovascular Aortic Aneurysm Repair

The purpose of this study was to evaluate the incidence and durability of additional proximal cuffs during endovascular abdominal aortic aneurysm repair (EVAR). A retrospective review of 90 EVAR patients was conducted. Postoperative survival, proximal sealing zone–related complications, and secondary procedures were analyzed.

Additional proximal cuffs were used in 11%. Their use did not affect postoperative survival ( p = .58), type I endoleak rate (4.4%; p = .19), or the need for sealing zone–related secondary procedures (6.3%; p = .38) compared with patients without cuff placement but was related to a higher cumulative graft migration rate (2.2% overall p = .02). Two patients (2.5%; p = .79) underwent conversion to open surgery, both for proximal sealing zone–related complications.

Application of proximal cuffs appears to be an effective intraoperative adjunctive procedure to achieve a proximal seal during EVAR, with favorable midterm results. However, the risk of late endograft migrations may be elevated in this group.

Thromboembolic complications after endovascular repair of abdominal aortic aneurysm with neck thrombus

OBJECTIVE

To evaluate outcomes after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) with neck thrombus.

METHODS

We retrospectively reviewed patients who underwent EVAR for AAA at our institution from 2007 to 2011. Patients with ruptured AAA, chronic renal failure, or hostile neck characteristics other than thrombus were excluded. Patients were divided into 2 groups: group T (with neck thrombus) and group N (without neck thrombus). We compared complications and mid-term outcomes.

RESULTS

There were no differences in success rates between the groups, but there were higher rates of thromboembolic complications such as distal embolization (20% vs 0%, P = .02) and renal dysfunction (36.8% vs 11.1%, P = .03) in group T than in group N. Suprarenal thrombus and suprarenal fixation in the presence of suprarenal thrombus were associated with postoperative renal dysfunction (P = .01).

CONCLUSION

The EVAR for AAA with neck thrombus is associated with thromboembolic complications.

Aortomonoiliac stent-grafts for abdominal aortic aneurysm repair: association with iliofemoral crossover grafts

PURPOSE

To analyze the outcome of endovascular exclusion of abdominal aortic aneurysm (AAA) using aortomonoiliac stent-grafts.

METHODS

Fifty-seven consecutive patients (49 men; median age 70, range 56-89) with AAA >5 cm were treated in a 6-year period with the conical ELLA stent-graft. Forty-two (73.9%) patients were classified ASA (American Society of Anesthesiologists) IV and 6 as ASA V. In the majority of cases, the implantation procedure featured device delivery through the external iliac artery, transrenal placement of a bare stent in selected cases, and an iliofemoral crossover graft through a prevesical tunnel.

RESULTS

Successful deployment was achieved in 56 (98.2%) patients. Mean time to discharge was 8.7 days (range 2-125). Two patients died in the 30-day period. Nine endoleaks occurred in 8 (14%) patients; 4 required further intervention. Mean follow-up was 35.3 months (range 1-66), during which 5 patients died from unrelated causes. No late endoleak, graft occlusion, device twisting/migration, or aneurysm rupture was observed. No correlation between type I endoleaks and unfavorable proximal neck or iliac artery anatomical characteristics could be found. Primary technical and clinical success rates were 86.0% and 94.7%, respectively.

CONCLUSIONS

In this approach, the crossover graft remains in a retropubic space and consequently does not have all the disadvantages of a subcutaneously placed prosthesis. The results achieved in this group of high-risk patients support recommendation of this technique as a simple and safe alternative to bifurcated systems.

Factors and forces influencing stent-graft migration after endovascular aortic aneurysm repair

PURPOSE

To assess and validate the clinical features predisposing to stent-graft migration and to calculate the distal displacement forces exerted at the proximal fixation site following endovascular aortic aneurysm repair (EVAR).

METHODS

Demographic, anatomical, and graft-related features from 2862 patients were analyzed in a regression model to identify variables associated with stent-graft migration, which was defined as device movement >5 mm or considered significant by the investigator. Using the principles of continuity and momentum, a mathematical model of blood flow was created. The pulse pressure, proximal aortic and distal iliac diameters, and the degree of iliac angulation were varied in the calculations, and the distal displacement force exerted at the proximal fixation site was calculated.

RESULTS

Ninety-nine patients developed stent-graft migration, which was clinically relevant in 85 (3.0%). Hypertension (p=0.015), smoking (p=0.009), maximal aortic diameter (p=0.004), and distal transverse aortic diameter (p=0.03) correlated with migration in the univariate analysis, but iliac angulation did not quite achieve significance (p=0.06). On multivariate analysis, current smoking, hypertension, distal transverse aortic diameter, maximum common iliac diameter, and increasing proximal graft size were significantly associated with stent-graft migration. The mathematical model calculated the distal displacement force exerted on the proximal fixation site of the stent-graft and validated the clinical findings. The ratio of graft-diameter change from proximal aorta to distal iliac influenced the greatest increase in the displacement force.

CONCLUSIONS

The mathematical model validated hypertension, aneurysm morphology, and endograft size as clinical factors significantly associated with stent-graft migration. These findings may have important implications for the choice and design of future stent-grafts.

Intraoperative proximal endoleaks during AAA stent-graft repair: evaluation of risk factors and treatment with Palmaz stents

PURPOSE

To study factors that might contribute to intraoperative proximal type I endoleak and to evaluate the placement of giant Palmaz stents as a therapeutic option.

METHODS

Thirty-three patients (30 men; median age 72 years, range 50-85) with abdominal aortic aneurysms underwent implantation of fully supported Gianturco Z-stent-based endografts (12 custom-made aortomonoiliac and 21 bifurcated Zenith devices). Ten (30%) patients were treated for intraoperative proximal endoleaks. Stent-graft oversizing and neck angulation, length, and shape were compared between patients with and without leaks.

RESULTS

In 9 cases, the endoleaks were successfully treated with intraoperative placement of Palmaz stents without complications. In 1 patient, a leak that was resolved intraoperatively with balloon dilation reappeared 1 month later; a Palmaz stent was deployed successfully. Stent-graft oversizing did not differ significantly between patients who developed proximal endoleaks and those who did not (median 4.0 mm in both groups, p = 0.47). Median neck length was 21.0 mm in patients with endoleak and 28.0 mm in those without (p > 0.99). Median neck angulation was 30 degrees in both groups (p = 0.33), and the presence of a conical aneurysm neck was not significantly different (2/10 versus 6/23, p > 0.99). All aneurysms remained excluded at a median follow-up of 13 months (range 6-24).

CONCLUSIONS

Stent-graft oversizing and neck morphology (length, angulation, and conical shape) do not seem to correlate with the incidence of proximal type I endoleaks. Palmaz stent placement appears to be a feasible and safe treatment option for this complication.

Endovascular repair of perisplanchnic abdominal aortic aneurysm with visceral vessel transposition

PURPOSE

To report a combined endoluminal and open surgical approach for a suprarenal abdominal aortic aneurysm (AAA) with coexistent splanchnic vessel stenoses.

METHODS AND RESULTS

A 64-year-old man presented with an aneurysm of the proximal abdominal aorta and severe stenoses of the celiac axis and superior mesenteric artery (SMA). An initial 2-stage plan to stent the visceral vessel stenoses and exclude the aneurysm with a fenestrated stent-graft failed when the celiac lesion could not be crossed. The approach was changed to restore visceral perfusion with a bifurcated left iliosplenic and ilio-SMA bypass graft. Exclusion of the aneurysm was achieved with a custom-made suprarenal aortic tube stent-graft (Ivancev-Malmö) system. The patient is free of symptoms at 22 months, and there was no aneurysm visible on the 14-month CT scan.

CONCLUSIONS

Hybrid techniques are an alternative treatment for complex perivisceral aortic aneurysms when total endovascular reconstruction is not possible.

Quality of life before and after endovascular and open repair of asymptomatic AAAs: a prospective study

PURPOSE

To assess how patients perceive health-related quality of life (HRQOL) after endovascular and open abdominal aortic aneurysm (AAA) repair.

METHODS

Forty-two consecutive patients (33 men; mean age 74 years, range 46-81) were assessed prospectively before and after elective endovascular (n = 21) and open (n = 21) AAA repair. Aneurysm morphology dictated the type of repair. The two patient groups were similar regarding age, gender, comorbidities, and cardiopulmonary function. Data concerning surgical trauma were compiled. The Nottingham Health Profile (NHP) score was used to assess the perceived HRQOL (criteria: pain, mobility, sleep, emotion, energy, and isolation) preoperatively and at 5, 30, and 90 days postoperatively. Specific treatment perception questions were added.

RESULTS

One patient from each group died, leaving 40 patients to complete the study. Two patients with open repair and 1 patient with endovascular repair were unfit to answer the questionnaire on day 5. The HRQOL improved at 3 months compared with the preoperative values (p < 0.05). No significant difference was found at any time between the open and endovascular groups regarding the NHP score, although the operative time, blood loss, analgesic use, and hospital stay were significantly in favor of endovascular repair. Reinterventions were required in 5 patients with endovascular and 2 patients with open repair.

CONCLUSIONS

In general, 3 months after AAA repair, the perceived HRQOL seems better than before treatment. Perceived HRQOL is similar after endovascular and open AAA repair despite greater surgical trauma in open surgery. This may reflect the higher number of reinterventions following endovascular repair but also difficulties in defining HRQOL.

Aortic stent-grafting with transrenal fixation: use of newly designed spiral Z-stent endograft

PURPOSE

To evaluate the feasibility and efficacy of a newly designed stent-graft placed across the renal arteries for exclusion of abdominal aortic aneurysms (AAAs) with short or tortuous proximal necks.

METHODS

Among a group of AAA patients treated with endovascular grafting, 5 had tortuous proximal necks and 13 had necks <20 mm (mean 13 mm). In these 18 cases, a 2- to 3-cm uncovered segment of the stent-graft was placed transrenally using a catheter inserted into the renal artery as a guide for graft margin positioning. A newly designed stent-graft was constructed from a custom-made spiral Z-stent covered with a thin-walled Dacron material; the endografts were deployed through 16-F (aortoaortic model) or 18-F sheaths (bifurcated devices). Renal function was assessed by preoperative and postoperative measurement of urea nitrogen and creatinine. Aneurysm exclusion and renal artery patency were evaluated during follow-up using spiral computed tomography and angiography.

RESULTS

The stent-grafts were correctly placed at the intended site in all 18 patients. Renal function was not affected except transiently in 1 patient who developed bilateral renal artery stenoses 24 hours after the procedure; Palmaz stents were deployed in each renal artery to reestablish satisfactory blood flow. Of the 33 renal arteries crossed by the bare stent-graft segment, all were patent over a mean 14-month follow-up (range 7-24), including the patient with Palmaz stents implanted for postprocedural renal stenosis. Complete aneurysm exclusion was maintained in 15 (83%) of 18 patients; proximal leaks persisted in 3 patients, including 2 with severely angled proximal necks.

CONCLUSIONS

Transrenal placement of the uncovered leading edge of custom-made spiral Z-stent-based endografts appears feasible and clinically effective in the treatment of AAAs with short or tortuous proximal necks.

An endoluminal method of hemorrhage control and repair of ruptured abdominal aortic aneurysms

PURPOSE

To report our initial experience with endovascular grafting to treat ruptured abdominal aortic aneurysms (AAAs).

METHODS

Three consecutive patients with severe comorbid illnesses and symptoms of aneurysm rupture and hemodynamic instability were treated with aortomonoiliac grafts. The Z-stent-based devices were implanted with the assistance of an occlusion balloon placed in the distal descending thoracic aorta.

RESULTS

All patients survived the procedure with successfully excluded AAAs. Two patients had relatively short hospital stays (4 and 14 days), while the third required prolonged treatment for pre-existing conditions. All patients required blood transfusions; 2 developed significant coagulopathies. Definitive management was delayed significantly by imaging protocols and graft construction.

CONCLUSIONS

Endovascular repair of ruptured aortic aneurysms is feasible. Proximal aortic control is readily attainable with the use of an aortic occlusion balloon placed through the left axillary artery. The absence of a laparotomy, extensive retroperitoneal dissection, and aortic cross-clamping likely contributes to patient survival; however, the delay in operative therapy to obtain adequate imaging and construct an endograft could be a hindrance to the ultimate success of this approach. The concepts of alternative aortic imaging techniques and endograft design, construction, and storage must be addressed.

Slimgraft: a percutaneous endovascular graft system

PURPOSE

To describe an in vitro feasibility trial of a new percutaneous endograft delivery technique.

METHODS AND RESULTS

A water flow model of 9-mm (inner diameter) transparent plastic tubing was used to test the feasibility of sequentially delivering the components of an endograft through a 7-F sheath for assembly in situ. The tubular endovascular graft was fabricated from a 10-mm x 68-mm Wallstent and 50-microm-thick Dacron graft. The graft material was formed into a tube, attached with a suture to a guidewire, and delivered into the plastic tubing. The Wallstent was then delivered through the tubular graft and deployed, affixing the graft to the plastic tube wall. In 4 trials, only 1 attempt was not successful.

CONCLUSIONS

These concepts and techniques may have implications in the development of percutaneously deliverable endovascular grafts.

Abdominal aortic aneurysm morphology in candidates for endovascular repair evaluated with spiral computed tomography and digital subtraction angiography

PURPOSE

To analyze the morphology of abdominal aortic aneurysms (AAAs) and to study the usefulness of spiral computed tomography (CT) versus digital subtraction angiography (DSA) in the evaluation of patients for endovascular repair.

METHODS

Of 133 AAA patients (120 men, mean age 67 years, range 52 to 84) evaluated preoperatively with CT imaging, 77 endograft candidates (68 men) were also assessed with intra-arterial DSA. Arterial parameters were measured on axial CT scans and angiographic films for comparison.

RESULTS

Mean maximum AAA diameter was 58 +/- 11 mm (range 39 to 95). Aneurysmal neck diameter was consistently smaller on DSA than on CT (20.7 +/- 3.6 mm versus 23.0 +/ 3.5 mm, p < 0.0001). The distance from the most distal renal artery to the aortic bifurcation was longer on angiography than on CT (mean difference 10.0 mm, p < 0.0001). There was a positive correlation between the maximum AAA diameter and the AAA length (r = 0.49, p < 0.0001) and an inverse relationship between the neck length and the neck diameter (r = -0.36, p < 0.0001). No correlation was found between the maximum AAA diameter and maximum iliac diameter, angulation, or length.

CONCLUSIONS

AAA anatomy varies widely and independently of the aneurysm size. Therefore, the maximum size of the aneurysm is a poor predictor of whether or not an aneurysm is suitable for endovascular repair. The discrepancy between angiographic and axial CT measurements suggests that neither alone is sufficient as a preoperative imaging technique when evaluating a patient for an endovascular graft procedure.