The ins and outs of the excluded abdominal aortic aneurysm: decreasing diameters and dilating necks

Disparate outcome after endovascular treatment of small versus large abdominal aortic aneurysm

OBJECTIVES

The size of an abdominal aortic aneurysm is the most important parameter for determining whether repair is appropriate. This decision, however, must be considered in the context of long-term outcome of treatment, balancing risk for rupture with mortality from the initial procedure and all subsequent secondary procedures necessary when durability is not ideal. Information on the results of endovascular repair of small versus large aneurysms has not been available.

METHODS

Preoperative imaging studies and postoperative outcome were assessed in 700 patients who underwent endovascular repair of abdominal aortic aneurysm over 6 years at a single institution. Patients were divided into two groups: 416 patients (59.4%) with aneurysms smaller than 5.5 cm in diameter and 284 patients (40.6%) with aneurysms 5.5 cm or larger in diameter. Outcome variables were assessed with the Kaplan-Meier method and the log-rank test.

RESULTS

Patients with small and large aneurysms were comparable with regard to all baseline parameters assessed, with the single exception of a small increase in age (2.3 years) in patients with large aneurysms (P =.031). While there were no differences in rate of type II endoleaks, mid-term changes in sac diameter, or aneurysm rupture between the two groups, at 24 months patients with large aneurysms had more type I leaks (6.4% +/- 2.3% vs 1.4% +/- 0.6%; P =.011), device migration (13% +/- 4.0% vs 4.4% +/- 1.8%; P =.006), and conversion to open surgical repair (8.2% +/- 3.2% vs 1.4% +/- 1.1%; P =.031). Of greatest importance, at 24 months patient survival was diminished (71% +/- 4.6% vs 86% +/- 2.8%; P <.001) and risk for aneurysm-related death was increased (6.1% +/- 2.6% vs 1.5% +/- 1.0%; P =.011) in the group with large aneurysms.

CONCLUSIONS

Outcome after endovascular repair of abdominal aortic aneurysm depends on size; results appear inferior in patients with larger aneurysms. These differences attain importance when choosing between observation and repair, balancing risk for rupture against size-dependent outcome.

Longitudinal aneurysm shrinkage following endovascular aortic aneurysm repair: a source of intermediate and late complications

PURPOSE

To report the incidence of delayed complications following endovascular abdominal aortic aneurysm (AAA) repair and the relationship of these sequelae to morphological changes in the sac and endograft.

METHODS

Twenty-six AAA patients treated with Vanguard endografts had completed > or = 1-year follow-up. Postoperative angiograms and spiral computed tomographic (CT) scans with 3-dimensional reconstruction were compared to the 1-year images to determine morphological changes in the aneurysm sac and the endograft. These changes were then related to complications occurring between 1 and 12 months postoperatively in the study group.

RESULTS

Comparison of angiograms uncovered endograft buckling in 18 (69%) patients and acutely angled or kinked endografts in 10 (38%). Measurements from the CT scans found that undistorted endografts had a mean change in sac length of +6.6 mm. Mean sac length change in buckled endografts was -3.1 mm, while kinked endografts displayed a mean change of -6.2 mm (p < 0.002, Student's t-test). Five (19%) patients, all with distorted endografts, demonstrated late (1 to 12 months) complications (4 endoleaks and 1 graft limb thrombosis) owing to component separation, distal stent migration, and acute angulation. No movement in the proximal stent was observed. Elongation of the endograft (flow line measurement) was observed in one tube graft only.

CONCLUSIONS

In this study, longitudinal shrinkage of the sac following endovascular aortic aneurysm repair led to buckling or kinking of the endograft within 1 year in 69% of patients. This appears to be an important source of delayed complications.

Thrombus distribution and changes in aneurysm size following endovascular aortic aneurysm repair

OBJECTIVES

To determine (a) changes in aneurysm size following endovascular repair, (b) the significance of collateral lumbar artery blood flow and (c) the relationship between thrombus distribution within the aneurysm sac and the development of a "lumbar endoleak".

MATERIALS AND METHODS

72 patients treated with endovascular stent-grafts were followed up with spiral computed tomography for a median of 11 (range 3-27) months. The cross-sectional area of the aneurysm was measured at the point of maximum diameter pre- and post-operatively. The distribution and quantity of thrombus was recorded pre-operatively and this was related to changes in aneurysm size and the development of lumbar endoleaks post-operatively.

RESULTS

An increase in aneurysm size occurred in 22 patients, of whom 10 had endoleaks. Fifteen aneurysms did not change in size, including four with endoleak, and 35 aneurysms decreased in size with no endoleaks. There was a significant difference between the endoleak and no endoleak groups (Chi-squared test = 17.1 with 2 degrees of freedom (d.f.), p < 0.001). Nine endoleaks were from patent lumbar arteries. No patients with thick circumferential or posteriorly placed thrombus developed an endoleak arising from lumbar vessels (0/23 cases) compared to those with minimal or anteriorly placed thrombus (9/49 cases) (Chi-squared test with Yate's correction = 3.17 with 1 d.f., p < 0.1).

CONCLUSIONS

Aneurysms do not decrease in size in the presence of a lumbar endoleak, and some expand significantly. A number of aneurysms increase in size despite no evidence of an endoleak on computed tomography (CT). Patterns of thrombus distribution may be able to predict patients at risk from persistent endoleak via lumbar vessels.

The role of infrarenal aortic side branches in the pathogenesis of endoleaks after endovascular aneurysm repair

AIM

To investigate the relation between the number of preoperative patent side branches and the presence or absence of postoperative endoleaks, and to study the fate of patent branches after operation.

PATIENTS AND METHODS

Thirty consecutive patients were included. Cine mode viewing of axial CT angiography images was applied to detect infrarenal aortic side branches. The position of side branches relative to the renal arteries, branch patency and run-off pathways were studied.

RESULTS

A total of 160 patent side branches were found. All patients had two or more patent side branches. A patent inferior mesenteric artery was found in 22/30 patients (73%). Postoperative CT scans revealed major endoleaks in five patients (16%) and minor endoleaks in eight (27%). There was no significant difference in the number of preoperative patent side branches in patients with a completely thrombosed aneurysm sac (five; range 2-8) compared to patients with postoperative endoleaks (six; range 3-9; p = 0.12). Backbleeding from patent side branches as the sole cause of endoleak was seen in one patient only (3.3%).

CONCLUSION

Postoperative endoleaks are not related to the number of preoperative patent side branches. In patients without endoleaks, contrast enhancement of side branches was repeatedly seen in the vicinity of the aneurysm wall. Although close follow-up of these branches is warranted, they did not affect the outcome of endovascular aneurysm repair.

Endoluminal repair of large abdominal aortic aneurysms using PTFE: a feasibility study

PURPOSE

To investigate the feasibility of using predilated thin-wall polytetrafluoroethylene (PTFE) secured by extra-large Palmaz stents for endoluminal repair of abdominal aortic aneurysms (AAA).

METHODS

Thirty-two patients (26 males; aged 69 to 83 years) from three centers (two in Europe, one in Australia) were selected for endoluminal stent-grafting using predilated B-mm PTFE graft material fitted with extra-large Palmaz stents at the terminal ends. Aortoaortic tube grafts were implanted in 12 patients, while the remainder received aortomonoiliac endografts and femorofemoral bypass. Follow-up at 5 days and then biannually was by contrast-enhanced computed tomography (CT) or duplex scanning.

RESULTS

There were 13 conversions to open surgery; these patients died within 30 days. Nineteen patients were discharged with functioning endografts within 5 days of treatment. Of these, two have had their grafts removed owing to infection in one and distal stent migration in the other. Two endoleaks have been detected in follow-up; one has been sealed by covered stenting. One twisted graft was repaired by Wallstent implantation. Seventeen patients remain well, one with persistent distal endoleak, but none shows an increase in AAA diameter on imaging over the 6- to 26-month (median 13) follow-up.

CONCLUSIONS

These results represent the learning curves of three separate centers. Technical failure and complications were more common early in the study. Advantages of the technique include relative low cost and the ability to tailor the stent-graft to the individual aneurysm.