Intraoperative Proximal Endoleaks During AAA Stent-Graft Repair:Evaluation of Risk Factors and Treatment With Palmaz Stents

A retrospective review of Palmaz stenting of the aortic neck for endovascular aneurysm repair

BACKGROUND

To review the aortic neck characteristics, graft types, and technical results of Palmaz stent placement as an adjunct to endovascular aneurysm repair (EVAR).

METHODS

A retrospective review of 110 consecutive EVAR cases identified 18 cases in which Palmaz stents were placed as an adjunct to EVAR. Graft types, hostile aortic neck features (neck diameter: >26 mm, length: <15 mm, angulation: >60°, reverse taper necks), and treatment success were identified.

RESULTS

Technical success in the placement of a proximal Palmaz stent was achieved in 17 of 18 cases. Palmaz stenting was attempted for the treatment of type I endoleak in 17 of 18 patients. One prophylactic stent was deployed in the setting of hostile neck anatomy. Proximal stent deployment resulted in immediate treatment success of type I endoleaks in 16 of 17 patients-one failure occurred in a patient who presented with a delayed type I endoleak. Analysis of aortic neck anatomy revealed that two of 18 patients had no criteria for a hostile neck, seven had one criterion, and nine met at least two criteria. With respect to stent-graft types, nine of 18 (50%) cases used the Endologix Powerlink, six used Gore Excluder, two used Cook Zenith, and one used Medtronic Talent. With a mean follow-up of 254 days, 16 of 17 type I endoleaks remain resolved.

CONCLUSIONS

With proper patient selection and additional adjunctive treatments, Palmaz stenting can effectively treat proximal type I endoleaks.

Influence of Severe Infrarenal Aortic Neck Angulation on Complications at the Proximal Neck Following Endovascular AAA Repair: A EUROSTAR Study

PURPOSE

To examine the influence of severe infrarenal neck angulation (SNA) on complications after endovascular repair of abdominal aortic aneurysm (AAA).

METHODS

From October 1996 to January 2006, 5183 patients who underwent endovascular aneurysm repair using a Talent, Zenith, or Excluder stent-graft were enrolled into the EUROSTAR registry. Incidence of proximal type I endoleak, stent-graft migration, proximal neck dilatation, aneurysm rupture, secondary interventions, and all-cause and aneurysm-related mortality were compared between patients with and without severe infrarenal neck angulation (>60 degrees angle between the infrarenal aortic neck and the longitudinal axis of the aneurysm).

RESULTS

In the short term (before discharge), proximal type I endoleak (OR 2.32, 95% CI 1.60 to 3.37, p<0.0001) and stent-graft migration (OR 2.17, 95% CI 1.20 to 3.91, p=0.0105) were observed more frequently in patients with SNA. Over the long term, higher incidences of proximal neck dilatation > or =4 mm (HR 1.26, 95% CI 1.11 to 1.43, p=0.0004), proximal type I endoleak (HR 1.80, 95% CI 1.25 to 2.58, p=0.0016), and need for secondary interventions (HR 1.29, 95% CI 1.00 to 1.67, p=0.0488) were seen in patients with SNA. All-cause mortality, aneurysm-related mortality, and rupture of the aneurysm were similar in patients with and without severe neck angulation. In the subgroup of patients with an Excluder endograft, proximal endoleak at the completion angiogram (OR 4.49, 95% CI 1.31 to 15.32, p=0.0166) and long-term proximal neck dilatation (HR 1.67, 95% CI 1.20 to 2.33, p=0.0026) were more frequently observed in patients with SNA. In the Zenith subgroup, proximal endoleak at the completion angiogram (OR 2.62, 95% CI 1.49 to 4.63, p=0.0009) and proximal stent-graft migration before discharge (OR 2.34, 95% CI 1.06 to 5.19, p=0.0353) were more common in patients with SNA. In the Talent subgroup, long-term proximal endoleak (HR 2.09, 95% CI 1.27 to 3.44, p=0.0036), proximal neck dilatation (HR 1.29, 95% CI 1.05 to 1.60, p=0.0168), and secondary interventions (HR 1.54, 95% CI 1.05 to 2.24, p=0.0259) were more frequently observed in patients with SNA.

CONCLUSION

Severe infrarenal aortic neck angulation was clearly associated with proximal type I endoleak, while the relationship with stent-graft migration was not clear. Excluder, Zenith, and Talent stent-grafts perform well in patients with severe neck angulation, with only a few differences among devices.

Assessment of Automatic Vessel Tracking Techniques in Preoperative Planning of Transluminal Aortic Stent Graft Implantation

OBJECTIVE

To evaluate automatic vessel tracking techniques in the course of preoperative planning prior to transluminal aortic endograft implantation by comparing accuracy, reproducibility, and postprocessing time with source image and volume-rendered analysis methods.

METHODS

Multislice computed tomography datasets of 5 patients with abdominal aortic aneurysms were preoperatively examined, performing volumetric analysis of diameter and position of renal artery orifices, aneurysmal neck, maximal aneurysmal extension, aortic bifurcation, and iliac arteries and bifurcation. Analysis was realized by utilizing transverse datasets, volume rendering, and automated vessel tracking strategies (MxView, Philips, Best, The Netherlands). Measurement techniques were evaluated by 2 independent readers 3 times for each patient and measurement modality. Statistical analysis evaluated accuracy of the measurements and intra- and interobserver reliability. Postprocessing time was documented.

RESULTS

Using transverse source datasets, intraobserver reliability ranged from 0.49 to 0.58. Intraobserver reliability improved to 0.7 to 0.98 when volume-rendered datasets were evaluated. Interobserver variability for transverse and volume-rendered datasets ranged from 0.49 to 0.76 and 0.70 to 0.96, respectively. Automated vessel tracking datasets did not demonstrate any intra- or interobserver variability. Based on transverse datasets, the length and diameter of iliac arteries and location and diameter of the aneurysmal neck were measured as statistically different in all cases in contrast to volume rendering and automated segmentation techniques. Postprocessing time consumption for measurements based on transverse, volume-rendered, and automated tracking segmentation datasets averaged 3.32 minutes, 25.43 minutes, and 2.24 minutes, respectively.

CONCLUSIONS

Preoperative measurements improve significantly if datasets are evaluated based on volume-rendering techniques. This time-consuming procedure can be shortened, while further reducing observer variability, with automatic segmentation techniques.

Transrenal versus infrarenal endograft fixation: influence on type I endoleaks

The purpose of this study was to compare the rate of proximal type I endoleaks in patients undergoing endoluminal repair of infrarenal abdominal aortic aneurysms with endografts having either transrenal or infrarenal fixation. From September 1998 to May 2000, 42 patients received endoluminal aortic grafts for the treatment of infrarenal abdominal aortic aneurysms. Patients received either transrenal or infrarenal devices, based on the surgeon's preference. All patients had infrarenal aortic neck lengths measuring at least 1.5 cm and proximal neck angulation of <60 degrees. The endoluminal grafts were oversized by 10-20% relative to the diameter of the infrarenal aorta. The presence of endoleaks was determined at the initial procedure by contrast angiography and during subsequent follow-up at 1 month and 3 months by CT scan or duplex ultrasound. No significant differences in the rate of proximal type I endoleaks can be demonstrated between transrenal and infrarenal device types in this small cohort. Proper patient selection is more important than type of proximal fixation in preventing endoleaks.