A simple technique to improve the accuracy of proximal AAA endograft deployment

Normal renal arterial anatomy assessed by multidetector CT angiography: are there differences between men and women?

The purpose of this study was to determine renal arterial anatomy and gender differences in adults without renovascular disease using multidetector computed tomography angiography (MDCTA). MDCTA datasets of 399 patients were retrospectively reviewed. Measurements of the aortorenal diameters, the angulation of the renal ostia and pedicles as well as the distance between the origins of the renal arteries were measured. Differences in measurements between genders were tested for statistical significance using analysis of variance (ANOVA) and Pearson's Chi-Square tests. A total of 798 renal arteries were available for analysis in 207 female (mean age = 52.91 years) and 192 male patients (mean age = 53.04 years). Female patients were found to have smaller aortae (at the level of the right renal ostium) and bilateral renal arteries than males (mean aortic diameter M/F = 18.33/15.89 mm, mean right renal artery ostial diameter M/F = 5.06/4.59 mm, mean left ostial renal diameter M/F = 5.14/4.66 mm) (p < .001). There was no statistical significance for the renal ostia level in relation to the vertebrae and the majority of renal arteries originated at the L1 and L2 levels. The longitudinal distance between right and left renal artery ostia ranged from 0 to 32 mm (mean = 4,6 mm, median = 5mm). The mean anteroposterior orientation of the right renal ostia was M/F = 29.45 degrees/28.20 degrees , and M/F = -7.96 degrees/-11.14 degrees for left renal artery ostia. The mean anteroposterior orientation of the right renal pedicle was M/F = 41.37 degrees/44.34 degrees and M/F = 42.31 degrees/43.95 degrees for the left pedicle. There are some differences in normal renal arterial anatomy between genders. Normal renal arterial information is useful not only for planning and performing of endovascular and laparoscopic urologic procedures, but also for medical device development.

Prediction of altered endograft path during endovascular abdominal aortic aneurysm repair with the Gore Excluder

OBJECTIVE

During endovascular abdominal aortic aneurysm (AAA) repair (EVAR), the rapid deployment of the Gore Excluder endograft may be associated with anatomic shortening of the endograft path. This shortened path may result in coverage of the hypogastric artery origin or overly conservative graft length selection that may lead to unnecessary extensions. We quantified the degree of path alteration with this endograft and developed an algorithm to predict it.

METHODS

Preoperative and postoperative three-dimensional (3D) computed tomographic (CT) scans were evaluated for 50 consecutive patients with Gore Excluder endografts by using 21 anatomic measurements and 6 calculated indices. Measurements were evaluated as if only 3D lumen centerline measurements were available, rather than complete 3D computer-aided measurement and "virtual graft" simulation. Tortuosity was quantitated from the renal artery to the hypogastric origin, using the difference between a straight line and the lumen centerline.

RESULTS

The endograft was deployed successfully in all cases. The graft end points were typically quite close to the preoperative plan: mean renal artery-to-graft distance was within 2.0 +/- .5 mm, and the limb end point-to-hypogastric origin differed by an average of only 1.8 +/- 1.6 mm. Although accurate in most cases, the actual graft path shortened 1 cm or more relative to the centerline in 11% of limbs. On univariate analysis, determinants of alteration of >1 cm in the graft deployment path were (1) aortoiliac tortuosity (renal-to-hypogastric artery, P < .002), (2) the degree of planned graft rotation (73% of cases altered >10 mm were in the rotated position, P < .05), and (3) the insertion side (73% of alterations >or=10 mm were ipsilateral to the main device, P < .05). On multivariate analysis, the renal-to-hypogastric artery tortuosity index (RHTI) was significant ( P < .004), and device type and rotation approached significance ( P < .08). We developed a classification scheme based on RHTI to predict the risk of alteration of the graft path >or=1 cm (low risk, 0%; medium risk, 10%; high risk, 25%) and an algorithm to predict the degree of alteration of the anatomy that reduced the number of cases shortening >or=1 cm to zero.

CONCLUSIONS

The graft deployment path will be altered significantly in a minority of cases with the Gore Excluder endograft, but this can cause hypogastric occlusion or other problems. Anatomic shortening is predictable from morphologic features such as tortuosity, graft insertion side, and rotation. We developed an algorithm based on a tortuosity index that quantitates the risk and degree of shortening associated with endograft deployment.

Endovascular repair of abdominal aortic aneurysm without preoperative arteriography

OBJECTIVE

Clinical trials of endovascular aortic aneurysm repair (EVAR) have required both preoperative aortography and computed tomography (CT). We codeveloped specialized three-dimensional (3-D) reconstruction and computer-aided measurement, planning, and simulation software (3-D CAMPS) based on CT or magnetic resonance imaging, to eliminate the need for preoperative arteriography.

METHODS

EVAR with 3-D CAMPS as the sole preoperative imaging method was performed in 196 patients from 1996 to 2001, with six endograft types in three configurations. Physical examination, abdominal radiography, and CT (3D-CAMPS) were performed at 1, 6, and 12 months, then annually.

RESULTS

For a subset of cases in which a comparison could be made, 3-D CAMPS was superior to angiography for prediction of endograft length and iliac access. Hospital mortality was zero, and 30-day mortality was 0.5%. In three patients immediate conversion to open repair (1.5%) was necessary because of previously unknown stent-graft mechanical limits. Incidence of endoleak was 15% at 1 month, 10% at 6 months, 6% at 12 months, and 7% at 24 months, and 92% of endoleaks were type II. Mean follow-up was 18 months. Aneurysm-related mortality was zero. Nineteen secondary procedures (all endovascular) were performed in 16 patients (8%). For all graft types, freedom from secondary procedure was 94% at 1 year and 90% at 2 years, and this was better for endografts ultimately approved by the US Food and Drug Administration (96% at 1 year, 95% at 2 years; P =.02). No known measurement-related complications occurred in the series. Results for secondary intervention and endoleak compare favorably to series with similar endograft types.

CONCLUSIONS

EVAR can be performed with 3-D CAMPS as the sole preoperative imaging method to achieve outcomes comparable to the best series published for each endograft type. CT with 3-D CAMPS can effectively eliminate the need for preoperative arteriography and avert associated morbidity, expense, and exposure to contrast agent and radiation.

Buttress technique to insure accurate placement of AneuRx stent-grafts in patients with complex anatomy

PURPOSE

To describe a technique that prevents caudal displacement of the AneuRx stent-graft during removal of the nose cone and runners.

TECHNIQUE

The buttress technique uses a 16-F sheath positioned from the contralateral femoral approach at the inferior edge of the endograft's main body to provide safe retraction of the runners and the nose cone and accurate endograft deployment.

CONCLUSIONS

If accurate deployment of the stent-graft according to the manufacturer's directions is not possible, this buttress technique can insure proper positioning. It adds no additional time or equipment to the procedure, and it appears to be a safe and easily applied maneuver.