1. Characterization of Human Aortic Anatomy Project
A Critical Path Initiative – Food and Drug Administration
ELIGIBILITY FOR ENDOVASCULAR REPAIR OF SHORT NECK ABDOMINAL AORTIC ANEURYSMS
Tina M. Morrison1, Clark A. Meyer1, Mark F. Fillinger2, Ron M. Fairman3, Marc H. Glickman4, Richard P. Cambria5, Mark A. Farber6, Thomas C. Naslund7, Peter S. Fail8, James R. Elmore9, Rodney A. White10; Carlo A. Dall’Olmo11; David M. Williams12
1Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD; 2Dartmouth Hitchcock Medical Center, Lebanon, NH; 3University of Pennsylvania Medical Center, Philadelphia, PA; 4Sentara Norfolk General Hospital, Norfolk, VA; 5Massachusetts General Hospital, Boston, MA; 6University of North Carolina Medical Center, Chapel Hill, NC; 7Vanderbilt Medical Center, Nashville, TN; 8Cardiovascular Institute of the South, Houma, LA; 9Geisinger Medical Center, Danville, PA; 10Harbor UCLA Medical Center; Los Angeles, CA; 11Michigan Vascular Center, Flint, MI; 12University of Michigan Medical Center, Ann Arbor, MI

2. Background
200,000 people are diagnosed with an abdominal aortic aneurysms (AAA) annually.
25% women and 75% men
CHAP studies to date indicate that,
about 70% of AAA are infrarenal;
50% of women and 70% of men have suitable neck criteria for potential treatment with an endograft;
The two main factors driving ineligibility are both infrarenal neck length and angulation; and
Women are 8 times more likely to have an infrarenal neck length < 10 mm and angulation > 45o. 2

3. Objective
To collect detailed, unadjusted 3D anatomic data from unbiased broad samples to better understand gender differences in anatomy for patients with short infrarenal neck lengths
To understand ineligibility and identify gender disparities treatment options
Medical Device Daily – May 14, 2013
“Women are less likely to be offered EVAR to correct an AAA, mainly because they have smaller arteries and the current endovascular devices are made to fit the male anatomy.”
-- Dr. Eva Rzucidlo, Dartmouth-Hitchcock Medical Center, Lebanon, NH

4. Methods
We collected pre-operative CT scan data from eleven U.S. clinical centers that consecutively submit their AAA cases to M2S, Inc. for 3D anatomical analysis. De-identified data were collected from time periods where all or nearly all cases were submitted, covering 7/96 to 11/12. Data were tested and found to be homogenous (p = NS).
Cardiovascular Institute of the South, LA
Dartmouth Hitchcock Medical Center, NH
Geisinger Medical Center, PA
Harbor UCLA Biomedical Research Center, CA
Massachusetts General Hospital, MA
Michigan Vascular Center, MI
Sentara Norfolk General Hospital, VA
University of North Carolina Medical Center, NC
University of Michigan Medical Center, MI
University of Pennsylvania Medical Center, PA
Vanderbilt Medical Center, TN

5. Methods
The CHAP database contains unique patients with a variety of untreated abdominal aortic pathologies.
We filtered the database using anatomic criteria to isolate patients with short neck infrarenal aneurysms (snAAA):
Retained patients with AAA sac diameter ≥ 40 mm to eliminate non-aneurysm pathology.
9454 (65%) patients remaining
Retained patients with an infrarenal neck length < 10 mm based the shortest neck length criteria for endografts with 60o angulation.
3395 (36%) patients with AAA have short infrarenal neck

6. Methods
To further isolate the AAA to infrarenal snAAA, we retained patients with an infrarenal neck diameter ≤ 32 mm.
2837 (30%) patients remaining with short neck AAA
We retained the patients with snAAA that have moderate aortic tapering as defined by
Infrarenal : Suprarenal diameter ≤ 1.1
Suprarenal : Infrarenal diameter ≤ 1.2
2343 (25%) patients remaining with short neck AAA
In addition to the 25 standard anatomic parameters measured by M2S, Inc., we matched the most recent scan with the patient’s year-of-birth and gender.

7. Methods
The data were binned by gender and snAAA sac size in 5 mm increments for investigating ineligibility.
Evaluated the anatomic data against the anatomic criteria for two commercially available endovascular grafts in the U.S. labeled for snAAA.
Cook
Trivascular
Fenestrated
Ovationb
Year of Release
2012
Neck diameter, mm
19-31
16-30
Neck length, mm
≥ 4
> 7
Infrarenal neck angulation, deg
≤ 45 c
≤ 45c
Iliac diameter, mm
7-21
8-20
Smallest delivery system ODd Profile, Fr 23 14
b – Because the mid-line of the fill ring is 13 mm distal to the top of the graft, we also included a criteria that the diameter 15 mm below the renal artery ≤ 30 mm (for neck lengths < 15 mm) to ensure adequate sealing, which is a conservative estimate because we do not have the aortic diameter at 13 mm.
c – infrarenal and suprarenal, d – outer diameter of sheath

8. Methods
The non-parametric method Kolmogorov-Smirnov test was used to compare the distributions of each anatomic parameter between men and women.
One way ANOVA model was used to compare the means of each anatomic parameter between men and women for the entire dataset and each of the binned categories of AAA size:
anatomic variable = gender + error,
where error is the random error following a normal distribution with mean of zero and a constant variance.

9. Results 1631 (70%) men and 712 (30%) women
The anatomic criteria were analyzed in 2343 patients with untreated short neck infrarenal AAA (25% of infrarenal AAA).
1631 (70%) men and 712 (30%) women
The ages (mean ± standard deviation and range) are:
Men: 75 ± 9 [49 92] years
Women: 78 ± 8 [53 93] years p <

10. Results Aortic anatomy for the 11-center snAAA patient cohort (percentiles) by gender
M-W
Women (n = 712, 30%)
Men (n = 1631,70%)
Difference
Percentile 10 25 50 75 90
Age 67 73 78 83 87 63 69 76 82 86 -4 -2 -1
AAA Sac diameter 44 49 53 59 66 46 51 55 62 2 7
Infrarenal neck length 3 5 9 4 6 8 1
Infrarenal neck diameter 18 20 22 28 24 26 29
Infrarenal angle 33 56 17 34 -5
-10
Suprarenal angle 13 48 11 19 38 -3
Suprarenal diameter (min) 21 23 27
Aortic diameter 15 mm below the renal arteries 35 40 30 41
Diameter at aortic bifurcation 12 14 16 31
Centerline path from renal arteries to aortic bifurcation
103
113
124
135
148
105
115
126
139
152
Common iliac diameter (ave) 15
Femoral diameter (ave)
Femoral diameter (min)
Common iliac length 32 64 43 81
Iliac Tortuosity 39

11. Results While the suprarenal neck angulation is moderate, it is higher
for women. The difference is more dramatic for the infrarenal
neck angulation, a 10o difference.
M-W
Women (n = 712, 30%)
Men (n = 1631,70%)
Difference
Percentile 10 25 50 75 90
Suprarenal angle 8 13 22 34 48 7 11 19 28 38 -1 -3
-10
Infrarenal angle 33 44 56 69 17 46 59 -5

12. Results The diameter at the aortic bifurcation is smaller for women.
The length of the centerline path from the renal arteries to the
aortic bifurcation was not noticeably different, as one would
expect.
M-W
Women (n = 712, 30%)
Men (n = 1631,70%)
Difference
Percentile 10 25 50 75 90
Diameter at aortic bifurcation 12 14 16 20 24 31 2 4 7
Centerline path from renal arteries to aortic bifurcation
103
113
124
135
148
105
115
126
139
152
Iliac Tortuosity Index 18 38 19 32 39 -1 1

13. Percent of patients eligible for on-label treatment with commercially available endografts
neck criteria only
Men, Cook Fenestrated
Women, Cook Fenestrated
Men, Trivascular Ovation
Women, Trivascular Ovation

14. 35% of Men and 60% of Women with snAAA are ineligible for EVAR in the treatment range.

15. Reasons for Ineligibility
Cook Fenestrated
A majority of ineligibility is due to the angulation criteria
of the infrarenal and suprarenal neck.
Men
Women

16. Reasons for Ineligibility
Trivascular Ovation
A majority of ineligibility is due to the infrarenal neck length,
and a combination of infrarenal neck angulation and length.
Men
Women

17. Limitations
We have excluded patients with an infrarenal neck length of mm. This enabled us to focus on the critical anatomic issues, but lowered the denominator of patients with potential eligibility for devices that can treat an infrarenal neck < 15 mm.
We solely examined ineligibility based on anatomic criteria of the instruction for use – this does not necessarily reflect clinical practice or confer medical eligibility for the procedure.

18. Conclusions
From a representative sample of the AAA population, we learned that 1/3 of patients have a short infrarenal neck.
We further characterized the anatomy of those patients
Clinically meaningful gender differences were noted in the angulation of the infrarenal and suprarenal neck, along with the diameter at the aortic bifurcation.
Treating AAA below the standard threshold diameter would have a minor impact on eligibility.

19. Conclusions
We compared the anatomic data of snAAA to the IFU criteria of commercially available endografts.
For Cook Fenestrated, both suprarenal and infrarenal neck angulation are the driving factors for ineligibility.
For Trivascular Ovation, it is a combination of infrarenal neck angulation and length that are the driving factors for ineligibility.
At least 30% of Men and 60% of Women with snAAA are not eligible for EVAR with the current commercially available endografts at the current treatment threshold of 55 mm
Ineligibility increases with larger size AAA

20. Acknowledgements
Contact: