• SCVS Home
• President's Message
• Council
• Commitees
• Annual Meeting
• 37th Annual Symposium
• 36th Annual Symposium
• 35th Annual Symposium
• 34th Annual Symposium
• 33rd Annual Symposium
• Membership
• Join SCVS
• Members Only Area
• Find a Vascular Specialist
• Newsletters
• Journal
• History
• Mission Statement
• Bylaws
• Contact Us
• 37th Annual Symposium
• 36th Annual Symposium
• 35th Annual Symposium
• 34th Annual Symposium
• 33rd Annual Symposium
• Join SCVS
• Members Only Area
• Find a Vascular Specialist

A Biological Basis For Anatomic Variation In Descending Thoracic Aneurysms

Back to 33rd Annual Symposium
Back to Final Program

Indranil Sinha, BA, Siddharth Bethi, MBBS, Paul Cronin, MD, Gorav Ailawadi, MD, Jonathan L. Eliason, MD, David M. Williams, MD, Peter K. Henke, MD, Matthew J. Eagleton, MD, James C. Stanley, MD, Gilbert R. Upchurch, Jr., MD.
University of Michigan, Ann Arbor, MI, USA.

Background: This study investigates matrix metalloproteinase (MMP) expression in the anterior and posterior wall of descending thoracic aortic aneurysms (TAAs) and correlates the biochemical environment at each site to CT images of the descending aorta.
Methods: Serial CT images of patients with TAAs were compared to age- and gender-matched descending thoracic aortas at levels T4-T12. The mean circumference of the TAAs was 152mm (N=18) and 158mm (N=15) at T8 and T10, respectively as compared to 76mm (N=20) and 74mm (N=20) in controls. Aortic tissue was collected from patients undergoing descending TAA resection (N=8). Cadaveric thoracic aortic samples (N=6) were used as controls. Tissue collected between the intercostals arteries was defined as posterior wall, and opposite to this site as anterior wall. Messenger RNA extracted from aortic tissue was analyzed by quantitative real time RT-PCR for MMP-9 and MMP-2 expression, and normalized to β-actin. CT aortic measurements and MMP expression were compared by t-tests.
Results: The ratio of arc distance between the intercostals on the posterior wall to total aortic circumference was .091 in TAAs at T8 as compared to .128 in the healthy controls (P=.003). At T10, the ratio was .110 in TAAs as compared to 0.145 in the healthy controls (P=.002), suggesting that the posterior wall is relatively preserved compared to the anterior wall in TAAs. MMP-9 expression in TAAs was 4.3 fold higher in the anterior wall compared to the posterior wall (P=.03). Conversely, MMP-2 expression in TAAs was 3.2 fold higher in the posterior wall in comparison to the anterior wall (P=.008). No MMP expression was detectable in the cadaveric controls.
Conclusions: The anterior wall of an expanding TAA lengthens at a greater rate than the posterior wall based on the lower ratio of intercostal arc distance to total circumference in TAAs. Differential MMP expression may serve as a biological basis for the difference in observed growth rates in the thoracic aortic wall.