OBJECTIVES: Ascending thoracic aortic aneurysms (aTAAs) carry a risk of acute type
A dissection. Elective repair guidelines are based on diameter, but complications
often occur below diameter threshold. Biomechanically, dissection can occur when wall
stress exceeds wall strength. Aneurysm wall stresses may better capture dissection
risk. Our aim was to investigate patient-specific aTAA wall stresses associated with
a tricuspid aortic valve (TAV) by anatomic region.METHODS: Patients with aneurysm
diameter >= 4.0 cm underwent computed tomography angiography. Aneurysm geometries
were reconstructed and loaded to systemic pressure while taking prestress into account.
Finite element analyses were conducted to obtain wall stress distributions. The 99th
percentile longitudinal and circumferential stresses were determined at systole. Wall
stresses between regions were compared using one-way analysis of variance with post
hoc Tukey HSD for pairwise comparisons.RESULTS: Peak longitudinal wall stresses on
aneurysms (n = 204) were 326 [standard deviation (SD): 61.7], 246 (SD: 63.4) and 195
(SD: 38.7) kPa in sinuses of Valsalva, sinotubular junction (STJ) and ascending aorta
(AscAo), respectively, with significant differences between AscAo and both sinuses
(P <0.001) and STJ (P <0.001). Peak circumferential wall stresses were 416 (SD: 85.1),
501 (SD: 119) and 340 (SD: 57.6) kPa for sinuses, STJ and AscAo, respectively, with
significant differences between AscAo and both sinuses (P < 0.001) and STJ (P <0.001).CONCLUSIONS:
Circumferential and longitudinal wall stresses were greater in the aortic root than
AscAo on aneurysm patients with a TAV. Aneurysm wall stress magnitudes and distribution
relative to respective regional wall strength could improve understanding of aortic
regions at greater risk of dissection in a particular patient.
