OBJECTIVES
We aimed to determine whether non-A non-B aortic dissection differs in morphologic and haemodynamic properties from type B aortic dissection.
METHODS
We simulated and compared haemodynamics of patients with acute type B or acute non-A non-B aortic dissection by means of computational fluid dynamics. Wall pressure and wall shear stress in both the true lumen and false lumen at early, mid-, and late systole were evaluated. Morphology, wall shear stress, and the false lumen/true lumen wall pressure ratio were compared between groups.
RESULTS
Nineteen patients (type B, n = 7; non-A non-B, n = 12) were included. Median age (51 [46, 67] vs 53 [50, 63] years; P = 0.71) and a complicated course (14% vs 33%; P = 0.6) did not differ between the type B group and non-A non-B group. However, median entry tear width was increased in the non-A non-B group (9.7 [7.3, 12.7] vs 16.3 [11.9, 24.9] mm; P = 0.010). Streamlines showed, in patients with non-A non-B aortic dissection, blood from the true lumen flowed into the false lumen via the entry tear. Prevalence of a false lumen/true lumen wall pressure ratio >1.0 (type B vs non-A non-B) at early, mid-, and late systole was 57% vs 83% (P = 0.31), 43% vs 83% (P = 0.13), and 57% vs 75% (P = 0.62), respectively. Wall shear stress did not differ between the groups.
CONCLUSIONS
The increased false lumen/true lumen wall pressure ratio observed during systole in non-A non-B aortic dissection may beget a complicated presentation.