Use of computational fluid dynamics studies in predicting aneurysmal degeneration of acute type B aortic dissections

Objective: Whereas uncomplicated acute type B aortic dissections are often medically managed with good outcomes, a subset develop subacute or chronic aneurysmal dilation. We hypothesized that computational fluid dynamics (CFD) simulations may be useful in identifying patients at risk for this complication. Methods: Patients with acute type B dissection complicated by rapidly expanding aortic aneurysms (N = 7) were compared with patients with stable aortic diameters (N = 7). Three-dimensional patient-specific dissection geometries were generated from computed tomography angiography and used in CFD simulations of pulsatile blood flow. Hemodynamic parameters including false lumen flow and wall shear stress were compared. Results: Patients with rapid aneurysmal degeneration had a growth rate of 5.3 +/- 2.7 mm/mo compared with those with stable aortic diameters, who had rates of 0.2 +/- 0.02 mm/mo. Groups did not differ in initial aortic diameter (36.1 +/- 2.9 vs 34.4 +/- 3.6 mm; P = .122) or false lumen size (22.6 +/- 2.9 vs 20.2 +/- 4.5 mm; P = .224). In patients with rapidly expanding aneurysms, a greater percentage of total flow passed through the false lumen (78.3% +/- 9.3% vs 56.3% +/- 11.8%; P = .016). The time-averaged wall shear stress on the aortic wall was also significantly higher (12.6 +/- 3.7 vs 7.4 +/- 2.8 Pa; P = .028). Conclusions: Hemodynamic parameters derived from CFD simulations of acute type B aortic dissections were significantly different in dissections complicated by aneurysm formation. Thus, CFD may assist in predicting which patients may benefit from early stent grafting.