[Dominant false lumen flow and abnormally high shear stress: a hemodynamic analysis of multichanneled aortic...

Objective: To explore the hemodynamic characteristics of multichanneled aortic dissection (MCAD). Methods: This is a retrospective cohort study. Patients with acute uncomplicated Stanford-type B aortic dissection who presented at Zhongshan Hospital, Fudan University between January 2019 and December 2023 were enrolled. Patients were diagnosed as having either double-channeled aortic dissection (DCAD) or MCAD based on preoperative standardized computed-tomography angiography (CTA). Centered on 4 MCAD cases with preprocedural death, 4 non-preprocedural-death MCAD patients and 4 non-preprocedural-death DCAD patients with balanced baseline characteristics, complete preoperative CTA datasets and well-defined outcomes were matched, yielding a total of 12 male patients. The ages of patients in preprocedural-death MCAD group, non-preprocedural-death MCAD group and non-preprocedural- death DCAD group were (62.0±5.7) years (range:54 to 66 years), (61.5±5.8) years (range:54 to 67 years) and (61.3±8.1) years (range:52 to 71 years), respectively. Using computational fluid dynamics (CFD) and patient-specific aortic models, preoperative hemodynamic indices were quantitatively analyzed, including blood flow velocity, pressure distribution, flow distribution, wall shear stress (WSS) and time-averaged wall shear stress (TAWSS). Results: Hemodynamic analyses revealed a stepwise decreasing trend of false lumen (FL) flow rate across the three groups. The preoperative death MCAD group exhibited a significantly higher FL flow ((62.81±7.59)ml/s (range: 56.29 to 73.78 ml/s)) than the non-preoperative death MCAD group ((24.84±9.25)ml/s (range: 17.23 to 36.84 ml/s)) and the non-preoperative death DCAD group ((11.86±5.62)ml/s (range: 6.72 to 19.84 ml/s)). The intergroup variation patterns of FL flow ratio and maximum FL TAWSS were highly consistent. The preoperative death MCAD group yielded values of 0.77±0.16 (range: 0.56 to 0.93) and (34.44±6.50)Pa (range: 27.54 to 41.38 Pa),which were elevated compared with the non-preoperative death MCAD group (0.44±0.17(range: 0.33 to 0.70), (15.46±7.75)Pa (range: 6.69 to 25.01 Pa)) and the non-preoperative death DCAD group (0.22±0.11(range: 0.14 to 0.37), (20.80±7.34)Pa (range: 15.23 to 31.60 Pa)),whereas no obvious disparities were observed between the latter two groups. In addition,the maximum FL WSS in the preoperative death MCAD group reached (125.76±26.57)Pa (range: 87.55 to 147.91 Pa),markedly exceeding that of the non-preoperative death MCAD group ((64.89±30.45)Pa (range: 28.62 to 102.40 Pa)) and the non-preoperative death DCAD group ((91.15±28.16)Pa (range: 61.51 to 126.41 Pa)). Conclusions: Elevated FL flow and abnormally high shear stress may correlate with poor outcomes in patients with MCAD,and these parameters could serve as potential biomechanical biomarkers. CFD simulation can act as an auxiliary tool to identify high-risk aortic dissection patients,which helps refine clinical management and facilitate individualized precision treatment for MCAD.