Management options for large fenestrations between true and false lumens in aortic dissection.

Background: Type B aortic dissection (TBAD) is a dangerous pathological condition with a high mortality rate. TBAD is initiated by an intimal tear that allows blood to flow between the aortic wall layers, causing them to separate. As a result, alongside the original aorta (true lumen), a false lumen (FL) develops. TBAD compromises the whole cardiovascular system, in the worst case resulting in complete aortic rupture. Clinical studies have shown that dilation and rupture of the FL are related to the failure of the FL to thrombose. Complete FL thrombosis has been found to improve the clinical outcomes of patients with chronic TBAD and is the desired outcome of any treatment. Partial FL thrombosis has been associated with late dissection-related deaths and the requirement for re-intervention, thus the level of FL thrombosis is dominant in classifying the risk of TBAD patients. Therefore, it is important to investigate and understand under which conditions complete thrombosis of the FL occurs.Method: Local FL hemodynamics play an essential role in thrombus formation and growth. In this study, we developed a simplified phenomenological model to predict FL thrombosis in TBAD under physiological flow conditions. Based on an existing shear-driven thrombosis model, a comprehensive model reduction study was performed to improve computational efficiency. The reduced model has been implemented in Ansys CFX and applied to a TBAD case following thoracic endovascular aortic repair (TEVAR) to test the model. Predicted thrombus formation based on post-TEVAR geometry at 1-month was compared to actual thrombus formation observed on a 3-year follow-up CT scan.Results: The predicted FL status is in excellent agreement with the 3-year follow-up scan, both in terms of thrombus location and total volume, thus validating the new model. The computational cost of the new model is significantly lower than the previous thrombus model, with an approximate 65% reduction in computational time. Such improvement means the new model is a significant step towards clinical applicability.Conclusion: The thrombosis model developed in this study is accurate and efficient at predicting FL thrombosis based on patient-specific data, and may assist clinicians in choosing individualized treatments in the future.

Commentary: The secret life of aortic dissections

Background: Thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD) induces false lumen (FL) thrombosis, promotes favorable aortic remodeling, and makes an impact on abdominal aortic branch perfusion patterns. However, little is known about the long-term fate of aortic remodeling and abdominal aortic branch perfusion after TEVAR for TBAD and the effect of FL thrombosis status on these changes.Materials and methods: Between January 2014 and May 2021, 59 enrolled patients with acute TBAD were treated with TEVAR and had post-operative or follow-up images. Pre-operative, post-operative, and latest follow-up CT angiography (CTA) data were analyzed for the largest diameter of true lumen (TL), FL, and transaorta and for the FL thrombosis status on the stented thoracic aorta, unstented thoracic aorta, and abdominal aorta. Abdominal aorta perfusion patterns were characterized.Results: The mean follow-up period was 17.1 months. In the stented thoracic aorta, average TL diameters increased, average FL diameters decreased, and average transaortic diameters did not change; 82.6% of the patients had either a stable or shrinking transaortic size and 87% of the patients achieved total FL thrombosis. In the unstented thoracic aorta, average TL diameters increased, transaortic growth and no changes occurred in 39.1 and 45.7% of the patients, respectively, and complete FL thrombosis was present in 50% of the patients. In the abdominal aorta, average FL and transaortic diameters increased, aorta was expanded in 52.2% of the patients, and FL remained patent in 65.2% of the patients. Of the 354 branches, 37 branches (10.5%) exhibited changes in perfusion patterns, 22 branches (6.2%) demonstrated an increased TL perfusion, and 15 branches (4.2%) had an increased FL contribution. Compared with patent or partially thrombosed FL, complete FL thrombosis was accompanied by a bigger decrease in FL diameters, a larger increase in TL diameters, and a higher percentage of abdominal branch TL perfusion.Conclusions: In majority of the patients, TEVAR stabilized the size of the stented thoracic aorta, namely TL expansion and FL obliteration. However, abdominal aortic FL remained patent FL, and it was expanded with the resultant transaortic growth over a long follow-up period. Abdominal aortic branch perfusion patterns remained largely stable after TEVAR. The failure to achieve FL thrombosis negatively affects the remodeling of a contagious abdominal aortic dissection.

Objective: To investigate the different types of renal artery involvement in Stanford type B aortic dissection (TBAD) and the comparison of clinical effecacy after thoracic endovascular aortic repair (TEVAR). Methods: This is a retrospective cohort study included 330 patients with TBAD and renal artery involvement treated with TEVAR from June 2002 to September 2021 in General Hospital of Northern Theater Command of the PLA. According to aortic CTA image, unilateral renal artery involvement conditions were divided into 5 types: the true lumen type (renal artery opening completely from the true lumen), false lumen type (renal artery opening completely from the false lumen), double lumen type (renal artery opening from the true and false double lumen), compression type (renal artery opening connected with the true lumen, but the renal artery opening was extremely squeezed by the inner membrane), open type (renal artery opening with intimal tear). There were seven types of bilateral renal artery involvement: true-true type (true lumen-true lumen type), true and false type (true lumen-false lumen type), true-double type (true lumen-double lumen type), true-opening type (true lumen-opening type), false-false type (false lumen-false lumen type), false-compression type (false lumen-compression type), double-double type (double lumen-double lumen type). The primary observation index of this study was the comparison of postoperative renal function and the incidence of clinical adverse events of different types of renal artery involvement. One-way ANOVA test, Kruskal-Wallis H test and paired sample rank sum test were used to compare postoperative renal function between different types of bilateral renal artery involvement. The Chi-square test or Fisher's exact probability test were used to compare the near and long term adverse events between different types of bilateral renal artery involvement. Kaplan-Meier method was used to compare the all-cause mortality of patients with severe renal functional injury and non-severe renal functional injury before surgery. Results: The average age of the patients included in this study was (53±11) years, including 276 males (83.6%) and 54 females (16.4%). There were statistical difference in the level of serum creatinine (preoperative:H=18.686, P=0.005, postoperative:H=18.101, P=0.006) and cystatin C (preoperative:H=17.566, P=0.007, postoperative:H=10.433, P=0.016), pre-and post-operative, between the seven groups of TBAD patients with different renal artery involvement types (P<0.05), and the false-false type group shown the worst kidney function. However, no statistically significant differences were shown when comparing their pre- and post-operative change values (P>0.05). The 30-day follow-up result showed that there were statistically significant differences in the incidence of postoperative acute kidney injury (χ2=15.623, P=0.007), aorta-related adverse events (χ2=15.523, P=0.010), and intraoperative endoleak (χ2=17.935, P=0.004) among the seven groups, and the false-false group was the highest (2/9, 5/9 and 5/9, respectively). In terms of long-term follow-up results, there were statistically significant differences in all-cause death (χ2=14.772, P=0.011) and non-aortic death (χ2=15.589,P=0.008) among the seven groups. Kaplan-Meier survival analysis showed that patients with worse pre-operative renal function showed higher long-term all cause death (17.7% vs. 4.8%, P=0.009). Conclusions: For TBAD patients with renal artery involvement, there were differences in renal function among different types, and TEVAR showed no significant effect on renal function in TBAD patients. The long-term all cause death was higher in patients with worse renal function pre-operative.

Tear size and location impacts false lumen pressure in an ex vivo model of chronic type B aortic dissection

BackgroundThis study was performed to compare aortic remodeling and clinical outcomes in patients with acute, subacute, and chronic type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR).MethodsWe retrospectively examined 323 consecutive patients with acute (n = 129), subacute (n = 161), and chronic (n = 33) TBAD who underwent TEVAR from June 2013 to December 2016 in in multicenter institution. Patient demographics, clinical data, and imaging characteristics were recorded and compared among the three groups.ResultsThe three groups had comparable baseline characteristics. Perioperative mortality rates were similar among the acute (2.3%), subacute (0.0%), and chronic (0.0%) groups (P = 0.34). Perioperative morbidity rates, including the rates of visceral and lower limb malperfusion and cerebral infraction, were also similar. The rate of perioperative endoleak was significantly higher in the chronic group (18.1%) than in the acute (3.9%) and subacute (3.7%) groups (P = 0.02). The mean follow-up duration was 78 ± 22 months (range, 36–101 months). The mortality rates were comparable among the three groups. The rates of reintervention and lower limb malperfusion were higher in the chronic group than in the acute and subacute groups. FL diameter reduction were more robust in the acute and subacute groups than in the chronic group.ConclusionPatients with acute, subacute, and chronic TBAD had different outcomes in this study. Patients with acute and subacute TBAD had fewer complications than those with chronic TBAD. Aortic remodeling after TEVAR was more favorable in patients with acute and subacute TBAD than in patients with chronic TBAD. TEVAR promotes more positive remodeling at the stent graft level than at the distal level of the aorta.

Stanford type B aortic dissection (TB-AD) is a life-threatening vascular condition with high rates of morbidity and mortality. Currently, thoracic endovascular aortic repair (TEVAR) is widely performed to treat TB-AD, and some studies have analyzed the influence of stents on hemodynamics using computational fluid dynamics (CFD) models. However, the accuracy of TB-AD simulation models are not satisfactory, they are often constructed as a regular ideal model. Furthermore, it is unclear which tear should be closed for the best treatment when there are multi entry tears. The aims of this paper were to provide an assessment method for the selection of the surgical closure location for type B aortic dissection. Five 3D models of multiple entry tears in type B aortic dissection were produced using real patient computed tomography (CT) images to perform hemodynamic analyses of flow velocity streamlines, wall pressure, and wall shear stress. A Boolean operation was adopted to establish 3D models with multiple entry tears in type B aortic dissection based on patient-specific CT images. The Mimics and Ansys plug-in The Integrated Computer Engineering and Manufacturing code for Computational Fluid Dynamics (ICEM CFD) software were applied to mesh the 3D models. The flow velocity streamlines, wall pressures, and wall shear stresses were then analyzed in the finite element analysis software Fluent. Five 3D models were produced to compare the hemodynamic characteristics of different entry tear numbers, as well as the changes of different closure positions before and after closure. The false lumen of the model with two entry tears had a higher wall pressure than that of model with multiple entry tears, which may tend to squeeze the true lumen and expand the false lumen. The load distribution of the vessel in the model with multiple entry tears had a more balanced flow velocity, and its wall pressure and shear stress were lower than that of model with two entry tears. For aortic dissection with two entry tears, the closure of the proximal entry tear was recommended, which helped to isolate and thrombose the false lumen, thereby improving the blood supply function of the true lumen. Because the postoperative vascular flow velocity and mechanical load performance of the vascular wall were still higher than those of normal blood vessels, the postoperative blood vessels remained pathological, and TEVAR did not restore the blood vessels to their original healthy state. Type B aortic dissection with two entry tears tend to squeeze the true lumen and expand the false lumen, resulting in a new entry tear and deterioration into multiple entry type B aortic dissection. The model of the vessel with multiple entry tears had a more balanced distribution in flow velocity and a smaller wall pressure and shear stress than that of the vessel with two entry tears. The closure of the proximal entry tear was considered an ideal solution for type B aortic dissection with two entry tears.

Application of "Fabulous" stent system to improve aortic remodeling after TEVAR for type B aortic dissection.

Evolving Experience of Percutaneous Management of Type B Aortic Dissection

Part One: For the Motion. Level 1 Evidence is Necessary Comparing TEVAR and Medical Management of Uncomplicated Type B Aortic Dissection

Initial experience with a modified “candy-plug” technique for false lumen embolization in chronic type B aortic dissection

Computational Study of Anatomical Risk Factors in Idealized Models of Type B Aortic Dissection

Endovascular Stent Graft Treatment of Stanford Type B Aortic Dissection with Retrograde Type A Intramural Haematoma: A Multicentre Retrospective Study

Therapeutic window for obtaining favorable remodeling after thoracic endovascular aortic repair of type B aortic dissection

Beta-blocker use after thoracic endovascular aortic repair in patients with type B aortic dissection is associated with improved early aortic remodeling.