Hemodynamic analysis of physician-modified stent grafts in the treatment of distal residual dissection of type B aortic dissection

Hemodynamic analysis of physician-modified stent grafts in the treatment of distal residual dissection of type B aortic dissection | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Hemodynamic analysis of physician-modified stent grafts in the treatment of distal residual dissection of type B aortic dissection Wei Liu, Xingbo Cao, Chi Cui This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6091190/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: There have been very few reports which specifically address the use of physician-modified stent grafts (PMEGs) to isolate and repair distal residual dissection of type B aortic dissection (TBAD). This study aimed to assess the usage of PMEGs in the treatment of distal residual dissection of TBAD by analyzing the relevant hemodynamical indicators. Methods: One patient with TBAD underwent thoracic endovascular aortic repair surgery in the first stage, and in the second stage PMEGs were used to repair the residual dissection. Computational fluid dynamics (CFD) and three-dimensional structural analyses were performed, based on computed tomography angiography (CTA) datasets. The prognostic post-implantation improvement was studied using both quantitative and qualitative functional analysis. Results: The true lumen of the patient was expanded significantly in the post-operation period. The vascular pressure of the patient was high and unevenly distributed before the operation. Significant reductions in the wall shear stress related parameters of the region around the PMEGs—namely, time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI)—were observed after the implantation of the stent. Quantitative analysis showed that, while the blood flow decreased in the celiac trunk artery, the blood flow in the superior mesenteric artery and bilateral renal arteries increased. Conclusions: In the short term, the results of PMEGs in the treatment of distal residual dissection of TBAD were encouraging. Further evaluation with CFD may lead to new insights into the efficacy of this treatment, and help to guide the further treatment of complex abdominal aortic lesions. type B aortic dissection hemodynamics physician-modified stent grafts distal tears and residual dissection Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 INTRODUCTION Thoracic endovascular aortic repair (TEVAR) surgery is the preferred treatment for type B aortic dissection (TBAD)[ 1 , 2 ]. A drawback of standard TEVAR is that it only repairs proximal tears, meaning that distal tears and residual dissection are left to heal without surgical assistance[ 3 , 4 ]. A growing body of researchers have suggested that these conditions should also be treated surgically. The incidence of distal aortic dilatation has been reported to be between 25% and 40%, and the 3-year mortality rate can reach up to 36%[ 5 – 7 ]. Therefore, residual aortic dissection resulting from TEVAR, including both the abdominal aorta and iliac artery segments, remains an open issue to be solved. Open surgery is the gold standard for treating distal TBAD dissection, but it is an invasive procedure with unacceptably high mortality and complication rates[ 8 , 9 ]. There is no consensus among researchers on the method of endovascular treatment of residual aortic dissection due to TBAD; however, complete isolation and repair of distal tears and residual dissection using fenestrated and branched stent grafts is recognized as the most effective treatment[ 4 , 6 , 10 ]. No specific treatment model currently exists for the distal residual dissection of TBAD stent-grafts, although physician-modified stent grafts (PMEGs) are a promising option. The use of this approach to treat distal TBAD dissections has not been widely explored in the literature, however, begging the question of its efficacy in this treatment. This article presents a retrospective report of a case of a patient with TBAD distal dissection who was treated successfully with PMEGs. Computational fluid dynamics (CFD) was used to assess the hemodynamic characteristics of the PMEGs in both the pre- and post-operative periods. The detailed morphological and functional information provided by these results can serve as a reliable reference for evaluating PMEGs in terms of their therapeutic effect, thereby providing guidance for the future clinical treatment of distal residual dissection of TBAD. METHODS Patients A 60-year-old male was admitted to the emergency department for chest pain and was treated with TEVAR after being diagnosed with type B aortic dissection. The follow-up appointment revealed dissecting aneurysmal dilatation of both the thoracic aorta and abdominal aorta (Fig. 1A-C), with a maximum diameter of approximately 70 mm. As a result, the patient and his family requested surgical intervention. The patient had a clinical history of hypertension, chronic obstructive pulmonary disease (COPD), smoking and drinking, and was physically weak, so open surgery and hybrid repair were refused. PMEGs were therefore used to repair completely the residual dissection and thus to restore the aortic morphology (Fig. 1D). This study was approved by the Ethics Review Committee of Chengdu Third People's Hospital, and the patient provided written informed consent before this study. Image Acquisition and Geometry Reconstruction The patient underwent two aortic computed tomography angiography (CTA) scans before surgery and one week after surgery. Both CTA datasets were acquired using a dual-source CT scanner (BrillianceiCT256, Royal Philips, The Netherlands). Export DICOM files of pre- and post-operative CTA datasets. Mimics (Mimics Medical version 21.0, Materialise, Belgium) was used to reconstruct the computed tomography (CT) model data into a 3D model, and SCDM software (version 2020R2, ANSYS, USA) was used for geometric processing of the vascular model. The image segmentation of each slice was then reviewed by an expert in CT image reading, supervised by a vascular surgery specialist. Manual corrections were performed when necessary to ensure that the 3D reconstructed model represented the actual contours of the vascular lumen. Figure 2A and 2B show the 3D reconstructed aorta model both before and after surgery. TL and FL Volumes Measurements The true and false lumen volumes were estimated using the 3D reconstructed model. CFDPOST (version 19.0, ANSYS, USA) was used for post-processing; the vascular model was segmented and cut in order to compare and measure the volumes. SCDM (version 2020R2, ANSYS, USA) was used to measure the volume (Fig. 2C-E). Doppler Ultrasound and Boundary Conditions The time-varying velocities of the ascending aorta, descending aorta, four visceral branches (celiac trunk, superior mesenteric arteries, and bilateral renal arteries), and iliac arteries were measured with Doppler ultrasound. These measurements provided patient-specific boundary conditions on the flow velocity for the computational model. The flow distribution ratios of the three visceral aortal branches mentioned above were calculated using Doppler ultrasound data. This quantity was defined as the ratio of branch flow to inflow flow. Numerical Models ANSA (version 18.11, Cadence, USA) was used to mesh the 3D aorta model. The volume and surface mesh size used were 0.5-2 mm, the branch pipe was 1 mm, the main pipe was 2 mm, the branch connection feature was 0.5 mm, the boundary layer consisted of 7 layers, the growth rate was 1.2, and the first layer was 0.12 (Fig. 2F-G). The non-Newtonian fluid Carreau model was used with a blood density of 1060 kg/m 3 . The flow physical model employed was incompressible laminar flow with velocity inlet boundary conditions. From two simulated cardiac cycles, each with a period of 0.8 seconds, the second more stable cycle was used to analyze the results. The relative pressure at the pressure outlet was zero. The following is the formula for simulating the heart beat cycle function: Analysis of Hemodynamic Parameters Both qualitative and quantitative analyses were used to assess the hemodynamic patterns before and after surgical intervention. The quantities measured were the aortic pressure distribution and blood flow pattern at the peak systolic phase. Wall shear stress (WSS)-related parameters were selected to quantify the changes induced by the surgery. These included the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT). RESULTS Morphometric Analysis The preoperative and postoperative morphological features were quantified using the methods described above. As shown in Fig. 3A, the TL volume increased, while that of the FL disappeared. Pressure Fields and Velocity Figure 3B-E shows the streamlining of the pressure distribution and flow velocity before and after the operation at the peak of systolic blood pressure. In the figure, the color maps of pressure and velocity are constrained in all cases to assist visualization. Before the operation, the pressure was high and unevenly distributed, and it was significantly reduced and more evenly distributed after the operation. There was an increase in pressure in the celiac artery, although no significant pressure change was measured in the other branches (superior mesenteric and bilateral renal arteries) after surgery. The preoperative TL exhibited rapid and organized flow, whereas eddy currents and relatively slower flow were present in the FL. The implantation of the stent accelerated significantly the flow velocity of the TL and of the four branches of the visceral area (celiac trunk artery, superior mesenteric artery and bilateral renal arteries). WSS-Based Parameter Analysis WSS-related parameters are crucial for the hemodynamic analysis of vascular remodeling after stent implantation. In Fig. 4, the distributions of TAWSS, OSI, and RRT before and after surgery are presented. A higher concentration of TAWSS above the celiac artery and at the abdominal aortic rupture was observed before surgery (Fig. 4A). The stent implantation stimulated a significant decrease in TAWSS in these areas, as shown in Fig. 4B. Figure 4C-D shows the OSI contour: in the FT area, the OSI was greatly increased before the operation, while in the aorta it was significantly reduced and distributed more evenly as a result of the operation. The RRT cloud map, shown in Fig. 4E-F, was low in the TL before the operation, whereas that of the FL of the thoracic aorta and abdominal aorta was significantly larger (red value). Scattered high RRT values were observed ​​in the stents of the thoracic aorta and abdominal aorta following the operation. Quantitative Analysis of Hemodynamic Status The visceral artery blood flow distribution diagram within one cardiac cycle before and after the operation is shown in Fig. 5. It can be seen that, except for the decreased blood flow in the celiac trunk artery, an increase was measured in the other arteries (superior mesenteric artery and bilateral renal arteries), with the most pronounced rise in the superior mesenteric artery. DISCUSSION This research was based on a dataset of a patient with TBAD who initially underwent TEVAR in the first stage to close the proximal rupture, and was treated subsequently with PMEGs in the second stage to close the distal rupture. It was observed that PMEG technology both blocked the distal rupture and restored the TL morphology, maintaining blood flow to the visceral branch vessels of the abdominal aorta. Two key factors of the vascular system were calculated, namely morphology and hemodynamics, in order to assess the therapeutic efficacy of this method. Morphological analysis is currently widely used in clinical practice, while hemodynamics, as a functional assessment, may be helpful in evaluating surgical indicators and predicting prognosis after treatment. CFD has been very effective to evaluate the hemodynamic characteristics of TBAD[ 11 , 12 ]; however, the impact of PMEGs on hemodynamics after closure of the distal TBAD breach deserves a deeper evaluation. This study reconstructed a patient-specific model using CTA images, with patient-specific flow boundaries obtained from ultrasound velocimetry. The morphological and hemodynamic changes of the patient were then measured both before and after surgery. Stiffening of the aorta is often associated with stent implantation, as is a reduction of radial strain within the stented segment. A heightened pulse pressure can also result from increased catheter stiffness, which accelerates the pulse wave velocity[ 13 – 15 ]. This can in turn lead to adverse cardiac remodeling[ 16 ]. Furthermore, flow acceleration may increase the risk of stent-graft migration[ 17 , 18 ]. Therefore, it is crucial to monitor flow and pressure patterns after PMEGs implantation. The flow environment is expected to be strongly correlated with the morphology of the vessel. The positive remodeling of the aorta due to stent expansion is often associated with a decrease in blood flow velocity and pressure. However, there is no consensus among experts on the surgical treatment of TBAD distal dissection, although complete repair with a covered stent is recognized as the most effective solution. Although this technique is difficult, it is not the reason why its usage is limited in clinical practice. Rather, the related surgical risks (paraplegia and surgical re-intervention), one of which is stent displacement, have thus far prevented its widespread adoption. The results presented here showed a slight increase in pressure in the surgical area around the PMEGs, but also that the flow rate rose significantly as a result of the surgery (Fig. 3B-E). Analysis of the patient's pressure and blood flow patterns indicated a high probability of stent migration in this patient, a finding that is inconsistent with previous research results[ 19 ]. This may be due to the short follow-up time after the operation. More follow-up images may be necessary to evaluate further the luminal remodeling. The surgical areas around the PMEGs were analyzed to investigate the prognostic improvement. The analysis of the volumes of the TL and FL before and after the operation revealed the complete isolation of the patient’s FL after the operation, and a significant expansion of the TL, indicating that the patient's aorta was well remodeled and that the patient had a good prognosis. Previous research has shown that elevated TAWSS and OSI may indicate a poor prognosis, for example, graft migration[ 20 ]. A notable reduction has been measured in the TAWSS and OSI of patients after surgery, suggesting that PMEGs have a good prognosis after surgery. An elevated RRT has been associated with thrombosis[ 19 , 21 , 22 ]; the high pre-surgery RRT of this patient was mainly located in the FL, which was caused by the low blood flow velocity. This also meant that the FL was thrombosed. Scattered high RRT areas appeared in the stent from the thoracic aorta to the abdominal aorta following the surgery. There is a distinct possibility of stent thrombosis in this patient; therefore, in addition to close follow-up, antiplatelet or anticoagulant drugs should also be used. Hemodynamic analysis can thus guide both our surgical methods and our medication. Quantitative analysis was used to assess the ability of PMEGs to maintain blood flow in branch vessels by calculating the flow distribution ratio. The Fig. 5 shows that after treatment, the flow distribution rate of each abdominal aorta branch grew, save for that of the celiac trunk artery. This decrease could be related to the fact that no bridging stent was implanted in the celiac artery. PMEGs can therefore maintain blood flow to branch vessels, although the flow distribution ratio of the branches was still smaller than that of the standard model[ 23 ]. As mentioned above, this could be due to the short follow-up period (seven days after intervention). There are some limitations to this study. First, this was a single-patient study, and a large number of patients with long-term close follow-up should be assessed in clinical practice to draw more substantial conclusions. However, distal TBAD rupture is not often treated with PMEGs, making the systematic collection of many cases difficult. Second, in order to save computational time, the flow analysis in this study was based on CFD with the rigid wall assumption. This could have overestimated the hemodynamic parameters. Despite the fact that this simulation pipeline has been validated previously using 4D phase-contrast MRI[ 24 , 25 ], continued improvement in accuracy is needed. This can be achieved by conducting fluid-structure interaction analyses to provide more detailed and accurate information on functional metrics in the future. CONCLUSIONS This study assessed the efficacy of PMEG technology to treat TBAD distal dissection, and proposed a hemodynamic assessment tool to evaluate the treatment of this complex aortic disease. It was found that PMEGs can lead to positive remodeling of the aorta and the preservation of blood flow in the abdominal aortic branches, confirming the effectiveness of this technology in treating TBAD distal dissection. Hemodynamic indicators may also indicate potential negative remodeling, thereby suggesting the need for subsequent intervention. Declarations Author Contribution W.L. and X.B.C. wrote the main manuscript text and prepared figures 1-5. C.C . made modifications to the manuscript. Funding Declaration There was no Funding. Clinical Trial Number : Clinical trial number: not applicable. 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Menichini C, Cheng Z, Gibbs RG, Xu XY: Predicting false lumen thrombosis in patient-specific models of aortic dissection . J R Soc Interface 2016, 13 (124). Chen D, Liang S, Li Z, Mei Y, Dong H, Ma Y, Zhao J, Xu S, Zheng J, Xiong J: A Mock Circulation Loop for In Vitro Hemodynamic Evaluation of Aorta: Application in Aortic Dissection . J Endovasc Ther 2022, 29 (1):132-142. Zhu Y, Xu XY, Rosendahl U, Pepper J, Mirsadraee S: Advanced risk prediction for aortic dissection patients using imaging-based computational flow analysis . Clin Radiol 2023, 78 (3):e155-e165. Pirola S, Guo B, Menichini C, Saitta S, Fu W, Dong Z, Xu XY: 4-D Flow MRI-Based Computational Analysis of Blood Flow in Patient-Specific Aortic Dissection . IEEE Trans Biomed Eng 2019, 66 (12):3411-3419. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6091190","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":421747433,"identity":"e2644284-013e-4987-baaa-a7e9e8f5714e","order_by":0,"name":"Wei Liu","email":"","orcid":"","institution":"The Third People’s Hospital of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chongqing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Wei","middleName":"","lastName":"Liu","suffix":""},{"id":421747434,"identity":"3d783461-6e09-4512-b54a-c8fb5531c135","order_by":1,"name":"Xingbo 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06:17:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2496770,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6091190/v1/4901945c-c3b4-45ec-a24b-f2fc2e6b3171.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Hemodynamic analysis of physician-modified stent grafts in the treatment of distal residual dissection of type B aortic dissection","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThoracic endovascular aortic repair (TEVAR) surgery is the preferred treatment for type B aortic dissection (TBAD)[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. A drawback of standard TEVAR is that it only repairs proximal tears, meaning that distal tears and residual dissection are left to heal without surgical assistance[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. A growing body of researchers have suggested that these conditions should also be treated surgically. The incidence of distal aortic dilatation has been reported to be between 25% and 40%, and the 3-year mortality rate can reach up to 36%[\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Therefore, residual aortic dissection resulting from TEVAR, including both the abdominal aorta and iliac artery segments, remains an open issue to be solved.\u003c/p\u003e \u003cp\u003eOpen surgery is the gold standard for treating distal TBAD dissection, but it is an invasive procedure with unacceptably high mortality and complication rates[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. There is no consensus among researchers on the method of endovascular treatment of residual aortic dissection due to TBAD; however, complete isolation and repair of distal tears and residual dissection using fenestrated and branched stent grafts is recognized as the most effective treatment[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eNo specific treatment model currently exists for the distal residual dissection of TBAD stent-grafts, although physician-modified stent grafts (PMEGs) are a promising option. The use of this approach to treat distal TBAD dissections has not been widely explored in the literature, however, begging the question of its efficacy in this treatment.\u003c/p\u003e \u003cp\u003eThis article presents a retrospective report of a case of a patient with TBAD distal dissection who was treated successfully with PMEGs. Computational fluid dynamics (CFD) was used to assess the hemodynamic characteristics of the PMEGs in both the pre- and post-operative periods. The detailed morphological and functional information provided by these results can serve as a reliable reference for evaluating PMEGs in terms of their therapeutic effect, thereby providing guidance for the future clinical treatment of distal residual dissection of TBAD.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatients\u003c/h2\u003e \u003cp\u003eA 60-year-old male was admitted to the emergency department for chest pain and was treated with TEVAR after being diagnosed with type B aortic dissection. The follow-up appointment revealed dissecting aneurysmal dilatation of both the thoracic aorta and abdominal aorta (Fig.\u0026nbsp;1A-C), with a maximum diameter of approximately 70 mm. As a result, the patient and his family requested surgical intervention. The patient had a clinical history of hypertension, chronic obstructive pulmonary disease (COPD), smoking and drinking, and was physically weak, so open surgery and hybrid repair were refused. PMEGs were therefore used to repair completely the residual dissection and thus to restore the aortic morphology (Fig.\u0026nbsp;1D). This study was approved by the Ethics Review Committee of Chengdu Third People's Hospital, and the patient provided written informed consent before this study.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eImage Acquisition and Geometry Reconstruction\u003c/h3\u003e\n\u003cp\u003eThe patient underwent two aortic computed tomography angiography (CTA) scans before surgery and one week after surgery. Both CTA datasets were acquired using a dual-source CT scanner (BrillianceiCT256, Royal Philips, The Netherlands). Export DICOM files of pre- and post-operative CTA datasets. Mimics (Mimics Medical version 21.0, Materialise, Belgium) was used to reconstruct the computed tomography (CT) model data into a 3D model, and SCDM software (version 2020R2, ANSYS, USA) was used for geometric processing of the vascular model. The image segmentation of each slice was then reviewed by an expert in CT image reading, supervised by a vascular surgery specialist. Manual corrections were performed when necessary to ensure that the 3D reconstructed model represented the actual contours of the vascular lumen. Figure\u0026nbsp;2A and 2B show the 3D reconstructed aorta model both before and after surgery.\u003c/p\u003e\n\u003ch3\u003eTL and FL Volumes Measurements\u003c/h3\u003e\n\u003cp\u003eThe true and false lumen volumes were estimated using the 3D reconstructed model. CFDPOST (version 19.0, ANSYS, USA) was used for post-processing; the vascular model was segmented and cut in order to compare and measure the volumes. SCDM (version 2020R2, ANSYS, USA) was used to measure the volume (Fig.\u0026nbsp;2C-E).\u003c/p\u003e\n\u003ch3\u003eDoppler Ultrasound and Boundary Conditions\u003c/h3\u003e\n\u003cp\u003eThe time-varying velocities of the ascending aorta, descending aorta, four visceral branches (celiac trunk, superior mesenteric arteries, and bilateral renal arteries), and iliac arteries were measured with Doppler ultrasound. These measurements provided patient-specific boundary conditions on the flow velocity for the computational model. The flow distribution ratios of the three visceral aortal branches mentioned above were calculated using Doppler ultrasound data. This quantity was defined as the ratio of branch flow to inflow flow.\u003c/p\u003e\n\u003ch3\u003eNumerical Models\u003c/h3\u003e\n\u003cp\u003eANSA (version 18.11, Cadence, USA) was used to mesh the 3D aorta model. The volume and surface mesh size used were 0.5-2 mm, the branch pipe was 1 mm, the main pipe was 2 mm, the branch connection feature was 0.5 mm, the boundary layer consisted of 7 layers, the growth rate was 1.2, and the first layer was 0.12 (Fig.\u0026nbsp;2F-G). The non-Newtonian fluid Carreau model was used with a blood density of 1060 kg/m\u003csup\u003e3\u003c/sup\u003e. The flow physical model employed was incompressible laminar flow with velocity inlet boundary conditions. From two simulated cardiac cycles, each with a period of 0.8 seconds, the second more stable cycle was used to analyze the results. The relative pressure at the pressure outlet was zero. The following is the formula for simulating the heart beat cycle function:\u003c/p\u003e \u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"480\" height=\"82\"\u003e\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eAnalysis of Hemodynamic Parameters\u003c/h2\u003e \u003cp\u003eBoth qualitative and quantitative analyses were used to assess the hemodynamic patterns before and after surgical intervention. The quantities measured were the aortic pressure distribution and blood flow pattern at the peak systolic phase. Wall shear stress (WSS)-related parameters were selected to quantify the changes induced by the surgery. These included the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT).\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eMorphometric Analysis\u003c/h2\u003e \u003cp\u003eThe preoperative and postoperative morphological features were quantified using the methods described above. As shown in Fig.\u0026nbsp;3A, the TL volume increased, while that of the FL disappeared.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePressure Fields and Velocity\u003c/h2\u003e \u003cp\u003eFigure 3B-E shows the streamlining of the pressure distribution and flow velocity before and after the operation at the peak of systolic blood pressure. In the figure, the color maps of pressure and velocity are constrained in all cases to assist visualization. Before the operation, the pressure was high and unevenly distributed, and it was significantly reduced and more evenly distributed after the operation. There was an increase in pressure in the celiac artery, although no significant pressure change was measured in the other branches (superior mesenteric and bilateral renal arteries) after surgery. The preoperative TL exhibited rapid and organized flow, whereas eddy currents and relatively slower flow were present in the FL. The implantation of the stent accelerated significantly the flow velocity of the TL and of the four branches of the visceral area (celiac trunk artery, superior mesenteric artery and bilateral renal arteries).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eWSS-Based Parameter Analysis\u003c/h2\u003e \u003cp\u003eWSS-related parameters are crucial for the hemodynamic analysis of vascular remodeling after stent implantation. In Fig.\u0026nbsp;4, the distributions of TAWSS, OSI, and RRT before and after surgery are presented. A higher concentration of TAWSS above the celiac artery and at the abdominal aortic rupture was observed before surgery (Fig.\u0026nbsp;4A). The stent implantation stimulated a significant decrease in TAWSS in these areas, as shown in Fig.\u0026nbsp;4B. Figure\u0026nbsp;4C-D shows the OSI contour: in the FT area, the OSI was greatly increased before the operation, while in the aorta it was significantly reduced and distributed more evenly as a result of the operation. The RRT cloud map, shown in Fig.\u0026nbsp;4E-F, was low in the TL before the operation, whereas that of the FL of the thoracic aorta and abdominal aorta was significantly larger (red value). Scattered high RRT values were observed ​​in the stents of the thoracic aorta and abdominal aorta following the operation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eQuantitative Analysis of Hemodynamic Status\u003c/h2\u003e \u003cp\u003eThe visceral artery blood flow distribution diagram within one cardiac cycle before and after the operation is shown in Fig.\u0026nbsp;5. It can be seen that, except for the decreased blood flow in the celiac trunk artery, an increase was measured in the other arteries (superior mesenteric artery and bilateral renal arteries), with the most pronounced rise in the superior mesenteric artery.\u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis research was based on a dataset of a patient with TBAD who initially underwent TEVAR in the first stage to close the proximal rupture, and was treated subsequently with PMEGs in the second stage to close the distal rupture. It was observed that PMEG technology both blocked the distal rupture and restored the TL morphology, maintaining blood flow to the visceral branch vessels of the abdominal aorta. Two key factors of the vascular system were calculated, namely morphology and hemodynamics, in order to assess the therapeutic efficacy of this method. Morphological analysis is currently widely used in clinical practice, while hemodynamics, as a functional assessment, may be helpful in evaluating surgical indicators and predicting prognosis after treatment.\u003c/p\u003e \u003cp\u003eCFD has been very effective to evaluate the hemodynamic characteristics of TBAD[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]; however, the impact of PMEGs on hemodynamics after closure of the distal TBAD breach deserves a deeper evaluation. This study reconstructed a patient-specific model using CTA images, with patient-specific flow boundaries obtained from ultrasound velocimetry. The morphological and hemodynamic changes of the patient were then measured both before and after surgery.\u003c/p\u003e \u003cp\u003eStiffening of the aorta is often associated with stent implantation, as is a reduction of radial strain within the stented segment. A heightened pulse pressure can also result from increased catheter stiffness, which accelerates the pulse wave velocity[\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This can in turn lead to adverse cardiac remodeling[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Furthermore, flow acceleration may increase the risk of stent-graft migration[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Therefore, it is crucial to monitor flow and pressure patterns after PMEGs implantation. The flow environment is expected to be strongly correlated with the morphology of the vessel. The positive remodeling of the aorta due to stent expansion is often associated with a decrease in blood flow velocity and pressure. However, there is no consensus among experts on the surgical treatment of TBAD distal dissection, although complete repair with a covered stent is recognized as the most effective solution. Although this technique is difficult, it is not the reason why its usage is limited in clinical practice. Rather, the related surgical risks (paraplegia and surgical re-intervention), one of which is stent displacement, have thus far prevented its widespread adoption. The results presented here showed a slight increase in pressure in the surgical area around the PMEGs, but also that the flow rate rose significantly as a result of the surgery (Fig.\u0026nbsp;3B-E). Analysis of the patient's pressure and blood flow patterns indicated a high probability of stent migration in this patient, a finding that is inconsistent with previous research results[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. This may be due to the short follow-up time after the operation. More follow-up images may be necessary to evaluate further the luminal remodeling.\u003c/p\u003e \u003cp\u003eThe surgical areas around the PMEGs were analyzed to investigate the prognostic improvement. The analysis of the volumes of the TL and FL before and after the operation revealed the complete isolation of the patient\u0026rsquo;s FL after the operation, and a significant expansion of the TL, indicating that the patient's aorta was well remodeled and that the patient had a good prognosis. Previous research has shown that elevated TAWSS and OSI may indicate a poor prognosis, for example, graft migration[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. A notable reduction has been measured in the TAWSS and OSI of patients after surgery, suggesting that PMEGs have a good prognosis after surgery. An elevated RRT has been associated with thrombosis[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]; the high pre-surgery RRT of this patient was mainly located in the FL, which was caused by the low blood flow velocity. This also meant that the FL was thrombosed. Scattered high RRT areas appeared in the stent from the thoracic aorta to the abdominal aorta following the surgery. There is a distinct possibility of stent thrombosis in this patient; therefore, in addition to close follow-up, antiplatelet or anticoagulant drugs should also be used. Hemodynamic analysis can thus guide both our surgical methods and our medication.\u003c/p\u003e \u003cp\u003eQuantitative analysis was used to assess the ability of PMEGs to maintain blood flow in branch vessels by calculating the flow distribution ratio. The Fig.\u0026nbsp;5 shows that after treatment, the flow distribution rate of each abdominal aorta branch grew, save for that of the celiac trunk artery. This decrease could be related to the fact that no bridging stent was implanted in the celiac artery. PMEGs can therefore maintain blood flow to branch vessels, although the flow distribution ratio of the branches was still smaller than that of the standard model[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. As mentioned above, this could be due to the short follow-up period (seven days after intervention).\u003c/p\u003e \u003cp\u003eThere are some limitations to this study. First, this was a single-patient study, and a large number of patients with long-term close follow-up should be assessed in clinical practice to draw more substantial conclusions. However, distal TBAD rupture is not often treated with PMEGs, making the systematic collection of many cases difficult. Second, in order to save computational time, the flow analysis in this study was based on CFD with the rigid wall assumption. This could have overestimated the hemodynamic parameters. Despite the fact that this simulation pipeline has been validated previously using 4D phase-contrast MRI[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], continued improvement in accuracy is needed. This can be achieved by conducting fluid-structure interaction analyses to provide more detailed and accurate information on functional metrics in the future.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eThis study assessed the efficacy of PMEG technology to treat TBAD distal dissection, and proposed a hemodynamic assessment tool to evaluate the treatment of this complex aortic disease. It was found that PMEGs can lead to positive remodeling of the aorta and the preservation of blood flow in the abdominal aortic branches, confirming the effectiveness of this technology in treating TBAD distal dissection. Hemodynamic indicators may also indicate potential negative remodeling, thereby suggesting the need for subsequent intervention.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eW.L. and X.B.C. wrote the main manuscript text and prepared figures 1-5. C.C . made modifications to the manuscript.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eFunding Declaration\u003c/strong\u003e \u003cp\u003eThere was no Funding.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eClinical Trial Number\u003c/b\u003e: Clinical trial number: not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRiambau V, Bockler D, Brunkwall J, Cao P, Chiesa R, Coppi G, Czerny M, Fraedrich G, Haulon S, Jacobs MJ\u003cem\u003e et al\u003c/em\u003e: \u003cstrong\u003eEditor\u0026apos;s Choice - Management of Descending Thoracic Aorta Diseases: Clinical Practice Guidelines of the European Society for Vascular Surgery (ESVS)\u003c/strong\u003e. \u003cem\u003eEur J Vasc Endovasc Surg \u003c/em\u003e2017, \u003cstrong\u003e53\u003c/strong\u003e(1):4-52.\u003c/li\u003e\n\u003cli\u003eErbel R, Aboyans V, Boileau C, Bossone E, Di Bartolomeo R, Eggebrecht H, Evangelista A, Falk V, Frank H, Gaemperli O\u003cem\u003e et 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al\u003c/em\u003e: \u003cstrong\u003eEndovascular aortic repair increases vascular stiffness and alters cardiac structure and function\u003c/strong\u003e. \u003cem\u003eCirc J \u003c/em\u003e2014, \u003cstrong\u003e78\u003c/strong\u003e(2):322-328.\u003c/li\u003e\n\u003cli\u003eLi Z, Kleinstreuer C: \u003cstrong\u003eAnalysis of biomechanical factors affecting stent-graft migration in an abdominal aortic aneurysm model\u003c/strong\u003e. \u003cem\u003eJ Biomech \u003c/em\u003e2006, \u003cstrong\u003e39\u003c/strong\u003e(12):2264-2273.\u003c/li\u003e\n\u003cli\u003ePolanczyk A, Piechota-Polanczyk A, Stefanczyk L, Strzelecki M: \u003cstrong\u003eSpatial Configuration of Abdominal Aortic Aneurysm Analysis as a Useful Tool for the Estimation of Stent-Graft Migration\u003c/strong\u003e. \u003cem\u003eDiagnostics (Basel) \u003c/em\u003e2020, \u003cstrong\u003e10\u003c/strong\u003e(10).\u003c/li\u003e\n\u003cli\u003eXu H, Li Z, Dong H, Zhang Y, Wei J, Watton PN, Guo W, Chen D, Xiong J: 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\u003cstrong\u003e78\u003c/strong\u003e(3):e155-e165.\u003c/li\u003e\n\u003cli\u003ePirola S, Guo B, Menichini C, Saitta S, Fu W, Dong Z, Xu XY: \u003cstrong\u003e4-D Flow MRI-Based Computational Analysis of Blood Flow in Patient-Specific Aortic Dissection\u003c/strong\u003e. \u003cem\u003eIEEE Trans Biomed Eng \u003c/em\u003e2019, \u003cstrong\u003e66\u003c/strong\u003e(12):3411-3419.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"type B aortic dissection, hemodynamics, physician-modified stent grafts, distal tears and residual dissection","lastPublishedDoi":"10.21203/rs.3.rs-6091190/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6091190/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eThere have been very few reports which specifically address the use of physician-modified stent grafts (PMEGs) to isolate and repair distal residual dissection of type B aortic dissection (TBAD). This study aimed to assess the usage of PMEGs in the treatment of distal residual dissection of TBAD by analyzing the relevant hemodynamical indicators.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eOne patient with TBAD underwent thoracic endovascular aortic repair surgery in the first stage, and in the second stage PMEGs were used to repair the residual dissection. Computational fluid dynamics (CFD) and three-dimensional structural analyses were performed, based on computed tomography angiography (CTA) datasets. The prognostic post-implantation improvement was studied using both quantitative and qualitative functional analysis.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eThe true lumen of the patient was expanded significantly in the post-operation period. The vascular pressure of the patient was high and unevenly distributed before the operation. Significant reductions in the wall shear stress related parameters of the region around the PMEGs\u0026mdash;namely, time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI)\u0026mdash;were observed after the implantation of the stent. Quantitative analysis showed that, while the blood flow decreased in the celiac trunk artery, the blood flow in the superior mesenteric artery and bilateral renal arteries increased.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eIn the short term, the results of PMEGs in the treatment of distal residual dissection of TBAD were encouraging. Further evaluation with CFD may lead to new insights into the efficacy of this treatment, and help to guide the further treatment of complex abdominal aortic lesions.\u003c/p\u003e","manuscriptTitle":"Hemodynamic analysis of physician-modified stent grafts in the treatment of distal residual dissection of type B aortic dissection","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-05 06:29:19","doi":"10.21203/rs.3.rs-6091190/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e11969c8-461a-47e8-8b21-761da231bfa7","owner":[],"postedDate":"March 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-03-06T06:09:00+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-05 06:29:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6091190","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6091190","identity":"rs-6091190","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}