scholarly journals The effect of beta-blockers on hemodynamic parameters in patient-specific blood flow simulations of type-B aortic dissection: a virtual study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Amin Abazari ◽  
Deniz Rafieianzab ◽  
M. Soltani ◽  
Mona Alimohammadi
Keyword(s):  
Aortic Dissection ◽  
Clinical Decision Making ◽  
Beta Blockers ◽  
False Lumen ◽  
Specific Treatment ◽  
Left Ventricular ◽  
Patient Specific ◽  
Type B ◽  
Windkessel Model ◽  
Computed Tomography Images

AbstractAortic dissection (AD) is one of the fatal and complex conditions. Since there is a lack of a specific treatment guideline for type-B AD, a better understanding of patient-specific hemodynamics and therapy outcomes can potentially control the progression of the disease and aid in the clinical decision-making process. In this work, a patient-specific geometry of type-B AD is reconstructed from computed tomography images, and a numerical simulation using personalised computational fluid dynamics (CFD) with three-element Windkessel model boundary condition at each outlet is implemented. According to the physiological response of beta-blockers to the reduction of left ventricular contractions, three case studies with different heart rates are created. Several hemodynamic features, including time-averaged wall shear stress (TAWSS), highly oscillatory, low magnitude shear (HOLMES), and flow pattern are investigated and compared between each case. Results show that decreasing TAWSS, which is caused by the reduction of the velocity gradient, prevents vessel wall at entry tear from rupture. Additionally, with the increase in HOLMES value at distal false lumen, calcification and plaque formation in the moderate and regular-heart rate cases are successfully controlled. This work demonstrates how CFD methods with non-invasive hemodynamic metrics can be developed to predict the hemodynamic changes before medication or other invasive operations. These consequences can be a powerful framework for clinicians and surgical communities to improve their diagnostic and pre-procedural planning.

scholarly journals Predicting false lumen thrombosis in patient-specific models of aortic dissection

2016 ◽  
Vol 13 (124) ◽  
pp. 20160759 ◽  
Author(s):  
Claudia Menichini ◽  
Zhuo Cheng ◽  
Richard G. J. Gibbs ◽  
Xiao Yun Xu
Keyword(s):  
Aortic Dissection ◽  
Clinical Decision Making ◽  
Thrombus Formation ◽  
False Lumen ◽  
Clinical Decision ◽  
Growth Patterns ◽  
Diffusion Reaction ◽  
Patient Specific ◽  
Type B ◽  
Type B Dissection

Aortic dissection causes splitting of the aortic wall layers, allowing blood to enter a ‘false lumen’ (FL). For type B dissection, a significant predictor of patient outcomes is patency or thrombosis of the FL. Yet, no methods are currently available to assess the chances of FL thrombosis. In this study, we present a new computational model that is capable of predicting thrombus formation, growth and its effects on blood flow under physiological conditions. Predictions of thrombus formation and growth are based on fluid shear rate, residence time and platelet distribution, which are evaluated through convection–diffusion–reaction transport equations. The model is applied to a patient-specific type B dissection for which multiple follow-up scans are available. The predicted thrombus formation and growth patterns are in good qualitative agreement with clinical data, demonstrating the potential applicability of the model in predicting FL thrombosis for individual patients. Our results show that the extent and location of thrombosis are strongly influenced by aortic dissection geometry that may change over time. The high computational efficiency of our model makes it feasible for clinical applications. By predicting which aortic dissection patient is more likely to develop FL thrombosis, the model has great potential to be used as part of a clinical decision-making tool to assess the need for early endovascular intervention for individual dissection patients.

Abstract 102: Number of Reentry Tears Influences Flap Motion and Flow Reversal in an in vitro Model of Type B Aortic Dissection

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Joav Birjiniuk ◽  
Mark Young ◽  
Lucas H Timmins ◽  
Bradley G Leshnower ◽  
John N Oshinski ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
False Lumen ◽  
Flow Reversal ◽  
Patient Specific ◽  
Type B ◽  
True Lumen ◽  
Flow Rates ◽  
Custom Made ◽  
Type B Dissection

Objectives: Aortic remodeling after dissection is poorly understood. Thus, optimal patient-specific recommendations for treatment are lacking. An in vitro aortic model of Type B dissection was used to interrogate local aortic hemodynamic parameters implicated in thrombosis and aneurysm formation. We hypothesize that dissections with multiple reentry tears will exhibit decreased flap motion, and, as a result, reduce flow reversal. Methods: Anatomic models of aortic dissection with fidelity to patient CT images were fabricated out of silicone. Models with primary entry and single fenestration (Figure 1A), two fenestrations (Figure 1B), and three fenestrations (Figure 1C) were installed in a flow loop. Physiologic flow was established at a cardiac index of 4 L/min. Flow velocities were acquired using phase contrast magnetic resonance (PCMR) imaging. Flow rates and flap motion were quantified using custom made software. Results: Relative true lumen area (RTLA) varied along the dissection (entry: 55% +/- 3, middle: 34% +/-7, exit: 91%+/-3, p<0.00001 pair-wise for 2-tear model). At mid-dissection, RTLA was lower in dissections with fewer tears (p<0.01). Total flow was nearly identical in all cases, while true and false lumen flow rates differed significantly across tear configurations and along the dissection (p<0.01). Secondary tears allowed for flow communication within the dissected portion of the aortic model. Flow reversal was seen in the false lumen at the mid-dissection plane in the absence of secondary tears (Figure 1D). However, as secondary tears were added, the flow reversal in the false lumen decreased, with concomitant flow reversal in the true lumen (Figure 1E,F). Conclusions: Anatomic characteristics of dissection, such as number of tears, affect blood flow and motion of the dissection flap, as shown quantitatively. This compliant aorta model illustrates alterations in flow reversal in both true and false lumina that may lead to aneurysmal degeneration.

scholarly journals A patient-specific study of type-B aortic dissection: evaluation of true-false lumen blood exchange

2013 ◽  
Vol 12 (1) ◽  
pp. 65 ◽  
Author(s):  
Duanduan Chen ◽  
Matthias Müller-Eschner ◽  
Hendrik von Tengg-Kobligk ◽  
David Barber ◽  
Dittmar Böckler ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
False Lumen ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Specific Study ◽  
Blood Exchange ◽  
True False

scholarly journals THE IMPACT OF THE NUMBER OF TEARS IN PATIENT-SPECIFIC STANFORD TYPE B AORTIC DISSECTING ANEURYSM: CFD SIMULATION

2014 ◽  
Vol 14 (02) ◽  
pp. 1450017 ◽  
Author(s):  
WAN NAIMAH WAN AB NAIM ◽  
POO BALAN GANESAN ◽  
ZHONGHUA SUN ◽  
KAHAR OSMAN ◽  
EINLY LIM
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Aortic Dissection ◽  
False Lumen ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Wall Shear ◽  
The Impact ◽  
Stanford Type B

It is believed that the progression of Stanford type B aortic dissection is closely associated with vascular geometry and hemodynamic parameters. The hemodynamic differences owing to the presence of greater than two tears have not been explored. The focus of the present study is to investigate the impact of an additional re-entry tear on the flow, pressure and wall shear stress distribution in the dissected aorta. A 3D aorta model with one entry and one re-entry tear was generated from computed tomography (CT) angiographic images of a patient with Stanford Type B aortic dissection. To investigate the hemodynamic effect of more than two tear locations, an additional circular re-entry tear was added 24 mm above the original re-entry tear. Our simulation results showed that the presence of an additional re-entry tear provided an extra return path for blood back to the true lumen during systole, and an extra outflow path into the false lumen during diastole. The presence of this additional path led to a decrease in the false lumen pressure, particularly at the distal region. Meanwhile, the presence of this additional tear causes no significant difference on the time average wall shear stress (TAWSS) distribution except at regions adjacent to re-entry tear 2. Moderate and concentrated TAWSS was observed at the bottom region of this additional tear which may lead to further extension of the tear distally.

scholarly journals Multilayer flow modulator enhances vital organ perfusion in patients with type B aortic dissection

2018 ◽  
Vol 315 (5) ◽  
pp. H1182-H1193 ◽  
Author(s):  
Farhad Rikhtegar Nezami ◽  
Lambros S. Athanasiou ◽  
Junedh M. Amrute ◽  
Elazer R. Edelman
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Aortic Dissection ◽  
False Lumen ◽  
Organ Perfusion ◽  
Type B ◽  
Local Flow ◽  
Dynamic Framework ◽  
Computed Tomography Images ◽  
Flow Disturbances

Management of aortic dissections (AD) is still challenging, with no universally approved guideline among possible surgical, endovascular, or medical therapies. Approximately 25% of patients with AD suffer postintervention malperfusion syndrome or hemodynamic instability, with the risk of sudden death if left untreated. Part of the issue is that vascular implants may themselves induce flow disturbances that critically impact vital organs. A multilayer mesh construct might obviate the induced flow disturbances, and it is this concept we investigated. We used preintervention and post-multilayer flow modulator implantation (PM) geometries from clinical cases of type B AD. In-house semiautomatic segmentation routines were applied to computed tomography images to reconstruct the lumen. The device was numerically reconstructed and adapted to the PM geometry concentrically fit to the true lumen centerline. We also numerically designed a pseudohealthy case, where the geometry of the aorta was extracted interpolating geometric features of preintervention, postimplantation, and published representative healthy volunteers. Computational fluid dynamics methods were used to study the time-dependent flow patterns, shear stress metrics, and perfusion to vital organs. A three-element Windkessel lumped parameter module was coupled to a finite-volume solver to assign dynamic outlet boundary conditions. Multilayer flow modulator not only significantly reduced false lumen blood flow, eliminated local flow disturbances, and globally regulated wall shear stress distribution but also maintained physiological perfusion to peripheral vital organs. We propose further investigation to focus the management of AD on both modulation of blood flow and restoration of physiologic end-organ perfusion rather than mere restoration of vascular lamina morphology. NEW & NOTEWORTHY The majority of aortic dissection modeling efforts have focused on the maintenance of physiological flow using minimally invasive placed grafts. The multilayer flow modulator is a complex mesh construct of wires, designed to eliminate flow disruptions in the lumen, regulate the physiological wall stresses, and enhance endothelial function and offering the promise of improved perfusion of vital organs. This has never been fully proved or modeled, and these issues we confirmed using a dynamic framework of time-varying arterial waveforms.

Management of Residual False Lumen Flow After Thoracic Endovascular Repair in Chronic Type B Aortic Dissection

2020 ◽  
Vol 04 (05) ◽  
Author(s):  
Hervé Rousseau ◽  
Paul Revel-Mouroz ◽  
Charline Zadro ◽  
Camille Dambrin ◽  
Christophe Cron ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Endovascular Repair ◽  
False Lumen ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Chronic Type ◽  
Thoracic Endovascular Repair

Spinal Cord Ischemia in the Setting of Acute Type B Aortic Dissection: Successful Rescue with Thoracic Endovascular Aortic Repair

2021 ◽  
pp. 153857442110451
Author(s):  
Masaki Kano ◽  
Toru Iwahashi ◽  
Toshiya Nishibe ◽  
Kentaro Kamiya ◽  
Hitoshi Ogino
Keyword(s):  
Spinal Cord ◽  
Aortic Dissection ◽  
Medical Management ◽  
Spinal Cord Ischemia ◽  
False Lumen ◽  
Thoracic Endovascular Aortic Repair ◽  
Endovascular Aortic Repair ◽  
Acute Type ◽  
Type B ◽  
Type B Aortic Dissection

We report 2 cases of successful thoracic endovascular aortic repair (TEVAR) for acute type B aortic dissection (ABAD) complicated with spinal cord ischemia (SCI). Case 1. A 70-year-old gentleman found with an uncomplicated ABAD with false lumen occluded, developed SCI shortly after admission during the initial medical management. Cerebrospinal fluid drainage (CSFD) was initiated followed by emergent TEVAR. SCI improved, and the patient was discharged. Case 2. A 52-year-old gentleman developed uncomplicated ABAD with patent false lumen. 5 hours after admission, he developed SCI during the initial medical management. Emergent TEVAR was performed followed by CSFD, and the SCI improved before discharge. These cases prompted us to address prompt TEVAR for primary entry closure and true lumen dilatation with postoperative hypertensive management to relieve the dynamic obstruction of the segmental arteries responsible for the compromised spinal cord circulation in complicated ABAD.

Optimal image segmentation protocol for 3D printing of aortic dissection through open-source software

2021 ◽  
Author(s):  
Chia-An Wu ◽  
Andrew Squelch ◽  
Zhonghua Sun
Keyword(s):  
Computed Tomography ◽  
Image Segmentation ◽  
3D Printing ◽  
Aortic Dissection ◽  
Open Source ◽  
Open Source Software ◽  
Type B ◽  
Manual Intervention ◽  
Computed Tomography Images ◽  
Computed Tomography Image

Aim: To determine the optimal image segmentation protocol that minimizes the amount of manual intervention and correction required while extracting 3D model geometries suitable for 3D printing of aortic dissection (AD) using open-source software. Materials & methods: Computed tomography images of two type B AD cases were selected with images segmented using a 3D Slicer to create a hollow model containing the aortic wall and intimal tear. A workflow composed of filters, lumen extraction and outer surface creation was developed. Results & conclusion: The average difference in measurements at 14 anatomical locations between the Standard Tessellation Language file and the computed tomography image for cases 1 and 2 were 0.29 and 0.32 mm, respectively. The workflow for the image segmentation of type B AD was able to produce a high-accuracy 3D-printed model in a short time through open-source software.

Investigation of three-dimensional printing materials for printing aorta model replicating Type B aortic dissection

2021 ◽  
Vol 17 ◽  
Author(s):  
Chia-An Wu ◽  
Andrew Squelch ◽  
Zhonghua Sun
Keyword(s):  
3D Printing ◽  
Aortic Dissection ◽  
Three Dimensional ◽  
Ct Images ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Ct Attenuation ◽  
Significant Difference ◽  
3D Printed

Aim: To determine a printing material that has both elastic property and radiology equivalence close to real aorta for simulation of endovascular stent graft repair of aortic dissection. Background: With the rapid development of three-dimensional (3D) printing technology, a patient-specific 3D printed model is able to help surgeons to make better treatment plan for Type B aortic dissection patients. However, the radiological properties of most 3D printing materials have not been well characterized. This study aims to investigate the appropriate materials for printing human aorta with mechanical and radiological properties similar to the real aortic computed tomography (CT) attenuation. Objective: Quantitative assessment of CT attenuation of different materials used in 3D printed models of aortic dissection for developing patient-specific 3D printed aorta models to simulate type B aortic dissection. Method: A 25-mm length of aorta model was segmented from a patient’s image dataset with diagnosis of type B aortic dissection. Four different elastic commercial 3D printing materials, namely Agilus A40 and A50, Visijet CE-NT A30 and A70 were selected and printed with different hardness. Totally four models were printed out and conducted CT scanned twice on a 192-slice CT scanner using the standard aortic CT angiography protocol, with and without contrast inside the lumen.Five reference points with region of interest (ROI) of 1.77 mm2 were selected at the aortic wall and intimal flap and their Hounsfield units (HU) were measured and compared with the CT attenuation of original CT images. The comparison between the patient’s aorta and models was performed through a paired-sample t-test to determine if there is any significant difference. Result: The mean CT attenuation of aortic wall of the original CT images was 80.7 HU. Analysis of images without using contrast medium showed that the material of Agilus A50 produced the mean CT attenuation of 82.6 HU, which is similar to that of original CT images. The CT attenuation measured at images acquired with other three materials was significantly lower than that of original images (p<0.05). After adding contrast medium, Visijet CE-NT A30 had an average CT attenuation of 90.6 HU, which is close to that of the original images with statistically significant difference (p>0.05). In contrast, the CT attenuation measured at images acquired with other three materials (Agilus A40, A50 and Visiject CE-NT A70) was 129 HU, 135 HU and 129.6 HU, respectively, which is significantly higher than that of original CT images (p<0.05). Conclusion: Both Visijet CE-NT and Agilus have tensile strength and elongation close to real patient’s tissue properties producing similar CT attenuation. Visijet CE-NT A30 is considered the appropriate material for printing aorta to simulate contrast-enhanced CT imaging of type B aortic dissection. Due to lack of body phantom in the experiments, further research with simulation of realistic anatomical body environment should be conducted.

Safety and Effectiveness of TEVAR in Native Proximal Landing Zone 2 for Chronic Type B Aortic Dissection in Patients With Genetic Aortic Syndrome

2021 ◽  
pp. 152660282110612
Author(s):  
Ahmed Eleshra ◽  
Giuseppe Panuccio ◽  
Konstantinos Spanos ◽  
Fiona Rohlffs ◽  
Yskert von Kodolitsch ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
False Lumen ◽  
Thoracic Endovascular Aortic Repair ◽  
Endovascular Aortic Repair ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Chronic Type ◽  
Ehlers Danlos Syndrome ◽  
Landing Zone ◽  
Aortic Repair

Objectives The aim of this study is to report the safety and effectiveness of thoracic endovascular aortic repair (TEVAR) in a native proximal landing zone (PLZ) 2 for chronic type B aortic dissection (TBAD) patients with genetic aortic syndrome (GAS). Methods A retrospective review of a single center database to identify patients with GAS treated with TEVAR in native PLZ 2 for chronic TBAD and thoracic false lumen aneurysm between February 2012 and February 2018 was undertaken. Results In total, 31 patients with GAS (24 Marfan syndrome [MFS], 5 Loeys-Dietz syndrome [LDS], and 2 vascular Ehlers-Danlos syndrome [vEDS]) were treated by endovascular repair. Nineteen patients were treated by TEVAR as index procedures with 8 patients (5 females, mean age = 55, range = 36–79 years old) receiving TEVAR in native PLZ 2. Left subclavian artery (LSA) perfusion was preserved in all 8 patients: by left common carotid artery-LSA bypass in 6 patients, chimney stenting of the LSA in 1 patient, and partial coverage of LSA ostium in 1 patient. Technical success was achieved in all patients (100%). There was no 30 day mortality (0%). The 30 day morbidity (0%) was free from major complications. The median follow-up was 40 months (range = 7–79). One patient died due to non-aortic-related cause. Native PLZ 2 was free from complications in MFS patients (5/8). Two patients with LDS developed type Ia endoleak with aneurysmal progression. One patient was treated by proximal extension with a double inner branched arch stent-graft landing in the replaced ascending aorta. The other one was treated with frozen elephant trunk. Conclusion Thoracic endovascular aortic repair in native PLZ 2 was safe and effective with no early or midterm PLZ complications in patients with MFS with chronic TBAD in this limited series. Native PLZ 2 is not safe in patients with LDS and should only be used in emergencies as a bridging to open repair.

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