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

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.

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

Scientific Reports ◽

10.1038/s41598-021-95315-w ◽

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.

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Treatment of Acute Stanford Type B Aortic Dissection With a Novel Cylindrical Balloon Catheter in Dogs

Circulation ◽

10.1161/circ.102.suppl_3.iii-259 ◽

2000 ◽

Vol 102 (suppl_3) ◽

Author(s):

Hiromu Terai ◽

Nobushige Tamura ◽

Tatsuo Nakamura ◽

Kazunobu Nishimura ◽

Norimasa Tsutsui ◽

...

Keyword(s):

Blood Flow ◽

Aortic Dissection ◽

Balloon Catheter ◽

False Lumen ◽

Aortic Blood Flow ◽

Acute Type ◽

Type B ◽

Type B Aortic Dissection ◽

True Lumen ◽

Descending Aorta

Background —Despite recent progress in medical and surgical treatment, acute type B aortic dissection still carries a high mortality rate. We have developed a novel cylindrical balloon catheter for less invasive treatment to block the entry of the dissection and induce thrombotic occlusion of the false lumen. The balloon has the shape of a sheet when deflated but a double-cylinder shape when inflated. Therefore, aortic blood flow is maintained through the cylindrical lumen during balloon inflation. Methods and Results —Six beagle dogs underwent a left thoracotomy at the 6th intercostal space. An acute dissection of 4-cm length was created surgically on the descending aorta. The balloon catheter was inserted through the distal descending aorta and advanced to the entry site. The balloon catheter was inflated for 6 hours. The blood flow in the descending aorta and the position of the balloon was monitored by color Doppler echovasculography. Four dogs were killed humanely on the following day and 2 dogs 10 days after the surgery. The descending aorta was examined macroscopically and microscopically in all dogs. In all dogs, the false lumen was occluded by thrombi. Although no dog had clinical evidence of distal thromboembolism, 2 of the 4 dogs that were killed on the second postoperative day had fresh mural thrombi in the true lumen. Conclusions —The false lumen of the acute type B aortic dissection was effectively occluded by the novel cylindrical balloon catheter in the canine experimental model. The thrombus formation in the true lumen is the problem to be solved.

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Repeated Peripheral Embolisms associated with Chronic Aortic Dissection

International Journal of Angiology ◽

10.1055/s-0039-1692144 ◽

2019 ◽

Vol 29 (03) ◽

pp. 210-214

Author(s):

Shigeaki Aoyagi ◽

Mau Amako ◽

Kumiko Wada ◽

Tomokazu Kosuga ◽

Hiroshi Yasunaga

Keyword(s):

Blood Flow ◽

Aortic Dissection ◽

Femoral Artery ◽

Bypass Graft ◽

False Lumen ◽

External Iliac Artery ◽

Renal Infarction ◽

Acute Type ◽

Type B ◽

The Right

AbstractA male patient developed acute type B aortic dissection (AD) extending to the right external iliac artery (EIA) and left common femoral artery at the age of 56 years. Two months after the diagnosis of AD, he developed right renal infarction suggesting embolism, as the right renal artery arose from a false lumen containing a mural thrombus. Seven years later, at the age of 63 years, the patient was readmitted for acute onset of intermittent claudication in the right leg. On admission, arterial pulses distal to the right femoral artery were absent. The right ankle-brachial pressure index (ABI) was 0.66, while the left ABI was 1.06. Computed tomography (CT) confirmed chronic type B AD and revealed a localized occlusion of the right EIA and disappearance of a small protruding thrombus in the false lumen that was found on the previous CT, suggesting a second embolism. Since recovery of antegrade blood flow was insufficient after catheter embolectomy, femorofemoral bypass was performed with resolution of ischemic symptoms. Postoperatively, the ABI recovered to 0.99 in the right and 1.12 in the left, and CT showed a patent bypass graft and restoration of blood flow to the right leg. This case indicates that embolism should be recognized as one of the possible causes of acute organ ischemia in patients with AD, even in patients with chronic AD.

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

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519414500171 ◽

2014 ◽

Vol 14 (02) ◽

pp. 1450017 ◽

Cited By ~ 13

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.

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The Effect of Beta-Blockers on Hemodynamic Parameters in Patient-Specific Blood Flow Simulations of Type-B Aortic Dissection: An Virtual Study

10.21203/rs.3.rs-255605/v1 ◽

2021 ◽

Author(s):

Mohammad Amin Abazari ◽

Deniz Rafieianzab ◽

M. Soltani ◽

Mona Alimohammadi

Keyword(s):

Blood Flow ◽

Shear Stress ◽

Wall Shear Stress ◽

Aortic Dissection ◽

Antihypertensive Drugs ◽

Patient Specific ◽

Hemodynamic Parameters ◽

Type B ◽

Type B Aortic Dissection ◽

Wall Shear

Abstract Type-B aortic dissection (AD) is one of the greatest complex and fatal conditions with co-occurring disorders, challenging to treat. The initial treatment for patients presenting with AD is medical intervention to stabilize the condition. In the present study, a patient-specific geometry of type-B AD is generated from computed tomography images, and a three-element Windkessel lumped parameter model is implemented at the outlets to realistic boundary conditions. According to the physiological response of the antihypertensive drugs in the reduction of aortic blood flow and heart rate, three case studies with different heart rates have been created. Hemodynamic distributions including wall shear stress indicators, velocity and pressure are investigated and compared in each model. Results show that there is a considerable reduction in pressure furthermore, time-averaged wall shear stress (TAWSS) values decreased by 25% and 30%, respectively. Main goal is to critically analysis the use of biomechanical and computational simulation tools to measure hemodynamic parameters in the absence and presence of antihypertensive drugs. It would be of significant use to clinicians to improve diagnostic and treatment planning.

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Late false-lumen expansion predicted by preoperative blood flow simulation in a patient with chronic type B aortic dissection

Journal of Thoracic and Cardiovascular Surgery ◽

10.1016/j.jtcvs.2018.09.108 ◽

2019 ◽

Vol 157 (6) ◽

pp. e311-e317 ◽

Cited By ~ 1

Author(s):

Chikara Ueki ◽

Hiroshi Tsuneyoshi

Keyword(s):

Blood Flow ◽

Aortic Dissection ◽

False Lumen ◽

Flow Simulation ◽

Type B ◽

Type B Aortic Dissection ◽

Chronic Type ◽

Blood Flow Simulation

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

Cardiology and Cardiovascular Medicine ◽

10.26502/fccm.92920155 ◽

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

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

Vascular and Endovascular Surgery ◽

10.1177/15385744211045156 ◽

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.

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

Journal of 3D Printing in Medicine ◽

10.2217/3dp-2020-0025 ◽

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.

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