scholarly journals Computational tools for clinical support: a multi-scale compliant model for haemodynamic simulations in an aortic dissection based on multi-modal imaging data

2017 ◽  
Vol 14 (136) ◽  
pp. 20170632 ◽  
Author(s):  
Mirko Bonfanti ◽  
Stavroula Balabani ◽  
John P. Greenwood ◽  
Sapna Puppala ◽  
Shervanthi Homer-Vanniasinkam ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Moving Boundary ◽  
Computational Cost ◽  
False Lumen ◽  
Patient Specific ◽  
Model Parameters ◽  
High Morbidity ◽  
Multi Scale ◽  
Clinical Support

Aortic dissection (AD) is a vascular condition with high morbidity and mortality rates. Computational fluid dynamics (CFD) can provide insight into the progression of AD and aid clinical decisions; however, oversimplified modelling assumptions and high computational cost compromise the accuracy of the information and impede clinical translation. To overcome these limitations, a patient-specific CFD multi-scale approach coupled to Windkessel boundary conditions and accounting for wall compliance was developed and used to study a patient with AD. A new moving boundary algorithm was implemented to capture wall displacement and a rich in vivo clinical dataset was used to tune model parameters and for validation. Comparisons between in silico and in vivo data showed that this approach successfully captures flow and pressure waves for the patient-specific AD and is able to predict the pressure in the false lumen (FL), a critical variable for the clinical management of the condition. Results showed regions of low and oscillatory wall shear stress which, together with higher diastolic pressures predicted in the FL, may indicate risk of expansion. This study, at the interface of engineering and medicine, demonstrates a relatively simple and computationally efficient approach to account for arterial deformation and wave propagation phenomena in a three-dimensional model of AD, representing a step forward in the use of CFD as a potential tool for AD management and clinical support.

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.

Spontaneous Resolution of a Descending Aortic Dissection

1989 ◽  
Vol 30 (3) ◽  
pp. 305-306 ◽  
Author(s):  
B. Thorvinger ◽  
U. Albrechtsson
Keyword(s):  
Computed Tomography ◽  
Natural History ◽  
Aortic Dissection ◽  
Contrast Medium ◽  
False Lumen ◽  
Complete Healing ◽  
Spontaneous Resolution ◽  
History Of ◽  
Enhanced Computed Tomography

The natural history of an aortic dissection is either endothelialization of the false lumen forming a so-called double-barrelled aorta, or thrombosis of the sack leading to fibrosis and scarring. Complete healing of an aortic dissection is extremely rare, and has to our knowledge only been reported once in vivo. Here we report a second case of spontaneous resolution of an aortic dissection, disclosed by contrast medium enhanced computed tomography.

scholarly journals A Combined In Vivo, In Vitro, In Silico Approach for Patient-Specific Haemodynamic Studies of Aortic Dissection

2020 ◽  
Vol 48 (12) ◽  
pp. 2950-2964
Author(s):  
Mirko Bonfanti ◽  
Gaia Franzetti ◽  
Shervanthi Homer-Vanniasinkam ◽  
Vanessa Díaz-Zuccarini ◽  
Stavroula Balabani
Keyword(s):  
Aortic Dissection ◽  
In Silico ◽  
Clinical Decision ◽  
Patient Specific ◽  
Type B ◽  
Non Invasive ◽  
Cfd Models ◽  
Numerical Predictions

AbstractThe optimal treatment of Type-B aortic dissection (AD) is still a subject of debate, with up to 50% of the cases developing late-term complications requiring invasive intervention. A better understanding of the patient-specific haemodynamic features of AD can provide useful insights on disease progression and support clinical management. In this work, a novel in vitro and in silico framework to perform personalised studies of AD, informed by non-invasive clinical data, is presented. A Type-B AD was investigated in silico using computational fluid dynamics (CFD) and in vitro by means of a state-of-the-art mock circulatory loop and particle image velocimetry (PIV). Both models not only reproduced the anatomical features of the patient, but also imposed physiologically-accurate and personalised boundary conditions. Experimental flow rate and pressure waveforms, as well as detailed velocity fields acquired via PIV, are extensively compared against numerical predictions at different locations in the aorta, showing excellent agreement. This work demonstrates how experimental and numerical tools can be developed in synergy to accurately reproduce patient-specific AD blood flow. The combined platform presented herein constitutes a powerful tool for advanced haemodynamic studies for a range of vascular conditions, allowing not only the validation of CFD models, but also clinical decision support, surgical planning as well as medical device innovation.

scholarly journals Intravascular Ultrasound–Assisted Endovascular Treatment of Mesenteric Malperfusion in a Multichannel Aortic Dissection With Full True Lumen Collapse

2018 ◽  
Vol 26 (1) ◽  
pp. 83-87 ◽  
Author(s):  
Baolei Guo ◽  
Daqiao Guo ◽  
Zhenyu Shi ◽  
Zhihui Dong ◽  
Weiguo Fu
Keyword(s):  
Aortic Dissection ◽  
Endovascular Treatment ◽  
Intravascular Ultrasound ◽  
Mesenteric Ischemia ◽  
False Lumen ◽  
Patient Specific ◽  
Chronic Mesenteric Ischemia ◽  
True Lumen ◽  
True Lumen Collapse ◽  
Ivus Imaging

Purpose: To describe endovascular treatment of mesenteric malperfusion in a multichannel aortic dissection (MCAD) with full true lumen (TL) collapse following thoracic endovascular aortic repair (TEVAR). Case Report: A 54-year-old man presented with chronic mesenteric ischemia and a previous TEVAR for MCAD complicated by superior mesenteric artery (SMA) malperfusion. Computed tomography angiography (CTA) demonstrated a 3-channel aortic dissection with a “false-true-false” configuration. The SMA was malperfused through the collapsed TL. CTA also showed a secondary entry tear, measuring 18 mm in diameter, at the end of the previous endograft. Direct open surgery or endovascular revascularization of the SMA was not feasible. A plan was devised to improve SMA perfusion by increasing the TL inflow. With the assistance of intravascular ultrasound (IVUS), an endograft was placed through one false lumen in the abdominal aorta and through the TL in the descending thoracic aorta to seal the secondary entry tear. Symptoms of mesenteric ischemia resolved 2 days after the procedure. At 1 year, he is asymptomatic, has gained weight, and has improved SMA perfusion and remodeling of the 3-channel dissection on CTA. Conclusion: IVUS imaging can help evaluate the complex hemodynamics of MCAD. Patient-specific endovascular treatment of MCAD with mesenteric malperfusion seems to be a feasible bailout alternative treatment for urgent, complex cases without reconstruction options.

scholarly journals Calibration of an Electrical Analog Model of Liver Hemodynamics in Fontan Patients

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Elyar Abbasi Bavil ◽  
Matthew G. Doyle ◽  
Charlotte Debbaut ◽  
Rachel M. Wald ◽  
Luc Mertens ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Venous Pressure ◽  
Portal Pressure ◽  
Lumped Parameter Model ◽  
Patient Specific ◽  
Model Parameters ◽  
Liver Health ◽  
Liver Hemodynamics ◽  
Fontan Patients

Abstract Fontan associated liver disease is a common complication in patients with Fontan circulation, who were born with a single functioning heart ventricle. The hepatic venous pressure gradient (HVPG) is used to assess liver health and is a surrogate measure of the pressure gradient across the entire liver (portal pressure gradient (PPG)). However, it is thought to be inaccurate in Fontan patients. The main objectives of this study were (1) to apply an existing detailed lumped parameter model (LPM) of the liver to Fontan patients using patient-specific clinical data and (2) to determine whether HVPG is a suitable measurement of PPGs in these patients. An existing LPM of the liver blood circulation was applied and tuned to simulate patient-specific liver hemodynamics. Geometries were collected from seven adult Fontan patients and used to evaluate model parameters. The model was solved and tuned using waveform measurements of flows, inlet and outlet pressures. The predicted ratio of portal to hepatic venous pressures is comparable to in vivo measurements. The results confirmed that HVPG is not suitable for Fontan patients, as it would underestimate the portal pressures gradient by a factor of 3 to 4. Our patient-specific liver model provides an estimate of the pressure drop across the liver, which differs from the clinically used metric HVPG. This work represents a first step toward models suitable to assess liver health in Fontan patients and improve its long-term management.

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 Hybrid Strategy for Residual Arch and Thoracic Aortic Dissection following Acute Type A Aortic Dissection Repair

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Sidharth Viswanathan ◽  
Vivek Agrawal ◽  
Shashidhar Kallappa Parameshwarappa ◽  
Ajay Savlania ◽  
Santhosh Kumar ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Circulatory Arrest ◽  
Management Strategies ◽  
False Lumen ◽  
Type A ◽  
High Morbidity ◽  
Acute Type ◽  
Hybrid Strategy ◽  
Type A Aortic Dissection ◽  
Thoracic Aortic Dissection

Progressive dilatation of the false lumen in the arch and descending aorta has been encountered in one-third of survivors as a late sequelae following repair of ascending aortic dissection. Conventional treatment for the same requiring cardiopulmonary bypass and deep hypothermic circulatory arrest is associated with high morbidity and mortality especially in the elderly cohort of patients. Herein we report a case of symptomatic progressive aneurysmal dilatation of residual arch and descending thoracic aortic dissection following repair of type A aortic dissection, successfully treated by total arch debranching and ascending aortic prosthesis to bicarotid and left subclavian bypass followed by staged retrograde aortic stent-graft deployment. This case report with relevant review of the literature highlights this clinical entity and the present evidence on its appropriate management strategies. Close surveillance is mandatory following surgical repair of type A aortic dissection and hybrid endovascular procedures seem to be the most dependable modality for salvage of patients detected to have progression of residual arch dissection.

scholarly journals Influence of Distal Resistance and Proximal Stiffness on Hemodynamics and RV Afterload in Progression and Treatments of Pulmonary Hypertension: A Computational Study with Validation Using Animal Models

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Zhenbi Su ◽  
Wei Tan ◽  
Robin Shandas ◽  
Kendall S. Hunter
Keyword(s):  
Pulmonary Hypertension ◽  
Ex Vivo ◽  
Computational Study ◽  
Vascular Wall ◽  
Patient Specific ◽  
Model Parameters ◽  
Theoretical Treatment ◽  
Pulmonary Hemodynamics ◽  
Mean Pulmonary Arterial Pressure

We develop a simple computational model based on measurements from a hypoxic neonatal calf model of pulmonary hypertension (PH) to investigate the interplay between vascular and ventricular measures in the setting of progressive PH. Model parameters were obtained directly fromin vivoandex vivomeasurements of neonatal calves. Seventeen sets of model-predicted impedance and mean pulmonary arterial pressure (mPAP) show good agreement with the animal measurements, thereby validating the model. Next, we considered a predictive model in which three parameters, PVR, elastic modulus (EM), and arterial thickness, were varied singly from one simulation to the next to study their individual roles in PH progression. Finally, we used the model to predict the individual impacts of clinical (vasodilatory) and theoretical (compliance increasing) PH treatments on improving pulmonary hemodynamics. Our model (1) displayed excellent patient-specific agreement with measured global pulmonary parameters; (2) quantified relationships between PVR and mean pressure and PVS and pulse pressure, as well as studiying the right ventricular (RV) afterload, which could be measured as a hydraulic load calculated from spectral analysis of pulmonary artery pressure and flow waves; (3) qualitatively confirmed the derangement of vascular wall shear stress in progressive PH; and (4) established that decreasing proximal vascular stiffness through a theoretical treatment of reversing proximal vascular remodeling could decrease RV afterload.

Patient-Specific Modeling and Hemodynamic Simulation in Healthy and Diseased Coronary Arteries

2012 ◽  
Author(s):  
Lucian Itu ◽  
Puneet Sharma ◽  
Xudong Zheng ◽  
Viorel Mihalef ◽  
Ali Kamen ◽  
...  
Keyword(s):  
Patient Specific ◽  
Multi Scale ◽  
Routine Clinical Setting ◽  
Patient Specific Modeling ◽  
Artery Disease ◽  
Diagnostic Modalities ◽  
Causes Of Deaths ◽  
Computational Resources

Coronary Artery Disease is one of the leading causes of deaths worldwide, with an estimated 7.2 million deaths each year. In spite of the improvements in imaging and other diagnostic modalities, the incidence of premature morbidity and mortality is still very high, the main reason being the lack of accurate in-vivo and in-vitro patient-specific estimates for diagnosis and disease progression. Recently, CFD-based models have been proposed for analyzing the coronary circulation [1, 2]. The main challenges for such methods are the lack of patient-specific data (anatomy, boundary conditions), inefficient multi-scale coupling and computational resources. These challenges limit the scope of such methods in a routine clinical setting.

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