scholarly journals Surgical Planning and Optimization of Patient-Specific Fontan Grafts With Uncertain Post-Operative Boundary Conditions and Anastomosis Displacement

2021 ◽  
Author(s):  
Xiaolong Liu ◽  
Narutoshi Hibino ◽  
Yue-Hin Loke ◽  
Byeol Kim ◽  
Paige Mass ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Surgical Planning ◽  
Health Benefit ◽  
Flow Distribution ◽  
Optimization Under Uncertainty ◽  
Design Parameters ◽  
Patient Specific ◽  
Fontan Patient ◽  
Mean Values

AbstractObjectiveFontan surgical planning involves designing grafts to perform optimized hemodynamic performance for the patient’s long-term health benefit. The uncertainty of post-operative boundary conditions (BC) and graft anastomisis displacements may significantly affect the optimized graft designs and lead to undesired outcomes, especially for hepatic flow distribution (HFD). We aim to develop a computation framework to automatically optimize patient-specific Fontan grafts with the maximized possibility of keeping the post-operative results within clinical acceptable thresholds.MethodsThe uncertainties of BC and anastomosis displacements were modeled by using Gaussian distributions according to prior research studies. By parameterizing the Fontan grafts, we built surrogate models of hemodynamic parameters by taking the design parameters and BC as inputs. A two-phased reliability-based robust optimization (RBRO) strategy was developed by combining deterministic optimization (DO) and optimization under uncertainty (OUU) to reduce the computation cost.ResultsWe evaluated the performance of the RBRO framework by comparing it with the DO method on four Fontan patient cases. The results showed that the surgical plans computed from the proposed method yield up to 79.2% improvement on the reliability of HFD than those from the DO method (p < 0.0001). The mean values of iPL and %WSS satisfied the clinically acceptable thresholds.ConclusionThis study demonstrated the effectiveness of our RBRO framework to address uncertainties of BC and anastomosis displacements for Fontan surgical planning.SignificanceThe technique developed in this paper demonstrates a significant improvement in the reliability of predicted post-operative outcomes for Fontan surgical planning. This planning technique is immediately applicable as a building block to enable technology for optimal long-term outcomes for pediatric Fontan patients and can also be used to other pediatric and adult cardiac surgeries.

scholarly journals Structured Tree Impedance Outflow Boundary Conditions for 3D Lung Simulations

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Andrew Comerford ◽  
Christiane Förster ◽  
Wolfgang A. Wall
Keyword(s):  
Boundary Conditions ◽  
Flow Distribution ◽  
Left Lobe ◽  
Patient Specific ◽  
Outflow Boundary Conditions ◽  
Human Lungs ◽  
Clinical Scenarios ◽  
Mean Pressure ◽  
Acceleration And Deceleration ◽  
Outflow Boundary

In this paper, we develop structured tree outflow boundary conditions for modeling the airflow in patient specific human lungs. The utilized structured tree is used to represent the nonimageable vessels beyond the 3D domain. The coupling of the two different scales (1D and 3D) employs a Dirichlet–Neumann approach. The simulations are performed under a variety of conditions such as light breathing and constant flow ventilation (which is characterized by very rapid acceleration and deceleration). All results show that the peripheral vessels significantly impact the pressure, however, the flow is relatively unaffected, reinforcing the fact that the majority of the lung impedance is due to the lower generations rather than the peripheral vessels. Furthermore, simulations of a hypothetical diseased lung (restricted flow in the superior left lobe) under mechanical ventilation show that the mean pressure at the outlets of the 3D domain is about 28% higher. This hypothetical model illustrates potential causes of volutrauma in the human lung and furthermore demonstrates how different clinical scenarios can be studied without the need to assume the unknown flow distribution into the downstream region.

Personalized Computational Models of Tissue-Rearrangement in the Scalp Predict the Mechanical Stress Signature of Rotation Flaps

2020 ◽  
pp. 105566562095409
Author(s):  
Taeksang Lee ◽  
Sergey Y. Turin ◽  
Casey Stowers ◽  
Arun K. Gosain ◽  
Adrian Buganza Tepole
Keyword(s):  
Surgical Planning ◽  
Computational Models ◽  
Design Parameters ◽  
Patient Specific ◽  
Noninvasive Methods ◽  
Tension Distribution ◽  
Scalp Reconstruction ◽  
Scalp Defects ◽  
3D Geometry ◽  
Flap Design

Objective: To elucidate the mechanics of scalp rotation flaps through 3D imaging and computational modeling. Excessive tension near a wound or sutured region can delay wound healing or trigger complications. Measuring tension in the operating room is challenging, instead, noninvasive methods to improve surgical planning are needed. Design: Multi-view stereo allows creation of 3D patient-specific geometries based on a set of photographs. The patient-specific 3D geometry is imported into a finite element (FE) platform to perform a virtual procedure. The simulation is compared with the clinical outcome. Additional simulations quantify the effect of individual flap parameters on the resulting tension distribution. Participants: Rotation flaps for reconstruction of scalp defects following melanoma resection in 2 cases are presented. Rotation flaps were designed without preoperative FE preparation. Main Outcome Measure: Tension distribution over the operated region. Results: The tension from FE shows peaks at the base and distal ends of the scalp rotation flap. The predicted geometry from the simulation aligns with postoperative photographs. Simulations exploring the flap design parameters show variation in the tension. Lower tensions were achieved when rotation was oriented with respect to skin tension lines (horizontal tissue fibers) and smaller rotation angles. Conclusions: Tension distribution following rotation of scalp flaps can be predicted through personalized FE simulations. Flaps can be designed to reduce tension using FE, which may greatly improve the reliability of scalp reconstruction in craniofacial surgery, critical in complex cases when scalp reconstruction is essential for coverage of hardware, implants, and/or bone graft.

Mechanics of Healthy and Functionally Diseased Mitral Valves: A Critical Review

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Jean-Pierre M. Rabbah ◽  
Neelakantan Saikrishnan ◽  
Andrew W. Siefert ◽  
Arvind Santhanakrishnan ◽  
Ajit P. Yoganathan
Keyword(s):  
Mitral Valve ◽  
Left Atrium ◽  
Surgical Planning ◽  
Patient Specific ◽  
Mitral Valves ◽  
Medical Device Design ◽  
Unidirectional Flow ◽  
Patient Health

The mitral valve is a complex apparatus with multiple constituents that work cohesively to ensure unidirectional flow between the left atrium and ventricle. Disruption to any or all of the components—the annulus, leaflets, chordae, and papillary muscles—can lead to backflow of blood, or regurgitation, into the left atrium, which deleteriously effects patient health. Through the years, a myriad of surgical repairs have been proposed; however, a careful appreciation for the underlying structural mechanics can help optimize long-term repair durability and inform medical device design. In this review, we aim to present the experimental methods and significant results that have shaped the current understanding of mitral valve mechanics. Data will be presented for all components of the mitral valve apparatus in control, pathological, and repaired conditions from human, animal, and in vitro studies. Finally, current strategies of patient specific and noninvasive surgical planning will be critically outlined.

Comparative Study of effectiveness of mobilization with movement (MWM) and End range mobilization (ERM) techniques in frozen shoulder

2018 ◽  
Vol 4 (4) ◽  
pp. 519-522
Author(s):  
Jeyakumar S ◽  
Jagatheesan Alagesan ◽  
T.S. Muthukumar
Keyword(s):  
Range Of Motion ◽  
Frozen Shoulder ◽  
Type I ◽  
Mean Values ◽  
Functional Activities ◽  
Group A ◽  
The Mean ◽  
Group B

Background: Frozen shoulder is disorder of the connective tissue that limits the normal Range of motion of the shoulder in diabetes, frozen shoulder is thought to be caused by changes to the collagen in the shoulder joint as a result of long term Hypoglycemia. Mobilization is a therapeutic movement of the joint. The goal is to restore normal joint motion and rhythm. The use of mobilization with movement for peripheral joints was developed by mulligan. This technique combines a sustained application of manual technique “gliding” force to the joint with concurrent physiologic motion of joint, either actively or passively. This study aims to find out the effects of mobilization with movement and end range mobilization in frozen shoulder in Type I diabetics. Materials and Methods: 30 subjects both male and female, suffering with shoulder pain and clinically diagnosed with frozen shoulder was recruited for the study and divided into two groups with 15 patients each based on convenient sampling method. Group A patients received mobilization with movement and Group B patients received end range mobilization for three weeks. The outcome measurements were SPADI, Functional hand to back scale, abduction range of motion using goniometer and VAS. Results: The mean values of all parameters showed significant differences in group A as compared to group B in terms of decreased pain, increased abduction range and other outcome measures. Conclusion: Based on the results it has been concluded that treating the type 1 diabetic patient with frozen shoulder, mobilization with movement exercise shows better results than end range mobilization in reducing pain and increase functional activities and mobility in frozen shoulder.

Numerical Analysis of the VAD Outflow Cannula Positioning on the Blood Flow in the Patient–Specific Brain Supplying Arteries

2020 ◽  
Vol 22 (2) ◽  
pp. 619-636 ◽  
Author(s):  
Zbigniew Tyfa ◽  
Damian Obidowski ◽  
Krzysztof Jóźwik
Keyword(s):  
Blood Flow ◽  
Computer Aided Design ◽  
Volume Flow Rate ◽  
Flow Distribution ◽  
Primary Objective ◽  
Patient Specific ◽  
Blood Flow Distribution ◽  
Reconstruction Process ◽  
Outflow Cannula ◽  
The Brain

AbstractThe primary objective of this research can be divided into two separate aspects. The first one was to verify whether own software can be treated as a viable source of data for the Computer Aided Design (CAD) modelling and Computational Fluid Dynamics CFD analysis. The second aspect was to analyze the influence of the Ventricle Assist Device (VAD) outflow cannula positioning on the blood flow distribution in the brain-supplying arteries. Patient-specific model was reconstructed basing on the DICOM image sets obtained with the angiographic Computed Tomography. The reconstruction process was performed in the custom-created software, whereas the outflow cannulas were added in the SolidWorks software. Volumetric meshes were generated in the Ansys Mesher module. The transient boundary conditions enabled simulating several full cardiac cycles. Performed investigations focused mainly on volume flow rate, shear stress and velocity distribution. It was proven that custom-created software enhances the processes of the anatomical objects reconstruction. Developed geometrical files are compatible with CAD and CFD software – they can be easily manipulated and modified. Concerning the numerical simulations, several cases with varied positioning of the VAD outflow cannula were analyzed. Obtained results revealed that the location of the VAD outflow cannula has a slight impact on the blood flow distribution among the brain supplying arteries.

scholarly journals Consumption Threshold at Which Virtue Products Become Vice Products: The Case of Beer

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1688
Author(s):  
Enar Ruiz-Conde ◽  
Francisco Mas-Ruiz ◽  
Josefa Parreño-Selva
Keyword(s):  
Survey Data ◽  
Health Benefit ◽  
Time Inconsistent

Relative vices and virtues have traditionally been defined according to time-inconsistent preferences. Vice products exchange small immediate rewards (e.g., pleasure) for larger delayed costs (e.g., health), while virtue products exchange small immediate costs for larger delayed rewards. This definition can be criticized because there is evidence that small amounts of beer (or chocolate) convey a long-term health benefit, whereas large quantities impose a delayed cost. Thus, we assume that virtue products can become vice products when consumption is above a certain threshold. Survey data identifies alcoholic beer as a product that gives immediate rewards and does not impose a delayed cost. Our analysis reveals a consumption threshold that supports our assumptions.

scholarly journals Minimally Invasive Mini-orbitozygomatic Approach for Clipping an Anterior Communicating Artery Aneurysm: Virtual Reality Surgical Planning

2020 ◽  
Author(s):  
Nicolás González Romo ◽  
Franco Ravera Zunino
Keyword(s):  
Virtual Reality ◽  
Minimally Invasive ◽  
Surgical Planning ◽  
Artery Aneurysm ◽  
Patient Specific ◽  
Anterior Communicating Artery ◽  
Imaging Data ◽  
Advantages And Disadvantages ◽  
Orbitozygomatic Approach ◽  
Skull Base Anatomy

AbstractVirtual reality (VR) has increasingly been implemented in neurosurgical practice. A patient with an unruptured anterior communicating artery (AcoA) aneurysm was referred to our institution. Imaging data from computed tomography angiography (CTA) was used to create a patient specific 3D model of vascular and skull base anatomy, and then processed to a VR compatible environment. Minimally invasive approaches (mini-pterional, supraorbital and mini-orbitozygomatic) were simulated and assessed for adequate vascular exposure in VR. Using an eyebrow approach, a mini-orbitozygomatic approach was performed, with clip exclusion of the aneurysm from the circulation. The step-by-step process of VR planning is outlined, and the advantages and disadvantages for the neurosurgeon of this technology are reviewed.

Severe conduit stenosis in a patient with Fontan circulation with a Y-shaped Dacron conduit

2021 ◽  
pp. 1-3
Author(s):  
Daiji Takajo ◽  
Preetha L. Balakrishnan ◽  
Sanjeev Aggarwal
Keyword(s):  
Energy Loss ◽  
Polyethylene Terephthalate ◽  
Rare Complication ◽  
Flow Distribution ◽  
Fontan Circulation ◽  
Distribution Data ◽  
Extracardiac Fontan ◽  
Fontan Palliation

Abstract Conduit stenosis is a major, albeit rare, complication following the Fontan palliation. A single-baffle conduit with polytetrafluoroethylene is widely used for an extracardiac type Fontan palliation. A polyethylene terephthalate conduit (Dacron) is sometimes used for the conduit when more flexibility is required. A Y-shaped conduit is rarely used, but it may reduce the energy loss and achieve better hepatic flow distribution. Data on the long-term patency and complications when using a Y-shaped Dacron conduit is lacking. We report a case of a severely stenotic Y-shaped Dacron conduit in a patient who underwent extracardiac Fontan palliation.

Sign in / Sign up

Export Citation Format

Share Document