Preliminary findings in quantification of changes in septal motion during follow-up of type B aortic dissections

Karmonik, Christof; Duran, Cassidy; Shah, Dipan J.; Anaya‐Ayala, Javier E.; Lumsden, Alan B.; Bismuth, Jean

doi:10.1016/j.jvs.2011.10.127

Cited by 31 publications

(34 citation statements)

References 22 publications

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“…As discussed in the paper by Alimohammadi et al [12], the displacements obtained for this case study are comparable to those reported by clinical imaging studies [17,27]. However, in some acute settings, abnormal motion of the IF leading to the obstruction of distal aortic branches can be observed [34].…”

Section: Limitationssupporting

confidence: 87%

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A simplified method to account for wall motion in patient-specific blood flow simulations of aortic dissection: Comparison with fluid-structure interaction

Bonfanti

Balabani

Alimohammadi

et al. 2018

Medical Engineering & Physics

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Aortic dissection (AD) is a complex and highly patient-specific vascular condition difficult to treat. Computational fluid dynamics (CFD) can aid the medical management of this pathology, yet its modelling and simulation are challenging. One aspect usually disregarded when modelling AD is the motion of the vessel wall, which has been shown to significantly impact simulation results. Fluid-structure interaction (FSI) methods are difficult to implement and are subject to assumptions regarding the mechanical properties of the vessel wall, which cannot be retrieved non-invasively. This paper presents a simplified 'moving-boundary method' (MBM) to account for the motion of the vessel wall in type-B AD CFD simulations, which can be tuned with non-invasive clinical images (e.g. 2D cine-MRI). The method is firstly validated against the 1D solution of flow through an elastic straight tube; it is then applied to a type-B AD case study and the results are compared to a state-of-the-art, full FSI simulation. Results show that the proposed method can capture the main effects due to the wall motion on the flow field: the average relative difference between flow and pressure waves obtained with the FSI and MBM simulations was less than 1.8% and 1.3%, respectively and the wall shear stress indices were found to have a similar distribution. Moreover, compared to FSI, MBM has the advantage to be less computationally expensive (requiring half of the time of an FSI simulation) and easier to implement, which are important requirements for clinical translation.

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Section: Limitationssupporting

confidence: 87%

“…where [17]. The tuning of Ki and Kj is based on patient-specific displacement data obtainable, for instance, from cine 2D MR images.…”

Section: Description Of the Methodsmentioning

confidence: 99%

A simplified method to account for wall motion in patient-specific blood flow simulations of aortic dissection: Comparison with fluid-structure interaction

Bonfanti

Balabani

Alimohammadi

et al. 2018

Medical Engineering & Physics

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“…The change in cross-sectional area of the TL and FL was calculated from ECG-gated CT scans by Ganten et al [ 33 ] and they observed a mean TL cross-sectional area reduction (-4.4%), comparable to the A * values shown in Figure 3 a. The median IF oscillation observed by Ganten et al [ 33 ] was 1.3 mm , while Karmonik et al [ 34 ] reported average IF displacements of approximately 0.48-0.68 mm from MRI data. These values compare favourably with the IF deformation shown in Figure 2 .…”

Section: Discussionmentioning

confidence: 83%

“…If it transpires that the imaging data of Yang et al [ 35 ] is more characteristic of true flap motion than previous reports [ 33 , 34 ], then it is clear that the loss of accuracy through the rigid wall simplification would be exacerbated. However, further developments are required, particularly in calculating the vessel wall properties of a dissected aorta, before this technology will be able to truly predict the fluid and solid dynamics of this condition.…”

Section: Discussionmentioning

confidence: 96%

Aortic dissection simulation models for clinical support: fluid-structure interaction vs. rigid wall models

et al. 2015

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BackgroundThe management and prognosis of aortic dissection (AD) is often challenging and the use of personalised computational models is being explored as a tool to improve clinical outcome. Including vessel wall motion in such simulations can provide more realistic and potentially accurate results, but requires significant additional computational resources, as well as expertise. With clinical translation as the final aim, trade-offs between complexity, speed and accuracy are inevitable. The present study explores whether modelling wall motion is worth the additional expense in the case of AD, by carrying out fluid-structure interaction (FSI) simulations based on a sample patient case.MethodsPatient-specific anatomical details were extracted from computed tomography images to provide the fluid domain, from which the vessel wall was extrapolated. Two-way fluid-structure interaction simulations were performed, with coupled Windkessel boundary conditions and hyperelastic wall properties. The blood was modelled using the Carreau-Yasuda viscosity model and turbulence was accounted for via a shear stress transport model. A simulation without wall motion (rigid wall) was carried out for comparison purposes.ResultsThe displacement of the vessel wall was comparable to reports from imaging studies in terms of intimal flap motion and contraction of the true lumen. Analysis of the haemodynamics around the proximal and distal false lumen in the FSI model showed complex flow structures caused by the expansion and contraction of the vessel wall. These flow patterns led to significantly different predictions of wall shear stress, particularly its oscillatory component, which were not captured by the rigid wall model.ConclusionsThrough comparison with imaging data, the results of the present study indicate that the fluid-structure interaction methodology employed herein is appropriate for simulations of aortic dissection. Regions of high wall shear stress were not significantly altered by the wall motion, however, certain collocated regions of low and oscillatory wall shear stress which may be critical for disease progression were only identified in the FSI simulation. We conclude that, if patient-tailored simulations of aortic dissection are to be used as an interventional planning tool, then the additional complexity, expertise and computational expense required to model wall motion is indeed justified.

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“…27 FL patency status was detected from the arterial and venous phase of postoperative CTA, and it is conceivable that this is not the most sensitive or specific method for analyzing this end point given reports on efficacy of various dynamic MRI techniques. 32,33 …”

Section: Discussionmentioning

confidence: 99%

Efficacy of thoracic endovascular stent repair for chronic type B aortic dissection with aneurysmal degeneration

Scali

Feezor

Chang

et al. 2013

Journal of Vascular Surgery

102

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Background The Food and Drug Administration has approved devices for endovascular management of thoracic endovascular aortic aneurysm repair (TEVAR); however, limited data exist describing the outcomes of TEVAR for aneurysms attributable to chronic type B aortic dissection (cTBAD). This study was undertaken to determine the results of endovascular treatment of cTBAD with aneurysmal degeneration. Methods A retrospective analysis of all patients treated for cTBAD with aneurysmal degeneration at the University of Florida from 2004 to 2011 was performed. Computed tomograms with centerline reconstruction were analyzed to determine change in aortic diameter, relative proportions of aortic treatment lengths, and false lumen perfusion status. Reintervention and mortality were estimated using life-tables. Cox regression analysis was completed to predict mortality. Results Eighty patients underwent TEVAR for aneurysm due to cTBAD (mean age [± standard deviation], 60 ± 13 years [male, 87.5%; n = 70]; median follow-up, 26 [range, 1–74] months). Median time from diagnosis of TBAD to TEVAR was 16 (range, 1–72) months. Prior aortic root/arch replacement had been performed in 29% (n = 23) at a median interval of 28.5 (range, 0.5–312) months. Mean preoperative aneurysm diameter was 62.0 ± 9.9 mm. In 75% (n = 60) of cases, coverage was proximal to zone 3, and 24% (n = 19) underwent carotid-subclavian bypass or other arch debranching procedure. Spinal drains were used in 78% (pre-op 71%, n = 57; post-op 6%, n = 5). Length of stay was 6.5 ± 4.7 days with a composite morbidity of 26% and in-hospital mortality of 2.5% (n = 2). Overall neurologic event rate was 17% (spinal cord ischemia 10% [n = 8], with a permanent deficit observed in 6.2% [n = 5]; stroke 7.5%). Aneurysm diameter reduced or stabilized in 65%. The false lumen thrombosed completely within the thoracic aorta in 52%, and reintervention within the treated aortic segment was required in 16% (n = 13). One- and 3-year freedom from reintervention (with 95% confidence interval [CI]) was 80% (range, 68%–88%) and 70% (range, 57%–80%), respectively. Survival at 1 and 5 years was 89% (range, 80%–94%) and 70% (range, 55%–81%) and was not significantly different among patients requiring reintervention or experiencing favorable aortic remodeling. Multivariable analysis identified coronary artery disease (hazard ratio [HR], 6.4; 95% CI, 2.3–17.7; P < .005), prior infrarenal aortic surgery (HR, 8.6; 95% CI, 2.3–31.7; P = .001), and congestive heart failure (HR, 11.9; 95% CI, 1.9–73.8; P = .008) as independent risk factors for mortality. Hyperlipidemia was found to be protective (HR, 0.2; 95% CI, 0.05–0.6; P = .004). No significant difference in predictors of mortality were found between patients who underwent reintervention vs those who did not (P = .2). Conclusions TEVAR for cTBAD with aneurysmal degeneration can be performed safely but spinal cord ischemia rates may be higher than previously reported. Liberal use of procedural adjuncts to reduce this complication, such as spin...

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Preliminary findings in quantification of changes in septal motion during follow-up of type B aortic dissections

Cited by 31 publications

References 22 publications

A simplified method to account for wall motion in patient-specific blood flow simulations of aortic dissection: Comparison with fluid-structure interaction

A simplified method to account for wall motion in patient-specific blood flow simulations of aortic dissection: Comparison with fluid-structure interaction

Aortic dissection simulation models for clinical support: fluid-structure interaction vs. rigid wall models

Efficacy of thoracic endovascular stent repair for chronic type B aortic dissection with aneurysmal degeneration

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