Sex-specific Impact of the first COVID-19 Lockdown on Age Structure and Case Acuity at Admission in a Patient Population in southwestern Germany: a retrospective comparative Study in Neuroradiology.

OBJECTIVES: A hard lockdown was presumed to lead to delayed diagnosis and treatment of serious diseases, resulting in higher acuity at admission. This should be elaborated based on the estimated acuity of the cases, changes in findings during hospitalisation, age structure and biological sex. DESIGN: Retrospective monocentric cross-sectional study. SETTING: German Neuroradiology Department at a . PARTICIPANTS: In 2019, n=1158 patients were admitted in contrast to n=884 during the first hard lockdown in 2020 (11th-13th week). MAIN OUTCOME MEASURES: Three radiologists evaluated the initial case acuity, classified them into three groups (not acute, subacute and acute), and evaluated if there was a relevant clinical deterioration. The data analysis was conducted using non-parametric methods and multivariate regression analysis. RESULTS: A 24% decrease in the number of examinations from 2019 to 2020 (p=0.025) was revealed. In women, the case acuity increased by 21% during the lockdown period (p=0.002). A 30% decrease in acute cases in men was observable (in women 5% decrease). Not acute cases decreased in both women and men (47%; 24%), while the subacute cases remained stable in men (0%) and decreased in women (28%). Regression analysis revealed the higher the age, the higher the acuity (p<0.001 in both sexes), particularly among women admitted during the lockdown period (p=0.006). CONCLUSION: The lockdown led to a decrease in neuroradiological consultations, with delays in seeking medical care. In women, the number of most severe cases remained stable, whereas the mean case acuity and age increased. This could be due to greater pandemic-related anxiety among women, however, with severe symptoms they were seeking for medical help. In contrast in men, the absolute number of most severe cases decreased, whereas the mean acuity and age remained nearly unaffected. This could be attributable to a reduced willingness to seek for medical consultation.

A Rapid Late Enhancement MRI Protocol Improves Differentiation between Brain Tumor Recurrence and Treatment-Related Contrast Enhancement of Brain Parenchyma.

PURPOSE: Differentiation between tumor recurrence and treatment-related contrast enhancement in MRI can be difficult. Late enhancement MRI up to 75 min after contrast agent application has been shown to improve differentiation between tumor recurrence and treatment-related changes. We investigated the diagnostic performance of late enhancement using a rapid MRI protocol optimized for clinical workflow. METHODS: Twenty-three patients with 28 lesions suspected for glioma recurrence underwent MRI including T1-MPRAGE-series acquired 2 and 20 min after contrast agent administration. Early contrast series were subtracted from late contrast series using motion correction. Contrast enhancing lesions were retrospectively and independently evaluated by two readers blinded to the patients' later clinical course and histology with or without the use of late enhancement series. Sensitivity, specificity, NPV, and PPV were calculated for both readers by comparing results of MRI with histological samples. RESULTS: Using standard MR sequences, sensitivity, specificity, PPV, and NPV were 0.84, 0, 0.875, and 0 (reader 1) and 0.92, 0, 0.885, and 0 (reader 2), respectively. Early late enhancement increased sensitivity, specificity, PPV, and NPV to 1 for each value and for both readers. Inter-reader reliability increased from 0.632 (standard MRI sequences) to 1.0 (with early late enhancement). CONCLUSION: The described rapid late enhancement MRI protocol improves MRI-based discrimination between tumor tissue and treatment-related changes of the brain parenchyma.

Imaging of the medial rectus muscle predicts the development of optic neuropathy in thyroid eye disease.

Goal of the study was to evaluate bony orbit remodeling and extraocular muscle (EOM) volume in thyroid eye disease (TED) and their role as predicting factors for development of dysthyroid optic neuropathy (DON). Orbital computed tomography of 92 patients with TED with (76 orbits) or without DON (98 orbits) were retrospectively evaluated. Orbits (n = 40) of subjects without TED served as controls. Measurements of the bony orbit as well as EOM volume were incorporated into a generalized linear mixed model to predict DON. The angle of the medial orbital wall was significantly smaller (p < 0.001) in patients with TED (- 2.3 ± 3.6°) compared to patients with TED + DON (1.0 ± 4.1°). Both groups differed significantly from controls (- 4.2 ± 2.7°). Bowing of the medial orbital wall correlated positively with muscle volume (r = 0.564; p < 0.001). Total EOM volume was significantly larger in TED + DON (7.6 ± 2.5cm3) compared to TED only (5.6 ± 3.0cm3; p < 0.001) or controls (2.6 ± 0.5cm3). Multivariate analysis revealed the medial rectus muscle volume (TED: 1.06 ± 0.48cm3 vs. TED + DON: 2.16 ± 0.84cm3) as the strongest predictor, achieving a specifity of 86.7% and a sensitivity of 73.7% in diagnosing DON in univariate analysis. Though characterized by a wide range of variability, increased medial rectus muscle volume is the strongest predictor for DON in our patient cohort with TED when analyzing a single muscle.

How Precise Are Preinterventional Measurements Using Centerline Analysis Applications? Objective Ground Truth Evaluation Reveals Software-Specific Centerline Characteristics.

PURPOSE: To evaluate different centerline analysis applications using objective ground truth from realistic aortic aneurysm phantoms with precisely defined geometry and centerlines to overcome the lack of unknown true dimensions in previously published in vivo validation studies. METHODS: Three aortic phantoms were created using computer-aided design (CAD) software and a 3-dimensional (3D) printer. Computed tomography angiograms (CTAs) of phantoms and 3 patients were analyzed with 3 clinically approved and 1 research software application. The 3D centerline coordinates, intraluminal diameters, and lengths were validated against CAD ground truth using a dedicated evaluation software platform. RESULTS: The 3D centerline position mean error ranged from 0.7±0.8 to 2.9±2.5 mm between tested applications. All applications calculated centerlines significantly different from ground truth. Diameter mean errors varied from 0.5±1.2 to 1.1±1.0 mm among 3 applications, but exceeded 8.0±11.0 mm with one application due to an unsteady distortion of luminal dimensions along the centerline. All tested commercially available software tools systematically underestimated centerline total lengths by -4.6±0.9 mm to -10.4±4.3 mm (maximum error -14.6 mm). Applications with the highest 3D centerline accuracy yielded the most precise diameter and length measurements. CONCLUSION: One clinically approved application did not provide reproducible centerline-based analysis results, while another approved application showed length errors that might influence stent-graft choice and procedure success. The variety and specific characteristics of endovascular aneurysm repair planning software tools require scientific evaluation and user awareness.

Time-Resolved Three-Dimensional Contrast-Enhanced Magnetic Resonance Angiography in Patients with Chronic Expanding and Stable Aortic Dissections.

Objective: To prospectively evaluate our hypothesis that three-dimensional time-resolved contrast-enhanced magnetic resonance angiography (TR-MRA) is able to detect hemodynamic alterations in patients with chronic expanding aortic dissection compared to stable aortic dissections. Materials and Methods: 20 patients with chronic or residual aortic dissection in the descending aorta and patent false lumen underwent TR-MRA of the aorta at 1.5 T and repeated follow-up imaging (mean follow-up 5.4 years). 7 patients showed chronic aortic expansion and 13 patients had stable aortic diameters. Regions of interest were placed in the nondissected ascending aorta and the false lumen of the descending aorta at the level of the diaphragm (FL-diaphragm level) resulting in respective time-intensity curves. Results: For the FL-diaphragm level, time-to-peak intensity and full width at half maximum were significantly shorter in the expansion group compared to the stable group (p = 0.027 and p = 0.003), and upward and downward slopes of time-intensity curves were significantly steeper (p = 0.015 and p = 0.005). The delay of peak intensity in the FL-diaphragm level compared to the nondissected ascending aorta was significantly shorter in the expansion group compared to the stable group (p = 0.01). Conclusions: 3D TR-MRA detects significant alterations of hemodynamics within the patent false lumen of chronic expanding aortic dissections compared to stable aortic dissections.

Frequency of abdominal aortic expansion after thoracic endovascular repair of type B aortic dissection.

PURPOSE: To determine abdominal aortic expansion after thoracic endovascular aortic repair (TEVAR) in patients with aortic dissection type B and 36 months minimum follow-up. METHODS: Retrospective study of 18 TEVAR patients with follow-up >36 months. Abdominal aortic diameters at celiac trunk (location B) and infrarenal aorta (location C) were recorded on the first and last imaging after TEVAR. False lumen thrombosis was determined at level of endograft (A) and at B and C. Aortic expansion was defined as diameter increase of 5 mm or 15%. Correlation analyses were performed to investigate potential determinants of expansion. RESULTS: Median follow-up was 75.2 months. Sixteen of 18 patients (88.9%) demonstrated abdominal expansion. Mean expansion was 9.9 ± 6.1 mm at B and 11.7 ± 6.5 mm at C, without a difference between acute and chronic dissections. Critical diameters of 55 mm were reached in two patients treated for chronic dissection (11.1%). Annual diameter increase was significantly greater at locations with baseline diameters >30 mm (2.1 ± 1.1 mm vs. 1.0 ± 0.6 mm, p = 0.009). Baseline diameters were greater in patients with chronic dissections. CONCLUSION: Abdominal aortic expansion can be frequently recognized after TEVAR for aortic dissection type B and occurs independently from thoracic false lumen thrombosis. Clinical significant abdominal aortic expansion may occur more frequently in patients treated with TEVAR for chronic dissection.

Hemodynamics analyses in treated and untreated carotid arteries of the same patient: A preliminary study based on three patient cases.

Carotid atherosclerotic disease is highly related to cerebrovascular events. Carotid endarterectomy is the common operation method to treat this disease. In this study, hemodynamics analyses are performed on the carotid arteries in three patients, whose right carotid artery had been treated by carotid endarterectomy and the left carotid artery remained untreated. Flow and loading conditions are compared between these treated and untreated carotid arteries and evaluation of the operative results is discussed. Patient-specific models are reconstructed from MDCT data. Intraoperative ultrasound flow measurements are performed on the treated carotid arteries and the obtained data are used as the boundary conditions of the models and the validations of the computational results. Finite volume method is employed to solve the transport equations and the flow and loading conditions of the models are reported. The results indicate that: (i) in two of the three patients, the internal-to-external flow rate ratio in the untreated carotid artery is larger than that in the treated one, and the average overall flow split ratio by summing up the data of both the left and right carotid arteries is about 2.15; (ii) in the carotid bulb, high wall shear stress occurs at the bifurcation near the external carotid artery in all of the cases without hard plaques; (iii) the operated arteries present low time-averaged wall shear stress at the carotid bulb, especially for the treated arteries with patch technique, indicating the possibility of the recurrence of stenosis; (iv) high temporal gradient of wall shear stress (>35 Pa/s) is shown in the narrowing regions along the vessels; and (v) in the carotid arteries without serious stenosis, the maximum velocity magnitude during mid-diastole is 32~37% of that at systolic peak, however, in the carotid artery with 50% stenosis by hard plaques, this value is nearly doubled (64%). The computational work quantifies flow and loading distributions in the treated and untreated carotid arteries of the same patient, contributing to evaluation of the operative results and indicating the recurrent sites of potential atheromatous plaques.

Hemodynamic assessment of partial mechanical circulatory support: data derived from computed tomography angiographic images and computational fluid dynamics.

Partial mechanical circulatory support represents a new concept for the treatment of advanced heart failure. The Circulite Synergy Micro Pump(®), where the inflow cannula is connected to the left atrium and the outflow cannula to the right subclavian artery, was one of the first devices to introduce this concept to the clinic. Using computational fluid dynamics (CFD) simulations, hemodynamics in the aortic tree was visualized and quantified from computed tomography angiographic (CTA) images in two patients. A realistic computational model was created by integrating flow information from the native heart and from the Circulite device. Diastolic flow augmentation in the descending aorta but competing/antagonizing flow patterns in the proximal innominate artery was observed. Velocity time curves in the ascending aorta correlated well with those in the left common carotid, the left subclavian and the descending aorta but poorly with the one in the innominate. Our results demonstrate that CFD may be useful in providing a better understanding of the main flow patterns in mechanical circulatory support devices.

Type IIIb endoleak after thoracic endovascular aortic repair caused by endoanchor dislocation.

BACKGROUND: The aim of this study was to report the occurrence of a type IIIb endoleak after endovascular repair of a thoracic aortic aneurysm caused by endoanchor dislocation. CASE REPORT: An 84-year-old female patient underwent thoracic endovascular repair for aneurysmal disease of her thoracic aorta. The procedure included primary left subclavian artery revascularization and the placement of endoanchors to enhance fixation of the endograft within the aortic arch. Dislocation of one of the endoanchors resulted in a graft defect leading to a type IIIb endoleak and aortic diameter expansion. CONCLUSIONS: Endoanchors represent a promising adjunct in endovascular repair settings. However, their use requires careful procedure planning and special attention during follow-up.

Device Conformability and Morphological Assessment After TEVAR for Aortic Type B Dissection: A Single-Centre Experience with a Conformable Thoracic Stent-Graft Design.

BACKGROUND The aim of this study was to analyze device conformability in TEVAR of acute and chronic (a/c) type B aortic dissections (TBAD) using the Gore Conformable Thoracic Aortic Stent-graft (CTAG). MATERIAL AND METHODS From January 1997 to February 2014, a total of 90 out of 405 patients in our center received TEVAR for TBAD. Since November 2009, 23 patients (16 men; median age: 62 years) were treated with the CTAG. Indications were complicated aTBAD in 15 (65%) and expanding cTBAD in 8 (35%) patients. Primary endpoints were the assessment of device conformability by measuring the distance (D) from the radiopaque gold band marker (GM) at the proximal CTAG end to the inner curvature (IC) of the arch on parasagittal multiplanar reformations of CT angiography, as well as the evaluation of aortic diameter changes following TEVAR. Median follow-up was 13.3 months (range: 2 days to 35 months). RESULTS Primary and secondary success rates were 91.3% (21/23) and 95.6% (22/23), respectively. There was 1 type Ia endoleak, retrograde dissection or primary conversion was not observed. Median GM-IC-D was 0 mm (range: 0 mm to 10 mm). GM-IC-D was associated with zone 2 placement compared to zone 3 (P=0.036). There was no association between GM-IC-D formation and arch type. In aTBAD cases the true lumen significantly increased after TEVAR (P=0.017) and the false lumen underwent shrinkage (P=0.025). In cTBAD patients the false lumen decreased after TEVAR (P=0.036). CONCLUSIONS The CTAG shows favorable conformability and wall apposition in challenging arch pathologies such as TBAD.

3D morphometry using automated aortic segmentation in native MR angiography: an alternative to contrast enhanced MRA?

INTRODUCTION: Native-MR angiography (N-MRA) is considered an imaging alternative to contrast enhanced MR angiography (CE-MRA) for patients with renal insufficiency. Lower intraluminal contrast in N-MRA often leads to failure of the segmentation process in commercial algorithms. This study introduces an in-house 3D model-based segmentation approach used to compare both sequences by automatic 3D lumen segmentation, allowing for evaluation of differences of aortic lumen diameters as well as differences in length comparing both acquisition techniques at every possible location. METHODS AND MATERIALS: Sixteen healthy volunteers underwent 1.5-T-MR Angiography (MRA). For each volunteer, two different MR sequences were performed, CE-MRA: gradient echo Turbo FLASH sequence and N-MRA: respiratory-and-cardiac-gated, T2-weighted 3D SSFP. Datasets were segmented using a 3D model-based ellipse-fitting approach with a single seed point placed manually above the celiac trunk. The segmented volumes were manually cropped from left subclavian artery to celiac trunk to avoid error due to side branches. Diameters, volumes and centerline length were computed for intraindividual comparison. For statistical analysis the Wilcoxon-Signed-Ranked-Test was used. RESULTS: Average centerline length obtained based on N-MRA was 239.0±23.4 mm compared to 238.6±23.5 mm for CE-MRA without significant difference (P=0.877). Average maximum diameter obtained based on N-MRA was 25.7±3.3 mm compared to 24.1±3.2 mm for CE-MRA (P<0.001). In agreement with the difference in diameters, volumes obtained based on N-MRA (100.1±35.4 cm(3)) were consistently and significantly larger compared to CE-MRA (89.2±30.0 cm(3)) (P<0.001). CONCLUSIONS: 3D morphometry shows highly similar centerline lengths for N-MRA and CE-MRA, but systematically higher diameters and volumes for N-MRA.

Dynamic contrast-enhanced magnetic resonance imaging: fundamentals and application to the evaluation of the peripheral perfusion.

INTRODUCTION: The ability to ascertain information pertaining to peripheral perfusion through the analysis of tissues' temporal reaction to the inflow of contrast agent (CA) was first recognized in the early 1990's. Similar to other functional magnetic resonance imaging (MRI) techniques such as arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) MRI, dynamic contrast-enhanced MRI (DCE-MRI) was at first restricted to studies of the brain. Over the last two decades the spectrum of ailments, which have been studied with DCE-MRI, has been extensively broadened and has come to include pathologies of the heart notably infarction, stroke and further cerebral afflictions, a wide range of neoplasms with an emphasis on antiangiogenic treatment and early detection, as well as investigations of the peripheral vascular and musculoskeletal systems. APPLICATIONS TO PERIPHERAL PERFUSION: DCE-MRI possesses an unparalleled capacity to quantitatively measure not only perfusion but also other diverse microvascular parameters such as vessel permeability and fluid volume fractions. More over the method is capable of not only assessing blood flowing through an organ, but in contrast to other noninvasive methods, the actual tissue perfusion. These unique features have recently found growing application in the study of the peripheral vascular system and most notably in the diagnosis and treatment of peripheral arterial occlusive disease (PAOD). REVIEW OUTLINE: The first part of this review will elucidate the fundamentals of data acquisition and interpretation of DCE-MRI, two areas that often remain baffling to the clinical and investigating physician because of their complexity. The second part will discuss developments and exciting perspectives of DCE-MRI regarding the assessment of perfusion in the extremities. Emerging clinical applications of DCE-MRI will be reviewed with a special focus on investigation of physiology and pathophysiology of the microvascular and vascular systems of the extremities.

State-of-the-art aortic imaging: Part II - applications in transcatheter aortic valve replacement and endovascular aortic aneurysm repair.

Transcatheter aortic valve replacement (TAVR) as well as thoracic and abdominal endovascular aortic repair (TEVAR and EVAR) rely on accurate pre- and postprocedural imaging. This review article discusses the application of imaging, including preprocedural assessment and measurements as well as postprocedural imaging of complications. Furthermore, the exciting perspective of computational fluid dynamics (CFD) based on cross-sectional imaging is presented. TAVR is a minimally invasive alternative for treatment of aortic valve stenosis in patients with high age and multiple comorbidities who cannot undergo traditional open surgical repair. Given the lack of direct visualization during the procedure, pre- and peri-procedural imaging forms an essential part of the intervention. Computed tomography angiography (CTA) is the imaging modality of choice for preprocedural planning. Routine postprocedural follow-up is performed by echocardiography to confirm treatment success and detect complications. EVAR and TEVAR are minimally invasive alternatives to open surgical repair of aortic pathologies. CTA constitutes the preferred imaging modality for both preoperative planning and postoperative follow-up including detection of endoleaks. Magnetic resonance imaging is an excellent alternative to CT for postoperative follow-up, and is especially beneficial for younger patients given the lack of radiation. Ultrasound is applied in screening and postoperative follow-up of abdominal aortic aneurysms, but cross-sectional imaging is required once abnormalities are detected. Contrast-enhanced ultrasound may be as sensitive as CTA in detecting endoleaks.

State-of-the-art aortic imaging: part I - fundamentals and perspectives of CT and MRI.

Over the last two decades, imaging of the aorta has undergone a clinically relevant change. As part of the change non-invasive imaging techniques have replaced invasive intra-arterial digital subtraction angiography as the former imaging gold standard for aortic diseases. Computed tomography (CT) and magnetic resonance imaging (MRI) constitute the backbone of pre- and postoperative aortic imaging because they allow for imaging of the entire aorta and its branches. The first part of this review article describes the imaging principles of CT and MRI with regard to aortic disease, shows how both technologies can be applied in every day clinical practice, offering exciting perspectives. Recent CT scanner generations deliver excellent image quality with a high spatial and temporal resolution. Technical developments have resulted in CT scan performed within a few seconds for the entire aorta. Therefore, CT angiography (CTA) is the imaging technology of choice for evaluating acute aortic syndromes, for diagnosis of most aortic pathologies, preoperative planning and postoperative follow-up after endovascular aortic repair. However, radiation dose and the risk of contrast induced nephropathy are major downsides of CTA. Optimisation of scan protocols and contrast media administration can help to reduce the required radiation dose and contrast media. MR angiography (MRA) is an excellent alternative to CTA for both diagnosis of aortic pathologies and postoperative follow-up. The lack of radiation is particularly beneficial for younger patients. A potential side effect of gadolinium contrast agents is nephrogenic systemic fibrosis (NSF). In patients with high risk of NSF unenhanced MRA can be performed with both ECG- and breath-gating techniques. Additionally, MRI provides the possibility to visualise and measure both dynamic and flow information.

Computational fluid dynamics investigation of chronic aortic dissection hemodynamics versus normal aorta.

OBJECTIVES: To evaluate hemodynamic changes during aneurysmal dilatation in chronic type B aortic dissections compared to hemodynamic parameters in the healthy aorta with the use of computational fluid dynamics (CFD). METHODS: True lumen (TL)/false lumen (FL) dimensional changes, changes in total pressure (TP), and wall shear stress (WSS) were evaluated at follow-up (FU) compared to initial examination (IE) with transient CFD simulation with geometries derived from clinical image data and inflow boundary conditions from magnetic resonance images. The TL/FL pressure gradient between ascending and descending aorta (DAo) and maximum WSS at the site of largest dilatation was compared to values for the healthy aorta. RESULTS: Hemodynamic changes at site of largest FL dilatation included 77% WSS reduction and 69% TP reduction. Compared to the healthy aorta, pressure gradient between ascending and DAo was a factor of 1.4 higher in the TL and a factor of 1.5 in the FL and increased at FU (1.6 and 1.7, respectively). Maximum WSS at the site of largest dilatation was a factor of 3 lower than that for the healthy aorta at IE and decreased by more than a factor of 2 at FU. CONCLUSIONS: The FL dilatation at FU favorably reduced TP. In contrast, unfavorable increase in pressure gradient between ascending and DAo was observed with higher values than in the healthy aorta. Maximum WSS was reduced at the site of largest dilation compared to healthy aorta.

Bouveret's syndrome: presentation of two cases with review of the literature and development of a surgical treatment strategy.

BACKGROUND: Bouveret's syndrome causes gastric outlet obstruction when a gallstone is impacted in the duodenum or stomach via a bilioenteric fistula. It is a rare condition that causes significant morbidity and mortality and often occurs in the elderly with significant comorbidities. Individual diagnostic and treatment strategies are required for optimal management and outcome. The purpose of this paper is to develop a surgical strategy for optimized individual treatment of Bouveret's syndrome based on the available literature and motivated by our own experience. CASE PRESENTATION: Two cases of Bouveret's syndrome are presented with individual management and restrictive surgical approaches tailored to the condition of the patients and intraoperative findings. CONCLUSIONS: Improved diagnostics and restrictive individual surgical approaches have shown to lower the mortality rates of Bouveret's syndrome. For optimized outcome of the individual patient: The medical and perioperative management and time of surgery are tailored to the condition of the patient. CT-scan is most often required to secure the diagnosis. The surgical approach includes enterolithotomy alone or in combination with simultaneous or subsequent cholecystectomy and fistula repair. Lower overall morbidity and mortality are in favor of restrictive surgical approaches. The surgical strategy is adapted to the intraoperative findings and to the risk for secondary complications vs. the age and comorbidities of the patient.

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

BACKGROUND: Aortic dissection is a severe pathological condition in which blood penetrates between layers of the aortic wall and creates a duplicate channel - the false lumen. This considerable change on the aortic morphology alters hemodynamic features dramatically and, in the case of rupture, induces markedly high rates of morbidity and mortality. METHODS: In this study, we establish a patient-specific computational model and simulate the pulsatile blood flow within the dissected aorta. The k-ω SST turbulence model is employed to represent the flow and finite volume method is applied for numerical solutions. Our emphasis is on flow exchange between true and false lumen during the cardiac cycle and on quantifying the flow across specific passages. Loading distributions including pressure and wall shear stress have also been investigated and results of direct simulations are compared with solutions employing appropriate turbulence models. RESULTS: Our results indicate that (i) high velocities occur at the periphery of the entries; (ii) for the case studied, approximately 40% of the blood flow passes the false lumen during a heartbeat cycle; (iii) higher pressures are found at the outer wall of the dissection, which may induce further dilation of the pseudo-lumen; (iv) highest wall shear stresses occur around the entries, perhaps indicating the vulnerability of this region to further splitting; and (v) laminar simulations with adequately fine mesh resolutions, especially refined near the walls, can capture similar flow patterns to the (coarser mesh) turbulent results, although the absolute magnitudes computed are in general smaller. CONCLUSIONS: The patient-specific model of aortic dissection provides detailed flow information of blood transport within the true and false lumen and quantifies the loading distributions over the aorta and dissection walls. This contributes to evaluating potential thrombotic behavior in the false lumen and is pivotal in guiding endovascular intervention. Moreover, as a computational study, mesh requirements to successfully evaluate the hemodynamic parameters have been proposed.

Clinical significance of type II endoleaks after thoracic endovascular aortic repair.

BACKGROUND: To evaluate the clinical significance of type II endoleaks (ELII) after thoracic endovascular aortic repair (TEVAR). METHODS: From January 1997 to June 2012, a total of 344 patients received TEVAR in our institution. ELII was diagnosed in 30 patients (8.7%; 13 males; median age: 65 years, range: 24 to 84 years), representing the study population of this retrospective, single-center analysis. Mean follow-up was 29.5 months (range, 8 months to 9.5 years). RESULTS: Primary ELII was observed in all but two cases (28/30; 93.3%). The most common sources of ELII were the left subclavian artery (LSA; 13/30; 43.3%) and intercostal/bronchial vessels (13/30; 43.3%), followed by visceral arteries (4/30; 13.4%). Overall mortality was 33.3% (10/30). ELII-related death (secondary rupture) was observed in 20% (2/10). Reintervention (RI) procedures for ELII were performed in 9 of 30 patients (30.0%); 5 of 9 (55.6%) in cases with ELII via the LSA. Indications for RI were diameter expansion in five and extensive leakage in four cases. Treatment was successful in five patients (55.6%) but failed in four cases (44.4%). In 12 of 21 (57.1%) untreated patients, ELII sealed during follow-up. In conservatively treated patients, an increase in aortic diameter has been only observed in a patient with secondary ELII. CONCLUSIONS: The results presented herein suggest that the clinical impact of ELII after TEVAR must not be underestimated. Albeit a transient finding in most cases, ELII is associated with a relevant RI rate, particularly in cases involving the LSA. RI seems indicated in patients with increasing aortic diameter and/or extensive leakage. Careful surveillance of all patients with ELII is recommended.