Search results for "Ascending"
showing 10 items of 109 documents
Difference in hemodynamic and wall stress of ascending thoracic aortic aneurysms with bicuspid and tricuspid aortic valve.
2012
The aortic dissection (AoD) of an ascending thoracic aortic aneurysm (ATAA) initiates when the hemodynamic loads exerted on the aneurysmal wall overcome the adhesive forces holding the elastic layers together. Parallel coupled, two-way fluid–structure interaction (FSI) analyses were performed on patient-specific ATAAs obtained from patients with either bicuspid aortic valve (BAV) or tricuspid aortic valve (TAV) to evaluate hemodynamic predictors and wall stresses imparting aneurysm enlargement and AoD. Results showed a left-handed circumferential flow with slower-moving helical pattern in the aneurysm's center for BAV ATAAs whereas a slight deviation of the blood flow toward the anterolater…
Deep learning approach for the segmentation of aneurysmal ascending aorta.
2020
Diagnosis of ascending thoracic aortic aneurysm (ATAA) is based on the measurement of the maximum aortic diameter, but size is not a good predictor of the risk of adverse events. There is growing interest in the development of novel image-derived risk strategies to improve patient risk management towards a highly individualized level. In this study, the feasibility and efficacy of deep learning for the automatic segmentation of ATAAs was investigated using UNet, ENet, and ERFNet techniques. Specifically, CT angiography done on 72 patients with ATAAs and different valve morphology (i.e., tricuspid aortic valve, TAV, and bicuspid aortic valve, BAV) were semi-automatically segmented with Mimic…
On the severity of aortic stenosis in ascending aortic aneurysm: A computational tool to examine ventricular-arterial interaction and aortic wall str…
2020
Abstract An ascending thoracic aortic aneurysm (ATAA) is a life-threatening cardiovascular consequence of vessel dilatation that portends adverse events and death. From a clinical perspective, ATAA should not be treated as an isolated disease, and surgery is often carried out in the presence of AS, aortic insufficiency or a calcified valve leaflet. Aortic stenosis (AS) is common in ATAAs and leads to both vessel rigidity and left ventricular (LV) impairment. In this study, lumped-parameter modeling and computational analysis were used to assess the change in the wall shear stress (WSS) and intramural wall stress of patient-specific ATAA models with different degrees of AS (i.e., mild to sev…
Constitutive modeling of ascending thoracic aortic aneurysms using microstructural parameters.
2016
Ascending thoracic aortic aneurysm (ATAA) has been associated with diminished biomechanical strength and disruption in the collagen fiber microarchitecture. Additionally, the congenital bicuspid aortic valve (BAV) leads to a distinct extracellular matrix structure that may be related to ATAA development at an earlier age than degenerative aneurysms arising in patients with the morphological normal tricuspid aortic valve (TAV). The purpose of this study was to model the fiber-reinforced mechanical response of ATAA specimens from patients with either BAV or TAV. This was achieved by combining image-analysis derived parameters of collagen fiber dispersion and alignment with tensile testing dat…
Chronic atrial fibrillation in presence of aortic stenosis in a patient with polysplenia syndrome.
2013
We report a rare case of “situs viscerum ambiguous” with polysplenia syndrome, in a 69 year old female patient with aortic stenosis and chronic atrial fibrillation. The presenting symptom was dyspnoea on moderate exertion and an ECG showed supra ventricular arrhythmia. Patients trans-thoracic echocardiogram revealed a dilated left atrium, reduced ejection fraction, mild tricuspid regurgitation, moderate-severe pulmonary hypertension and severe aortic stenosis. The patient was successfully treated with a replacement of her aortic valve and ascending aorta.
Three-Dimensional Echocardiographic Evaluation of Aortic and Mitral Valve Stenosis
2001
Dynamic volume rendered three-dimensional echocardiography allows the spatial recognition of anatomy and function of the aortic and mitral valves with acceptable image quality. The aortic valve can be best visualized in a view from the ascending aorta down to the valve level, thus allowing an overview of the aortic aspect of the valve in a surgeon's perspective in ∼ 80% of patients. Planimetric measurement of the aortic valve area was possible in 88% of patients, and there is no systematic overestimation or underestimation of aortic valve area compared with two-dimensional echocardiography and catheterization. The entire valvular circumference of the mitral valve can be assessed from both a…
Tissue and circulating miRNAs as biomarkers in bicuspid aortic valve disease.
2019
Recent data suggested that bicuspid aortic valve (BAV) with left-right (L-R), right-non coronary (R-NC) and left-non coronary (L-NC) cusp fusion represents distinct pathological entities1. The rate of aortic enlargement varies according to the pattern of cusps fusion, with faster rates of aortic sinus and ascending aortic dilatation associated with the L-R compared to R-NC and L-NC morphology. In our study, we sought to investigate the histological fea-tures of aneurysms associated to different BAV phenotypes and we looked for specific mi-croRNAs (miRNA) as biomarkers of medial degeneration severity in order to optimize surgi-cal indication and prevent catastrophic complications such as rup…
Two mesalazine regimens in the prevention of the post-operative recurrence of Crohn's disease: a pragmatic, double-blind, randomized controlled trial
2003
Summary Background : The role of mesalazine in preventing the clinical recurrence of Crohn's disease after surgery has been shown in a meta-analysis of all published studies. No clear relationship, however, has been shown between dosage and response. Aim : To evaluate whether 4.0 g/day of mesalazine may offer therapeutic advantages over 2.4 g/day in the prevention of both endoscopic and clinical post-operative recurrence of Crohn's disease. Methods : The study was a double-blind, randomized, multi-centre, prospective, controlled clinical trial. Two hundred and six patients, submitted to first or second intestinal resection for Crohn's disease limited to the terminal ileum, with or without i…
Systematische Analyse der Geometrie eines definierten Kontrastmittelbolus - Implikationen für die kontrastmittelverstärkte 3D-MR-Angiographie thoraka…
2005
Purpose: Little is known about the dispersion of a defined contrast bolus during its passage through the heart and pulmonary vasculature. The purpose of this study was to analyze factors influencing a defined contrast bolus for ce-MRA of thoracic vessels. Materials and Methods: For analysis of bolus geometry, an ECG-gated saturation-recovery Turbo-Flash sequence with a TI of 20 msec was used. It was acquired axially at the level of the pulmonary trunc, so that with one data acquisition a curve analysis was possible in the ascending and descending aorta, and in the pulmonary trunc. Twenty-nine patients received 3 ml of Gd-DTPA diluted with saline to a total of 20 ml. Contrast injection was d…
Regional variation of wall shear stress in ascending thoracic aortic aneurysms.
2014
The development of an ascending thoracic aortic aneurysm is likely caused by excessive hemodynamic loads exerted on the aneurysmal wall. Computational fluid-dynamic analyses were performed on patient-specific ascending thoracic aortic aneurysms obtained from patients with either bicuspid aortic valve or tricuspid aortic valve to evaluate hemodynamic and wall shear parameters, imparting aneurysm enlargement. Results showed an accelerated flow along the outer aortic wall with helical flow in the aneurysm center for bicuspid aortic valve ascending thoracic aortic aneurysms. In a different way, tricuspid aortic valve ascending thoracic aortic aneurysms exhibited normal systolic flow without su…