SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Ascending aorta

171

Aortic root enlargement (ARE) procedures are believed to allow implantation of larger valve prostheses; however, little evidence exists to support the specific efficacy of various techniques.

Concepts: Aorta, Ascending aorta

169

Takayasu’s arteritis is an inflammatory arteriopathy which involves the aorta and its major branches, causing mainly stenosis of their lumen, though aneurysmal lesions can also occur. A young female with Takayasu’s disease presented to our hospital with acute lung oedema due to severe aortic insufficiency and ascending aorta dilatation. She had already undergone distal ascending aorta and hemiarch replacement due to Standford type A aortic dissection five years ago. The patient had also undergone reconstruction of abdominal arteries' stenoses with extraanatomical bypass. We performed a Bentall procedure with a valved conduit and implantation of the coronary ostia as buttons on the conduit. A mechanical valved graft was used instead of a bioprosthesis, due to possible early degradation of a bioprosthesis. The postoperative course was uneventful and the one year follow-up was normal. Valve-sparing aortic root replacement should be avoided in Takayasu’s arteritis due to high rate of recurrent regurgitation.

Concepts: Cardiology, Heart, Aortic aneurysm, Aortic dissection, Aorta, Ascending aorta, Takayasu's arteritis, Arteritis

28

About 1-2% of the babies are born with bicuspid aortic valves instead of the normal aortic valve with three leaflets. A significant portion of the patients with the congenital bicuspid valve morphology suffer from aortic valve stenosis and/or ascending aortic dilatation and dissection thus requiring surgical intervention when they are young adults. Patients with bicuspid aortic valves (BAVs) have also been found to develop valvular stenosis earlier than those with the normal aortic valve. This paper overviews current knowledge of BAVs, where several studies have suggested that the mechanical stresses induced on the valve leaflets and the abnormal flow development in the ascending aorta may be an important factor in the diseases of the valve and the aortic root. The long-term goals of the studies being performed in our laboratory are aimed towards potential stratification of bicuspid valve patients who may be at risk for developing these pathologies based on analyzing the hemodynamic environment of these valves using fluid-structure interaction (FSI) modeling. Patient-specific geometry of the normal tri-cuspid and bicuspid valves are reconstructed from real-time 3D ultrasound images and the dynamic analyses performed in order to determine the potential effects of mechanical stresses on the valve leaflet and aortic root pathology. This paper describes the details of the computational tools and discusses challenges with patient-specific modeling.

Concepts: Aortic dissection, Aorta, Ascending aorta, Left ventricle, Aortic valve, Aortic valve stenosis, Aortic insufficiency, Bicuspid aortic valve

25

In pre-surgery decisions in hospital emergency cases, fast and reliable results of the solid and fluid mechanics problems are of great interest to clinicians. In the current investigation, an iterative process based on a pressure-type boundary condition is proposed in order to reduce the computational costs of blood flow simulations in arteries, without losing control of the important clinical parameters. The incorporation of cardiovascular autoregulation, together with the well-known impedance boundary condition, forms the basis of the proposed methodology. With autoregulation, the instabilities associated with conventional pressure-type or impedance boundary conditions are avoided without an excessive increase in computational costs. The general behaviour of pulsatile blood flow in arteries, which is important from the clinical point of view, is well reproduced through this new methodology. In addition, the interaction between the blood and the arterial walls occurs via a modified weak coupling, which makes the simulation more stable and computationally efficient. Based on in vitro experiments, the hyperelastic behaviour of the wall is characterised and modelled. The applications and benefits of the proposed pressure-type boundary condition are shown in a model of an idealised aortic arch with and without an ascending aorta dissection, which is a common cardiovascular disorder.

Concepts: Blood, Myocardial infarction, Heart, Artery, Fluid mechanics, Aorta, Ascending aorta, Boundary conditions

25

In the field of computational hemodynamics, sensitivity quantification of pressure and flow wave dynamics has received little attention. This work presents a novel study of the sensitivity of pressure wave timing and amplitude in the arterial system with respect to arterial stiffness. Arterial pressure and flow waves were simulated with a one-dimensional distributed wave propagation model for compliant arterial networks. Sensitivity analysis of this model was based on a generalized polynomial chaos expansion combined with a stochastic collocation method. First-order statistical sensitivity indices were formulated to assess the effect of arterial stiffening on timing and amplitude of the pressure wave and backward propagating pressure wave (BPW) in the ascending aorta, at the maximum pressure and inflection point in the systolic phase. Only the stiffness of aortic arteries were found to significantly influence timing and amplitude of the BPW, whereas other large arteries in the systemic tree showed marginal impact. Furthermore, the ascending aorta, aortic arch, thoracic aorta and infrarenal abdominal aorta had the largest influence on amplitude, whereas only the thoracic aorta influenced timing. Our results showed that the non-intrusive polynomial chaos expansion is an efficient method to compute statistical sensitivity measures for wave propagation models. These sensitivities provide new knowledge in the relative importance of arterial stiffness at various locations in the arterial network. Moreover, they will significantly influence clinical data collection and effective composition of the arterial tree, for in-silico clinical studies. This article is protected by copyright. All rights reserved.

Concepts: Heart, Blood pressure, Artery, Abdominal aorta, Aorta, Ascending aorta, Descending aorta, Systemic circulation

24

Background Anomalous connection of the coronary artery to the pulmonary artery (ACAPA) has a low incidence rate in older children and adults. The aim of this article was to evaluate the outcome of treating ACAPA with aortic implantation in older children and adults. Methods We included 21 patients (9 children and 12 adults) with ACAPA in our hospital between January 1991 and January 2015. Among these patients, 19 had anomalous connection of the left coronary artery to the pulmonary artery, 2 had anomalous connection of the right coronary artery to the pulmonary artery (ARCAPA). All of the patients underwent aortic implantation, aged 4 to 62 years (median, 18). The mean left ventricular ejection fraction (LVEF) was 55.9 ± 7.6% (<50% in 4). Eleven patients underwent direct aortic implantation (including two ARCAPAs), while 10 patients underwent tubular implantation. Eleven patients had varying degrees of mitral regurgitation, while mitral valve plasty or replacement was performed in six patients (severe mitral regurgitation) concurrently. Results There was no early mortality. Follow-up observation was performed in all 21 patients, with a mean follow-up time of 6.4 ± 5.6 years (ranging from 0.5 to 23 years). Two patients died due to noncardiac reasons 1 and 10 years after operation, respectively. Seven patients had mild mitral regurgitation, while no patients had moderate or severe mitral regurgitation after operations. The postoperative mean LVEF was not improved at 54.7 ± 7.0%, p > 0.05. Conclusion Among the multiple surgical strategies for the treatment of ACAPA, aortic implantation was used commonly in older children and adults, while mitral valve repair can be performed concurrently.

Concepts: Cardiology, Ejection fraction, Heart, Coronary circulation, Ascending aorta, Mitral valve, Mitral regurgitation, Arteries of the thorax

23

A 10-month-old girl with type I Loeys-Dietz syndrome developed a conspicuous aortic root aneurysm that was well demonstrated on chest X-ray/CT reconstruction. She underwent successful valve-spare repair of the ascending aorta.

Concepts: Heart, Aortic aneurysm, Aortic dissection, Aorta, Marfan syndrome, Ascending aorta, Arteries of the thorax, Aneurysm of sinus of Valsalva

7

Anomalous aortic origin of a coronary artery (AAOCA) from the inappropriate sinus of Valsalva is increasingly recognized by cardiac imaging. Although most AAOCA subtypes are benign, autopsy studies report an associated risk of sudden death with interarterial anomalous left coronary artery (ALCA) and anomalous right coronary artery (ARCA). Despite efforts to identify high-risk ALCA and ARCA patients who may benefit from surgical repair, debate remains regarding their classification, prevalence, risk stratification, and management. We comprehensively reviewed 77 studies reporting the prevalence of AAOCA among >1 million patients, and 20 studies examining outcomes of interarterial ALCA/ARCA patients. Observational data suggests that interarterial ALCA is rare (weighted prevalence = 0.03%; 95% confidence interval [CI]: 0.01% to 0.04%) compared with interarterial ARCA (weighted prevalence = 0.23%; 95% CI: 0.17% to 0.31%). Recognizing the challenges in managing these patients, we review cardiac tests used to examine AAOCA and knowledge gaps in management.

Concepts: Heart, Artery, Coronary circulation, Cardiovascular system, Left coronary artery, Ascending aorta, Arteries of the thorax

3

Cardiovascular magnetic resonance (CMR) is considered the gold standard of cardiac volumetric measurements. Flow in the aortic root is often measured at the sinotubular junction, even though placing the slice just above valve level may be more precise. It is unknown how much flow measurements vary at different levels in the aortic root and which level corresponds best to left ventricle volumetry.

Concepts: Blood, Heart, Measurement, Metrology, Test method, Aorta, Ascending aorta, Left ventricle

2

Hemorrhage remains the leading cause of death in trauma patients. Proximal aortic occlusion, usually performed by direct aortic cross-clamping via thoracotomy, can provide temporary hemodynamic stability, permitting definitive injury repair. Resuscitative endovascular balloon occlusion of the aorta (REBOA) uses a minimally invasive, transfemoral balloon catheter, which is rapidly inserted retrograde and inflated for aortic occlusion, and may control inflow and allow time for hemostasis. We compared resuscitative thoracotomy with aortic cross-clamping (RT) with REBOA in trauma patients in profound hemorrhagic shock.

Concepts: Hemostasis, Bleeding, Aorta, Ascending aorta, Syphilis, Physical trauma