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A study of mathematical modelling of the competitions of flow in the cavopulmonary anastyomosis with persistent forward flow
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Computational fluid dynamics in paediatric cardiac surgery
No full textComputational fluid dynamics techniques have been applied to study both the local and the global haemodynamics created by different surgical reconstructions, currently used to treat complex congenital heart defects. These operations are characterised by competition of flows which can lead to postoperative failure of the surgical treatment. Different techniques have been used in order to improve knowledge of the global haemodynamics in patients submitted to such operations, and to devise possible optimal hydraulic designs of the connections. The adopted approach has combined highly-detailed, three-dimensional models of the connections with simplified zero-dimensional, lumped-parameter network models of the overall circulation of the patient. Three-dimensional models of the connections have been developed by means of the finite element method. Local fluid dynamics features have been analysed and then ‘incorporated’ in mathematical models able to predict some clinically relevant postoperative haemodynamic data. Results emphasise the impact of local geometry on global haemodynamics
On the use of computational models for the quantitative assessment of surgery in congenital heart disease
No full textEffects of respiration and gravity on infra-diaphragmatic venous flow in normal and Fontan patients
No full textBackground—In the Fontan circulation, pulmonary and systemic vascular resistances are in series. The implications of this unique arrangement on infradiaphragmatic venous physiology are poorly understood. Methods and Results—We studied the effects of respiration and gravity on infradiaphragmatic venous flows in 20 normal healthy volunteers (control) and 48 Fontan patients (atriopulmonary connection [APC] n515, total cavopulmonary connection [TCPC] n530). Hepatic venous (HV), subhepatic inferior vena caval (IVC), and portal venous (PV) flow rates were measured with Doppler ultrasonography during inspiration and expiration in both the supine and upright positions. The inspiratory-to-expiratory flow rate ratio was calculated to reflect the effect of respiration, and the supine-to-upright flow rate ratio was calculated to assess the effect of gravity. HV flow depended heavily on inspiration in TCPC compared with both control and APC subjects (inspiratory-to-expiratory flow rate ratio 3.4, 1.7, and 1.6, respectively; P,0.0001). Normal PV flow was higher in expiration, but this effect was lost in TCPC and APC patients (inspiratory-to-expiratory flow rate ratio 0.8, 1.0, and 1.1, respectively; P50.01). The respiratory influence on IVC flow was the same in all groups. Gravity decreased HV flow more in APC than in TCPC patients (supine-to-upright flow rate ratio 3.2 versus 2.1, respectively; P,0.04) but reduced PV flow equally in all groups. Conclusions—Gravity and respiration have important influences on infradiaphragmatic venous return in Fontan patients. Although gravity exerts a significant detrimental effect on lower body venous return, which is more marked in APC than in TCPC patients, the beneficial effects of respiration in TCPC patients are mediated primarily by an increase in HV flow. These effects may have important short- and long-term implications for the hemodynamics of the Fontan circulation
A lumped parameter model for the study of the venous return in the total cavo-pulmonary connection
No full textApplication of the multiscale approach to investigate fluidynamics in surgical procedures for the treatment of congenotal heart diseases
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