Scaling Approach to Study the Changes Through the Gestation of Human Fetal Cardiac and Circulatory Behaviors

Pennati, Giancarlo; Fumero, R.

doi:10.1114/1.282

Cited by 45 publications

(43 citation statements)

References 31 publications

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“…The adopted power (−4/3) accounts for the different dependence of the vascular resistances and compliances on vessels' dimensions (R ≈ l · r −4 and C ≈ l · r 3 , r and l being the radius and the length of a vessel, respectively [24]). …”

Section: (C) Pre-operative Lumped Parameter Model Of the Patient Cardmentioning

confidence: 99%

Virtual surgeries in patients with congenital heart disease: a multi-scale modelling test case

Baretta

Corsini

Yang

et al. 2011

Phil. Trans. R. Soc. A.

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The objective of this work is to perform a virtual planning of surgical repairs in patients with congenital heart diseases-to test the predictive capability of a closed-loop multi-scale model. As a first step, we reproduced the pre-operative state of a specific patient with a univentricular circulation and a bidirectional cavopulmonary anastomosis (BCPA), starting from the patient's clinical data. Namely, by adopting a closed-loop multi-scale approach, the boundary conditions at the inlet and outlet sections of the three-dimensional model were automatically calculated by a lumped parameter network. Successively, we simulated three alternative surgical designs of the total cavopulmonary connection (TCPC). In particular, a T-junction of the venae cavae to the pulmonary arteries (T-TCPC), a design with an offset between the venae cavae (O-TCPC) and a Y-graft design (Y-TCPC) were compared. A multi-scale closed-loop model consisting of a lumped parameter network representing the whole circulation and a patient-specific three-dimensional finite volume model of the BCPA with detailed pulmonary anatomy was built. The three TCPC alternatives were investigated in terms of energetics and haemodynamics. Effects of exercise were also investigated. Results showed that the pre-operative caval flows should not be used as boundary conditions in post-operative simulations owing to changes in the flow waveforms post-operatively. The multi-scale approach is a possible solution to overcome this incongruence. Power losses of the Y-TCPC were lower than all other TCPC models both at rest and under exercise conditions and it distributed the inferior vena cava flow evenly to both lungs. Further work is needed to correlate results from these simulations with clinical outcomes.*Author for correspondence (giancarlo.pennati@polimi.it).One contribution of 11 to a Theme Issue 'Towards the virtual physiological human: mathematical and computational case studies'.This journal is

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Section: (C) Pre-operative Lumped Parameter Model Of the Patient Cardmentioning

confidence: 99%

Virtual surgeries in patients with congenital heart disease: a multi-scale modelling test case

Baretta

Corsini

Yang

et al. 2011

Phil. Trans. R. Soc. A.

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“…The C tot-r /C tot-l ratio was kept constant and equal to (R tot-r /R tot-l ) 20.75 according to proper scaling rules [18]. Moreover, C tot-r and C tot-l were distributed among the two blocks of the right and left lung models, respectively (C 1r , C 2r and C 1l , C 2l ; table 2), according to the assumed r C .…”

Section: 32mentioning

confidence: 99%

Boundary conditions of patient-specific fluid dynamics modelling of cavopulmonary connections: possible adaptation of pulmonary resistances results in a critical issue for a virtual surgical planning

et al. 2011

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Cavopulmonary connections are surgical procedures used to treat a variety of complex congenital cardiac defects. Virtual pre-operative planning based on in silico patient-specific modelling might become a powerful tool in the surgical decision-making process. For this purpose, three-dimensional models can be easily developed from medical imaging data to investigate individual haemodynamics. However, the definition of patient-specific boundary conditions is still a crucial issue. The present study describes an approach to evaluate the vascular impedance of the right and left lungs on the basis of pre-operative clinical data and numerical simulations. Computational fluid dynamics techniques are applied to a patient with a bidirectional cavopulmonary anastomosis, who later underwent a total cavopulmonary connection (TCPC). Multi-scale models describing the surgical region and the lungs are adopted, while the flow rates measured in the venae cavae are used at the model inlets. Pre-operative and post-operative conditions are investigated; namely, TCPC haemodynamics, which are predicted using patient-specific pre-operative boundary conditions, indicates that the pre-operative balanced lung resistances are not compatible with the TCPC measured flows, suggesting that the pulmonary vascular impedances changed individually after the surgery. These modifications might be the consequence of adaptation to the altered pulmonary blood flows.

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“…In vasodilation or vasoconstriction, vascular resistance and capacitance scale to reflect changes in vessel diameters via an exponential coefficient of À4 and 3, respectively. Thus according to the resulting scaling of resistances due to exercise, we further scale capacitances in the corresponding blocks using the equation [16,18,48] where C/C i and R/R i are the capacitance and resistance scaling ratios, respectively. The capacitances in the leg circuit are not scaled since the exercise "effective resistances" largely represent the consequences of the muscle pump, rather than vasodilation alone.…”

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confidence: 99%

A Simulation Protocol for Exercise Physiology in Fontan Patients Using a Closed Loop Lumped-Parameter Model

Kung

Pennati

Migliavacca

et al. 2014

Journal of Biomechanical Engineering

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Background: Reduced exercise capacity is nearly universal among Fontan patients, though its etiology is not yet fully understood. While previous computational studies have attempted to model Fontan exercise, they did not fully account for global physiologic mechanisms nor directly compare results against clinical and physiologic data. Methods: In this study, we developed a protocol to simulate Fontan lower-body exercise using a closed-loop lumped-parameter model describing the entire circulation. We analyzed clinical exercise data from a cohort of Fontan patients, incorporated previous clinical findings from literature, quantified a comprehensive list of physiological changes during exercise, translated them into a computational model of the Fontan circulation, and designed a general protocol to model Fontan exercise behavior. Using inputs of patient weight, height, and if available, patient-specific reference heart rate (HR) and oxygen consumption, this protocol enables the derivation of a full set of parameters necessary to model a typical Fontan patient of a given body-size over a range of physiologic exercise levels. Results: In light of previous literature data and clinical knowledge, the model successfully produced realistic trends in physiological parameters with exercise level. Applying this method retrospectively to a set of clinical Fontan exercise data, direct comparison between simulation results and clinical data demonstrated that the model successfully reproduced the average exercise response of a cohort of typical Fontan patients. Conclusion: This work is intended to offer a foundation for future advances in modeling Fontan exercise, highlight the needs in clinical data collection, and provide clinicians with quantitative reference exercise physiologies for Fontan patients. [DOI: 10.1115/1.4027271] IntroductionSingle ventricle physiology is one of the most severe forms of congenital heart disease, in which an infant has only one functional pumping chamber. The condition is not compatible with life without treatment and these infants require immediate surgical intervention after birth, typically followed by two additional palliative procedures within the first few years of life. The Fontan procedure, in its various technical modifications, represents the final stage of the multistaged surgery that achieves complete separation of the deoxygenated and oxygenated blood in the circulation. The procedure involves directly connecting the superior venae cavae and inferior venae cavae (SVC and IVC) to the pulmonary arteries, thus bypassing the heart and resulting in the total venous return flowing passively into the pulmonary circulation.Exercise intolerance is among the myriad complications that contribute to the gradual attrition of post-Fontan patients in the years following surgery. Other causes of decreased survival include ventricular dysfunction, atrial arrhythmias, protein-losing enteropathy, arteriovenous malformations, thrombotic complications, and poor neurodevelopmental outcomes [1]. While ...

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Scaling Approach to Study the Changes Through the Gestation of Human Fetal Cardiac and Circulatory Behaviors

Cited by 45 publications

References 31 publications

Virtual surgeries in patients with congenital heart disease: a multi-scale modelling test case

Virtual surgeries in patients with congenital heart disease: a multi-scale modelling test case

Boundary conditions of patient-specific fluid dynamics modelling of cavopulmonary connections: possible adaptation of pulmonary resistances results in a critical issue for a virtual surgical planning

A Simulation Protocol for Exercise Physiology in Fontan Patients Using a Closed Loop Lumped-Parameter Model

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