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

2013 ◽  
Author(s):  
Ethan Kung ◽  
Alessandro Giardini ◽  
Francesco Migliavacca ◽  
Giancarlo Pennati ◽  
Tain-Yen Hsia ◽  
...  
Keyword(s):  
Exercise Physiology ◽  
Fontan Procedure ◽  
Pulmonary Arteries ◽  
Standard Of Care ◽  
Lumped Parameter Model ◽  
Lumped Parameter ◽  
Simulation Protocol ◽  
Automated Simulation ◽  
Clinical Measurements ◽  
The Right

Single ventricle physiology is one of the most severe forms of congenital heart disease in which an infant is born with only one functional pumping chamber. These patients must go through a series of surgical procedures concluding with the Fontan procedure, which connects the superior and inferior vena cavae to the pulmonary arteries, bypassing the right side of the heart entirely. Reduced exercise capacity is a common morbidity in Fontan patients1, leading to decreased quality of life, and the etiology of lowered exercise performance remains unclear. Exercise conditions place high demands on the cardiovascular system; any good surgical design must consider the behavior of the system at stress. Invasive clinical measurements during exercise pose many challenges and are typically not standard of care. There is a need to better understand Fontan exercise physiology and to predict clinical outcomes using computational tools.

Investigation of Vessel Growth and its Impact on Hemodynamics in Patients With Lateral Tunnel Total Cavopulmonary Connection

2012 ◽  
Author(s):  
Maria Restrepo ◽  
Lucia Mirabella ◽  
Elaine Tang ◽  
Chris Haggerty ◽  
Mark A. Fogel ◽  
...  
Keyword(s):  
Heart Defects ◽  
Fontan Procedure ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Total Cavopulmonary Connection ◽  
Lateral Tunnel ◽  
Vessel Growth ◽  
Original Size ◽  
The Right ◽  
Cavopulmonary Connection

Single ventricle heart defects affect 2 per 1000 live births in the US and are lethal if left untreated. The Fontan procedure used to treat these defects consists of a series of palliative surgeries to create the total cavopulmonary connection (TCPC), which bypasses the right heart. In the last stage of this procedure, the inferior vena cava (IVC) is connected to the pulmonary arteries (PA) using one of the two approaches: the extra-cardiac (EC), where a synthetic graft is used as the conduit; and the lateral tunnel (LT) where part of the atrial wall is used along with a synthetic patch to create the conduit. The LT conduit is thought to grow in size in the long term because it is formed partially with biological tissue, as opposed to the EC conduit that retains its original size because it contains only synthetic material. The growth of the LT has not been yet quantified, especially in respect to the growth of other vessels forming the TCPC. Furthermore, the effect of this growth on the hemodynamics has not been elucidated. The objective of this study is to quantify the TCPC vessels growth in LT patients from serial magnetic resonance (MR) images, and to understand its effect on the connection hemodynamics using computational fluid dynamics (CFD).

Effect of Flow Pulsatility on Modeling the Total Cavopulmonary Hemodynamics: A Numerical Investigation

2012 ◽  
Author(s):  
Reza H. Khiabani ◽  
Maria Restrepo ◽  
Elaine Tang ◽  
Diane De Zélicourt ◽  
Mark Fogel ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Heart Defects ◽  
Superior Vena ◽  
Fontan Procedure ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Venous Flow ◽  
Surgical Interventions ◽  
The Right

Single Ventricle Heart Defects (SVHD) are present in 2 per 1000 live births in the US. SVHD are characterized by cyanotic mixing between the de-oxygenated blood from the systemic circulation return and the oxygenated blood from the pulmonary arteries. Palliative surgical repairs (Fontan procedure) are performed to bypass the right ventricle in these patients. In current practice, the surgical interventions commonly result in the total cavopulmonary connection (TCPC). In this configuration the systemic venous returns (inferior vena cava, IVC, and superior vena cava, SVC) are directly routed to the right and left pulmonary arteries (RPA and LPA), bypassing the right heart. The resulting anatomy has complex and unsteady hemodynamics characterized by flow mixing and flow separation. Pulsation of the inlet venous flow during a cardiac cycle results in complex and unsteady flow patterns in the TCPC. Although various degrees of pulsatility have been observed in vivo, non-pulsatile (time-averaged) flow boundary conditions have traditionally been assumed in modeling TCPC hemodynamics, and only recently have pulsatile conditions been incorporated without completely characterizing their effect or importance. In this study, 3D numerical simulations were performed to predict TCPC hemodynamics with both pulsatile and non-pulsatile boundary conditions and to investigate the accuracy of applying non-pulsatile boundary conditions. Flow structures, energy dissipation rate and pressure drop were compared under rest and estimated exercise conditions. The results show that TCPC hemodynamics can be strongly influenced by the presence of pulsatile flow. However, there exists a minimum pulsatility threshold, identified by defining a weighted pulsatility index (wPI), above which the influence is significant.

Design of a Novel Cavopulmonary Assist Device for Fontan Procedures: CFD, PIV, and Hydraulic Testing

2010 ◽  
Author(s):  
Jeffrey R. Kennington ◽  
Steven Frankel ◽  
Jun Chen ◽  
Mark D. Rodefeld ◽  
Guruprasad A. Giridharan
Keyword(s):  
Inferior Vena ◽  
Fontan Procedure ◽  
Pulmonary Arteries ◽  
Hydraulic Testing ◽  
Assist Device ◽  
Lung Resistance ◽  
Left And Right ◽  
The Right ◽  
Cavopulmonary Connection ◽  
Cavopulmonary Assist Device

Single ventricle heart disease is the leading cause of death for birth defects in children under one years of age [1]. The current surgical procedure requires the use of a shunt for the first stage of the surgery. The following surgeries remove the shunt but cannot be performed on a newborn due to higher lung resistance during the first weeks of life. The overall surgical process, known as the Fontan procedure, results in a reconstructed anatomy where the left and right pulmonary arteries are sutured to the superior and inferior vena cavae (SVC/IVC), hence bypassing the right heart. This anatomy is called a total cavopulmonary connection or TCPC.

Is the “Perfect Fontan” operation routinely achievable in the modern era?

2008 ◽  
Vol 18 (3) ◽  
pp. 328-336 ◽  
Author(s):  
James K. Kirklin ◽  
Robert N. Brown ◽  
Ayesha S. Bryant ◽  
David C. Naftel ◽  
Edward V. Colvin ◽  
...  
Keyword(s):  
Operative Procedure ◽  
Fontan Procedure ◽  
Fontan Operation ◽  
Pulmonary Arteries ◽  
Left Pulmonary Artery ◽  
Fontan Circulation ◽  
Caval Vein ◽  
Entire Cohort ◽  
Inferior Caval Vein ◽  
The Right

AbstractObjectiveIn 1990, Fontan, Kirklin, and colleagues published equations for survival after the so-called “Perfect Fontan” operation. After 1988, we evolved a protocol using an internal or external polytetraflouroethylene tube of 16 to 19 millimetres diameter placed from the inferior caval vein to either the right or left pulmonary artery along with a bidirectional cava-pulmonary connection. The objective of this study was to test the hypothesis that a “perfect” outcome is routinely achievable in the current era when using a standardized surgical procedure.MethodsBetween 1 January, 1988, and 12 December, 2005, 112 patients underwent the Fontan procedure using an internal or external polytetraflouroethylene tube plus a bidirectional cava-pulmonary connection, the latter usually having been constructed as a previous procedure. This constituted 45% of our overall experience in constructing the Fontan circulation between 1988 and 1996, and 96% of the experience between 1996 and 2005. Among all surviving patients, the median follow-up was 7.3 years. We calculated the expected survival for an optimal candidate, given from the initial equations, and compared this to our entire experience in constructing the Fontan circulation.ResultsAn internal tube was utilized in 61 patients, 97% of whom were operated prior to 1998, and an external tube in 51 patients, the latter accounting for 95% of all operations since 1999. At 1, 5, 10 and 15 years, survival of the entire cohort receiving polytetraflouroethylene tubes is superimposable on the curve calculated for a “perfect” outcome. Freedom from replacement or revision of the tube was 97% at 10 years.ConclusionUsing a standardized operative procedure, combining a bidirectional cavopulmonary connection with a polytetraflouroethylene tube placed from the inferior caval vein to the pulmonary arteries for nearly all patients with functionally univentricular hearts, early and late survival within the “perfect” outcome as predicted by the initial equations of Fontan and Kirklin is routinely achievable in the current era. The need for late revision or replacement of the tube is rare.

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

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Ethan Kung ◽  
Giancarlo Pennati ◽  
Francesco Migliavacca ◽  
Tain-Yen Hsia ◽  
Richard Figliola ◽  
...  
Keyword(s):  
Clinical Data ◽  
Closed Loop ◽  
Exercise Physiology ◽  
Clinical Findings ◽  
Lumped Parameter Model ◽  
Patient Specific ◽  
Specific Reference ◽  
Fontan Patient ◽  
Lumped Parameter ◽  
Fontan Patients

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.

Beat-by-beat changes of viscoelastic and inertial properties of the pulmonary arteries

1994 ◽  
Vol 76 (6) ◽  
pp. 2348-2355 ◽  
Author(s):  
B. B. Lieber ◽  
Z. Li ◽  
B. J. Grant
Keyword(s):  
Pulmonary Arteries ◽  
Input Resistance ◽  
Lumped Parameter Model ◽  
Pulmonary Vasculature ◽  
Lumped Parameter ◽  
Rapid Changes ◽  
Anesthetized Dogs ◽  
Pulmonary Arterial ◽  
The Time Domain ◽  
Parameter Values

We tested the hypothesis that pulmonary arterial input impedance varies during the ventilatory cycle due to alterations not only of the viscoelastic components of the pulmonary vasculature but also due to changes of the inertial components. A four-element lumped-parameter model was used to fit the pulmonary arterial pressure-flow recordings in the time domain in 10 anesthetized dogs. The four elements consisted of a resistor (R) that represents input resistance, a second resistor (R1) and a capacitor (C1) that represent the viscoelastic properties of the pulmonary vasculature, and an inductor (L1) that represents inertial properties of blood within the pulmonary vasculature. The parameters were evaluated at each heartbeat throughout the ventilatory cycle at three levels of positive end-expiratory pressure. All four parameters varied significantly during the ventilatory cycle. R, C1, L1, and R1 varied by up to 97, 33, 13, and 17%, respectively. Changes in parameter values were most apparent at the start of expiration when the most rapid changes of lung volume occur. This pattern of the results is consistent with the hypothesis that the time variation of pulmonary arterial impedance is due to dynamic shifts of blood volume between the extra-alveolar and alveolar arteries.

The Child Following the Fontan Procedure: Nursing Strategies

1990 ◽  
Vol 1 (1) ◽  
pp. 46-58
Author(s):  
Patricia O’brien ◽  
E. Marsha Elixson
Keyword(s):  
Fontan Procedure ◽  
Pulmonary Arteries ◽  
Surgical Techniques ◽  
Volume Overload ◽  
Ventricular Volume ◽  
Venous Hypertension ◽  
Successful Outcome ◽  
Underlying Principle ◽  
Systemic Venous Return ◽  
The Right

The underlying principle of the Fontan procedure, perfusing the lungs without benefit of a ventricular pump, has been reinforced by its successful application in many children with complex cardiac anomalies involving only one functional ventricle. Several different techniques that direct systemic venous return through the right atrium directly to the pulmonary arteries can be used. By separating the pulmonary and systemic circulations, reducing ventricular volume overload, and relieving cyanosis, improved cardiac function and hemodynamics can be achieved. This article reviews the surgical techniques, perioperative nursing care with particular attention to the assessment, and management of systemic venous hypertension and the long-term outlook for these children. The collaboration of physicians and critical care nurses in the postoperative care of these children and their families is vital to a successful outcome.

Magnetic resonance imaging in patients after a modified Fontan operation

1992 ◽  
Vol 2 (2) ◽  
pp. 158-167 ◽  
Author(s):  
Heiko Stern ◽  
Richard Bauer ◽  
Gerrit Schrötera ◽  
Ursula Sauer ◽  
Peter Emmrich ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Right Atrium ◽  
Fontan Procedure ◽  
Pulmonary Veins ◽  
Pulmonary Arteries ◽  
Right Atrial ◽  
Resonance Imaging ◽  
Cross Sectional ◽  
The Right

SummaryMagnetic resonance imaging was performed in 26 patients who underwent a modified Fontan procedure. Their age ranged from 1.8 to 31 years with a mean of 12.2 years. A valveless anastomosis was performed between the right atrium and the rudimentary right ventricle in 12 patients and between the right atrium and the pulmonary arteries in 10 patients. A cavopulmonary connection was established in the remaining four patients. Spin echo and gradient echo scans of the heart were performed in orthogonal and angulated projections. The cross-sectional area of the atrioventricular, atriopulmonary or cavopulmonary anastomoses was measured using diameters in two orthogonal imaging planes. Recordings were examined for the presence of right atrial thrombosis, the site of drainage of the coronary sinus, compression of the pulmonary veins, as well as for the presence and extent of pericardial effusions. Cine recordings were used for the assessment of the pattern of flow within the right atrium. The cross-sectional area of the anastomoses could be determined in 24 of 26 patients. This was not statistically different between patients with different surgical procedures. Patients with a cavopulmonary connection, however, tended to have a smaller anastomosis (mean 1.4 cm2/m2BSA, S.D. 0.62) than patients with atrioventricular (mean 3.0 cm2/m2, S.D. 2.1) or atriopulmonary (2.4 cm2/m2, S.D. 1.1) connections. When compared to normal values for the size of the tricuspid valve, the size of the anastomosis was within the normal range in only four patients, it was larger in one and smaller in 19 patients. There were signs of right atrial thromboses in the scans in eight of 26 patients, as observed by two independent investigators. The site of drainage of the coronary sinus was imaged in 20 of 26 patients and was in accordance with the description of surgical procedure in eight. Compression of the right pulmonary veins by an enlarged right atrium was present in seven patients. This was severe in two children. Presence and extent of pericardial effusions could be adequately assessed in 11 of26 patients. Systolic regurgitation from the rudimentary right ventricle into the right atrium was shown in eight of 12 patients with an atrioventricular valveless anastomosis. Cine recordings revealed slow forward flow from the right atrium into the pulmonary arteries in seven of 22 patients, and there was a markedly altered pattern of intraatrial flow in two patients with anomalous systemic venous connections. Magnetic resonance imaging allows adequate examination of right atrial anatomy, determination of the size of the anastomosis with the pulmonary arteries, and semiquantitative assessment of pulmonary blood flow in the majority of patients after a modified Fontan procedure.

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