Effect of Flow Pulsatility and Wall Compliance on the Energy Loss in the Total Cavopulmonary Connection

2013 ◽  
Author(s):  
Reza H. Khiabani ◽  
Sulisay Phonekeo ◽  
Harish Srinimukesh ◽  
Elaine Tang ◽  
Mark Fogel ◽  
...  
Keyword(s):  
Energy Loss ◽  
Wall Motion ◽  
Heart Defects ◽  
Superior Vena ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Total Cavopulmonary Connection ◽  
Venous Flow ◽  
The Right ◽  
Cavopulmonary Connection

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. In the current practice, surgical interventions on SVHD patients commonly result in the total cavopulmonary connection (TCPC) [1]. 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 and wall motion may result in complex and unsteady flow patterns in the TCPC. Although vessel wall motion and different degrees of pulsatility have been observed in vivo, non-pulsatile (time-averaged) flow boundary conditions and rigid walls have traditionally been assumed in estimating the TCPC hemodynamic parameters (such as energy loss). Recent studies have shown that these assumptions may result in significant inaccuracies in modeling TCPC hemodynamics [2, 3].

Hemodynamic Impact of Stenting in the Total Cavopulmonary Connection With Lateral Tunnel Stenosis

2012 ◽  
Author(s):  
Elaine Tang ◽  
Doff B. McElhinney ◽  
Ajit P. Yoganathan
Keyword(s):  
Heart Defects ◽  
Superior Vena ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Total Cavopulmonary Connection ◽  
Lateral Tunnel ◽  
The Us ◽  
Intravascular Stent ◽  
The Right ◽  
Cavopulmonary Connection

2 per 1000 children in the US are born with functionally single ventricle (SV) heart defects. To restore the separate systemic and pulmonary circulations, a Total Cavopulmonary Connection (TCPC) is carried out through a series of surgical steps, which result in the direct connection of the superior vena cava (SVC) and inferior vena cava (IVC) to the pulmonary arteries without an intervening pulmonary ventricle. One way to complete the TCPC is by placing a synthetic patch in the right atrium, forming an intracardiac lateral tunnel (LT) as the final step. As patients grow, some LT pathways become stenosed. The stenosis can impose extra resistance to flow in addition to the TCPC in the SV circulation. One method of treating LT stenosis is by placement of an intravascular stent.

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.

scholarly journals Increased Energy Loss Due to Twist and Offset Buckling of the Total Cavopulmonary Connection

2017 ◽  
Vol 11 (2) ◽  
Author(s):  
Gokce Nur Oguz ◽  
Senol Piskin ◽  
Erhan Ermek ◽  
Samir Donmazov ◽  
Naz Altekin ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Energy Loss ◽  
Heart Defects ◽  
Venous Pressure ◽  
Vena Cava ◽  
Three Dimensions ◽  
Total Cavopulmonary Connection ◽  
Torsional Deformation ◽  
Porcine Pericardium ◽  
Cavopulmonary Connection

The hemodynamic energy loss through the surgically implanted conduits determines the postoperative cardiac output and exercise capacity following the palliative repair of single-ventricle congenital heart defects. In this study, the hemodynamics of severely deformed surgical pathways due to torsional deformation and anastomosis offset are investigated. We designed a mock-up total cavopulmonary connection (TCPC) circuit to replicate the mechanically failed inferior vena cava (IVC) anastomosis morphologies under physiological venous pressure (9, 12, 15 mmHg), in vitro, employing the commonly used conduit materials: Polytetrafluoroethylene (PTFE), Dacron, and porcine pericardium. The sensitivity of hemodynamic performance to torsional deformation for three different twist angles (0 deg, 30 deg, and 60 deg) and three different caval offsets (0 diameter (D), 0.5D, and 1D) are digitized in three dimensions and employed in computational fluid dynamic (CFD) simulations to determine the corresponding hydrodynamic efficiency levels. A total of 81 deformed conduit configurations are analyzed; the pressure drop values increased from 80 to 1070% with respect to the ideal uniform diameter IVC conduit flow. The investigated surgical materials resulted in significant variations in terms of flow separation and energy loss. For example, the porcine pericardium resulted in a pressure drop that was eight times greater than the Dacron conduit. Likewise, PTFE conduit resulted in a pressure drop that was three times greater than the Dacron conduit under the same venous pressure loading. If anastomosis twist and/or caval offset cannot be avoided intraoperatively due to the anatomy of the patient, alternative conduit materials with high structural stiffness and less influence on hemodynamics can be considered.

scholarly journals Case Report: An Anomalous Left Hepatic Venous Connection in a Patient With Unexpected Cyanosis

2021 ◽  
Vol 9 ◽  
Author(s):  
Fanyan Luo ◽  
Haisong Bu
Keyword(s):  
Rural Areas ◽  
Treatment Time ◽  
Superior Vena ◽  
Vena Cava ◽  
Total Cavopulmonary Connection ◽  
Blood Oxygen Saturation ◽  
Tunnel Technique ◽  
Cardiac Lesions ◽  
The Right ◽  
Cavopulmonary Connection

An anomalous left hepatic venous (LHV) connection is an extremely rare cardiac malformation, and left hepatic venous route abnormalities not associated with other cardiac lesions do not require surgical treatment because they are physiologically benign. However, when venous route abnormalities exist with associated cardiac lesions, the conduct of the cardiac surgical repair must accommodate the abnormal venous anatomy, especially in total cavopulmonary connection patients. Herein, we present a rare case of a 7-year-old Chinese boy about 1 year post bilateral superior vena cava pulmonary anastomosis who presented with severe cyanosis and was referred to our department. However, the patient showed an unexpected gradual decrease in blood oxygen saturation to 60–70% after the extracardiac total cavopulmonary connection (ETCPC) operation. Emergency echocardiography and computed tomography confirmed that the LHV entered the right atrium. Subsequently, the patient undergone completion of a staged TCPC with intra-atrial tunnel technique. This illustrative report highlights the essence of improving the preoperative accurate diagnosis to avoid unplanned reoperation in China, especially for the remote rural areas of eastern countries where the level of health care and services is relatively backward. Failure to identify anomalous LHV connection, in this case, will delay effective treatment past the optimal treatment time.

In Vitro Investigation of the Effect of Flow Pulsatility on Power Loss in the Total Cavopulmonary Connection

2011 ◽  
Author(s):  
Elaine Tang ◽  
Reza H. Khiabani ◽  
Christopher M. Haggerty ◽  
Ajit P. Yoganathan
Keyword(s):  
Heart Defects ◽  
Pulmonary Arteries ◽  
Patient Specific ◽  
Total Cavopulmonary Connection ◽  
Unique Challenge ◽  
Venae Cavae ◽  
In Vitro Investigation ◽  
The Right ◽  
Cavopulmonary Connection

Total Cavopulmonary Connection (TCPC) is the most common surgical palliation for single ventricle heart defects. In such connections, venae cavae are connected to the pulmonary arteries, bypassing the right ventricle. The patient-specific anatomical complexity makes characterization and optimization of the fluid mechanics a unique challenge.

Hemodynamics Characteristics of a Four-Way Right-Atrium Bypass Connector

2017 ◽  
Author(s):  
Elizabeth Mack ◽  
Alexandrina Untaroiu
Keyword(s):  
Blood Flow ◽  
Superior Vena Cava ◽  
Right Atrium ◽  
Superior Vena ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Design Parameters ◽  
Patient Specific ◽  
Optimal Size ◽  
The Right

Currently, the surgical procedure followed by the majority of cardiac surgeons to address right ventricular dysfunction is the Fontan procedure, which connects the superior and inferior vena cava directly to the left and right pulmonary arteries bypassing the right atrium. However, this is not the most efficient configuration from a hemodynamics perspective. The goal of this study is to develop a patient-specific 4-way connector to bypass the dysfunctional right ventricle and augment the pulmonary circulation. The 4-way connector is intended to channel the blood flow from the inferior and superior vena cava directly to the right and left pulmonary arteries. By creating a connector with proper hemodynamic characteristics, one can control the jet flow interactions between the inferior and superior vena cava and streamline the flow towards the right and left pulmonary arteries. In this study the focus is on creating a system that can identify the optimal configuration for the 4-way connector for patients from 0–20 years of age. A platform is created in ANSYS that utilizes the DOE function to minimize power-loss and blood damage propensity in the connector based on junction geometries. A CFD model is created to simulate the blood flow through the connector. Then the geometry of the bypass connector is parameterized for DOE process. The selected design parameters include inlet and outlet diameters, radius at the intersection, and length of the connector pathways. The chosen range for each geometric parameter is based on the relative size of the patient’s arteries found in the literature. It was confirmed that as the patient’s age and artery size change, the optimal size and shape of the connector also changes. However, the corner radius did not decrease at the same rate as the opening diameters. This means that creating different sized connectors is not just a matter of scaling the original connector to match the desired opening diameter. However, it was found that power losses within the connector decrease and average and maximum blood traversal time through the connector increased for increasing opening radius. This information could be used to create a more specific relationship between the opening radius and the flow characteristics. So in order to create patient specific connectors, either a new more complicated trend needs to be found or an optimization program would need to be run on each patient’s specific geometry when they need a new connector.

scholarly journals Changes in Heart Rate and Heart Rate Variability During Surgical Stages to Completed Fontan Circulation

2021 ◽  
Author(s):  
Jenny Alenius Dahlqvist ◽  
Urban Wiklund ◽  
Marcus Karlsson ◽  
Katarina Hanséus ◽  
Eva Strömvall Larsson ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Heart Defects ◽  
Superior Vena ◽  
Univentricular Heart ◽  
Total Cavopulmonary Connection ◽  
Healthy Controls ◽  
Autonomic Nervous ◽  
Age Related ◽  
Cavopulmonary Connection

AbstractArrhythmia is related to heart rate variability (HRV), which reflects the autonomic nervous regulation of the heart. We hypothesized that autonomic nervous ganglia, located at the junction of the superior vena cava’s entrance to the heart, may be affected during the bidirectional Glenn procedure (BDG), resulting in reduced HRV. We aimed to investigate changes in heart rate and HRV in a cohort of children with univentricular heart defects, undergoing stepwise surgery towards total cavopulmonary connection (TCPC), and compare these results with healthy controls. Twenty four hours Holter-ECG recordings were obtained before BDG (n = 47), after BDG (n = 47), and after total cavopulmonary connection (TCPC) (n = 45) in patients and in 38 healthy controls. HRV was analyzed by spectral and Poincaré methods. Age-related z scores were calculated and compared using linear mixed effects modeling. Total HRV was significantly lower in patients before BDG when compared to healthy controls. The mean heart rate was significantly reduced in patients after BDG compared to before BDG. Compared to healthy controls, patients operated with BDG had significantly reduced heart rate and reduced total HRV. Patients with TCPC showed reduced heart rate and HRV compared with healthy controls. In patients after TCPC, total HRV was decreased compared to before TCPC. Heart rate was reduced after BDG procedure, and further reductions of HRV were seen post-TCPC. Our results indicate that autonomic regulation of cardiac rhythm is affected both after BDG and again after TCPC. This may be reflected as, and contribute to, postoperative arrhythmic events.

A Study of TCPC-Stent Conjunction for Cavopulmonary Assist in Fontan Patients With Right Ventricular Dysfunction

2016 ◽  
Author(s):  
Jakin Jagani ◽  
Alexandrina Untaroiu
Keyword(s):  
Energy Loss ◽  
Power Loss ◽  
Therapeutic Option ◽  
Superior Vena ◽  
Fontan Operation ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Paediatric Population ◽  
Circulatory Support ◽  
Blood Distribution

Mechanical circulatory support devices have gained significant importance in recent years as a viable therapeutic option to support paediatric population and children with single functional ventricle. The Fontan operation helps to reroute the deoxygenated blood to the lungs by bypassing the dysfunctional right ventricle. Total Cavopulmonary Connection (TCPC) is usually a method opted by the clinicians to connect the superior vena cava (SVC) and inferior vena cava (IVC) to the left and right pulmonary artery (LPA and RPA). However, the non-physiologic flow patterns created by the Fontan procedure leads to an increase in chances of platelet deposition and pressure loss which calls for heart transplantation to prevent early and late stage pathophysiology. This had led to modification of TCPC geometry to reduce the pressure and energy loss and thereby unload the single functional ventricle to ensure longer survival period. A study on mechanical circulatory device in conjunction with the modified TCPC geometry has seen little exposure and has opened new gates to develop a variety of state-of-art cavopulmonary assist devices. This study is focused on the selection of optimal TCPC to reduce energy loss and the effect of stent inside the modified TCPC on hemodynamics and flow structures. Four TCPC connections, developed for a particular age group of children, were studied for the velocity field, overall pressure and energy loss. In addition, the four TCPC connection geometries were also studied for distribution of hepatic blood from the IVC to both pulmonary arteries, and hence the lungs, to prevent development of any arteriovenous malformations. The entire stent assembly mounted inside the two best performing TCPC connections was examined for the hemodynamic effects using a series of 3D-CFD simulations. The curved-type connection for the TCPC proved to provide minimum pressure and energy loss along with reduced traces of vortex and recirculation. However, it was not efficient in terms of hepatic blood distribution. The flared geometry performed second best in terms of both minimum power loss and even hepatic blood distribution. There was a slight difference in power loss between the flared and the curved TCPC configuration with stent but the flared geometry had better hepatic blood distribution. This study demonstrated that a stent in conjunction with a TCPC leads to development of a helical flow pattern which provides better mixing of blood and even distribution to both the pulmonary arteries. The design of a stent with the best performing flared TCPC configuration can be optimized to reduce the amount of power loss and vortex generation and can be used to design similar scaled models for paediatric population of various age groups.

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