Distribution of Hepatic Venous Blood in the Total Cavo Pulmonary Connection: An In Vitro Study Into the Effects of Connection Geometry

2001 ◽  
Vol 123 (6) ◽  
pp. 558-564 ◽  
Author(s):  
Peter G. Walker ◽  
Ghanem F. Oweis ◽  
Kevin G. Watterson
Keyword(s):  
Low Power ◽  
Power Loss ◽  
Heart Defects ◽  
Superior Vena ◽  
Venous Blood ◽  
Vena Cava ◽  
Fluid Distribution ◽  
Large Power ◽  
Zero Offset

The total cavo pulmonary connection, or TCPC, is a surgical correction to congenital heart defects. The geometry of this connection has been shown to determine the fluid power loss as well as the distribution of hepatic fluid that enters through the inferior vena cava. In vitro studies were performed to measure the power loss and hepatic fluid distribution in models of the TCPC with four different geometries. It was found that a zero offset straight geometry provided good hepatic fluid distribution but large power loss. A zero offset flared geometry provided low power loss but poor hepatic fluid distribution. The optimal geometry from those tested was found to be the zero offset cowl geometry whereby an enlargement was made on one side of the inferior and superior vena cava. So long as the cowl was directed toward the pulmonary artery of lowest flow rate, low power loss and relatively good distribution of hepatic flow could be obtained.

Effect of Flow Pulsatility on 2nd Stage Fontan Hemodynamics: An In Vitro Investigation

2009 ◽  
Author(s):  
Christopher M. Haggerty ◽  
Lakshmi P. Dasi ◽  
Jessica Kanter ◽  
Ajit P. Yoganathan
Keyword(s):  
Congenital Heart ◽  
Single Ventricle ◽  
Heart Defects ◽  
Superior Vena ◽  
Fontan Procedure ◽  
Pulmonary Arteries ◽  
Vena Cava ◽  
Second Stage ◽  
In Vitro Investigation

The Fontan procedure [1] is the staged, palliative surgical approach used to treat patients suffering from single ventricle congenital heart defects. The second stage of this procedure involves the connection of the superior vena cava (SVC) to the pulmonary arteries (PAs) in either an end-to-side (known as the Bi-Directional Glenn (BDG)) or side-to-side (or Hemi-Fontan (HF)) fashion. Because of obvious disparities at the connection site, there are understandable differences in the fluid dynamics between the two geometries.

Superior vena cava (SVC) filters placed over central lines – analysis of line trapping and difficulties with line retrieval: an in-vitro experimental study

2014 ◽  
Vol 55 (6) ◽  
pp. 732-736 ◽  
Author(s):  
Jorge E Lopera ◽  
Murray Shapiro ◽  
Darlene Sanchez ◽  
Carolina Maya ◽  
Ghazwan Kroma ◽  
...  
Keyword(s):  
Experimental Study ◽  
Superior Vena Cava ◽  
Superior Vena ◽  
Vena Cava ◽  
Central Lines

scholarly journals Repetitive and Brief Occlusion of Total Right Atrium Venous Blood Flow Improves Experimental Pulmonary Arterial Hypertension: a novel potential therapeutic strategy

2020 ◽  
Author(s):  
Nan Liu ◽  
Ying Xing ◽  
Chen Wang
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Therapeutic Strategy ◽  
Superior Vena ◽  
Venous Blood ◽  
Vena Cava ◽  
Vegf Receptor ◽  
Venous Blood Flow ◽  
History Of ◽  
Pulmonary Arterial

AbstractPulmonary arterial hypertension (PAH) is a vascular disorder associated with significant morbidity and mortality. The pathophysiology of PAH remains controversial, but the only currently available therapies for PAH are pharmacological pulmonary artery vasodilation, decreasing right ventricular (RV) afterload, and relieving symptoms. By now, there is no therapy being able to minimize vascular remodeling processes and thus to reverse or delay the natural history of the disease. It has been generally thought that reduction of RV preload was detrimental, which deteriorated the systemic hemodynamics. In the present study, however, we repetitively and briefly occluded (RBO) both superior vena cava and inferior vena cava by ligation (occlusion for less than 5 seconds then re-open for 30 seconds and repeated 5 cycles as one sequence, 1 sequence every 6 hours) to intermittently restrict RV preload, for continuous 24 hours, total 5 sequences, in the Sugen 5416 (VEGF receptor blocker) and hypoxia induced PAH rat models and we found this strategy was beneficial for lowering pulmonary vascular resistance (PVR).

scholarly journals Candida Parapsilosis Endocarditis in a Very Low Birth Weight Premature Infant Successfully Treated with the Association of Caspofungin and Voriconazole

2008 ◽  
Vol 1 ◽  
pp. IDRT.S895
Author(s):  
Vanessa A. Aguiare Lopes ◽  
Alexandre Ordones Lopes ◽  
Orlei Ribeiro De Araújo ◽  
Valeska A. Schauer Aguiare
Keyword(s):  
Premature Infant ◽  
Antifungal Agents ◽  
Candida Parapsilosis ◽  
Very Low Birth Weight ◽  
Prolonged Mechanical Ventilation ◽  
Superior Vena ◽  
Combined Therapy ◽  
Vena Cava ◽  
Surgical Removal

Objectives To report a case in where a mural endocarditis caused by Candida parapsilosis was successfully treated with the combination of 2 antifungal agents, caspofungin and voriconazole, in an extremely premature infant. Description A female infant born at 30.7 weeks with weight 925 g. The infant had a pneumothorax and respiratory distress syndrome, requiring prolonged mechanical ventilation, 1 venous umbilical and 3 central catheters, and broad-spectrum antibiotics. At 51 days of life, an echocardiogram showed an image compatible with fungal vegetation on the junction of the superior vena cava to the right atrium. Blood cultures grew Candida parapsilosis in various sequential samples, despite treatment with fluconazole and amphotericin-B and in vitro sensitivity to these drugs. A treatment of combined voriconazole and caspofungin was initiated resulting in clinical improvement and no need for surgical removal of vegetation. Comments Combined therapy with newer antifungal agents can be life-saving in premature infants with Candida parapsilosis complicated sepsis.

Hemodynamics Characteristics of a Four-Way Right-Atrium Bypass Connector With an Optimized Central Diverter

2018 ◽  
Author(s):  
Elizabeth Mack ◽  
Jakin Jagani ◽  
Alexandrina Untaroiu
Keyword(s):  
Pulmonary Artery ◽  
Inferior Vena Cava ◽  
Stagnation Point ◽  
Superior Vena Cava ◽  
Right Atrium ◽  
Power Loss ◽  
Inferior Vena ◽  
Superior Vena ◽  
Fontan Procedure ◽  
Vena Cava

The most common surgical procedure used to treat right ventricular heart failure is the Fontan procedure, which connects the superior vena cava and the inferior vena cava directly to the left and right pulmonary arteries bypassing the right atrium. Many studies have been performed to improve the Fontan procedure. Research has been done on a four-way connector that can both passively and actively improve flow characteristics of the junction between the Superior Vena Cava (SVC), Inferior Vena Cava (IVC), Left Pulmonary Artery (LPA) and Right Pulmonary Artery (RPA), using an optimized connector and dual propeller system. However, the configuration of these devices do not specify propeller motor placement and has a stagnation point in the center of the connector. This study focuses on creating a housing for the motor in the center of the connector to reduce the stagnation area and further stabilize the propellers. To do this, we created a program in ANSYS that utilizes the design-of-experiment (DOE) function to minimize power-loss and stagnation points in the connector for a given geometry. First, a CFD model is created to simulate the blood flow inside the connector with different housing geometries. The shape and size of the housing are used as parameters for the DOE process. In this study, an enhanced central composite design technique is used to discretize the design space. The objective functions in the DOE are red blood cell residence time and power loss. It was confirmed that the addition of the housing did decrease the size of the stagnation point. In fact, the housing added in stabilizing the flow through the connector by creating a more defined flow path. Because the flowrates from the IVC and SVC are not the same, the best configuration for the housing was found to be asymmetric along the axis of the pulmonary artery. While this is a continuation of previous studies, the creation of an optimized housing for the motors for the propellers makes implementation of the propeller idea more viable in a real life situation. The added stability of the propellers provided by the housing can also decrease the risk of propeller failure due to rotordynamic instability.

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.

The Zero-Stress State of Rat Veins and Vena Cava

1991 ◽  
Vol 113 (1) ◽  
pp. 36-41 ◽  
Author(s):  
J. P. Xie ◽  
S. Q. Liu ◽  
R. F. Yang ◽  
Y. C. Fung
Keyword(s):  
Stress State ◽  
Cross Sections ◽  
Superior Vena ◽  
Smooth Muscles ◽  
Vena Cava ◽  
Cylindrical Tube ◽  
Opening Angle ◽  
Wall Thickening ◽  
Environment Change

The zero-stress state of a vein is, like that of an artery, not a closed cylindrical tube, but is a series of segments whose cross-sections are open sectors. An opening angle of each sector is defined as the angle subtended between two radii joining the midpoint of the inner wall to the tips of the inner wall. Data on the opening angles (mean ± standard deviation) of the veins and vena cava of the rat are presented. For the superior vena cava and subclavian, jugular, facial, renal, common iliac, saphenous, and plantar veins, the opening angle varies in the range of 25 to 75 deg. The inferior vena cava (below the heart), however, has noncircular, nonaxisymmetric cross-sections, a curved axis, and a rapid longitudinal variation of its “diameter;” its zero-stress state is not circular sectors; but the opening angle is still a useful characterization. The mean opening angle of the interior vena cava varies in the range of 40 to 150 deg in the thoracic portion, and 75 to 130 deg in the abdominal portion, with the larger values occurring about the middle of each portion. There are considerable length, diameter reductions, and wall thickening of the vena cava from the homeostatic state to the no-load state in vitro. Physically, the zero-stress state is the basis of the stress analysis of blood vessels. The change of opening angle is a convenient parameter to characterize any nonuniform remodeling of the vessel wall due to changes in physical stress or chemical environment. Change of zerostress state influences the compliance and collapsibility of the viens, their pressure-volume and pressure-flow relationships, the waterfall phenomenon, and the tone in the vascular smooth muscles if the homeostatic stress is changed.

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.

scholarly journals Efficacy of gefitinib and radiotherapy combination in Indonesian patients with lung adenocarcinoma

2018 ◽  
Vol 56 (3) ◽  
pp. 173-181
Author(s):  
Elisna Syahruddin ◽  
Aida Lufti Huswatun ◽  
Ari Prabowo ◽  
Jamal Zaini ◽  
Fariz Nurwidya ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Point Mutation ◽  
Egfr Mutation ◽  
Kinase Inhibitor ◽  
Superior Vena ◽  
Vena Cava ◽  
Egfr Mutations ◽  
Radio Therapy ◽  
Egfr Mutant

Abstract Introduction. Combinations of gefitinib and radiotherapy have been observed to have synergistic and anti-proliferative effects on lung cancer in vitro. In the clinical setting, patients who presented with respiratory difficulties such as superior vena cava syndrome (SVCS), radiotherapy should be given immediately to address the emergency while waiting for the results of epidermal growth factor receptor (EGFR) mutation test. However, there has been no study that described the role of radio-therapy in Indonesian patients with EGFR-mutant lung adenocarcinoma. Methods. This preliminary study aimed to evaluate the efficacy and toxicities of gefitinib and radiotherapy combination in lung adenocarcinoma patients in Persahabatan National Respiratory Referral Hospital, Jakarta, Indonesia. Subjects were consecutively recruited between January 2013 and December 2016. Results. Thirty-one lung adenocarcinoma with EGFR mutations were enrolled. Most of them were male (51.61%) with a median age of 54.5 years old (range 38-70 years old). EGFR mutation characteristics were on exon 21 L858R point mutation (61.30%), exon 21 L861Q point mutation (16.12%) and exon 19 deletion (22.58%). Radiotherapy was given at doses between 30-60 Gy. Among these subjects, median progression-free survival (PFS) was 185 days (95%CI; 123.69 – 246.30), 1-year survival rate (1-yr) was 45.2%, and median overall survival (OS) was 300 days (95%CI; 130.94 – 469.06). There were no grade 3/4 hematological and nonhematological toxicities recorded. The most frequent grade 1 and 2 non-hematological toxicities were skin rash, diarrhea, and paronychia that might be related to tyrosine kinase inhibitor (TKI). Conclusion. The combination of TKI with radiation may be considered in EGFR-mutant lung adenocarcinoma subjects.

Sign in / Sign up

Export Citation Format

Share Document