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Conijn M, Wintermans L, Metselaar R, Ruisch J, Bax E, van Egmond C, Nieuwenstein B, Warmerdam E, Krings G. A 3D printed pulmonary mock loop for hemodynamic studies in congenital heart disease. Biomed Phys Eng Express 2022; 8. [PMID: 35970091 DOI: 10.1088/2057-1976/ac8993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 08/15/2022] [Indexed: 11/11/2022]
Abstract
Background With the increasing survival of the congenital heart disease population, there is a growing need for in-depth understanding of blood circulation in these patients. Mock loops provide the opportunity for comprehensive hemodynamic studies without burden and risks for patients. This study aimed to evaluate the ability of the presented mock loop to mimic the hemodynamics of the pulmonary circulation with and without stenosis and the MR compatibility of the system. Methods A pulsatile pump with two chambers, separated by a flexible membrane, was designed and 3D printed. A cough assist device applied an alternating positive and negative pressure on the membrane. One adult, and three pediatric pulmonary bifurcations were 3D printed and incorporated in the setup. Two pediatric models had a 50% stenosis of the left branch. Bilateral compliance chambers allowed for individual compliance tuning. A reservoir determined the diastolic pressure. Two carbon heart valves guaranteed unidirectional flow. The positive pressure on the cough assist device was tuned until an adequate stroke volume was reached with a frequency of 60 bpm. Flow and pressure measurements were performed on the main pulmonary artery and the two branches. The MR compatibility of the setup was evaluated. Results A stroke volume with a cardiac index of 2L/min/m2 was achieved in all models. Physiological pressure curves were generated in both normal and stenotic models. The mock loop was MR compatible. Conclusion This MR compatible mock loop, closely resembles the pulmonary circulation thereby providing a controllable environment for hemodynamic studies.
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Affiliation(s)
- Maartje Conijn
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, 3584 EA, NETHERLANDS
| | - Lieke Wintermans
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3584 EA , NETHERLANDS
| | - Rutger Metselaar
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Janna Ruisch
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Eva Bax
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Carmen van Egmond
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA , NETHERLANDS
| | - Ben Nieuwenstein
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Evangeline Warmerdam
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
| | - Gregor Krings
- Wilhelmina Children's Hospital University Medical Centre, Lundlaan 6, Utrecht, Utrecht, 3581 EA, NETHERLANDS
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Schwärzel LS, Jungmann AM, Schmoll N, Seiler F, Muellenbach RM, Schenk J, Dinh QT, Bals R, Lepper PM, Omlor AJ. A mock circulation loop to test extracorporeal CO 2 elimination setups. Intensive Care Med Exp 2020; 8:52. [PMID: 32915322 PMCID: PMC7484925 DOI: 10.1186/s40635-020-00341-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/02/2020] [Indexed: 01/01/2023] Open
Abstract
Background Extracorporeal carbon dioxide removal (ECCO2R) is a promising yet limited researched therapy for hypercapnic respiratory failure in acute respiratory distress syndrome and exacerbated chronic obstructive pulmonary disease. Herein, we describe a new mock circuit that enables experimental ECCO2R research without animal models. In a second step, we use this model to investigate three experimental scenarios of ECCO2R: (I) the influence of hemoglobin concentration on CO2 removal. (II) a potentially portable ECCO2R that uses air instead of oxygen, (III) a low-flow ECCO2R that achieves effective CO2 clearance by recirculation and acidification of the limited blood volume of a small dual lumen cannula (such as a dialysis catheter). Results With the presented ECCO2R mock, CO2 removal rates comparable to previous studies were obtained. The mock works with either fresh porcine blood or diluted expired human packed red blood cells. However, fresh porcine blood was preferred because of better handling and availability. In the second step of this work, hemoglobin concentration was identified as an important factor for CO2 removal. In the second scenario, an air-driven ECCO2R setup showed only a slightly lower CO2 wash-out than the same setup with pure oxygen as sweep gas. In the last scenario, the low-flow ECCO2R, the blood flow at the test membrane lung was successfully raised with a recirculation channel without the need to increase cannula flow. Low recirculation ratios resulted in increased efficiency, while high recirculation ratios caused slightly reduced CO2 removal rates. Acidification of the CO2 depleted blood in the recirculation channel caused an increase in CO2 removal rate. Conclusions We demonstrate a simple and cost effective, yet powerful, “in-vitro” ECCO2R model that can be used as an alternative to animal experiments for many research scenarios. Moreover, in our approach parameters such as hemoglobin level can be modified more easily than in animal models.
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Affiliation(s)
- Leonie S Schwärzel
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
| | - Anna M Jungmann
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
| | - Nicole Schmoll
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
| | - Frederik Seiler
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
| | - Ralf M Muellenbach
- Department of Anaesthesiology and Critical Care, Campus Kassel of the University of Southampton, Kassel, Germany
| | - Joachim Schenk
- Department of Transfusion Medicine and Hemostaseology, University Hospital of Saarland, Homburg, Germany
| | - Quoc Thai Dinh
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
| | - Robert Bals
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
| | - Philipp M Lepper
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany.
| | - Albert J Omlor
- Department of Internal Medicine V - Pneumology and Intensive Care Medicine, University Hospital of Saarland, Kirrbergerstr. 1, 66421, Homburg, Germany
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Noor MR, Ho CH, Parker KH, Simon AR, Banner NR, Bowles CT. Investigation of the Characteristics of HeartWare HVAD and Thoratec HeartMate II Under Steady and Pulsatile Flow Conditions. Artif Organs 2015; 40:549-60. [PMID: 26611518 DOI: 10.1111/aor.12593] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of this study was to elucidate the dynamic characteristics of the Thoratec HeartMate II (HMII) and the HeartWare HVAD (HVAD) left ventricular assist devices (LVADs) under clinically representative in vitro operating conditions. The performance of the two LVADs were compared in a normothermic, human blood-filled mock circulation model under conditions of steady (nonpulsatile) flow and under simulated physiologic conditions. These experiments were repeated using 5% dextrose in order to determine its suitability as a blood analog. Under steady flow conditions, for the HMII, approximately linear inverse LVAD differential pressure (H) versus flow (Q) relationships were observed with good correspondence between the results of blood and 5% dextrose under all conditions except at a pump speed of 9000 rpm. For the HVAD, the corresponding relationships were inverse curvilinear and with good correspondence between the blood-derived and 5% dextrose-derived relationships in the flow rate range of 2-6 L/min and at pump speeds up to 3000 rpm. Under pulsatile operating conditions, for each LVAD operating at a particular pump speed, an counterclockwise loop was inscribed in the HQ domain during a simulated cardiac cycle (HQ loop); this showed that there was a variable phase relationship between LVAD differential pressure and LVAD flow. For both the HMII and HVAD, increasing pump speed was associated with a right-hand and upward shift of the HQ loop and simulation of impairment of left ventricular function was associated with a decrease in loop area. During clinical use, not only does the pressure differential across the LVAD and its flow rate vary continuously, but their phase relationship is variable. This behavior is inadequately described by the widely accepted representation of a plot of pressure differential versus flow derived under steady conditions. We conclude that the dynamic HQ loop is a more meaningful representation of clinical operating conditions than the widely accepted steady flow HQ curve.
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Affiliation(s)
- Mumin R Noor
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, Harefield Hospital, Middlesex, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Chong H Ho
- Department of Bioengineering, Imperial College London, London, UK
| | - Kim H Parker
- Department of Bioengineering, Imperial College London, London, UK
| | - Andre R Simon
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, Harefield Hospital, Middlesex, UK
| | - Nicholas R Banner
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, Harefield Hospital, Middlesex, UK.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Christopher T Bowles
- Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, Harefield Hospital, Middlesex, UK.,Department of Bioengineering, Imperial College London, London, UK
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