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Chopski SG, Govender K, May A, Garven E, Stevens RM, Tchantchaleishvili V, Throckmorton AL. Novel hybrid total artificial heart with integrated oxygenator. J Card Surg 2022; 37:5172-5186. [PMID: 36403254 PMCID: PMC9812888 DOI: 10.1111/jocs.17210] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/30/2022] [Accepted: 11/01/2022] [Indexed: 11/21/2022]
Abstract
There continues to be an unmet therapeutic need for an alternative treatment strategy for respiratory distress and lung disease. We are developing a portable cardiopulmonary support system that integrates an implantable oxygenator with a hybrid, dual-support, continuous-flow total artificial heart (TAH). The TAH has a centrifugal flow pump that is rotating about an axial flow pump. By attaching the hollow fiber bundle of the oxygenator to the base of the TAH, we establish a new cardiopulmonary support technology that permits a patient to be ambulatory during usage. In this study, we investigated the design and improvement of the blood flow pathway from the inflow-to-outflow of four oxygenators using a mathematical model and computational fluid dynamics (CFD). Pressure loss and gas transport through diffusion were examined to assess oxygenator design. The oxygenator designs led to a resistance-driven pressure loss range of less than 35 mmHg for flow rates of 1-7 L/min. All of the designs met requirements. The configuration having an outside-to-inside blood flow direction was found to have higher oxygen transport. Based on this advantageous flow direction, two designs (Model 1 and 3) were then integrated with the axial-flow impeller of the TAH for simulation. Flow rates of 1-7 L/min and speeds of 10,000-16,000 RPM were analyzed. Blood damage studies were performed, and Model 1 demonstrated the lowest potential for hemolysis. Future work will focus on developing and testing a physical prototype for integration into the new cardiopulmonary assist system.
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Affiliation(s)
- Steven G. Chopski
- BioCirc Research Laboratory, School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Krianthan Govender
- BioCirc Research Laboratory, School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Alexandra May
- Department of Bioengineering, McGowan Institute for Regenerative Medicine, Swanson School of Engineering, University, Pittsburgh, Pennsylvania, USA
| | - Ellen Garven
- BioCirc Research Laboratory, School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Randy M. Stevens
- College of Medicine, St. Christopher’s Hospital for Children, Drexel University, Philadelphia, Pennsylvania, USA
| | | | - Amy L. Throckmorton
- BioCirc Research Laboratory, School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
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Schmid Daners M, Hall S, Sündermann S, Cesarovic N, Kron M, Falk V, Starck C, Meboldt M, Dual SA. Real-Time Ventricular Volume Measured Using the Intracardiac Electromyogram. ASAIO J 2021; 67:1312-1320. [PMID: 33899813 PMCID: PMC8614557 DOI: 10.1097/mat.0000000000001444] [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] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Left ventricular end-diastolic volume (EDV) is an important parameter for monitoring patients with left ventricular assist devices (LVADs) and might be useful for automatic LVAD work adaptation. However, continuous information on the EDV is unavailable to date. The depolarization amplitude (DA) of the noncontact intracardiac electromyogram (iEMG) is physically related to the EDV. Here, we show how a left ventricular (LV) volume sensor based on the iEMG might provide beat-wise EDV estimates. The study was performed in six pigs while undergoing a series of controlled changes in hemodynamic states. The LV volume sensor consisted of four conventional pacemaker electrodes measuring the far-field iEMG inside the LV blood pool, using a novel unipolar amplifier. Simultaneously, noninvasive measurements of EDV and hematocrit were recorded. The proposed EDV predictor was tested for statistical significance using a mixed-effect model and associated confidence intervals. A statistically significant (p = 3e-07) negative correlation was confirmed between the DA of the iEMG and the EDV as measured by electric impedance at a slope of -0.069 (-0.089, -0.049) mV/mL. The DA was slightly decreased by increased hematocrit (p = 0.039) and moderately decreased with the opening of the thorax (p = 0.003). The DA of the iEMG proved to be a significant, independent predictor of EDV. The proposed LV volume sensor is simple to integrate into the inflow cannula of an LVAD and thus has the potential to inform the clinician about the state of LV volume in real time and to automatically control the LVAD.
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Affiliation(s)
| | - Sophie Hall
- From the Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - Simon Sündermann
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Cardiovascular Surgery, Berlin, Germany
- German Heart Center Berlin, Department of Cardiothoracic and Vascular Surgery, Berlin, Germany
| | - Nikola Cesarovic
- German Heart Center Berlin, Department of Cardiothoracic and Vascular Surgery, Berlin, Germany
- Division for Surgical Research, University Hospital Zurich and University of Zurich, Zurich, Switzerland
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Mareike Kron
- Division for Surgical Research, University Hospital Zurich and University of Zurich, Zurich, Switzerland
| | - Volkmar Falk
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Cardiovascular Surgery, Berlin, Germany
- German Heart Center Berlin, Department of Cardiothoracic and Vascular Surgery, Berlin, Germany
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Christoph Starck
- DZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
- Steinbeis University Berlin, Institute (STI) of Cardiovascular Perfusion, Berlin, Germany
| | - Mirko Meboldt
- From the Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - Seraina A. Dual
- From the Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
- Radiology, Stanford University, Stanford, California
- Cardiovascular Institute, Stanford University, Stanford, California
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Roberts N, Chandrasekaran U, Das S, Qi Z, Corbett S. Hemolysis associated with Impella heart pump positioning: In vitro hemolysis testing and computational fluid dynamics modeling. Int J Artif Organs 2020; 43:391398820909843. [PMID: 32126866 DOI: 10.1177/0391398820909843] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [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: 01/25/2023]
Abstract
INTRODUCTION Short-term mechanical circulatory support devices provide temporary hemodynamic support in heart failure and are increasingly used to enable recovery or as a bridge to decision. Blood damage with mechanical circulatory support devices is influenced by many factors, including the magnitude and duration of shear stress and obstruction to blood flow. This study aimed to evaluate the effects of the Impella CP® heart pump positioning on hemolysis using in vitro hemolysis testing and computational fluid dynamics modeling. METHODS The in vitro hemolysis testing was conducted per the recommended Food and Drug Administration and American Society for Testing and Materials guidelines. The bench hemolysis testing and computational fluid dynamics simulation analysis were performed for both normal operating (outlet unobstructed) and outlet-obstructed condition of Impella CP (mimicking outlet on the aortic valve due to improper positioning). RESULTS The modified index of hemolysis was 2.78 ± 0.69 at normal operating conditions compared to 18.7 ± 7.8 when the Impella CP outlet was obstructed (p = 0.002). Computational fluid dynamics modeling showed about three times increase in exposure time to regions of high shear stress when the Impella CP outlet was obstructed compared to unobstructed condition, thus supporting the experimental observations. CONCLUSION Based on these results, it is recommended to ensure proper placement of Impella CP via regular monitoring using echocardiographic guidance or other methods to minimize the risk of hemolysis associated with an obstructed outflow.
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Throckmorton AL, Chopski SG, Birewar SN, Joa TS, Huang P, Whitehead KK, Stevens RM, Kresh JY. Vortical flow characteristics of mechanical cavopulmonary assistance: Pre- and post-swirl dynamics. Technol Health Care 2016; 24:627-38. [PMID: 27061388 DOI: 10.3233/thc-161154] [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] [Indexed: 11/15/2022]
Abstract
Surgical optimization of the cavopulmonary connection and pharmacological therapy for dysfunctional Fontan physiology continue to advance, but these treatment approaches only slow the progression of decline to end-stage heart failure. The development of a mechanical cavopulmonary assist device will provide a viable therapeutic option in the bridging of patients to transplant or to stabilization. We hypothesize that rotational blood flow, delivered by an implantable axial flow blood pump, could effectively assist the venous circulation in Fontan patients by mimicking vortical blood flow patterns in the cardiovascular system. This study investigated seven new models of mechanical cavopulmonary assistance (single and dual-pump assist), created combinations of pump designs that deliver counter rotating vortical flow conditions, and analyzed pump performance, velocity streamlines, swirling strength, and energy augmentation in the cavopulmonary circuit for each support scenario. The model having an axial clockwise-oriented impeller in the inferior vena cava and an axial counterclockwise-oriented impeller rotating in the superior vena cava outperformed all of the support scenarios by enhancing the energy of the cavopulmonary circulation an average of 10.3% over the entire flow range and a maximum of 27.4% at %the higher flow rates. This research will guide the development of axial flow blood pumps for Fontan patients and demonstrated the high probability of %a cardiovascular benefit using counter rotating pumps in a dual support scenario, but found that this is dependent upon the patient-specific cavopulmonary anatomy.
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Affiliation(s)
- Amy L Throckmorton
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Steven G Chopski
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Shravani N Birewar
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Terence S Joa
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Pablo Huang
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Kevin K Whitehead
- Pediatric Cardiology, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Randy M Stevens
- St. Christopher's Hospital for Children, Tenet Healthcare Corporation, Philadelphia, PA, USA
| | - J Yasha Kresh
- Departments of Cardiothoracic Surgery and Medicine, College of Medicine, Drexel University, Philadelphia, PA, USA
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