1
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Li Y, Xi Y, Wang H, Sun A, Deng X, Chen Z, Fan Y. The Impact of Rotor Axial Displacement Variation on Simulation Accuracy of Fully Magnetic Levitation Centrifugal Blood Pump. ASAIO J 2024:00002480-990000000-00455. [PMID: 38569187 DOI: 10.1097/mat.0000000000002204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
The rotor axial displacement of the full magnetic levitation blood pump varies with the operating conditions. The effect of rotor axial displacement on simulation results is unclear. This study aimed to evaluate the effect of rotor axial displacement on the predicted blood pump flow field, hydraulic performance, and hemocompatibility through simulation. This study used the CentriMag blood pump as a model, and conducted computational fluid dynamics simulations to assess the impact of rotor displacement. Considering rotor axial displacement leads to opposite results regarding predicted residence time and thrombotic risk compared with not considering rotor axial displacement. Not considering rotor axial displacement leads to deviations in the predicted values, where the effects on the flow field within the blood pump, ratio of secondary flow, and amount of shear stress >150 Pa are significant. The variation in the back clearance of the blood pump caused by the ideal and actual rotor displacements is the main cause of the above phenomena. Given that the rotor axial displacement significantly impacts the simulation accuracy, the effect of rotor axial displacement must be considered in the simulation.
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Affiliation(s)
- Yuan Li
- From the Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
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2
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Antonopoulos M, Bonios MJ, Dimopoulos S, Leontiadis E, Gouziouta A, Kogerakis N, Koliopoulou A, Elaiopoulos D, Vlahodimitris I, Chronaki M, Chamogeorgakis T, Drakos SG, Adamopoulos S. Advanced Heart Failure: Therapeutic Options and Challenges in the Evolving Field of Left Ventricular Assist Devices. J Cardiovasc Dev Dis 2024; 11:61. [PMID: 38392275 PMCID: PMC10888700 DOI: 10.3390/jcdd11020061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/06/2024] [Accepted: 02/09/2024] [Indexed: 02/24/2024] Open
Abstract
Heart Failure is a chronic and progressively deteriorating syndrome that has reached epidemic proportions worldwide. Improved outcomes have been achieved with novel drugs and devices. However, the number of patients refractory to conventional medical therapy is growing. These advanced heart failure patients suffer from severe symptoms and frequent hospitalizations and have a dismal prognosis, with a significant socioeconomic burden in health care systems. Patients in this group may be eligible for advanced heart failure therapies, including heart transplantation and chronic mechanical circulatory support with left ventricular assist devices (LVADs). Heart transplantation remains the treatment of choice for eligible candidates, but the number of transplants worldwide has reached a plateau and is limited by the shortage of donor organs and prolonged wait times. Therefore, LVADs have emerged as an effective and durable form of therapy, and they are currently being used as a bridge to heart transplant, destination lifetime therapy, and cardiac recovery in selected patients. Although this field is evolving rapidly, LVADs are not free of complications, making appropriate patient selection and management by experienced centers imperative for successful therapy. Here, we review current LVAD technology, indications for durable MCS therapy, and strategies for timely referral to advanced heart failure centers before irreversible end-organ abnormalities.
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Affiliation(s)
- Michael Antonopoulos
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
- Cardiac Surgery Intensive Care Unit, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Michael J Bonios
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
- Division of Cardiovascular Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Stavros Dimopoulos
- Cardiac Surgery Intensive Care Unit, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Evangelos Leontiadis
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Aggeliki Gouziouta
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Nektarios Kogerakis
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Antigone Koliopoulou
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
- Division of Cardiovascular Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dimitris Elaiopoulos
- Cardiac Surgery Intensive Care Unit, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Ioannis Vlahodimitris
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Maria Chronaki
- Cardiac Surgery Intensive Care Unit, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Themistocles Chamogeorgakis
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Stavros G Drakos
- Division of Cardiovascular Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Stamatis Adamopoulos
- Heart Failure, Transplant and Mechanical Circulatory Support Units, Onassis Cardiac Surgery Center, 17674 Athens, Greece
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3
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Ray PK, Das AK, Das PK. Numerical assessment of hemodynamic perspectives of a left ventricular assist device and subsequent proposal for improvisation. Comput Biol Med 2022; 151:106309. [PMID: 36410098 DOI: 10.1016/j.compbiomed.2022.106309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 10/16/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022]
Abstract
Due to the unavailability of donors, the use of left ventricular assist devices has emerged to be a reliable line of alternative treatment for heart failure. However, ventricular assist devices (VAD) have been associated with several postoperative complications such as thrombosis, hemolysis, etc. Despite considerable improvements in technology, blood trauma due to high shear stress generation has been a major concern that is largely related to the geometrical feature of the VAD. This study aims to establish the design process of a centrifugal pump by considering several variations in the geometrical feature of a base design using the commercial solver ANSYS-CFX. To capture the uncertain behavior of blood as fluid, Newtonian, as well as non-Newtonian (Bird-Carreau model), models are used for flow field prediction. To assess the possibility of blood damage maximum wall shear stress and hemolysis index have been estimated for each operating point. The results of the simulations yield an optimized design of the pump based on parameters like pressure head generation, maximum shear stress, hydraulic efficiency, and hemolysis index. Further, the design methodology and the steps of development discussed in the paper can serve as a guideline for developing small centrifugal pumps handling blood.
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Affiliation(s)
- Pulak Kumar Ray
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India.
| | - Arup Kumar Das
- Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, India
| | - Prasanta Kumar Das
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India.
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Yan B. Actuators for Implantable Devices: A Broad View. MICROMACHINES 2022; 13:1756. [PMID: 36296109 PMCID: PMC9610948 DOI: 10.3390/mi13101756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/12/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
The choice of actuators dictates how an implantable biomedical device moves. Specifically, the concept of implantable robots consists of the three pillars: actuators, sensors, and powering. Robotic devices that require active motion are driven by a biocompatible actuator. Depending on the actuating mechanism, different types of actuators vary remarkably in strain/stress output, frequency, power consumption, and durability. Most reviews to date focus on specific type of actuating mechanism (electric, photonic, electrothermal, etc.) for biomedical applications. With a rapidly expanding library of novel actuators, however, the granular boundaries between subcategories turns the selection of actuators a laborious task, which can be particularly time-consuming to those unfamiliar with actuation. To offer a broad view, this study (1) showcases the recent advances in various types of actuating technologies that can be potentially implemented in vivo, (2) outlines technical advantages and the limitations of each type, and (3) provides use-specific suggestions on actuator choice for applications such as drug delivery, cardiovascular, and endoscopy implants.
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Affiliation(s)
- Bingxi Yan
- Department of Electrical and Computer Engineering, Ohio State University, Columbus, OH 43210, USA
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Goodman D, Stulak J, Rosenbaum AN. Left ventricular assist devices: A historical perspective at the intersection of medicine and engineering. Artif Organs 2022; 46:2343-2360. [PMID: 35929377 DOI: 10.1111/aor.14371] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/06/2022] [Accepted: 07/18/2022] [Indexed: 11/26/2022]
Abstract
Over the last half-century, left ventricular assist device (LVAD) technology has progressed from conceptual therapy for failed cardiopulmonary bypass weaning to an accepted destination therapy for advanced heart failure. The history of LVAD engineering is defined by an initial development phase, which demonstrated the feasibility of such an approach, to the more recent three major generations of commercial devices. In this review, we explore the engineering challenges of LVADs, how they were addressed over time, and the clinical outcomes that resulted from each major technological development. The first generation of commercial LVADs were pulsatile devices, which lacked the appropriate durability due to their number of moving components and hemocompatibility. The second generation of LVADs was defined by replacement of complex, pulsatile pumps with primarily axial, continuous-flow systems with an impeller in the blood passageway. These devices experienced significant commercial success, but the presence of excessive trauma to the blood and in-situ bearing resulted in an unacceptable burden of adverse events. Third generation centrifugal-flow pumps use magnetically suspended rotors within the pump chamber. Superior outcomes with this newest generation of devices have been observed, particularly with respect to hemocompatibility-related adverse events including pump thrombosis, with fully magnetically levitated devices. The future of LVAD engineering includes wireless charging foregoing percutaneous drivelines and more advanced pump control mechanisms, including synchronization of the pump flow with the native cardiac cycle, and varying pump output based on degree of physical exertion using sensor or advanced device-level data triggers.
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Affiliation(s)
- Daniel Goodman
- College of Osteopathic Medicine, Des Moines University, Des Moines, Iowa, USA
| | - John Stulak
- Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Andrew N Rosenbaum
- Department of Cardiovascular Diseases, Mayo Clinic Minnesota, Rochester, Minnesota, USA
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Malone G, Abdelsayed G, Bligh F, Al Qattan F, Syed S, Varatharajullu P, Msellati A, Mwipatayi D, Azhar M, Malone A, Fatimi SH, Conway C, Hameed A. Advancements in left ventricular assist devices to prevent pump thrombosis and blood coagulopathy. J Anat 2022; 242:29-49. [PMID: 35445389 PMCID: PMC9773170 DOI: 10.1111/joa.13675] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 04/01/2022] [Accepted: 04/06/2022] [Indexed: 12/25/2022] Open
Abstract
Mechanical circulatory support (MCS) devices, such as left ventricular assist devices (LVADs) are very useful in improving outcomes in patients with advanced-stage heart failure. Despite recent advances in LVAD development, pump thrombosis is one of the most severe adverse events caused by LVADs. The contact of blood with artificial materials of LVAD pumps and cannulas triggers the coagulation cascade. Heat spots, for example, produced by mechanical bearings are often subjected to thrombus build-up when low-flow situations impair washout and thus the necessary cooling does not happen. The formation of thrombus in an LVAD may compromise its function, causing a drop in flow and pumping power leading to failure of the LVAD, if left unattended. If a clot becomes dislodged and circulates in the bloodstream, it may disturb the flow or occlude the blood vessels in vital organs and cause internal damage that could be fatal, for example, ischemic stroke. That is why patients with LVADs are on anti-coagulant medication. However, the anti-coagulants can cause a set of issues for the patient-an example of gastrointestinal (GI) bleeding is given in illustration. On account of this, these devices are only used as a last resort in clinical practice. It is, therefore, necessary to develop devices with better mechanics of blood flow, performance and hemocompatibility. This paper discusses the development of LVADs through landmark clinical trials in detail and describes the evolution of device design to reduce the risk of pump thrombosis and achieve better hemocompatibility. Whilst driveline infection, right heart failure and arrhythmias have been recognised as LVAD-related complications, this paper focuses on complications related to pump thrombosis, especially blood coagulopathy in detail and potential strategies to mitigate this complication. Furthermore, it also discusses the LVAD implantation techniques and their anatomical challenges.
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Affiliation(s)
- Grainne Malone
- Tissue Engineering Research Group (TERG)Department of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Gerges Abdelsayed
- School of MedicineRCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Fianait Bligh
- School of MedicineRCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Fatma Al Qattan
- Tissue Engineering Research Group (TERG)Department of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin 2DublinIreland,School of Pharmacy and Biomolecular SciencesRCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Saifullah Syed
- School of MedicineRCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | | | - Augustin Msellati
- School of MedicineRCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Daniela Mwipatayi
- School of MedicineRCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Maimoona Azhar
- Department of SurgerySt. Vincent's University Hospital, Dublin 4DublinIreland
| | - Andrew Malone
- Tissue Engineering Research Group (TERG)Department of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin 2DublinIreland
| | - Saulat H. Fatimi
- Department of Cardiothoracic SurgeryAga Khan University HospitalKarachiPakistan
| | - Claire Conway
- Tissue Engineering Research Group (TERG)Department of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin 2DublinIreland,Trinity Centre for Biomedical Engineering (TCBE)Trinity College Dublin (TCD)DublinIreland
| | - Aamir Hameed
- Tissue Engineering Research Group (TERG)Department of Anatomy and Regenerative Medicine, RCSI University of Medicine and Health Sciences, Dublin 2DublinIreland,Trinity Centre for Biomedical Engineering (TCBE)Trinity College Dublin (TCD)DublinIreland
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Siewnicka A, Fajdek B, Janiszowski K. Extreme membrane position detection and pump output estimation in pulsatile VADs. Biomed Signal Process Control 2022. [DOI: 10.1016/j.bspc.2021.103409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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8
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Sharifi A, Bark D. Flow assessment as a function of pump timing of tubular pulsatile pump for use as a ventricular assist device in a left heart simulator. Artif Organs 2022; 46:1294-1304. [PMID: 35132629 DOI: 10.1111/aor.14196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 11/19/2021] [Accepted: 12/29/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Although mechanical circulatory support saved many lives during the last decade, clinical observations have shown that the continuous flow pumps are associated with a much higher incidence of gastrointestinal bleeding and kidney problems, among others, compared with the earlier generation pulsatile pumps. However, the presence of several moving mechanical components made pulsatile pumps less durable, bulky, and prone to malfunction, ultimately leading to bias in favor of continuous flow designs. OBJECTIVE The aim of the current work is to create a prototype tubular pulsatile pump and to test the timing of the pump in a left heart simulator. METHODS A left heart simulator to mimic pumping from a failing heart was created. This was used to experimentally test the output of a prototype ventricular assist device relative to a failing heart in the form of flow and pressure. The effect of pulsation timing was quantified. RESULTS A failing heart was simulated with an average flow rate of 1.1 L/min and a systolic pressure of 47 mmHg. With the pump, the flow rate increases to 4.8 L/min and a systolic pressure of 110mmHg, in a copulsation mode, while activating for 300-400 ms. If the activation time is reduced, or increased, the pump becomes less effective. Load on the heart is reduced when the pump operates in a counterpulsation mode. CONCLUSION A pulsatile pump, like the one proposed, provides adequate output for mechanical circulatory support, while minimizing the number of moving parts that could otherwise lead to tribological wear.
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Affiliation(s)
- Alireza Sharifi
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
| | - David Bark
- Department of Pediatrics, Division of Hematology and Oncology, Washington University in St. Louis, St. Louis, MO, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
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9
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Plecash AR, Byrne D, Flexman A, Toma M, Field TS. Stroke in Patients with Left Ventricular Assist Devices. Cerebrovasc Dis 2021; 51:3-13. [PMID: 34510039 DOI: 10.1159/000517454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 05/26/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Left ventricular assist devices (LVADs) are artificial pumps used in end-stage heart failure to support the circulatory system. These cardiac assist devices work in parallel to the heart, diverting blood from the left ventricle through an outflow graft and into the ascending aorta. LVADs have allowed patients with end-stage heart failure to live longer and with improved quality of life compared to best medical therapy alone. However, they are associated with significant risks related to both thrombosis and bleeding in this medically complex patient population. As LVADs continue to be used more widely, stroke neurologists need to become familiar with the unique physical exam and vascular imaging findings associated with this population. SUMMARY Reported rates of LVAD-associated stroke at 2 years post-implantation range from 10 to 30%, which is significantly higher than in age-matched controls. There are approximately equal rates of ischemic and hemorrhagic strokes, and rates are highest during the peri-implantation period and in the first year of therapy. Risk factors associated with ischemic and hemorrhagic stroke in this cohort can be grouped into treatment-related factors, including specific devices and antithrombotic/anticoagulation strategy, and patient-related factors. Evidence for reperfusion therapy for acute stroke in this population is limited. Intravenous tissue plasminogen activator (IV-tPA) is often contraindicated as events may occur in the perioperative setting, or in the context of therapeutic anticoagulation. Endovascular therapy with successful recanalization is reported, but there is little experience documented in the published literature. Key messages: LVAD use is increasingly common. Given the high associated risks of stroke, neurologists will need to become increasingly familiar with an approach to assessment and therapy for LVAD patients with cerebrovascular issues.
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Affiliation(s)
- Alyson R Plecash
- Division of Neurology, University of British Columbia, Vancouver, British Columbia, Canada,
| | - Danielle Byrne
- Division of Radiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alana Flexman
- Division of Anesthesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mustafa Toma
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Thalia S Field
- Division of Neurology, University of British Columbia, Vancouver, British Columbia, Canada.,Vancouver Stroke Program, Vancouver Coastal Health, Vancouver, British Columbia, Canada
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10
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Hockstein MA. Continuous-flow left ventricular assist devices: Management in the emergency department. J Am Coll Emerg Physicians Open 2020; 1:362-370. [PMID: 33000058 PMCID: PMC7493560 DOI: 10.1002/emp2.12178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 06/06/2020] [Accepted: 06/10/2020] [Indexed: 11/25/2022] Open
Abstract
With an increasing number of left ventricular assist devices (LVADs) being placed every year, emergency clinicians are increasingly likely to encounter them in their practice. Patients may present to the emergency department (ED) with significant hemodynamic perturbations with an LVAD and it is imperative that emergency clinicians are able to assess and treat conditions contributing to low cardiac output states. This review describes the important aspects of the third generation of LVADs and their complications as well as common management approaches for the emergency physician.
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Affiliation(s)
- Maxwell A. Hockstein
- Department of Emergency Medicine; Department of Anesthesia, Division of Critical CareEmory University School of MedicineAtlantaGeorgiaUSA
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11
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Papanastasiou CA, Kyriakoulis KG, Theochari CA, Kokkinidis DG, Karamitsos TD, Palaiodimos L. Comprehensive review of hemolysis in ventricular assist devices. World J Cardiol 2020; 12:334-341. [PMID: 32843935 PMCID: PMC7415236 DOI: 10.4330/wjc.v12.i7.334] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 05/02/2020] [Accepted: 05/27/2020] [Indexed: 02/07/2023] Open
Abstract
Ventricular assist devices (VADs) have played an important role in altering the natural history of end-stage heart failure. Low-grade hemolysis has been traditionally described in patients with VADs, indicating effective device functionality. However, clinically significant hemolysis could be crucial in terms of prognosis, calling for prompt therapeutic actions. The absence of solid and widely approved diagnostic criteria for clinically significant hemolysis, render the utilization of hemolysis laboratory markers challenging. Hemolysis incidence varies (5%-18%) depending on definition and among different VAD generations, being slightly higher in continuous-flow devices than in pulsatile devices. Increased shear stress of red blood cells and underlying device thrombosis appear to be the main pathogenetic pathways. No certain algorithm is available for the management of hemolysis in patients with VADs, while close clinical and laboratory monitoring remains the cornerstone of management. Imaging examinations such as echocardiography ramp test or computed tomography scan could play a role in revealing the underlying cause. Treatment should be strictly personalized, including either pharmacological (antithrombotic treatment) or surgical interventions.
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Affiliation(s)
- Christos A Papanastasiou
- 1st Department of Cardiology, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki 54621, Greece
| | - Konstantinos G Kyriakoulis
- 3rd Department of Medicine, Sotiria Hospital, National and Kapodistrian University of Athens, Athens 11527, Greece
| | | | - Damianos G Kokkinidis
- Department of Medicine, Jacobi Medical Center, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Theodoros D Karamitsos
- 1st Department of Cardiology, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki 54621, Greece
| | - Leonidas Palaiodimos
- Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY 10461, United States
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12
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Zhang J, Chen Z, Griffith BP, Wu ZJ. Computational characterization of flow and blood damage potential of the new maglev CH-VAD pump versus the HVAD and HeartMate II pumps. Int J Artif Organs 2020; 43:653-662. [PMID: 32043405 DOI: 10.1177/0391398820903734] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Left ventricular assist devices are routinely used to treat patients with advanced heart failure as a bridge to transplant or a destination therapy. However, non-physiological shear stress generated by left ventricular assist devices damages blood cells. The continued development of novel left ventricular assist devices is essential to improve the left ventricular assist device therapy for heart failure patients. The CH-VAD is a new maglev centrifugal left ventricular assist device. In this study, the CH-VAD pump was numerically analyzed and compared with the HVAD and HeartMate II pumps under two clinically relevant conditions (flow: 4.5 L/min, pressure head: normal ~80 and hypertension ~120 mmHg). The velocity and shear stress fields, washout, and hemolysis index of the three pumps were assessed with computational fluid dynamics analysis. Under the same condition, the CH-VAD hemolysis index was two times lower than the HVAD and HeartMate II pumps; the CH-VAD had the least percentage volume with shear stress larger than 100 Pa (i.e. normal condition: 0.4% vs HVAD 1.0%, and HeartMate II 2.9%). Under the normal condition, more than 98% was washed out of the three pumps within 0.4 s. The washout times were slightly shorter under the hypertension condition for the three pumps. No regions inside the CH-VAD or HVAD had extremely long residential time, while areas near the straightener of the HeartMate II pump had long residential time (>4 s) indicating elevated risks of thrombosis. The computational fluid dynamics results suggested that the CH-VAD pump has a better hemolytic biocompatibility than the HVAD and HeartMate II pumps under the normal and hypertension conditions.
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Affiliation(s)
- Jiafeng Zhang
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zengsheng Chen
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bartley P Griffith
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zhongjun J Wu
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD, USA
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13
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Filgueira CS, Igo SR, Wang DK, Hirsch M, Schulz DG, Bruckner BA, Grattoni A. Technologies for intrapericardial delivery of therapeutics and cells. Adv Drug Deliv Rev 2019; 151-152:222-232. [PMID: 30797957 DOI: 10.1016/j.addr.2019.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 12/12/2022]
Abstract
The pericardium, which surrounds the heart, provides a unique enclosed volume and a site for the delivery of agents to the heart and coronary arteries. While strategies for targeting the delivery of therapeutics to the heart are lacking, various technologies and nanodelivery approaches are emerging as promising methods for site specific delivery to increase therapeutic myocardial retention, efficacy, and bioactivity, while decreasing undesired systemic effects. Here, we provide a literature review of various approaches for intrapericardial delivery of agents. Emphasis is given to sustained delivery approaches (pumps and catheters) and localized release (patches, drug eluting stents, and support devices and meshes). Further, minimally invasive access techniques, pericardial access devices, pericardial washout and fluid analysis, as well as therapeutic and cell delivery vehicles are presented. Finally, several promising new therapeutic targets to treat heart diseases are highlighted.
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14
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Lazoglu I, Kucukaksu DS, Ozturk C, Aka IB, Bakuy V, Arat N, Yalcin O, Ugurel E, Celikbilek Erkasap P, Aksoy E, Ruacan S. A Short-Term In Vivo Evaluation of the Istanbul Heart Left Ventricular Assist Device in a Pig Model. EXP CLIN TRANSPLANT 2019. [PMID: 31580231 DOI: 10.6002/ect.2019.0110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVES A continuous-flow centrifugal blood pump system has been recently developed as an implantable left ventricular assist device for patients with endstage heart failure. The objective of this study was to evaluate the initial in vivo performance of a newly developed left ventricular assist device (iHeart or Istanbul heart; Manufacturing and Automation Research Center, Koc University, Istanbul, Turkey) in an acute setting using a pig model. MATERIALS AND METHODS Three pigs (77, 83, 92 kg) received implants via a median sternotomy, with animals supported for up to 6 hours. An outflow cannula was anastomosed to the ascending aorta. Anticoagulation was applied by intravenous heparin administration. During the support period, pump performance was evaluated under several flow and operating conditions. All pigs were humanely sacrificied after the experiments, and organs were examined macroscopically and histopathologically. RESULTS Flow rate ranged between 1.5 and 3.6 L/min with pump speeds of 1500 to 2800 revolutions/min and motor current of 0.6 to 1.3 A. Initial findings confirmed thatthe iHeart ventricular assist device had sufficient hydraulic performance to support the circulation. During the experimental period, plasma free hemoglobin levels were found to be within normalranges.Thrombus formation was not observed inside the pump in all experiments. CONCLUSIONS The iHeart ventricular assist device demonstrated encouraging hemodynamic performance and good biocompatibility in the pig model for use as an implantable left ventricular assist device. Further acute in vivo studies will evaluate the short-term pump performance prior to chronic studies for long-term evaluation.
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Affiliation(s)
- Ismail Lazoglu
- From the Manufacturing and Automation Research Center, College of Engineering, Koc University, Istanbul, Turkey
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15
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Ventricular Assist Device Self-Management Issues: The Patient and Caregiver Perspectives. ASAIO J 2019; 64:e148-e150. [PMID: 29251632 DOI: 10.1097/mat.0000000000000733] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Despite technological advancements, ventricular assist device (VAD) self-management (SM) remains complex. Using a descriptive mixed-method research, we examined the VAD care issues reported by nondyadic sample of 102 patients and 116 caregivers in the United States. Participants (mean age, 50.0 ± 13.1 years) were predominantly white (80%), female (59%), and married (77%). Quantitative and qualitative data revealed the patients/caregivers' need for competency assessment and reassessment of VAD care after discharge. Competent home-care registered nurses (RNs) and on-going communications with VAD care team are needed in support for VAD SM.
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16
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Ready, Set, Go: How Patients and Caregivers Are Prepared for Self-Management of an Implantable Ventricular Assist Device. ASAIO J 2019; 64:e151-e155. [PMID: 29608491 DOI: 10.1097/mat.0000000000000778] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Since the first use of an implantable ventricular assist device (VAD) nearly 3 decades ago, many VAD Centers in the United States expect patients and caregivers to manage the device and related care following hospital discharge. Despite this customary practice and the rapid advancements in VAD technology, no research data about the patient and caregiver preparations exist for self-management of VAD. This study explored the process of preparing patients and caregivers for VAD care before hospital discharge along with their perceived experiences of the discharge process. Using an exploratory research design, we collected the data with self-administered demographics and VAD Hospital Discharge Survey questionnaires. We analyzed the data provided by 102 patients and 116 caregivers from different regions in the United States. Patients' mean age was 51.4 ± 13.8 years; they were predominantly White (78%); male (66%); and duration of device between 2 and 74 months. Caregivers were predominantly White (80%); female (81%); and had a mean of age 48.9 ± 12.7 years. Participants reported that their VAD care preparations, a crucial component of hospital discharge, were extensive and intensive processes comprising education, training, competency validation, and provision of resources for VAD self-management in home settings. Participants were satisfied with the process and felt prepared for discharge. Further research is needed to rectify the study limitations, advance the science of VAD self-management, and develop evidenced-based VAD self-management guidelines that are aimed at optimizing longevity of the VAD, patients' health, and quality of life.
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17
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Severin R, Sabbahi A, Ozemek C, Phillips S, Arena R. Approaches to improving exercise capacity in patients with left ventricular assist devices: an area requiring further investigation. Expert Rev Med Devices 2019; 16:787-798. [PMID: 31453716 DOI: 10.1080/17434440.2019.1660643] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Introduction: Left ventricular assist device (LVAD) implantation has become a well-established treatment option for patients with end stage heart failure (HF) who are refractory to medical therapy. While LVADs implantation does effectively improve hemodynamic performance many patients still possess peripheral pathological adaptations often present in end-stage HF. Therefore, increased attention has been placed on investigating the effects of exercise training for patients with LVADs to improve clinical outcomes. However, the available evidence on exercise training for patients with LVADs is limited. Areas covered: The purpose of this narrative review is to summarize: 1) The evolution of LVAD technology and usage; 2) The physiological responses to exercise in patients with LVADs; 3) The available evidence regarding exercise training; 4) Potential strategies to implement exercise training programs for this patient population. Expert opinion: The available evidence for exercise training to improve physical function and clinical outcomes for patients with LVADs is promising but limited. Future research is needed to further elucidate the ideal exercise training parameters, method of delivery for exercise training, and unique barriers and facilitators to exercise training for patients receiving LVAD implantation.
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Affiliation(s)
- Richard Severin
- Department of Physical Therapy, University of Illinois , Chicago , IL , USA
| | - Ahmad Sabbahi
- Department of Physical Therapy, University of Illinois , Chicago , IL , USA
| | - Cemal Ozemek
- Department of Physical Therapy, University of Illinois , Chicago , IL , USA
| | - Shane Phillips
- Department of Physical Therapy, University of Illinois , Chicago , IL , USA
| | - Ross Arena
- Department of Physical Therapy, University of Illinois , Chicago , IL , USA
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18
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Mathew RP, Alexander T, Patel V, Low G. Chest radiographs of cardiac devices (Part 2): Ventricular assist devices. SA J Radiol 2019; 23:1732. [PMID: 31754537 PMCID: PMC6837777 DOI: 10.4102/sajr.v23i1.1732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 05/05/2019] [Indexed: 11/30/2022] Open
Abstract
Heart failure is considered a worldwide pandemic affecting 26 million people globally. Patients who are unfit or waiting for cardiac transplantation may benefit from alternate mechanical support therapies using ventricular assist devices. It is not uncommon for radiologists, especially those working in institutions with a high volume of cardiac transplantations, to be presented with radiographs containing these devices. The role of the radiologist is not only to accurately identify these devices, but also to evaluate for any complications.
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Affiliation(s)
- Rishi P Mathew
- Department of Radiology and Diagnostic Imaging, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Timothy Alexander
- Department of Radiology and Diagnostic Imaging, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Vimal Patel
- Department of Radiology and Diagnostic Imaging, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Gavin Low
- Department of Radiology and Diagnostic Imaging, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
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19
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Han J, Trumble DR. Cardiac Assist Devices: Early Concepts, Current Technologies, and Future Innovations. Bioengineering (Basel) 2019; 6:bioengineering6010018. [PMID: 30781387 PMCID: PMC6466092 DOI: 10.3390/bioengineering6010018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/21/2019] [Accepted: 02/02/2019] [Indexed: 01/31/2023] Open
Abstract
Congestive heart failure (CHF) is a debilitating condition that afflicts tens of millions of people worldwide and is responsible for more deaths each year than all cancers combined. Because donor hearts for transplantation are in short supply, a safe and durable means of mechanical circulatory support could extend the lives and reduce the suffering of millions. But while the profusion of blood pumps available to clinicians in 2019 tend to work extremely well in the short term (hours to weeks/months), every long-term cardiac assist device on the market today is limited by the same two problems: infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. A fundamental change in device design is needed to address both these problems and ultimately make a device that can support the heart indefinitely. Toward that end, several groups are currently developing devices without blood-contacting surfaces and/or extracorporeal power sources with the aim of providing a safe, tether-free means to support the failing heart over extended periods of time.
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Affiliation(s)
- Jooli Han
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Dennis R Trumble
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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20
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Siewnicka A, Janiszowski K. A model for estimating the blood flow of the POLVAD pulsatile ventricular assist device. IEEE Trans Biomed Eng 2018; 65:2552-2559. [PMID: 29993492 DOI: 10.1109/tbme.2018.2807879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The aim of this work was to model the blood flow rate of the POLVAD-MEV pulsatile ventricular assist device (VAD). An adequate flow rate is crucial to restore physiological cardiac output. Unfortunately, during clinical heart support, neither blood flows nor pressures can be measured within the device. In general, the flow rate depends on the control parameters and patient conditions. However, the patient's hemodynamic parameters are not constantly monitored. Therefore, blood flow must be evaluated based on the standard measurements from the device control unit. METHODS The model identification data were taken from a research stand consisting of a VAD connected to a hybrid cardiovascular simulator. The studies were conducted under different work and control conditions. A compound model of a ventricular assist device was proposed. First, the driving pressure waveform for an idle run of the supply unit is modeled. Next, the blood flow is estimated based on the difference between the measured value of driving pressure and the modeled value for an idle run. RESULTS The quality of the developed model is good (R=0.92) and similar for all tested cases, confirming the high versatility of the proposed solution. CONCLUSION The blood flow rate is estimated based on standard signals from the device control unit; therefore, no additional measurements are necessary. SIGNIFICANCE The developed model application in the VAD control unit will aid the selection of control parameters and might be useful for development of adaptive control system. A preliminary version of this work was reported at the [1].
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21
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Roche ET, Horvath MA, Wamala I, Alazmani A, Song SE, Whyte W, Machaidze Z, Payne CJ, Weaver JC, Fishbein G, Kuebler J, Vasilyev NV, Mooney DJ, Pigula FA, Walsh CJ. Soft robotic sleeve supports heart function. Sci Transl Med 2018; 9:9/373/eaaf3925. [PMID: 28100834 DOI: 10.1126/scitranslmed.aaf3925] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 12/23/2016] [Indexed: 12/19/2022]
Abstract
There is much interest in form-fitting, low-modulus, implantable devices or soft robots that can mimic or assist in complex biological functions such as the contraction of heart muscle. We present a soft robotic sleeve that is implanted around the heart and actively compresses and twists to act as a cardiac ventricular assist device. The sleeve does not contact blood, obviating the need for anticoagulation therapy or blood thinners, and reduces complications with current ventricular assist devices, such as clotting and infection. Our approach used a biologically inspired design to orient individual contracting elements or actuators in a layered helical and circumferential fashion, mimicking the orientation of the outer two muscle layers of the mammalian heart. The resulting implantable soft robot mimicked the form and function of the native heart, with a stiffness value of the same order of magnitude as that of the heart tissue. We demonstrated feasibility of this soft sleeve device for supporting heart function in a porcine model of acute heart failure. The soft robotic sleeve can be customized to patient-specific needs and may have the potential to act as a bridge to transplant for patients with heart failure.
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Affiliation(s)
- Ellen T Roche
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Discipline of Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Markus A Horvath
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Technische Universität München, Boltzmannstraße 15, 85748 Garching, Germany
| | - Isaac Wamala
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Ali Alazmani
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.,School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, U.K
| | - Sang-Eun Song
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - William Whyte
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Advanced Materials and Bioengineering Research Centre, Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, Ireland
| | - Zurab Machaidze
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Christopher J Payne
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA
| | - James C Weaver
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA
| | - Gregory Fishbein
- Department of Anatomic and Clinical Pathology, Ronald Reagan UCLA (University of California, Los Angeles) Medical Center, Los Angeles, CA 90095, USA
| | - Joseph Kuebler
- Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Nikolay V Vasilyev
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - David J Mooney
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA
| | - Frank A Pigula
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA. .,Cardiovascular Surgery, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Conor J Walsh
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA. .,Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA
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22
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Left Ventricular Assist Devices - A State of the Art Review. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 29532330 DOI: 10.1007/5584_2018_145] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Cardiovascular diseases are the leading cause of mortality rates throughout the world. Next to an insufficient number of healthy donors, this has led to increasing numbers of patients on heart transplant waiting lists with prolonged waiting times. Innovative technological advancements have led to the production of ventricular assist devices that play an increasingly important role in end stage heart failure therapy. This review is intended to provide an overview of current implantable left ventricular assist devices, different design concepts and implantation techniques. Challenges such as infections and thromboembolic events that may occur during LVAD implantations have also been discussed.
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23
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Payne CJ, Wamala I, Bautista-Salinas D, Saeed M, Van Story D, Thalhofer T, Horvath MA, Abah C, Del Nido PJ, Walsh CJ, Vasilyev NV. Soft robotic ventricular assist device with septal bracing for therapy of heart failure. Sci Robot 2017; 2:2/12/eaan6736. [PMID: 33157903 DOI: 10.1126/scirobotics.aan6736] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 10/30/2017] [Indexed: 01/25/2023]
Abstract
Previous soft robotic ventricular assist devices have generally targeted biventricular heart failure and have not engaged the interventricular septum that plays a critical role in blood ejection from the ventricle. We propose implantable soft robotic devices to augment cardiac function in isolated left or right heart failure by applying rhythmic loading to either ventricle. Our devices anchor to the interventricular septum and apply forces to the free wall of the ventricle to cause approximation of the septum and free wall in systole and assist with recoil in diastole. Physiological sensing of the native hemodynamics enables organ-in-the-loop control of these robotic implants for fully autonomous augmentation of heart function. The devices are implanted on the beating heart under echocardiography guidance. We demonstrate the concept on both the right and the left ventricles through in vivo studies in a porcine model. Different heart failure models were used to demonstrate device function across a spectrum of hemodynamic conditions associated with right and left heart failure. These acute in vivo studies demonstrate recovery of blood flow and pressure from the baseline heart failure conditions. Significant reductions in diastolic ventricle pressure were also observed, demonstrating improved filling of the ventricles during diastole, which enables sustainable cardiac output.
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Affiliation(s)
- Christopher J Payne
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA
| | - Isaac Wamala
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.,Department of Cardiovascular Surgery, Deutsches Herzzentrum Berlin, Berlin, Germany
| | - Daniel Bautista-Salinas
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Mossab Saeed
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - David Van Story
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Thomas Thalhofer
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Department of Mechanical Engineering, Technical University of Munich, Munich, Germany
| | - Markus A Horvath
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.,Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Colette Abah
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA.,Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA
| | - Pedro J Del Nido
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Conor J Walsh
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Longwood, Boston, MA 02115, USA. .,Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA
| | - Nikolay V Vasilyev
- Department of Cardiac Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
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24
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Csepe TA, Kilic A. Advancements in mechanical circulatory support for patients in acute and chronic heart failure. J Thorac Dis 2017; 9:4070-4083. [PMID: 29268418 DOI: 10.21037/jtd.2017.09.89] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cardiogenic shock (CS) continues to have high mortality and morbidity despite advances in pharmacological, mechanical, and reperfusion approaches to treatment. When CS is refractory to medical therapy, percutaneous mechanical circulatory support (MCS) should be considered. Acute MCS devices, ranging from intra-aortic balloon pumps (IABPs) to percutaneous temporary ventricular assist devices (VAD) to extracorporeal membrane oxygenation (ECMO), can aid, restore, or maintain appropriate tissue perfusion before the development of irreversible end-organ damage. Technology has improved patient survival to recovery from CS, but in patients whom cardiac recovery does not occur, acute MCS can be effectively utilized as a bridge to long-term MCS devices and/or heart transplantation. Heart transplantation has been limited by donor heart availability, leading to a greater role of left ventricular assist device (LVAD) support. In patients with biventricular failure that are ineligible for LVAD implantation, further advancements in the total artificial heart (TAH) may allow for improved survival compared to medical therapy alone. In this review, we discuss the current state of acute and durable MCS, ongoing advances in LVADs and TAH devices, improved methods of durable MCS implantation and patient selection, and future MCS developments in this dynamic field that may allow for optimization of HF treatment.
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Affiliation(s)
- Thomas A Csepe
- Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ahmet Kilic
- Division of Cardiac Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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25
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Closed-loop helium circulation system for actuation of a continuously operating heart catheter pump. Int J Artif Organs 2017; 40:272-281. [PMID: 28574110 DOI: 10.5301/ijao.5000593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Currently available, pneumatic-based medical devices are operated using closed-loop pulsatile or open continuous systems. Medical devices utilizing gases with a low atomic number in a continuous closed loop stream have not been documented to date. This work presents the construction of a portable helium circulation addressing the need for actuating a novel, pneumatically operated catheter pump. The design of its control system puts emphasis on the performance, safety and low running cost of the catheter pump. METHODS AND RESULTS Static and dynamic characteristics of individual elements in the circulation are analyzed to ensure a proper operation of the system. The pneumatic circulation maximizes the working range of the drive unit inside the catheter pump while reducing the total size and noise production.Separate flow and pressure controllers position the turbine's working point into the stable region of the pressure creation element. A subsystem for rapid gas evacuation significantly decreases the duration of helium removal after a leak, reaching subatmospheric pressure in the intracorporeal catheter within several milliseconds. CONCLUSIONS The system presented in the study offers an easy control of helium mass flow while ensuring stable behavior of its internal components.
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26
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Payne CJ, Wamala I, Abah C, Thalhofer T, Saeed M, Bautista-Salinas D, Horvath MA, Vasilyev NV, Roche ET, Pigula FA, Walsh CJ. An Implantable Extracardiac Soft Robotic Device for the Failing Heart: Mechanical Coupling and Synchronization. Soft Robot 2017; 4:241-250. [PMID: 29182083 DOI: 10.1089/soro.2016.0076] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Soft robotic devices have significant potential for medical device applications that warrant safe synergistic interaction with humans. This article describes the optimization of an implantable soft robotic system for heart failure whereby soft actuators wrapped around the ventricles are programmed to contract and relax in synchrony with the beating heart. Elastic elements integrated into the soft actuators provide recoiling function so as to aid refilling during the diastolic phase of the cardiac cycle. Improved synchronization with the biological system is achieved by incorporating the native ventricular pressure into the control system to trigger assistance and synchronize the device with the heart. A three-state electro-pneumatic valve configuration allows the actuators to contract at different rates to vary contraction patterns. An in vivo study was performed to test three hypotheses relating to mechanical coupling and temporal synchronization of the actuators and heart. First, that adhesion of the actuators to the ventricles improves cardiac output. Second, that there is a contraction-relaxation ratio of the actuators which generates optimal cardiac output. Third, that the rate of actuator contraction is a factor in cardiac output.
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Affiliation(s)
- Christopher J Payne
- 1 John A. Paulson Harvard School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts
- 2 Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts
| | - Isaac Wamala
- 3 Boston Children's Hospital , Harvard Medical School, Boston, Massachusetts
| | - Colette Abah
- 1 John A. Paulson Harvard School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts
- 2 Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts
| | - Thomas Thalhofer
- 1 John A. Paulson Harvard School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts
- 2 Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts
- 4 Department of Mechanical Engineering, Technical University of Munich , Munich, Germany
| | - Mossab Saeed
- 3 Boston Children's Hospital , Harvard Medical School, Boston, Massachusetts
| | | | - Markus A Horvath
- 1 John A. Paulson Harvard School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts
- 2 Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts
- 5 Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology , Cambridge, Massachusetts
| | - Nikolay V Vasilyev
- 3 Boston Children's Hospital , Harvard Medical School, Boston, Massachusetts
| | - Ellen T Roche
- 1 John A. Paulson Harvard School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts
- 2 Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts
- 6 Discipline of Biomedical Engineering, College of Engineering and Informatics, National University of Ireland , Galway, Ireland
| | - Frank A Pigula
- 3 Boston Children's Hospital , Harvard Medical School, Boston, Massachusetts
- 7 Department of Cardiovascular and Thoracic Surgery, University of Louisville School of Medicine , Louisville, Kentucky
| | - Conor J Walsh
- 1 John A. Paulson Harvard School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts
- 2 Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts
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27
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Barg FK, Kellom K, Ziv T, Hull SC, Suhail-Sindhu S, Kirkpatrick JN. LVAD-DT: Culture of Rescue and Liminal Experience in the Treatment of Heart Failure. THE AMERICAN JOURNAL OF BIOETHICS : AJOB 2017; 17:3-11. [PMID: 28112612 DOI: 10.1080/15265161.2016.1265162] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The purpose of this article is to investigate how cultural meanings associated with the left ventricular assist device (LVAD) inform acceptance and experience of this innovative technology when it is used as a destination therapy. We conducted open-ended, semistructured interviews with family caregivers and patients who had undergone LVAD-DT procedures at six U.S. hospitals. A grounded theory approach was used for the analysis. Thirty-nine patients and 42 caregivers participated. Participants described a sense of obligation to undergo the procedure because of its promise for salvation. However, once the device was implanted, patients described being placed into a liminal state of being neither sick nor healthy, with no culturally scripted role. Consideration of end-of-life decisions was complicated by the uncertainties about how patients with LVADs die. Pre-implantation communications among patient, family, and clinicians should take into account the impact of the technology on meaning, identity, and patient experience.
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Affiliation(s)
- Frances K Barg
- a Perelman School of Medicine at the University of Pennsylvania
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Amezcua R, Shirolkar A, Fraze C, Stout DA. Nanomaterials for Cardiac Myocyte Tissue Engineering. NANOMATERIALS (BASEL, SWITZERLAND) 2016; 6:E133. [PMID: 28335261 PMCID: PMC5224604 DOI: 10.3390/nano6070133] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 01/31/2023]
Abstract
Since their synthesizing introduction to the research community, nanomaterials have infiltrated almost every corner of science and engineering. Over the last decade, one such field has begun to look at using nanomaterials for beneficial applications in tissue engineering, specifically, cardiac tissue engineering. During a myocardial infarction, part of the cardiac muscle, or myocardium, is deprived of blood. Therefore, the lack of oxygen destroys cardiomyocytes, leaving dead tissue and possibly resulting in the development of arrhythmia, ventricular remodeling, and eventual heart failure. Scarred cardiac muscle results in heart failure for millions of heart attack survivors worldwide. Modern cardiac tissue engineering research has developed nanomaterial applications to combat heart failure, preserve normal heart tissue, and grow healthy myocardium around the infarcted area. This review will discuss the recent progress of nanomaterials for cardiovascular tissue engineering applications through three main nanomaterial approaches: scaffold designs, patches, and injectable materials.
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Affiliation(s)
- Rodolfo Amezcua
- Department of Mechanical and Aerospace Engineering, California State University, Long Beach, Long Beach, CA 90840, USA.
| | - Ajay Shirolkar
- Department of Mechanical and Aerospace Engineering, California State University, Long Beach, Long Beach, CA 90840, USA.
| | - Carolyn Fraze
- Deparment of Mechanical Engineering, Brigham Young University-Idaho, Rexburg, ID 83460, USA.
| | - David A Stout
- Department of Mechanical and Aerospace Engineering, California State University, Long Beach, Long Beach, CA 90840, USA.
- Department of Biomedical Engineering, California State University, Long Beach, Long Beach, CA 90840, USA.
- International Research Center for Translational Orthopaedics, Soochow University, Suzhou 215006, China.
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Abu Saleh WK, Al Jabbari O, Bruckner BA, Suarez EE, Estep JD, Loebe M. Left Ventricular Assist Device Implantation After Intracardiac Parachute Device Removal. Ann Thorac Surg 2015; 100:720-2. [PMID: 26234850 DOI: 10.1016/j.athoracsur.2014.10.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 09/22/2014] [Accepted: 10/03/2014] [Indexed: 11/28/2022]
Abstract
Left ventricular assist device implantation is a proven and efficient modality for the treatment of end-stage heart failure. Left ventricular assist device versatility as a bridge to heart transplantation or destination therapy has led to improved patient outcomes with a concomitant rise in its overall use. Other less invasive treatment modalities are being developed to improve heart function and morbidity and mortality for the heart failure population. Percutaneous ventricular restoration is a new investigational therapy that deploys an intracardiac parachute to wall off damaged myocardium in patients with dilated left ventricles and ischemic heart failure. Clinical trials are under way to test the efficacy of percutaneous ventricular restoration using the parachute device. This review describes our encounter with the parachute device, its explantation due to refractory heart failure, and surgical replacement with a left ventricular assist device.
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Affiliation(s)
- Walid K Abu Saleh
- Houston Methodist DeBakey Heart and Vascular Center, Department of Cardiovascular Surgery, Houston Methodist Hospital, Houston, Texas.
| | - Odeaa Al Jabbari
- Houston Methodist DeBakey Heart and Vascular Center, Department of Cardiovascular Surgery, Houston Methodist Hospital, Houston, Texas
| | - Brian A Bruckner
- Houston Methodist DeBakey Heart and Vascular Center, Department of Cardiovascular Surgery, Houston Methodist Hospital, Houston, Texas
| | - Erik E Suarez
- Houston Methodist DeBakey Heart and Vascular Center, Department of Cardiovascular Surgery, Houston Methodist Hospital, Houston, Texas
| | - Jerry D Estep
- Houston Methodist DeBakey Heart and Vascular Center, Department of Cardiovascular Surgery, Houston Methodist Hospital, Houston, Texas
| | - Matthias Loebe
- Houston Methodist DeBakey Heart and Vascular Center, Department of Cardiovascular Surgery, Houston Methodist Hospital, Houston, Texas
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Abstract
The left ventricular assist device (LVAD) has become an established treatment option for patients with refractory heart failure. Many of these patients experience chronic kidney disease (CKD) due to chronic cardiorenal syndrome type II, which is often alleviated quickly following LVAD implantation. Nevertheless, reversibility of CKD remains difficult to predict. Interestingly, initial recovery of GFR appears to be transient, being followed by gradual but significant late decline. Nevertheless, GFR often remains elevated compared to preimplant status. Larger GFR increases are followed by a proportionally larger late decline. Several explanations for this gradual decline in renal function after LVAD therapy have been proposed, yet a definitive answer remains elusive. Mortality predictors of LVAD implantation are the occurrence of either postimplantation acute kidney injury (AKI) or preimplant CKD. However, patient outcomes continue to improve as LVAD therapy becomes more widespread, and adverse events including AKI appear to decline. In light of a growing destination therapy population, it is important to understand the cumulative effects of long-term LVAD support on kidney function. Additional research and passage of time are required to further unravel the intricate relationships between the LVAD and the kidney.
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Affiliation(s)
- T R Tromp
- University Medical Center Utrecht, POB 85500, 3508 GA, Utrecht, The Netherlands,
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31
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QRS complex fragmentation and survival following left ventricular assist device implantation. IJC HEART & VASCULATURE 2015; 7:165-169. [PMID: 28785668 PMCID: PMC5497182 DOI: 10.1016/j.ijcha.2014.10.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 09/15/2014] [Accepted: 10/26/2014] [Indexed: 11/21/2022]
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Petukhov DS, Selishchev SV, Telyshev DV. Development of Left Ventricular Assist Devices as the Most Effective Acute Heart Failure Therapy. BIOMEDICAL ENGINEERING-MEDITSINSKAYA TEKNIKA 2015. [DOI: 10.1007/s10527-015-9480-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Mulukutla V, Franklin WJ, Villa CR, Morales DLS. Surgical device therapy for heart failure in the adult with congenital heart disease. Heart Fail Clin 2014; 10:197-206. [PMID: 24275304 DOI: 10.1016/j.hfc.2013.09.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Individuals with adult congenital heart disease (ACHD) are at a great risk for heart failure, and the underlying anatomic features are important predictors of heart failure. As the ACHD population grows older, multiple events, including years of an altered physiology, the neurohormonal cascade, and many still unknown, culminate in ventricular failure. Surgical device therapy is an effective method in supporting patients with heart failure. Ventricular assist devices have been used with success in bridging ACHD patients to heart transplantation or destination therapy.
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Affiliation(s)
- Venkatachalam Mulukutla
- Texas Children's Hospital, Pediatric Cardiology, 6621 Fannin Street, Houston, TX 77030, USA.
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Strecker T, Rösch J, Weyand M, Agaimy A. Pathological findings in cardiac apex removed during implantation of left ventricular assist devices (LVAD) are non-specific: 13-year-experience at a German Heart Center. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2014; 7:5549-5556. [PMID: 25337196 PMCID: PMC4203167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/21/2014] [Indexed: 06/04/2023]
Abstract
BACKGROUND AND AIM Ventricular assist devices (VAD) have become an established therapy for patients with end-stage heart failure. The two main reasons for this development are the shortage of appropriate donor organs and the increasing number of patients waiting for heart transplantation (HTX). Furthermore, the enormous advances in the technical equipment and the rising clinical experience have improved the implantation technique, the durability and the long-term patient outcomes. METHODS We reviewed all cases of left ventricular assist device (LVAD) implantation at our Erlangen Heart Center during January 2000-July 2013. The main aim of this study was to analyze the underlying pathology from the cardiac apex removed during the implantation. From all patients, we created a follow-up, analyzed the pathological features with the clinical diagnoses and described the overall outcome. RESULTS VAD implantation was performed in 266 cases at our center in the last 13 years (2.2% of the total of 12254 cardiac surgical operations in that period). From these patients, 223 underwent LVAD or biventricular (BVAD) implantation; the remaining received a right (RVAD) implantation. The most frequent underlying clinical diagnoses were dilated (n = 84, 37.7%, DCM) or ischemic (n = 61, 27.4%, ICM) cardiomyopathy. The pathological findings in the apex biopsy were generally non-specific and showed variable interstitial myocardial fibrosis with evidence of fibre loss, fatty degeneration and variable irregular atrophy of muscle fibres, consistent with dilated and ischemic cardiomyopathies as the most frequent causes of heart failure in these patients. Only a few cases showed other specific features such as myocarditis and AL-amyloidosis. CONCLUSIONS Pathological findings in cardiac apex removed during LVAD implantation are rather non-specific and they generally reflect the late stage or consequences of chronic myocardial damage in cases of dilated or ischemic cardiomyopathies. Variable patchy chronic inflammatory changes may be observed in cardiomyopathies as a non-specific reaction caused by myocardial fiber damage and should not lead to misinterpretation as evidence of myocarditis or revision of original diagnosis.
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Affiliation(s)
- Thomas Strecker
- Center of Cardiac Surgery, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Johannes Rösch
- Center of Cardiac Surgery, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Michael Weyand
- Center of Cardiac Surgery, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Abbas Agaimy
- Institute of Pathology, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
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Miller JR, Lawrance CP, Silvestry SC. Current Options and Practices in Long-Term Ventricular Assist Devices. CURRENT SURGERY REPORTS 2014. [DOI: 10.1007/s40137-014-0053-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Todaro MC, Khandheria BK, Paterick TE, Umland MM, Thohan V. The Practical Role of Echocardiography in Selection, Implantation, and Management of Patients Requiring LVAD Therapy. Curr Cardiol Rep 2014; 16:468. [DOI: 10.1007/s11886-014-0468-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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THOMAS ISACC, CORK DAVIDP, LEVY ANDREW, NAYAK HEMAL, BESHAI JOHNF, BURKE MARTINC, MOSS JOSHUAD. ICD Lead Parameters, Performance, and Adverse Events following Continuous-Flow LVAD Implantation. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2013; 37:464-72. [DOI: 10.1111/pace.12290] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Revised: 07/29/2013] [Accepted: 09/06/2013] [Indexed: 11/28/2022]
Affiliation(s)
- ISAC C. THOMAS
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
| | - DAVID P. CORK
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
| | - ANDREW LEVY
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
| | - HEMAL NAYAK
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
| | - JOHN F. BESHAI
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
| | - MARTIN C. BURKE
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
| | - JOSHUA D. MOSS
- Department of Medicine; Section of Cardiology; Heart Rhythm Center at the University of Chicago Medicine; Chicago Illinois
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