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Goff RP, Howard BT, Quallich SG, Iles TL, Iaizzo PA. The novel in vitro reanimation of isolated human and large mammalian heart-lung blocs. BMC PHYSIOLOGY 2016; 16:4. [PMID: 27259478 PMCID: PMC4893289 DOI: 10.1186/s12899-016-0023-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 05/24/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND In vitro isolated heart preparations are valuable tools for the study of cardiac anatomy and physiology, as well as for preclinical device testing. Such preparations afford investigators a high level of hemodynamic control, independent of host or systemic interactions. Here we hypothesize that recovered human and swine heart-lung blocs can be reanimated using a clear perfusate and elicit viable cardiodynamic and pulmonic function. Further, this approach will facilitate multimodal imaging, which is particularly valuable for the study of both functional anatomy and device-tissue interactions. Five human and 18 swine heart-lung preparations were procured using techniques analogous to those for cardiac transplant. Specimens were then rewarmed and reperfused using modifications of a closed circuit, isolated, beating and ventilated heart-lung preparation. Positive pressure mechanical ventilation was also employed, and epicardial defibrillation was applied to elicit native cardiac sinus rhythm. Videoscopy, fluoroscopy, ultrasound, and infrared imaging were performed for anatomical and experimental study. RESULTS Systolic and diastolic left ventricular pressures observed for human and swine specimens were 68/2 ± 11/7 and 74/3 ± 17/5 mmHg, respectively, with associated native heart rates of 80 ± 7 and 96 ± 16 beats per minute. High-resolution imaging within functioning human pulmonary vasculature was obtained among other anatomies of interest. Note that one human specimen elicited poor cardiac performance post defibrillation. CONCLUSIONS We report the first dynamic videoscopic images of the pulmonary vasculature during viable cardiopulmonary function in isolated reanimated heart-lung blocs. This experimental approach provides unique in vitro opportunities for the study of novel medical therapeutics applied to large mammalian, including human, heart-lung specimens.
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Affiliation(s)
- Ryan P Goff
- Departments of Biomedical Engineering, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.,Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Brian T Howard
- Departments of Biomedical Engineering, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.,Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Stephen G Quallich
- Departments of Biomedical Engineering, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.,Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Tinen L Iles
- Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Paul A Iaizzo
- Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.
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Granegger M, Aigner P, Haberl T, Mahr S, Tamez DA, Graham J, Nunez NJ, Schima H, Moscato F. Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup. Artif Organs 2016; 40:1113-1120. [PMID: 27230977 DOI: 10.1111/aor.12730] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 01/20/2016] [Accepted: 01/22/2016] [Indexed: 11/26/2022]
Abstract
New left ventricular assist devices (LVADs) offer both important advantages and potential hazards. VAD development requires better and expeditious ways to identify these advantages and hazards. We validated in an isolated working heart the hemodynamic performance of an intraventricular LVAD and investigated how its outflow cannula interacted with the aortic valve. Hearts from six pigs were explanted and connected to an isolated working heart setup. A miniaturized LVAD was implanted within the left ventricle (tMVAD, HeartWare Inc., Miami Lakes, FL, USA). In four experiments blood was used to investigate hemodynamics under various loading conditions. In two experiments crystalloid perfusate was used, allowing visualization of the outflow cannula within the aortic valve. In all hearts the transapical miniaturized ventricular assist device (tMVAD) implantation was successful. In the blood experiments hemodynamics similar to those observed clinically were achieved. Pump speeds ranged from 9 to 22 krpm with a maximum of 7.6 L/min against a pressure difference between ventricle and aorta of ∼50 mm Hg. With crystalloid perfusate, central positioning of the outflow cannula in the aortic root was observed during full and partial support. With decreasing aortic pressures the cannula tended to drift toward the aortic root wall. The tMVAD could unload the ventricle similarly to LVADs under conventional cannulation. Aortic pressure influenced central positioning of the outflow cannula in the aortic root. The isolated heart is a simple, accessible evaluation platform unaffected by complex reactions within a whole, living animal. This platform allowed detection and visualization of potential hazards.
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Affiliation(s)
- Marcus Granegger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna.,Ludwig Boltzmann Cluster for Cardiovascular Research
| | - Philipp Aigner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna.,Ludwig Boltzmann Cluster for Cardiovascular Research
| | - Thomas Haberl
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Stephane Mahr
- Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | | | | | | | - Heinrich Schima
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna.,Ludwig Boltzmann Cluster for Cardiovascular Research.,Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Francesco Moscato
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna.,Ludwig Boltzmann Cluster for Cardiovascular Research
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Benscoter MA, Iaizzo PA. Visualization of catheter ablation for atrial fibrillation: Impact of devices and anatomy. World J Cardiol 2015; 7:754-764. [PMID: 26635923 PMCID: PMC4660470 DOI: 10.4330/wjc.v7.i11.754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/26/2015] [Accepted: 10/19/2015] [Indexed: 02/06/2023] Open
Abstract
Endocardial access to the left atrium is commonly achieved to treat patients with atrial fibrillation, using different device delivery systems for cardiac ablation. But the large variation in human anatomy presses the limits of existing medical devices. In this unique study, we directly visualized the device-tissue interface in fresh reanimated human hearts using Visible Heart® methodologies. Our goal was to better understand any opportunities to improve therapeutic approaches. The visual images obtained in this study (also featured in this article) allow a more intimate grasp of the key steps required in various ablation procedures, as well as some limitations of current device designs. These images show the potential risks of conducting transseptal punctures and the difficulties of placing catheter tips in certain scenarios (e.g., when creating circumferential lesions); they also demonstrate potential problems that could occur while attempting to place catheter tips on such anatomies like the mitral isthmus. In our analysis of these images, we focus on where enhancements are needed to refine device functionality.
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Bateman MG, Iaizzo PA. Imaging in the context of replacement heart valve development: use of the Visible Heart(®) methodologies. Cardiovasc Diagn Ther 2013; 2:220-30. [PMID: 24282719 DOI: 10.3978/j.issn.2223-3652.2012.07.01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 07/02/2012] [Indexed: 11/14/2022]
Abstract
In recent years huge strides have been made in the fields of interventional cardiology and cardiac surgery which now allow physicians and surgeons to repair or replace cardiac valves with greater success in a larger demographic of patients. Pivotal to these advances has been significant improvements in cardiac imaging and improved fundamental understanding of valvular anatomies and morphologies. We describe here a novel series of techniques utilized within the Visible Heart(®) laboratory by engineers, scientists, and/or anatomists to visualize and analyze the form and function of the four cardiac valves and to assess potential repair or replacement therapies. The study of reanimated large mammalian hearts (including human hearts) using various imaging modalities, as well as specially prepared anatomical specimens, has enhanced the design, development, and testing of novel cardiac therapies.
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Affiliation(s)
- Michael G Bateman
- Department of Surgery and the Institute for Engineering in Medicine at the University of Minnesota, Minneapolis, MN 55455, USA
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Spencer JH, Quill JL, Bateman MG, Eggen MD, Howard SA, Goff RP, Howard BT, Quallich SG, Iaizzo PA. The benefits of the Atlas of Human Cardiac Anatomy website for the design of cardiac devices. Expert Rev Med Devices 2013; 10:729-34. [PMID: 24195457 DOI: 10.1586/17434440.2013.843449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This paper describes how the Atlas of Human Cardiac Anatomy website can be used to improve cardiac device design throughout the process of development. The Atlas is a free-access website featuring novel images of both functional and fixed human cardiac anatomy from over 250 human heart specimens. This website provides numerous educational tutorials on anatomy, physiology and various imaging modalities. For instance, the 'device tutorial' provides examples of devices that were either present at the time of in vitro reanimation or were subsequently delivered, including leads, catheters, valves, annuloplasty rings and stents. Another section of the website displays 3D models of the vasculature, blood volumes and/or tissue volumes reconstructed from computed tomography and magnetic resonance images of various heart specimens. The website shares library images, video clips and computed tomography and MRI DICOM files in honor of the generous gifts received from donors and their families.
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Affiliation(s)
- Julianne H Spencer
- University of Minnesota, 420 Delaware St. SE, Minneapolis, MN 55455, USA
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Investigation of hemodynamics in the assisted isolated porcine heart. Int J Artif Organs 2013; 36:878-86. [PMID: 24362896 DOI: 10.5301/ijao.5000257] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2013] [Indexed: 11/20/2022]
Abstract
BACKGROUND Currently, the interaction between rotary blood pumps (RBP) and the heart is investigated in silico, in vitro, and in animal models. Isolated and defined changes in hemodynamic parameters are unattainable in animal models, while the heart-pump interaction in its whole complexity cannot be modeled in vitro or in silico. AIM The aim of this work was to develop an isolated heart setup to provide a realistic heart-pump interface with the possibility of easily adjusting hemodynamic parameters. METHODS A mock circuit mimicking the systemic circulation was developed. Eight porcine hearts were harvested using a protocol similar to heart transplantation. Then, the hearts were resuscitated using Langendorff perfusion with rewarmed, oxygenated blood. An RBP was implanted and the setup was switched to the "working mode" with the left heart and the RBP working as under physiologic conditions. Both the unassisted and assisted hemodynamics were monitored. RESULTS In the unassisted condition, cardiac output was up to 9.5 l/min and dP/dtmax ranged from 521 to 3621 mmHg/s at a preload of 15 mmHg and afterload of 70 mmHg. With the RBP turned on, hemodynamics similar to heart-failure patients were observed in each heart. Mean pump flow and flow pulsatility ranged from 0 to 11 l/min. We were able to reproduce conditions with an open and closed aortic valve as well as suction events. CONCLUSIONS An isolated heart setup including an RBP was developed, which combines the advantages of in silico/vitro methods and animal experiments. This tool thus provides further insight into the interaction between the heart and an RBP.
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Bateman MG, Iaizzo PA. Comparative imaging of cardiac structures and function for the optimization of transcatheter approaches for valvular and structural heart disease. Int J Cardiovasc Imaging 2011; 27:1223-34. [DOI: 10.1007/s10554-011-9807-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 01/13/2011] [Indexed: 11/29/2022]
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