1
|
Davtyan R, Sarvazyan NA. Output of a valveless Liebau pump with biologically relevant vessel properties and compression frequencies. Sci Rep 2021; 11:11505. [PMID: 34075100 PMCID: PMC8169938 DOI: 10.1038/s41598-021-90820-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/18/2021] [Indexed: 11/09/2022] Open
Abstract
Liebau pump is a tubular, non-peristaltic, pulsatile pump capable of creating unidirectional flow in the absence of valves. It requires asymmetrical positioning of the pincher relative to the attachment sites of its elastic segment to the rest of the circuit. Biological feasibility of such valveless pumps remains a hotly debated topic. To test the feasibility of the Liebau-based pumping in vessels with biologically relevant properties we quantified the output of Liebau pumps with their compliant segments made of a silicone rubber that mimicked the Young modulus of soft tissues. The lengths, the inner diameters, thicknesses of the tested compliant segments ranged from 1 to 5 cm, 3 to 8 mm and 0.3 to 1 mm, respectively. The compliant segment of the setup was compressed at 0.5–2.5 Hz frequencies using a 3.5-mm-wide rectangular piston. A nearest-neighbor tracking algorithm was used to track movements of 0.5-mm carbon particles within the system. The viscosity of the aqueous solution was varied by increased percentage of glycerin. Measurements yielded quantitative relationships between viscosity, frequency of compression and the net flowrate. The use of the Liebau principle of valveless pumping in conjunction with physiologically sized vessel and contraction frequencies yields flowrates comparable to peristaltic pumps of the same dimensions. We conclude that the data confirm physiological feasibility of Liebau-based pumping and warrant further testing of its mechanism using excised biological conduits or tissue engineered components. Such biomimetic pumps can serve as energy-efficient flow generators in microdevices or to study the function of embryonic heart during its normal development or in diseased states.
Collapse
Affiliation(s)
- Rubina Davtyan
- Department of Pharmacology and Physiology, School of Medicine and Health Science, The George Washington University, 2300 Eye Street NW, Washington, DC, 20037, USA
| | - Narine A Sarvazyan
- Department of Pharmacology and Physiology, School of Medicine and Health Science, The George Washington University, 2300 Eye Street NW, Washington, DC, 20037, USA.
| |
Collapse
|
2
|
Tiporlini V, Ahderom S, Pratten P, Alameh K. Advanced fully integrated radiofrequency/optical-coherence-tomography irrigated catheter for atrial fibrillation ablation. JOURNAL OF BIOPHOTONICS 2021; 14:e202000243. [PMID: 33150714 DOI: 10.1002/jbio.202000243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 06/11/2023]
Abstract
The inability of current catheter ablation procedures to accurately monitor lesion formation limits their safety and efficacy. An advanced fully integrated radiofrequency (RF)/optical coherence tomography (OCT) ablation catheter is developed, which enables real-time monitoring during ablation. An OCT fiber array is especially designed, developed and integrated into an off-the-shelf irrigated RF ablation catheter. In-vitro experimental studies performed on poultry and ovine hearts demonstrate the ability of the integrated RF/OCT system to provide information on the quality and orientation of catheter/wall contact. Experimental results show that adipose tissue can be accurately identified from normal myocardial tissue with 94% accuracy and lesion formation is monitored with an overall accuracy of 93%. The ability to predict pop events is also demonstrated, with an accuracy of 86%.
Collapse
Affiliation(s)
- Valentina Tiporlini
- Electron Science Research Institute, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Selam Ahderom
- Electron Science Research Institute, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Peter Pratten
- Electron Science Research Institute, Edith Cowan University, Joondalup, Western Australia, Australia
- Lazcath PTY LTD, Mosman Park, Western Australia, Australia
| | - Kamal Alameh
- Electron Science Research Institute, Edith Cowan University, Joondalup, Western Australia, Australia
| |
Collapse
|
3
|
Armstrong K, Larson C, Asfour H, Ransbury T, Sarvazyan N. A Percutaneous Catheter for In Vivo Hyperspectral Imaging of Cardiac Tissue: Challenges, Solutions and Future Directions. Cardiovasc Eng Technol 2020; 11:560-575. [PMID: 32666326 PMCID: PMC7530025 DOI: 10.1007/s13239-020-00476-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 06/30/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE Multiple studies have shown that spectral analysis of tissue autofluorescence can be used as a live indicator for various pathophysiological states of cardiac tissue, including ischemia, ablation-induced damage, or scar formation. Yet today there are no percutaneous devices that can detect autofluorescence signals from inside a beating heart. Our aim was to develop a prototype catheter to demonstrate the feasibility of doing so. METHODS AND RESULTS Here we summarize technical solutions leading to the development of a percutaneous catheter capable of multispectral imaging of intracardiac surfaces. The process included several iterations of light sources, optical filtering, and image acquisition techniques. The developed system included a compliant balloon, 355 nm laser irradiance, a high-sensitivity CCD, bandpass filtering, and image acquisition synchronized with the cardiac cycle. It enabled us to capture autofluorescence images from multiple spectral bands within the visible range while illuminating the endocardial surface with ultraviolet light. Principal component analysis and other spectral unmixing post-processing algorithms were then used to reveal target tissue. CONCLUSION Based on the success of our prototype system, we are confident that the development of ever more sensitive cameras, recent advances in tunable filters, fiber bundles, and other optical and computational components makes it possible to create percutaneous catheters capable of acquiring hyper or multispectral hypercubes, including those based on autofluorescence, in real-time. This opens the door for widespread use of this methodology for high-resolution intraoperative imaging of internal tissues and organs-including cardiovascular applications.
Collapse
Affiliation(s)
- Kenneth Armstrong
- Nocturnal Product Development, LLC, 8128 Renaissance Pkwy #210, Durham, NC, 27713, USA.
| | - Cinnamon Larson
- Nocturnal Product Development, LLC, 8128 Renaissance Pkwy #210, Durham, NC, 27713, USA
| | - Huda Asfour
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye Street NW, Washington, DC, 20037, USA
| | - Terry Ransbury
- LuxMed Systems, Inc, 124 Country Drive, Weston, MA, 02493, USA
| | - Narine Sarvazyan
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye Street NW, Washington, DC, 20037, USA.
| |
Collapse
|
4
|
Key factors behind autofluorescence changes caused by ablation of cardiac tissue. Sci Rep 2020; 10:15369. [PMID: 32958843 PMCID: PMC7506017 DOI: 10.1038/s41598-020-72351-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/25/2020] [Indexed: 11/30/2022] Open
Abstract
Radiofrequency ablation is a commonly used clinical procedure that destroys arrhythmogenic sources in patients suffering from atrial fibrillation and other types of cardiac arrhythmias. To improve the success of this procedure, new approaches for real-time visualization of ablation sites are being developed. One of these promising methods is hyperspectral imaging, an approach that detects lesions based on changes in the endogenous tissue autofluorescence profile. To facilitate the clinical implementation of this approach, we examined the key variables that can influence ablation-induced spectral changes, including the drop in myocardial NADH levels, the release of lipofuscin-like pigments, and the increase in diffuse reflectance of the cardiac muscle beneath the endocardial layer. Insights from these experiments suggested simpler algorithms that can be used to acquire and post-process the spectral information required to reveal the lesion sites. Our study is relevant to a growing number of multilayered clinical targets to which spectral approaches are being applied.
Collapse
|
5
|
Parwani AS, Hohendanner F, Bode D, Kuhlmann S, Blaschke F, Lacour P, Heinzel FR, Pieske B, Boldt LH. The force stability of tissue contact and lesion size index during radiofrequency ablation: An ex-vivo study. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2020; 43:327-331. [PMID: 32091133 DOI: 10.1111/pace.13891] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 01/08/2020] [Accepted: 02/09/2020] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Radiofrequency (RF) ablation is a commonly used tool in the invasive electrophysiology laboratory to treat a variety of rhythm disorders. Reliable creation of transmural ablation lesions is crucial for long-term success. Lesion size index (LSI) is a multiparametric index that incorporates time, power, contact force (CF), and impedance data recorded during RF ablation in a weighted formula and has been shown to predict the extent of myocardial tissue lesions. Whether the force stability of contact influences lesion size in LSI-guided ablations is unknown. OBJECTIVES The aim of this study was to analyze the influence of the force stability of contact on lesion size during LSI-guided ablations in an ex-vivo model. METHODS AND RESULTS A total of 267 RF lesions (n = 6 hearts) were created on porcine myocardial slabs by using an open-tip irrigated ablation catheter with the following settings: 35 W with either intermittent (varied between 0 and up to 20 g), variable (10 to 20 g), or constant tissue contact (15 g) in a perpendicular or parallel fashion (applied manually) up to a target LSI of either 5 or 6. Subsequently, lesion width and depth were determined. Lesion width was mainly influenced by catheter tip orientation and LSI, whereas lesion depth was mainly influenced by LSI alone. The force stability of catheter contact had no relevant impact on lesion width or depth. CONCLUSION The force stability of catheter contact has only little effect on lesion depth or width in LSI-guided catheter ablation while the catheter orientation primarily affects lesion width.
Collapse
Affiliation(s)
- Abdul S Parwani
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Felix Hohendanner
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - David Bode
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Stefan Kuhlmann
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Florian Blaschke
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Philipp Lacour
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| | - Leif-Hendrik Boldt
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Department of Internal Medicine and Cardiology, German Heart Institute, Berlin, Germany
| |
Collapse
|
6
|
Guan S, Asfour H, Sarvazyan N, Loew M. Application of unsupervised learning to hyperspectral imaging of cardiac ablation lesions. J Med Imaging (Bellingham) 2018; 5:046003. [PMID: 30840727 DOI: 10.1117/1.jmi.5.4.046003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 11/12/2018] [Indexed: 12/24/2022] Open
Abstract
Atrial fibrillation is the most common cardiac arrhythmia. It is being effectively treated using the radiofrequency ablation (RFA) procedure, which destroys culprit tissue and creates scars that prevent the spread of abnormal electrical activity. Long-term success of RFA could be improved further if ablation lesions can be directly visualized during the surgery. We have shown that autofluorescence-based hyperspectral imaging (aHSI) can help to identify lesions based on spectral unmixing. We show that use of k -means clustering, an unsupervised learning method, is capable of detecting RFA lesions without a priori knowledge of the lesions' spectral characteristics. We also show that the number of spectral bands required for successful lesion identification can be significantly reduced, enabling the use of increased spectral bandwidth. Together, these findings can help with clinical implementation of a percutaneous aHSI catheter, since by reducing the number of spectral bands one can reduce hypercube acquisition and processing times, and by increasing the spectral width of individual bands one can collect more photons. The latter is of critical importance in low-light applications such as intracardiac aHSI. The ultimate goal of our studies is to help improve clinical outcomes for atrial fibrillation patients.
Collapse
Affiliation(s)
- Shuyue Guan
- George Washington University, Department of Biomedical Engineering, Washington, DC, United States
| | - Huda Asfour
- George Washington University Medical Center, Department of Pharmacology and Physiology, Washington, DC, United States
| | - Narine Sarvazyan
- George Washington University Medical Center, Department of Pharmacology and Physiology, Washington, DC, United States
| | - Murray Loew
- George Washington University, Department of Biomedical Engineering, Washington, DC, United States
| |
Collapse
|
7
|
Asfour H, Guan S, Muselimyan N, Swift L, Loew M, Sarvazyan N. Optimization of wavelength selection for multispectral image acquisition: a case study of atrial ablation lesions. BIOMEDICAL OPTICS EXPRESS 2018; 9:2189-2204. [PMID: 29760980 PMCID: PMC5946781 DOI: 10.1364/boe.9.002189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 03/08/2018] [Accepted: 04/09/2018] [Indexed: 05/17/2023]
Abstract
In vivo autofluorescence hyperspectral imaging of moving objects can be challenging due to motion artifacts and to the limited amount of acquired photons. To address both limitations, we selectively reduced the number of spectral bands while maintaining accurate target identification. Several downsampling approaches were applied to data obtained from the atrial tissue of adult pigs with sites of radiofrequency ablation lesions. Standard image qualifiers such as the mean square error, the peak signal-to-noise ratio, the structural similarity index map, and an accuracy index of lesion component images were used to quantify the effects of spectral binning, an increased spectral distance between individual bands, as well as random combinations of spectral bands. Results point to several quantitative strategies for deriving combinations of a small number of spectral bands that can successfully detect target tissue. Insights from our studies can be applied to a wide range of applications.
Collapse
Affiliation(s)
- Huda Asfour
- Department of Pharmacology & Physiology, The George Washington University Medical Center, 2300 Eye Street NW, Washington, DC 20037, USA
| | - Shuyue Guan
- Department of Biomedical Engineering, The George Washington University, 800 22nd Street NW, Washington, DC 20052, USA
| | - Narine Muselimyan
- Department of Pharmacology & Physiology, The George Washington University Medical Center, 2300 Eye Street NW, Washington, DC 20037, USA
| | - Luther Swift
- Department of Pharmacology & Physiology, The George Washington University Medical Center, 2300 Eye Street NW, Washington, DC 20037, USA
| | - Murray Loew
- Department of Biomedical Engineering, The George Washington University, 800 22nd Street NW, Washington, DC 20052, USA
| | - Narine Sarvazyan
- Department of Pharmacology & Physiology, The George Washington University Medical Center, 2300 Eye Street NW, Washington, DC 20037, USA
| |
Collapse
|