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Lafond M, Payne A, Lafon C. Therapeutic ultrasound transducer technology and monitoring techniques: a review with clinical examples. Int J Hyperthermia 2024; 41:2389288. [PMID: 39134055 PMCID: PMC11375802 DOI: 10.1080/02656736.2024.2389288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 07/02/2024] [Accepted: 08/01/2024] [Indexed: 09/07/2024] Open
Abstract
The exponential growth of therapeutic ultrasound applications demonstrates the power of the technology to leverage the combinations of transducer technology and treatment monitoring techniques to effectively control the preferred bioeffect to elicit the desired clinical effect.Objective: This review provides an overview of the most commonly used bioeffects in therapeutic ultrasound and describes existing transducer technologies and monitoring techniques to ensure treatment safety and efficacy.Methods and materials: Literature reviews were conducted to identify key choices that essential in terms of transducer design, treatment parameters and procedure monitoring for therapeutic ultrasound applications. Effective combinations of these options are illustrated through descriptions of several clinical indications, including uterine fibroids, prostate disease, liver cancer, and brain cancer, that have been successful in leveraging therapeutic ultrasound to provide effective patient treatments.Results: Despite technological constraints, there are multiple ways to achieve a desired bioeffect with therapeutic ultrasound in a target tissue. Visualizations of the interplay of monitoring modality, bioeffect, and applied acoustic parameters are presented that demonstrate the interconnectedness of the field of therapeutic ultrasound. While the clinical indications explored in this review are at different points in the clinical evaluation path, based on the ever expanding research being conducted in preclinical realms, it is clear that additional clinical applications of therapeutic ultrasound that utilize a myriad of bioeffects will continue to grow and improve in the coming years.Conclusions: Therapeutic ultrasound will continue to improve in the next decades as the combination of transducer technology and treatment monitoring techniques will continue to evolve and be translated in clinical settings, leading to more personalized and efficient therapeutic ultrasound mediated therapies.
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Affiliation(s)
- Maxime Lafond
- LabTAU, INSERM, Centre Léon Bérard, Université, Lyon, France
| | - Allison Payne
- Department of Radiology and Imaging Sciences, University of UT, Salt Lake City, UT, USA
| | - Cyril Lafon
- LabTAU, INSERM, Centre Léon Bérard, Université, Lyon, France
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Yang S, Zemzemi C, Escudero DS, Vela DC, Haworth KJ, Holland CK. Histotripsy and Catheter-Directed Lytic: Efficacy in Highly Retracted Porcine Clots In Vitro. ULTRASOUND IN MEDICINE & BIOLOGY 2024; 50:1167-1177. [PMID: 38777639 DOI: 10.1016/j.ultrasmedbio.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/02/2024] [Accepted: 04/05/2024] [Indexed: 05/25/2024]
Abstract
OBJECTIVE Standard treatment for deep vein thrombosis (DVT) involves catheter-directed anticoagulants or thrombolytics, but the chronic thrombi present in many DVT cases are often resistant to this therapy. Histotripsy has been found to be a promising adjuvant treatment, using the mechanical action of cavitating bubble clouds to enhance thrombolytic activity. The objective of this study was to determine if histotripsy enhanced recombinant tissue plasminogen activator (rt-PA) thrombolysis in highly retracted porcine clots in vitro in a flow model of occlusive DVT. METHODS Highly retracted porcine whole blood clots were treated for 1 h with either catheter-directed saline (negative control), rt-PA (lytic control), histotripsy, DEFINITY and histotripsy or the combination of rt-PA and histotripsy with or without DEFINITY. Five-cycle, 1.5 MHz histotripsy pulses with a peak negative pressure of 33.2 MPa and pulse repetition frequency of 40 Hz were applied along the clot. B-Mode and passive cavitation images were acquired during histotripsy insonation to monitor bubble activity. RESULTS Clots subjected to histotripsy with and without rt-PA exhibited greater thrombolytic efficacy than controls (7.0% flow recovery or lower), and histotripsy with rt-PA was more efficacious than histotripsy with saline (86.1 ± 10.2% compared with 61.7 ± 19.8% flow recovery). The addition of DEFINITY to histotripsy with or without rt-PA did not enhance either thrombolytic efficacy or cavitation dose. Cavitation dose generally did not correlate with thrombolytic efficacy. CONCLUSION Enhancement of thrombolytic efficacy was achieved using histotripsy, with and without catheter-directed rt-PA, in the presence of physiologic flow. This suggests these treatments may be effective as therapy for DVT.
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Affiliation(s)
- Shumeng Yang
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA.
| | - Chadi Zemzemi
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
| | | | - Deborah C Vela
- Cardiovascular Pathology, Texas Heart Institute, Houston, TX, USA
| | - Kevin J Haworth
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA; Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Christy K Holland
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA; Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
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Suarez Escudero D, Haworth KJ, Genstler C, Holland CK. Quantifying the Effect of Acoustic Parameters on Temporal and Spatial Cavitation Activity: Gauging Cavitation Dose. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:2388-2397. [PMID: 37648590 PMCID: PMC10581030 DOI: 10.1016/j.ultrasmedbio.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/28/2023] [Accepted: 08/01/2023] [Indexed: 09/01/2023]
Abstract
OBJECTIVE Cavitation-enhanced delivery of therapeutic agents is under development for the treatment of cancer and neurodegenerative and cardiovascular diseases, including sonothrombolysis for deep vein thrombosis. The objective of this study was to quantify the spatial and temporal distribution of cavitation activity nucleated by Definity infused through the EKOS catheter over a range of acoustic parameters controlled by the EKOS endovascular system. METHODS Three insonation protocols were compared in an in vitro phantom mimicking venous flow to measure the effect of peak rarefactional pressure, pulse duration and pulse repetition frequency on cavitation activity energy, location and duration. Inertial and stable cavitation activity was quantified using passive cavitation imaging, and a metric of cavitation dose based on energy density was defined. RESULTS For all three insonation protocols, cavitation was sustained for the entire 30 min Definity infusion. The evolution of cavitation energy during each pulse duration was similar for all three protocols. For insonation protocols with higher peak rarefactional acoustic pressures, inertial and stable cavitation doses also increased. A complex relationship between the temporal behavior of cavitation energy within each pulse and the pulse repetition frequency affected the cavitation dose for the three insonation protocols. The relative predominance of stable or inertial cavitation dose varied according to insonation schemes. Passive cavitation images revealed the spatial distribution of cavitation activity. CONCLUSION Our cavitation dose metric based on energy density enabled the impact of different acoustic parameters on cavitation activity to be measured. Depending on the type of cavitation to be promoted or suppressed, particular pulsing schemes could be employed in future studies, for example, to correlate cavitation dose with sonothrombolytic efficacy.
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Affiliation(s)
- Daniel Suarez Escudero
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH, USA
| | - Kevin J Haworth
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH, USA; Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | | | - Christy K Holland
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH, USA; Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA.
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Haworth KJ, Salido NG, Lafond M, Escudero DS, Holland CK. Passive Cavitation Imaging Artifact Reduction Using Data-Adaptive Spatial Filtering. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2023; 70:498-509. [PMID: 37018086 PMCID: PMC10335845 DOI: 10.1109/tuffc.2023.3264832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Passive cavitation imaging (PCI) with a clinical diagnostic array results in poor axial localization of bubble activity due to the size of the point spread function (PSF). The objective of this study was to determine if data-adaptive spatial filtering improved PCI beamforming performance relative to standard frequency-domain delay, sum, and integrate (DSI) or robust Capon beamforming (RCB). The overall goal was to improve source localization and image quality without sacrificing computation time. Spatial filtering was achieved by applying a pixel-based mask to DSI- or RCB-beamformed images. The masks were derived from DSI, RCB, or phase or amplitude coherence factors (ACFs) using both receiver operating characteristic (ROC) and precision-recall (PR) curve analyses. Spatially filtered passive cavitation images were formed from cavitation emissions based on two simulated sources densities and four source distribution patterns mimicking cavitation emissions induced by an EkoSonic catheter. Beamforming performance was assessed via binary classifier metrics. The difference in sensitivity, specificity, and area under the ROC curve (AUROC) differed by no more than 11% across all algorithms for both source densities and all source patterns. The computational time required for each of the three spatially filtered DSIs was two orders of magnitude less than that required for time-domain RCB and thus this data-adaptive spatial filtering strategy for PCI beamforming is preferable given the similar binary classification performance.
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Kennedy SR, Lafond M, Haworth KJ, Escudero DS, Ionascu D, Frierson B, Huang S, Klegerman ME, Peng T, McPherson DD, Genstler C, Holland CK. Initiating and imaging cavitation from infused echo contrast agents through the EkoSonic catheter. Sci Rep 2023; 13:6191. [PMID: 37062767 PMCID: PMC10106464 DOI: 10.1038/s41598-023-33164-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 04/07/2023] [Indexed: 04/18/2023] Open
Abstract
Ultrasound-enhanced delivery of therapeutic-loaded echogenic liposomes is under development for vascular applications using the EkoSonic Endovascular System. In this study, fibrin-targeted echogenic liposomes loaded with an anti-inflammatory agent were characterized before and after infusion through an EkoSonic catheter. Cavitation activity was nucleated by Definity or fibrin-targeted, drug-loaded echogenic liposomes infused and insonified with EkoSonic catheters. Passive cavitation imaging was used to quantify and map bubble activity in a flow phantom mimicking porcine arterial flow. Cavitation was sustained during 3-min infusions of Definity or echogenic liposomes along the distal 6 cm treatment zone of the catheter. Though the EkoSonic catheter was not designed specifically for cavitation nucleation, infusion of drug-loaded echogenic liposomes can be employed to trigger and sustain bubble activity for enhanced intravascular drug delivery.
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Affiliation(s)
- Sonya R Kennedy
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cardiovascular Center 3935, 231 Albert Sabin Way, Cincinnati, OH, 45267-0586, USA
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Maxime Lafond
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cardiovascular Center 3935, 231 Albert Sabin Way, Cincinnati, OH, 45267-0586, USA
- LabTAU, Inserm, Université Lyon 1, Lyon, France
| | - Kevin J Haworth
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cardiovascular Center 3935, 231 Albert Sabin Way, Cincinnati, OH, 45267-0586, USA
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Daniel Suarez Escudero
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cardiovascular Center 3935, 231 Albert Sabin Way, Cincinnati, OH, 45267-0586, USA
| | - Dan Ionascu
- Department of Radiation Oncology, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Brion Frierson
- Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Shaoling Huang
- Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Melvin E Klegerman
- Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Tao Peng
- Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - David D McPherson
- Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | | | - Christy K Holland
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cardiovascular Center 3935, 231 Albert Sabin Way, Cincinnati, OH, 45267-0586, USA.
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA.
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Benton RP, Al Rifai N, Stone K, Clark A, Zhang B, Haworth KJ. Impact of Perfluoropentane Microdroplets Diameter and Concentration on Acoustic Droplet Vaporization Transition Efficiency and Oxygen Scavenging. Pharmaceutics 2022; 14:pharmaceutics14112392. [PMID: 36365210 PMCID: PMC9694497 DOI: 10.3390/pharmaceutics14112392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/25/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
Acoustic droplet vaporization is the ultrasound-mediated phase change of liquid droplets into gas microbubbles. Following the phase change, oxygen diffuses from the surrounding fluid into the microbubble. An in vitro model was used to study the effects of droplet diameter, the presence of an ultrasound contrast agent, ultrasound duty cycle, and droplet concentration on the magnitude of oxygen scavenging in oxygenated deionized water. Perfluoropentane droplets were manufactured through a microfluidic approach at nominal diameters of 1, 3, 5, 7, 9, and 12 µm and studied at concentrations varying from 5.1 × 10-5 to 6.3 × 10-3 mL/mL. Droplets were exposed to an ultrasound transduced by an EkoSonicTM catheter (2.35 MHz, 47 W, and duty cycles of 1.70%, 2.34%, or 3.79%). Oxygen scavenging and the total volume of perfluoropentane that phase-transitioned increased with droplet concentration. The ADV transition efficiency decreased with increasing droplet concentration. The increasing duty cycle resulted in statistically significant increases in oxygen scavenging for 1, 3, 5, and 7 µm droplets, although the increase was smaller than when the droplet diameter or concentration were increased. Under the ultrasound conditions tested, droplet diameter and concentration had the greatest impact on the amount of ADV and subsequent oxygen scavenging occurred, which should be considered when using ADV-mediated oxygen scavenging in therapeutic ultrasounds.
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Affiliation(s)
- Rachel P. Benton
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Nour Al Rifai
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Kateryna Stone
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Abigail Clark
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Bin Zhang
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Kevin J. Haworth
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45229, USA
- Correspondence: ; Tel.: +1-513-558-3536
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Zheng X, Pan Y, Zhang Y, Meng K, Zhou J, Wang X, Cui Y, Li J, Li Y, Chen H. Interventional Microbubble Enhanced Sonothrombolysis on Left Ventricular Assist Devices. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2201291. [PMID: 35615977 PMCID: PMC9313509 DOI: 10.1002/advs.202201291] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/27/2022] [Indexed: 06/15/2023]
Abstract
The left ventricular assist device (LVAD) is often used in the treatment of heart failure. However, 4% to 9% implanted LVAD will have thrombosis problem in one year, which is fatal to the patient's life. In this work, an interventional sonothrombolysis (IST) method is developed to realize the thrombolysis on LVAD. A pair of ultrasound transducer rings is installed on the shell of LVAD, and drug-loaded microbubbles are injected into the LVAD through the interventional method. The microbubbles are adhere on the thrombus with the coated thrombus-targeted drugs, and the thrombolytic drugs carried by the bubbles are brought into the thrombus by the cavitation of bubbles under the ultrasound. In a proof-of-concept experiment in a live sheep model, the thrombus on LVAD is dissolved in 30 min, without damages on LVADs and organs. This IST exhibits to be more efficient and safer compared with other thrombolysis methods on LVAD.
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Affiliation(s)
- Xiaobing Zheng
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
| | - Yunfan Pan
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
| | - Yuan Zhang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Kuilin Meng
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
| | - Jianye Zhou
- Animal Experiment Center, Fuwai Hospital, Chinese Academy of Medical Sciences, Beijing, 100037, China
| | - Xin Wang
- Animal Experiment Center, Fuwai Hospital, Chinese Academy of Medical Sciences, Beijing, 100037, China
| | - Yongchun Cui
- Animal Experiment Center, Fuwai Hospital, Chinese Academy of Medical Sciences, Beijing, 100037, China
| | - Jiang Li
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yongjian Li
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
| | - Haosheng Chen
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
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Lafond M, Lambin T, Drainville RA, Dupré A, Pioche M, Melodelima D, Lafon C. Pancreatic Ductal Adenocarcinoma: Current and Emerging Therapeutic Uses of Focused Ultrasound. Cancers (Basel) 2022; 14:2577. [PMID: 35681557 PMCID: PMC9179649 DOI: 10.3390/cancers14112577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 11/27/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) diagnosis accompanies a somber prognosis for the patient, with dismal survival odds: 5% at 5 years. Despite extensive research, PDAC is expected to become the second leading cause of mortality by cancer by 2030. Ultrasound (US) has been used successfully in treating other types of cancer and evidence is flourishing that it could benefit PDAC patients. High-intensity focused US (HIFU) is currently used for pain management in palliative care. In addition, clinical work is being performed to use US to downstage borderline resectable tumors and increase the proportion of patients eligible for surgical ablation. Focused US (FUS) can also induce mechanical effects, which may elicit an anti-tumor response through disruption of the stroma and can be used for targeted drug delivery. More recently, sonodynamic therapy (akin to photodynamic therapy) and immunomodulation have brought new perspectives in treating PDAC. The aim of this review is to summarize the current state of those techniques and share our opinion on their future and challenges.
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Affiliation(s)
- Maxime Lafond
- LabTAU, The Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard, Université Lyon 1, University Lyon, 69003 Lyon, France; (R.A.D.); (A.D.); (D.M.); (C.L.)
| | - Thomas Lambin
- Endoscopy Division, Édouard Herriot Hospital, 69003 Lyon, France; (T.L.); (M.P.)
| | - Robert Andrew Drainville
- LabTAU, The Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard, Université Lyon 1, University Lyon, 69003 Lyon, France; (R.A.D.); (A.D.); (D.M.); (C.L.)
| | - Aurélien Dupré
- LabTAU, The Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard, Université Lyon 1, University Lyon, 69003 Lyon, France; (R.A.D.); (A.D.); (D.M.); (C.L.)
| | - Mathieu Pioche
- Endoscopy Division, Édouard Herriot Hospital, 69003 Lyon, France; (T.L.); (M.P.)
| | - David Melodelima
- LabTAU, The Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard, Université Lyon 1, University Lyon, 69003 Lyon, France; (R.A.D.); (A.D.); (D.M.); (C.L.)
| | - Cyril Lafon
- LabTAU, The Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard, Université Lyon 1, University Lyon, 69003 Lyon, France; (R.A.D.); (A.D.); (D.M.); (C.L.)
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Hendley SA, Bhargava A, Holland CK, Wool GD, Ahmed O, Paul JD, Bader KB. (More than) doubling down: Effective fibrinolysis at a reduced rt-PA dose for catheter-directed thrombolysis combined with histotripsy. PLoS One 2022; 17:e0261567. [PMID: 34982784 PMCID: PMC8726487 DOI: 10.1371/journal.pone.0261567] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 12/04/2021] [Indexed: 02/07/2023] Open
Abstract
Deep vein thrombosis is a major source of morbidity and mortality worldwide. For acute proximal deep vein thrombosis, catheter-directed thrombolytic therapy is an accepted method for vessel recanalization. Thrombolytic therapy is not without risk, including the potential for hemorrhagic bleeding that increases with lytic dose. Histotripsy is a focused ultrasound therapy that generates bubble clouds spontaneously in tissue at depth. The mechanical activity of histotripsy increases the efficacy of thrombolytic therapy at doses consistent with current pharmacomechanical treatments for venous thrombosis. The objective of this study was to determine the influence of lytic dose on histotripsy-enhanced fibrinolysis. Human whole blood clots formed in vitro were exposed to histotripsy and a thrombolytic agent (recombinant tissue plasminogen activator, rt-PA) in a venous flow model perfused with plasma. Lytic was administered into the clot via an infusion catheter at concentrations ranging from 0 (control) to 4.54 μg/mL (a common clinical dose for catheter-directed thrombolysis). Following treatment, perfusate samples were assayed for markers of fibrinolysis, hemolysis, and intact red blood cells and platelets. Fibrinolysis was equivalent between the common clinical dose of rt-PA (4.54 μg/mL) and rt-PA at a reduction to one-twentieth of the common clinical dose (0.23 μg/mL) when combined with histotripsy. Minimal changes were observed in hemolysis for treatment arms with or without histotripsy, potentially due to clot damage from insertion of the infusion catheter. Likewise, histotripsy did not increase the concentration of red blood cells or platelets in the perfusate following treatment compared to rt-PA alone. At the highest lytic dose, a refined histotripsy exposure scheme was implemented to cover larger areas of the clot. The updated exposure scheme improved clot mass loss and fibrinolysis relative to administration of lytic alone. Overall, the data collected in this study indicate the rt-PA dose can be reduced by more than a factor of ten and still promote fibrinolysis when combined with histotripsy.
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Affiliation(s)
- Samuel A. Hendley
- Committee on Medical Physics, University of Chicago, Chicago, Illinois, United States of America
| | - Aarushi Bhargava
- Department of Radiology, University of Chicago, Chicago, Illinois, United States of America
| | - Christy K. Holland
- Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Geoffrey D. Wool
- Department of Pathology, University of Chicago, Chicago, Illinois, United States of America
| | - Osman Ahmed
- Department of Radiology, University of Chicago, Chicago, Illinois, United States of America
| | - Jonathan D. Paul
- Department of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Kenneth B. Bader
- Committee on Medical Physics, University of Chicago, Chicago, Illinois, United States of America
- Department of Radiology, University of Chicago, Chicago, Illinois, United States of America
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