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Sound analysis of the magnetically levitated left ventricular assist device HeartMate 3
Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Cardiology in Linköping. Department of Medicine and Geriatrics, Höglandet Hospital, Eksjö.ORCID iD: 0000-0001-5485-1052
Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
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2019 (English)In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 42, no 12, p. 717-724Article in journal (Refereed) Published
Abstract [en]

INTRODUCTION: The HeartMate 3 has shown lower rates of adverse events compared to previous devices due to the design and absence of mechanical bearings. For previous devices, sound analysis emerged as a way to assess pump function. The aims of this study were to determine if sound analysis can be applied to the HeartMate 3 in vivo and in vitro and to evaluate an electronic stethoscope.

METHOD: Sound recordings were performed with microphones and clinical accessible electronic stethoscope. The recordings were studied in both the time and the frequency domains. Recordings from four patients were performed to determine if in vivo and in vitro recordings are comparable.

RESULTS: The results show that it is possible to detect sound from HeartMate 3 and the sound spectrum is clear. Pump frequency and frequency of the pulsatile mode are easily determined. Frequency spectra from in vitro and in vivo recordings have the same pattern, and the major proportion (96.7%) of signal power is located at the pump speed frequency ±40 Hz. The recordings from the patients show low inter-individual differences except from location of peaks originating from pump speed and harmonics. Electronic stethoscopes could be used for sound recordings, but the dedicated equipment showed a clearer sound spectrum.

DISCUSSION: The results show that acoustic analysis can also be performed with the HeartMate 3 and that in vivo and in vitro sound spectrum is similar. The frequency spectra are different from previous devices, and methods for assessing pump function or thrombosis need further evaluation.

Place, publisher, year, edition, pages
Sagamore Publishing, 2019. Vol. 42, no 12, p. 717-724
Keywords [en]
HeartMate 3, Spectral analysis, left ventricular assist device, sound
National Category
Biomedical Laboratory Science/Technology
Identifiers
URN: urn:nbn:se:liu:diva-161898DOI: 10.1177/0391398819857443ISI: 000493895600006PubMedID: 31250690Scopus ID: 2-s2.0-85068309681OAI: oai:DiVA.org:liu-161898DiVA, id: diva2:1369444
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2020-01-08Bibliographically approved
In thesis
1. Acoustic and afterload evaluation of left ventricular assist devices
Open this publication in new window or tab >>Acoustic and afterload evaluation of left ventricular assist devices
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Heart Failure is a serious condition with consequences not only for the individual patient but also for the society with a 5-year mortality rate of 45-60%, and a substantial economic burden. The estimated prevalence in Sweden is 2.2% and the age adjusted prevalence increases with higher age. The fundamental treatment for heart failure is pharmaceutical in combination with life-style changes, and physiotherapy. For patients with advanced heart failure, the use of long-term circulatory support can be an option as a bridge to transplantation, or as destination therapy. However, this treatment entails a risk of multiple adverse events. The incidence of pump thrombosis increased as a clinical problem in 2012 and the need for diagnostic methods were desired. The aim of this thesis was to develop and to evaluate the use of a mock loop circuit to study the acoustics of left ventricular assist devices, to evaluate different recording devices and to study the effect of afterload on pump function.

Methods: Two different mock loops, with the possibility to insert artificial thrombus and to adjust preload and afterload were created to facilitate recording of the left ventricular assist devices. An iPhone/iPodTM was used as recording device since remote monitoring is desirable. The sounds from HeartMate IITM during different conditions were studied. The iPhone/iPod was evaluated in comparison to dedicated recording equipment, and the mock loop recordings to clinical situation. The sound from HeartMate 3TM was studied, compared between in vivo and in vitro recordings, and the use of an electronic stethoscope was evaluated. The impact of afterload on left ventricular assist devices was studied in a mock loop circuit with different changes in preload and afterload.

Results: Mock loop circuit is a promising method to safely change the surrounding conditions as the pump is working. The sound from both HeartMate IITM and HeartMate 3TM can be recorded and analyzed in frequency and time domain. When inserting artificial thrombus in a HeartMate IITM the frequency spectrum is altered. The use of dedicated recording devices is superior to both electronic stethoscope and iPhone/iPodTM, but these handheld devices can be used in clinical settings. The recordings from mock loop circuit and patients appear similar for both HeartMate IITM and HeartMate 3TM. The flow of the devices is affected by the afterload. The HeartMate 3TM is more resistant to increased clot analogs within the pump. For both pumps, best efficacy is seen for clean circuits. The flow rate from the monitor might be misleading since the measured flow rate and the flow rate from monitor can differ due to surrounding conditions. The estimated flow might be adjusted by fitting a parabolic curve.

Conclusion: The use of mock loop circuit to study both flow and sound under different conditions is valid. It is possible to record and study the sound from both HeartMate IITM and HeartMate 3TM. The sound holds information of pump function and appears similar in vivo and in vitro. All recording devices can be used, but dedicated equipment is superior to the more handheld devices, although these might have a function as a screening device. The flow measurement on the monitor might not be valid and optimization of fluid status and afterload can further increase pump efficiency.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2019. p. 86
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1707
Keywords
Afterload, Electronic stethoscope, Flow, HeartMate II, HeartMate 3, iOS-devices, Sound Analysis
National Category
Medical Equipment Engineering
Identifiers
urn:nbn:se:liu:diva-161902 (URN)10.3384/diss.diva-161902 (DOI)9789179299880 (ISBN)
Public defence
2019-12-11, Granitsalen, Hus 448, Campus US, Linköping, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2020-02-04Bibliographically approved

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Sundbom, PerRoth, MichaelGranfeldt, HansKarlsson, Daniel M.Ahn, HenrikGustafsson, FredrikHübbert, Laila
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Division of Cardiovascular MedicineFaculty of Medicine and Health SciencesDepartment of Cardiology in LinköpingAutomatic ControlFaculty of Science & EngineeringDepartment of Biomedical EngineeringDepartment of Thoracic and Vascular SurgeryDepartment of Cardiology in Norrköping
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