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Analysis and processing of laser Doppler perfusion monitoring signals recorded from the beating heart
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
Östergötlands Läns Landsting, Heart Centre.
Östergötlands Läns Landsting, Heart Centre.
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. (MINT)ORCID iD: 0000-0002-0012-7867
2003 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 41, no 3, 255-262 p.Article in journal (Refereed) Published
Abstract [en]

Laser Doppler perfusion monitoring (LDPM) can be used for monitoring myocardial perfusion in the non-beating heart. However, the movement of the beating heart generates large artifacts. Therefore the aim of the study was to develop an LDPM system capable of correlating the laser Doppler signals to the cardiac cycle and to process the signals to reduce the movement artifacts. Measurements were performed on three calves, both on the normal beating heart and during occlusion of the left anterior descending coronary artery (LAD). The recorded LDPM signals were digitally processed and correlated to the sampled ECG. Large variations in the output (perfusion) and DC signals during the cardiac cycle were found, with average coefficients of variation of 0.36 and 0.14 (n-14), respectively. However, sections with a relatively low, stable output signal were found in late diastole, where the movement of the heart is at a minimum. Occlusion of the LAD showed the importance of recording the laser Doppler signals at an appropriate point in the cardiac cycle, in this case late systole, to minimise movement artifacts. It is possible to further reduce movement artifacts by increasing the lower cutoff frequency when calculating the output signal.

Place, publisher, year, edition, pages
Springer, 2003. Vol. 41, no 3, 255-262 p.
National Category
Medical Laboratory and Measurements Technologies
Identifiers
URN: urn:nbn:se:liu:diva-24478DOI: 10.1007/BF02348429ISI: 000183399600004Scopus ID: 2-s2.0-0037842891Local ID: 6594OAI: oai:DiVA.org:liu-24478DiVA: diva2:244798
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-02-22Bibliographically approved
In thesis
1. Movement artifact reduction in laser Doppler blood flowmetry: myocardial perfusion applications
Open this publication in new window or tab >>Movement artifact reduction in laser Doppler blood flowmetry: myocardial perfusion applications
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Laser Doppler perfusion monitoring (LDPM) and imaging (LDPI) enable assessment of tissue microvascular perfusion. The techniques are based on the Doppler broadening of the optical spectrum occurring when coherent laser light is scattered by moving red blood cells (RBC). However, if tissue motion not related to moving RBCs is present, artifacts arise in the derived perfusion estimate. The aim of this thesis was to develop and evaluate methods to reduce tissue motion influence on the perfusion estimate in general and for the specific purpose of enabling myocardial perfusion monitoring in the beating heart.

An LDPM system, based on digital signal processing, was developed for myocardial perfusion assessment. To achieve an accurate estimate of the local microvascular perfusion, the varying myocardial tissue motion during the cardiac cycle is taken into account. By means of ECG-triggering, periods of minimum myocardial tissue motion can be pinpointed. The system and proposed methods were successfully evaluated both in an animal model (3 calves) and during coronary artery bypass grafting (CABG) on 13 humans. Animal studies showed the importance of processing during minimum tissue motion, at late diastole and/or late systole, to reduce movement artifacts. The human evaluation confirmed earlier animal findings and revealed low flow situations in the intraoperative phase. Influence of mechanical ventilation on the myocardial blood flow was found. The results justify investigation postoperative of CABG, where myocardial perfusion monitoring may give a rapid response to potential ischemia.

The influence of tissue motion on LDPI was studied in model measurements and on the skin. A relatively large tissue velocity, compared to microvascular flow velocities, was needed to significantly influence the perfusion signal. Movement artifact magnitude depended on the movement direction and the surface structure. An LDPI system utilizing a polarization technique that blocks specularly reflected light is proposed. The method was evaluated in a flow model and on the skin of 12 subjects and was found to significantly reduce influence from tissue motion. Finally, a theoretical explanation of the origin of LDPI movement artifacts is proposed. Reduction of movement artifacts makes measurements more reliable and increases the potential of LDPI as a clinical tool.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2005. 84 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 935
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28804 (URN)13992 (Local ID)91-85297-73-9 (ISBN)13992 (Archive number)13992 (OAI)
Public defence
2005-04-29, Linden, ingång 65, Campus US, Linköpings universitet, Linköping, 09:15 (English)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-11-30Bibliographically approved

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Karlsson, Daniel M GAhn, Henrik CasimirLönn, UrbanWårdell, Karin

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