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Design of a single segment conductance catheter for measurement of left ventricular volume
KTH, Superseded Departments, KTH Syd.
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2001 (English)In: Annual Reports of the Research Reactor Institute, Kyoto University, 2001, 151-154 p.Conference paper, Published paper (Refereed)
Abstract [en]

The objective of this paper is to investigate how to best position the sensing electrodes on a single segment conductance catheter, and to calculate the expected performance. Using electrode potential data, obtained with the present five segment conductance catheter in pig experiments, we have interpolated the electrical field at any given point of time, and calculated what volume curve to expect with only two sensing electrodes. Comparison shows that the deviation between our calculated method and the present one is stable and small. Mean deviation with optimized electrode positions was 0.05% per sample, and the maximum deviation found for a single time sample was 2.57%. This indicates that it is possible to build a thin single segment catheter with as good performance as for the present five segment conductance catheter.

Place, publisher, year, edition, pages
2001. 151-154 p.
Keyword [en]
Left ventricular volume, conductance catheter, segment volume, pigs
National Category
Medical Laboratory and Measurements Technologies
Identifiers
URN: urn:nbn:se:kth:diva-6517DOI: 10.1109/IEMBS.2001.1018873OAI: oai:DiVA.org:kth-6517DiVA: diva2:11252
Note
QC 20100922Available from: 2006-12-06 Created: 2006-12-06 Last updated: 2010-09-22Bibliographically approved
In thesis
1. New approaches to monitoring of cardiac function
Open this publication in new window or tab >>New approaches to monitoring of cardiac function
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Left ventricular pumping performance may be described by intraventricular pressure and volume variables, usually presented as a pressure-volume plot. However, on-line monitoring of left ventricular pressure and volume with high temporal resolution requires the use of an invasive catheter technique such as, for example, the conductance catheter method. On the other hand, the very invasiveness and complexity of this approach makes it less suitable for clinical use. It is then not surprising that there has been long-felt need to make the conductance method less invasive and attempts have been made to adjust the method to clinical demands and routine in order to extract more information from pressure-volume interplay and possibly translate relevant data to their non-invasive estimates.

In the present studies, a standard five segmental conductance catheter was used in animal (pig) experiments. Segmental conductances were compared to global conductance. Since the mid-ventricular segment was shown to reflect global volume, which was also shown on theoretical basis, it was concluded that a single segmental catheter most probably could be used to estimate global left ventricular volume.

Subsequently, a thin and flexible single segmental conductance catheter was constructed and applied to an animal (pig) experimental model. Results were reproducible and very few arrythmias were detected.

At the next stage, left ventricular isovolumic phases were investigated using the standard conductance catheter method, as well as echocardiographically derived tissue velocity doppler. Conductance was shown to decrease during isovolumic contraction, and an adjustment method was proposed in order to account for the subsequent decrease in pressure-volume loop area.

In separate experiments, the left ventricular pressure wave form during left ventricular systole was examined, and an algorithm was proposed to discriminate between the changes in afterload, preload and contractility. Results showed clearly discernible patterns of the respective load and contractility alternation.

Finally, the left ventricular continuous area was monitored continuously during the entire cardiac cycle as a measure of left ventricular volume dynamics in normal subjects and three patients with left ventricular abnormalities using echocardiographic automatic boundary detection. The left ventricular area thus obtained was plotted against its first derivative, to form a flow-volume estimates loop, in accordance with the flow-volume examinations used in respiratory physiology. Data obtained from the abnormal ventricles were presented as flow-volume estimates loops, exemplifying the possible use of the method.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. 77 p.
Series
Trita-STH : report, ISSN 1653-3836 ; 2006:04
Keyword
left ventricle, pressure and volume
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:kth:diva-4211 (URN)978-91-7178-507-7 (ISBN)
Public defence
2006-12-15, 4X, plan 4, Nobels allé 8, Huddinge, 09:00
Opponent
Supervisors
Note
QC 20100922Available from: 2006-12-06 Created: 2006-12-06 Last updated: 2010-09-22Bibliographically approved

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