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The assessment of acute load and contractility changes by left ventricular pressure measurements
Department of Medical Engineering, Karolinska Institutet, Stockholm, Sweden.
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2006 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 27, no 12, 1281-1292 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to establish whether analysis of the left ventricular pressure waveform provides indicative information about cardiac load and contractility and to develop an algorithm for computer-based assessment of changes in these variables. In eight healthy standard breed anaesthetized open-chest pigs, a high frequency response guide-wire mounted pressure sensor was introduced into the left ventricle. Preload reduction was induced by vena cava occlusion, afterload increase by an i.v. injection of phenylephrine and increased contractility by an i.v. injection of adrenalin. Left ventricular pressure waveform analysis was performed by plotting the slope of the pressure curve during the systolic ejection period versus maximal systolic pressure. The analysis revealed characteristic changes in left ventricular pressure and pressure waveform and identified easily discernible reaction patterns in the slope versus maximal pressure plot, specific for each provocation. Analysis of the left ventricular waveform provides indicative information about loading conditions and contractility. The proposed algorithm can easily be implemented in pressure monitoring systems allowing real-time assessment and discrimination of acute changes in preload, afterload and myocardial performance.

Place, publisher, year, edition, pages
2006. Vol. 27, no 12, 1281-1292 p.
Keyword [en]
monitoring, left ventricle, pressure waves, loading conditions, contractility
National Category
Medical Laboratory and Measurements Technologies
URN: urn:nbn:se:kth:diva-6522DOI: 10.1088/0967-3334/27/12/003ISI: 000242549900005OAI: diva2:11257
QC 20100922Available from: 2006-12-06 Created: 2006-12-06 Last updated: 2012-03-23Bibliographically 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.
Trita-STH : report, ISSN 1653-3836 ; 2006:04
left ventricle, pressure and volume
National Category
Medical Laboratory and Measurements Technologies
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
QC 20100922Available from: 2006-12-06 Created: 2006-12-06 Last updated: 2010-09-22Bibliographically approved

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Söderqvist, EmilBrodin, Lars-Åke
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