Publications by authors named "Wilbert H Aarnoudse"

3 Publications

  • Page 1 of 1

Continuous infusion thermodilution for assessment of coronary flow: theoretical background and in vitro validation.

Med Eng Phys 2009 Jul 23;31(6):688-94. Epub 2009 Feb 23.

Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.

Direct volumetric assessment of coronary flow during cardiac catheterization has not been available so far. In the current study continuous infusion thermodilution, a method based on continuous infusion of saline into a selective coronary artery is evaluated. Theoretically, volumetric flow can be calculated from the known infusion rate (Q(i)), the temperatures of the blood (T(b)), the saline (T(i)), and the mixture downstream to the infusion site (T). We aimed to validate and optimize the measurement method in an in vitro model of the coronary circulation. Full mixing of infusate and blood was found to be the main prerequisite for accurate determination of the coronary flow. To achieve full mixing the influence of catheter design, infusion rate, and location of temperature measurement were assessed. We found that continuous infusion thermodilution slightly overestimated coronary flow determined by directly measured reference flow by 7+/-8%, over the entire physiological flow range of 50-250 ml/min. These results were found using a specially designed infusion catheter (infusion mainly through distally located sideholes), a high enough infusion rate (25 ml/min), and measurement of the mixing temperature between 5 and 8 cm distal from the tip of the infusion catheter. Absolute coronary flow rate can be measured reliably by the continuous infusion method when full mixing is present, under the conditions mentioned above.
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http://dx.doi.org/10.1016/j.medengphy.2009.01.006DOI Listing
July 2009

A physiologically representative in vitro model of the coronary circulation.

Physiol Meas 2004 Aug;25(4):891-904

Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.

With the development of clinical diagnostic techniques to investigate the coronary circulation in conscious humans, the in vitro validation of such newly developed techniques is of major importance. The aim of this study was to develop an in vitro model that is able to mimic the coronary circulation in such a way that coronary pressure and flow signals under baseline as well as hyperaemic conditions are approximated as realistically as possible and are in accordance with recently gained insights into such signals in conscious man. In the present in vitro model the heart, the systemic and coronary circulation are modelled on the basis of the elements of a lumped parameter mathematical model only consisting of elements that can be represented by segments in an experimental set-up. A collapsible tube, collapsed by the ventricular pressure, represents the variable resistance and volume behaviour of the endocardial part of the myocardium. The pressure and flow signals obtained are similar to physiological human coronary pressure and flow, both for baseline and hyperaemic conditions. The model allows for in vitro evaluation of clinical diagnostic techniques.
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http://dx.doi.org/10.1088/0967-3334/25/4/009DOI Listing
August 2004

False-negative myocardial scintigraphy in balanced three-vessel disease, revealed by coronary pressure measurement.

Int J Cardiovasc Intervent 2003 ;5(2):67-71

Department of Cardiology, Catharina Hospital, Eindhoven, The Netherlands.

In nuclear perfusion imaging of the myocardium, a false-negative test result in patients with balanced three-vessel disease is a well-known pitfall. This paper describes a patient with typical chest pain and a negative myocardial perfusion scintigram. At coronary angiography, intermediate stenoses in the left anterior descending (LAD), left circumflex (LCX), and right coronary (RCA) arteries were present. Fractional flow reserve, measured by coronary pressure measurement, was 0.54, 0.56, and 0.66 respectively for the LAD, LCX, and RCA, unequivocally demonstrating the presence of balanced three-vessel disease. The patient underwent successful bypass surgery and remained event-free thereafter.
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http://dx.doi.org/10.1080/14628840310003244DOI Listing
September 2003
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