Roberts, E.B.; (2008) Assessment of coronary artery stenosis using myocardial contrast echocardiography. Doctoral thesis , University of London.

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Abstract

The theoretical advantage of perfusion data over wall motion data for diagnosing coronary artery stenosis relates to the temporal sequence of these phenomena in the ischaemic cascade. Myocardial perfusion evaluation could thus provide earlier information than wall motion assessment, with important clinical consequences. This thesis examines myocardial perfusion assessment using ultrasound and micro-bubble contrast in stable coronary artery stenosis. The first set of experiments were undertaken to establish both a means of infusing Optison (GE Healthcare, UK), and of displaying static frame contrast signal using Power Contrast Imaging (Acuson Sequoia, Siemens Medical Solutions, Mountain View, CA, USA.). Three Optison concentrations, five infusion rates, and five trigger intervals were evaluated. This revealed an appropriate concentration and infusion rate for Optison and identified an ideal trigger interval of one in four cardiac cycles. The second part of this study evaluated Power Contrast Imaging with Optison infusion in stable single or double vessel coronary artery stenosis. Perfusion assessment during Adenosine vasodilator stress was compared with standard wall motion assessment during Dobutamine stress, coronary angiography being the diagnostic standard. Among twenty-eight subjects and eighty-four coronary territories, Power Contrast Imaging had low sensitivity but equivalent specificity compared to wall motion assessment. The third component of this research evaluated micro-bubble preserving real time Coherent Contrast Imaging (Acuson Sequoia , Siemens Medical Solutions) alongside Optison infusion in stable single or double vessel coronary stenosis. Thirty-eight subjects and one hundred and fourteen coronary arteries were evaluated. Each subject underwent Dobutamine stress, during which standard wall motion, contrast wall motion, and contrast perfusion imaging were all assessed, the diagnostic standard being coronary angiography. This demonstrated that contrast wall motion evaluation is accurate and that combined contrast wall motion and perfusion imaging is at least equivalent to standard wall motion imaging alone for detecting underlying coronary stenosis.

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