New techniques for the assessment of coronary microvascular abnormalities

Abstract

The assessment of abnormalities in the coronary microvasculature is particularly ­challenging since unlike the epicardial coronary arteries, the microcirculation cannot be readily imaged and thus its evaluation relies on functional techniques. These functional techniques infer the presence of microvascular coronary dysfunction by either (a) detecting the presence of myocardial ischaemia or one its ischaemic cascade surrogates, or (b) measuring coronary or myocardial blood flow as indicators of coronary resistance, in patients without obstructive coronary artery disease. The ischaemic cascade markers include the use of electrocardiography, metabolic imaging, transmyocardial metabolic studies, myocardial perfusion imaging, and imaging methods for the assessment of myocardial contractility. The blood flow techniques include coronary sinus thermodilution methods, myocardial perfusion reserve imaging, specialised angiographic techniques, coronary Doppler and pressure wire methods. As many of the earlier chapters have focussed on the ischaemic cascade markers, this chapter primarily focuses on the blood flow techniques, particularly those undertaken in the cardiac catheterisation laboratory setting.