Invasive assessment of the coronary circulation: intravascular ultrasound and Doppler.

Abstract

Advances in catheter-based technology have put many innovative techniques at the disposal of the clinical investigator. Intravascular ultrasound (IVUS), in particular, has facilitated the more detailed functional and morphological assessment of the coronary circulation, and will be the major focus of this review. Selective intracoronary drug infusion may be desirable for a number of reasons. When examining in vivo vascular responses, systemic drug administration causes concomitant effects on organs, such as the brain and kidney, and influences neurohumoral reflexes through changes in systemic haemodynamics. Intracoronary infusions have the advantage of assessing the heart and coronary circulation in relative isolation without invoking systemic effects. This is particularly important for the assessment of cardiac and coronary function which is heavily dependent on changes in the systemic vasculature and haemodynamics. In addition, relatively high doses can be administered locally which may be important for the desired physiological or therapeutic effect and may be further facilitated by the use of local drug delivery systems. Finally, combining intracoronary drug administration with coronary sinus catheterization and sampling can further extend the assessment of the coronary circulation to include additional aspects of cardiac metabolism and function. In addition to providing functional information, IVUS provides an invasive method of assessing arterial structure and morphology. Detailed and high-resolution examination of the proximal coronary vasculature is possible with precise and accurate definition of tissue planes [1, 2]. This permits the quantitative assessment of atherosclerotic burden and composition as well as enabling the assessment of systemic therapeutic interventions targeted at reducing atherosclerosis such as lipid-lowering therapy [3, 4].