New invasive techniques of assessment of the physiological significance of coronary stenoses in humans.

Pressure and flow velocity can be measured distal to coronary stenoses by means of miniaturized sensors with guidewire technology. This is an alternative non-invasive method of assessing functional coronary vessel stenosis severity, applicable for the intermediate stenoses and for the results of coronary interventions. The complexity of the coronary circulation, however, limits the possibility of establishing simple cut-off criteria to identify flow-limiting stenoses. In this paper, we review advantages and limitations of the different pressure and velocity indices and their application in different clinical settings.