[Measurements of intracoronary pressure and blood flow velocity]

Abstract

Quantitative coronary angiography and new intracoronary imaging devices are not able to provide functional data for the assessment of the severity of coronary artery stenotic lesions. The functional characterization of coronary artery stenosis gives insight into whether it compromises myocardial perfusion under conditions of pharmacologic or physical stress, i.e., whether the stenosis has hemodynamic relevance. The measurement of trans-stenotic pressure gradients and/or post-stenotic blood flow velocities using very recently developed, miniaturized pressure- and Doppler-angioplasty guidewires (1/3 mm in diameter) provides a valuable alternative to traditional, non-invasive means for the functional assessment of coronary artery disease. The most widely employed parameters for the functional characterization of coronary artery stenoses are the ratio between flow velocities during pharmacologically induced hyperemia and at resting conditions (coronary flow velocity reserve), and the pressure-derived fractional flow reserve, i.e., the ratio of mean poststenotic to mean aortic pressure during hyperemia. Furthermore, poststenotic pressure and flow velocity measurements during and after occlusion of stenosis can be used for the quantitative assessment of collateral circulation among different vascular regions.