Assessment of coronary vasomotor tone in humans.

The assessment of endothelium-mediated modulation of coronary vasomotor tone in the intact human circulation under physiologic conditions requires very precise determination of both epicardial artery diameters, reflecting effects within the conduit vessels, as well as coronary blood flow, reflecting effects within the resistance vasculature during cardiac catheterization. In the present report, the accuracy and limitations of quantitative approaches to assess arterial dimensions from coronary angiograms are discussed. Using state-of-the-art image-processing techniques and x-ray imaging, epicardial artery diameter changes within the range of 8-10% can be reliably detected by quantitative coronary angiography. In addition, advances in interventional techniques do provide a means to selectively assess intracoronary blood-flow velocities using intracoronary Doppler catheters. Combining epicardial artery diameter measurements and intracoronary blood-flow velocity parameters allows for a reasonably accurate instantaneous estimate of coronary arterial blood flow. The advantages and limitations of the intracoronary Doppler technique compared to other techniques are discussed.

[The significance of improved angiocardiography systems in the quantitative assessment of proximal coronary stenosis. Comparison of angiographic and hemodynamic measurements in vivo]. / Die Bedeutung verbesserter Angiokardiographiesysteme für die Quantifizierung proximaler Koronarstenosen. Vergleich angiographischer und hämodynamischer Messungen in vivo.

The use of high resolution X-ray techniques for biplane coronary angiography can improve the quantitative assessment of coronary stenoses when perpendicular projections in both views can be achieved. Angiograms thus obtained of coronary stenoses before (n = 17) and after (n = 14) coronary dilatation were evaluated for mean and minimal stenosis diameters of two planes and for percent narrowing of stenoses (caliper measurements). Comparisons with transstenotic pressure gradients showed significant or highly significant correlations for all dimensional parameters. It is concluded that quantitative angiographic analysis of coronary stenoses yields highly reliable results of hemodynamic relevance. In addition, a mean diameter of less than 1.6 mm could be identified as indicating hemodynamically significant stenosis.