ASSESSMENT OF CORONARY-ARTERY STENOSIS DURING PTCA BY MEASUREMENT OF THE TRANS-STENOTIC PRESSURE-GRADIENT - COMPARISON WITH QUANTITATIVE CORONARY ANGIOGRAPHY

A fibreoptic pressure sensor mounted on an 0.018 inch guidewire (Press ure Guide(TM), RadiMedical Systems, Uppsala, Sweden) was used to measu re the trans-stenotic pressure gradient in 20 patients admitted for pe rcutaneous transluminal coronary angioplasty (PTCA) of a single, discr ete stenosis. Pressure measurements were made both at rest and during maximal vasodilatation induced by intracoronary injection of papaverin e. From the ratio of distal coronary pressure divided by the proximal pressure, the relative coronary flow reserve was calculated. The aim o f the study was to compare the different pressure-derived parameters b y correlating them to stenosis geometry estimated by quantitative coro nary angiography. There was a moderate correlation between baseline pr essure gradient and percent area stenosis; r=0.64, P<0.001 and minimal cross-sectional area; r=0.45, P<0.005. A higher correlation was found between hyperaemic pressure gradient and area stenosis (r=0.80, P<0.0 01) and minimal cross-sectional areas, respectively (r=0.55, P<0.005). The best correlation was found between relative coronary flow reserve and area stenosis (r=0.86, P<0.001) and minimal cross-sectional area (r=0.70, P<0.001). In conclusion, pressure measurement using a pressur e guidewire is useful as a complement to angiography in evaluation of coronary stenoses during PTCA. Pressures should be measured during max imal vasodilatation. Relative coronary flow reserve calculated from th e pressure measurements provides additional information about the frac tion of normal maximal flow possible in the presence of a stenosis.