The impact of hydrostatic pressure on the result of physiological measurements in various coronary segments

Abstract Background The effect of hydrostatic pressure on physiological intracoronary measurements is usually ignored in the daily clinical practice. Purpose To investigate the effect of resting Pd/Pa (distal/aortic pressure) and FFR (fractional flow reserve) adjustment based on the calculation of hydrostatic pressure gradient between the coronary orifice and the pressure wire sensor. Methods 41 FFR measurements (between 0.7 and 0.9) were selected. The difference in height of the orifice and the sensor was defined in cm on the basis of 3D coronary reconstruction. The resting Pd/Pa and FFR were adjusted by subtracting the pressure gradient from the distal pressure. Measurements were also performed from 2D lateral projections for each coronary segment visible (n=305). Results In case of the left anterior descending artery (LAD), each segment was located higher (proximal: –13.69±5.4; middle: –46.13±6.1; distal: –56.80±7.7 mm), whereas for the circumflex (CX), lower (proximal: 14.98±8.3; distal: 28.04±6.3 mm) compared to the orifice. In case of the right coronary artery (RCA), the distance from the orifice was much less (proximal: –6.39±2.9; middle: –6.86±7.0; distal: 17.95±6.6 mm). The posterolateral (PL) and posterior descending (PD) branches of the distal RCA were located lower than the orifice (PL: 29.65±6.1; PD: 17.53±6.6 mm). The effect of these distances on pressure ratios at 100 Hgmm aortic pressure was between −0.044 and 0.023. After correction, values of 11 and 5 patients (27% and 12%) stepped the 0.92 Pd/Pa and 0.80 FFR cut-off values, respectively. There was a strong correlation between the 3D and 2D methods (r=0.98; p