ESTIMATION OF CORONARY FLOW RESERVE BY INTRACORONARY DOPPLER FLOW PROBES AND DIGITAL ANGIOGRAPHY

This prospective study investigated two different methods used clinically to estimate coronary flow reserve during cardiac catheterization. First, the relationship between simultaneous digital angiography and intracoronary Doppler velocity measurements was determined in 61 patients. The correlation coefficient for 233 simultaneous pairs of papaverine‐induced flow reserve was 0.70 (Doppler = 0.41 digital + 0.93, P<0.0001). Repeated basal flow determinations showed little variability (Doppler: 2 ± 5% (mean ± 95% confidence intervals); digital: 3 ± 10%). Repeated hyperemic flow estimates by the Doppler technique were more reproducible (10 ± 2%) than those by the digital method (26 ± 6%). Second, estimates of coronary flow reserve by side‐mounted and end‐mounted Doppler catheters were compared in vitro and in patients. In vitro measurement of blood velocity was linear for both catheter designs and was highly correlated with volume flow determined by electromagnetic flow meter (r = 0.99 side‐mounted; r = 0.96 end‐mounted). In patients (n=20), average coronary flow reserve for the side‐mounted Doppler crystal was 2.64 ± 0.15 and for the end‐mounted Doppler crystal was 2.40 ± 0.14 (P0.02). When flow reserve was determined twice for each catheter, there was greater variability in repeated measurements using the side‐mounted Doppler crystal (21 ± 10%, n = 14) than using the end‐mounted Doppler crystal (12 ± 4%, n = 32). When the two catheters were placed sequentially in the same patient, measurements of flow reserve varied by 19.0 ± 5.5% (n =20). A specially constructed catheter with both side‐ and end‐mounted crystals on the same shaft was evaluated in five patients. Coronary flow reserve was similar for both crystals (side: 2.54 ± .68, end: 2.60 ± .20) but variation between crystals remained high (19.8 ± 4.4%). Copyright © 1990 John Wiley & Sons, Ltd.