CORONARY-ARTERY FLOW MONITORING FOLLOWING CORONARY INTERVENTIONS

Technologic innovations have made it possible to measure coronary arte ry blood flow in awake patients. Both flow velocity as well as flow re serve can be assessed. In particular, the period of time immediately f ollowing coronary interventions offers a unique opportunity to study i mportant features of coronary flow behavior. In 22 patients, coronary flow reserve was measured before and after an intervention, either ang ioplasty or atherectomy, using a 0.018-in Doppler guidewire (Flowire). The minimum lumen diameter (MLD) was increased from 1.0 +/- 0.4 to 1. 7 +/- 0.4 mm, while coronary flow velocity increased significantly, ri sing from 29 +/- 13 to 39 +/- 14 cm/sec (p < 0.025). The maximum hyper emic velocity also increased, from 44 +/- 16 to 69 +/- 21 cm/sec. Usin g only the preintervention or postintervention values, the flow reserv e ratio was 1.53 +/- 0.4 prior to intervention and 1.84 +/- 0.5 after intervention (p = nonsignificant). However, the postintervention value may have been artifactually reduced by the fact that both resting as well as hyperemic velocities increased. When the postintervention flow reserve ratio was recalculated, using the preintervention resting val ue, flow reserve ratio was seen to increase from 1.53 +/- 0.4 to 2.73 +/- 1.2 (p < 0.001). Measurements of coronary flow in the postinterven tion period also revealed several interesting phenomena. Spasm of a co ronary artery was documented, and its resolution in response to intrac oronary nitroglycerin was observed. Elastic recoil following angioplas ty was documented by gradual decline in coronary flow over 30 minutes. Cyclic flow variations were observed; these are due to the accumulati on and dislodgement of platelet aggregates at sites of coronary stenos is with endothelial injury. Their prompt abolition with the administra tion of a monoclonal antiplatelet antibody [c7E3 F(ab)] was documented - In conclusion, we have begun to characterize several interesting and potentially useful coronary flow phenomena that may occur following c oronary interventions. We have found this information to be clinically useful.