The mechanisms of closure of a dissected vessel and

Doppler flow measurement Intracoronary flow velocity information can be obtained with a doppler-tipped guidewire. A continuous plot of average flow velocity allows the identification of stable or unstable flow velocity. Post-procedural cyclic flow variations have been associated with abrupt vessel closure, and experimental and clinical studies indicate that cyclic flow variation is a reliable marker of the formation of occlusive platelet aggregates.9,19,20 However, despite the great potential for the prediction of post-procedural vessel closure, the phenomenon of cyclic flow variation is rare in patients with an initially good or optimal post-procedure angiographic result, or with a dissection associated with an angiographic normal flow. The low incidence of the phenomenon, and the need for a significant prolongation of the procedure, have prevented the use of intracoronary doppler technique in routine interventional procedures. Nevertheless, according to the angioscopic study results, postprocedure doppler measurements have confirmed that abrupt vessel closure may be the result of a superimposed thrombosis on a dissected vessel.