ASSESSING CORONARY FLOW PHYSIOLOGY WITH INTRACORONARY DOPPLER FOLLOWING CORONARY INTERVENTIONS

Although coronary angiography has been the gold standard for assessing coronary artery stenoses, it yields information primarily about the a natomical severity of coronary artery disease, which frequently does n ot correlate with its physiological severity. Coronary interventions ( PTCA, atherectomy, laser, etc.) are performed primarily to improve cor onary flow physiology. Coronary flow physiology may be a more importan t end point than angiography following coronary interventions that wer e performed to normalize coronary flow physiology. in addition, the ph ysiological significance of angiographically intermediate stenoses sho uld be assessed before proceeding with catheter-based revascularizatio n. Currently, the Doppler guidewire is available for routine clinical assessment of coronary flow physiology in the Cardiac Catheterization Lab. Several Doppler measurements have been used to assess the physiol ogical effect of a stenosis, including the diastolic-systolic velocity ratio, proximal-distal velocity ratio, coronary flow reserve, continu ity equation, and the hyperemic diastolic pressure-flow relationship. The Doppler derived coronary flow reserve correlates highly with stres s nuclear perfusion images. These Doppler measurements have been made following PTCA, directional atherectomy, rotational atherectomy, and e xcimer laser. Following coronary interventions, adverse clinical event s may be predicted if there is impaired flow physiology or cyclic flow variations. Many of the Doppler measurements used for assessing the l esion severity remain abnormal following successful coronary intervent ions for reasons unrelated to the lesion. Conversely, normalization of coronary physiology does not guarantee an adequate anatomical result. Further clinical trials will provide a more complete definition of th e exact role for coronary flow velocity assessment following coronary interventions.