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(Circulation. 2000;101:e100.)
© 2000 American Heart Association, Inc.

Circulation Electronic Pages

Assessment of Coronary Flow Reserve by Contrast-Enhanced Second Harmonic Echo Doppler

Rolf Jenni, MD, MSEE; Andre Linka, MD; Matthias Barton, MD

Division of Echocardiography, Cardiology, University Hospital, Zürich, Switzerland

	Introduction

 
To the Editor:

With regard to the recent article by Caiati et al on the use of echo Doppler for the noninvasive determination of coronary flow reserve,¹ several issues regarding this methodology should be clarified to ensure correct interpretation of the data. The authors used contrast-enhanced Doppler to determine blood flow velocity in coronary arteries of patients with and without significant stenosis of the left anterior descending coronary artery. Irrespective of the Doppler device, the calculation of coronary flow reserve is based on velocity information only. Furthermore, these measurements are performed on the assumptions that (1) the shape of the velocity profile is an invariant one and (2) the cross-sectional area of the vessel remains constant both at rest and under hyperemia.

The authors cited previous work by Rossen et al,² who compared effects of intravenous dipyridamole and adenosine on blood flow velocity in patients with and without coronary artery disease. These data were validated by demonstrating that proximal coronary artery diameter was unchanged during infusion, as demonstrated by quantitative coronary angiography.² In contrast to that study, in which blood flow velocity was measured proximally, Caiati et al used the distal or the middle part of the left descending coronary artery for flow-reserve assessment after infusion of dipyridamole without determining coronary artery diameter, which is likely to be affected.³ Based on the assumptions mentioned above, coronary flow reserve will be underestimated. Furthermore, assessment of coronary flow reserve may be complicated by changes in the velocity profile, yielding an error as . . . [Full Text of this Article]

Carlo Caiati, MD; Cristiana Montaldo, MD; Norma Zedda, MD; Alessandro Bina, MD; Sabino Iliceto, MD, FACC

Institute of Cardiology, University of Cagliari, Cagliari, Italy