Submitted on March 3, 2008
Revised on May 26, 2008
Accepted on May 27, 2008
Christina Kolyva1, Jos A. E. Spaan2, Jan J Piek, and Maria Siebes1*
1 Academic Medical Center, University of Amsterdam
2 University of Amsterdam
* To whom correspondence should be addressed. E-mail: m.siebes{at}amc.uva.nl.
A novel single-point technique to calculate local arterial wave speed (SPc) has recently been presented and applied in healthy human coronary arteries at baseline flow. We investigated its applicability for conditions commonly encountered in the catheterization laboratory. Intracoronary pressure (Pd) and Doppler velocity (v) were recorded in 29 patients at rest and during adenosine-induced hyperemia in a distal segment of a normal reference vessel and downstream of a single stenosis before and after revascularization. Conduit vessel tone was minimized with nitroglycerin. Microvascular resistance (MR) and SPc were calculated from Pd and v. In the reference vessel, SPc decreased from 21.5 (SD 8.0) m/s to 10.5 (SD 4.1) m/s after microvascular dilation (P<0.0001). SPc was substantially higher in the presence of a proximal stenosis and decreased from 34.4 (SD 18.2) at rest to 27.5 (SD 13.4) m/s during hyperemia (P<0.0001), with a concomitant reduction in Pd by 20 mmHg and MR by 55.4%. Stent placement further reduced hyperemic MR by 26% and increased Pd by 26 mmHg, but paradoxically decreased SPc to 13.1 (SD 7.7) m/s (P<0.0001). Changes in SPc correlated strongly with changes in MR (P<0.001, but were inversely related to changes in Pd (P<0.01). In conclusion, the single-point method yielded erroneous predictions of changes in coronary wave speed induced by a proximal stenosis and distal vasodilation and is therefore not appropriate to estimate local wave speed in coronary vessels. Our findings are well described by a lumped reservoir model reflecting the "windkesselness" of the coronary arteries.
