The present study sought to compare the temporal relation between maximal coronary flow (peak hyperemia) and minimal coronary/aortic (Pd/Pa) pressure ratio for intracoronary (IC) and intravenous (IV) adenosine administration. Peak hyperemia is assumed to coincide with the minimal Pd/Pa value. However, this has not been confirmed for systemic hemodynamic variations during IV adenosine infusion. Hemodynamic responses to IV and IC adenosine administration were obtained in 12 patients (14 lesions) using combined intracoronary pressure and flow velocity measurements. A fluid dynamic model was used to predict the change in Pd/Pa for different stenosis severities and varying Pa. Hemodynamic variability during IV adenosine hyperemia was greater than during IC adenosine, assessed by coefficient of variation. During IV adenosine, flow velocity peaked 28 ± 4 s after the onset of hyperemia, while Pd/Pa reached a minimum (0.82 ± 0.01) 22 ± 7 s later (p<0.05), when Pa had declined by 6.1% and hyperemic velocity by 4.5% (p<0.01). Model outcomes corroborated the role of variable Pa in this dissociation. In contrast, maximal flow and minimal Pd/Pa coincided for IC adenosine, with IV-equivalent peak velocities and higher Pd/Pa ratio (0.86 ± 0.01, p<0.01). Hemodynamic variability during continuous IV adenosine infusion can lead to temporal dissociation of minimal Pd/Pa and peak hyperemia, in contrast to IC adenosine injection where maximal velocity and minimal Pd/Pa coincide. Despite this variability, stenosis hemodynamics remained stable with both ways of adenosine administration. Our findings suggest advantages of IC over IV adenosine to identify maximal hyperemia from pressure-only measurements.
- Coronary Artery Disease
- Coronary Blood Flow
- Fractional Flow Reserve
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology