Background: The aim of this study was to compare stenosis hemodynamics resulting from intravenous (iv) and intracoronary (ic) adenosine administration.

Methods: In 12 vessels with 25–57% DS (10 patients, 61 ± 8 years), aortic pressure, distal coronary pressure and flow velocity (v) were simultaneously measured during the hyperemic response to either ic injection (40μg bolus) or iv adenosine infusion (140μg/kg/min). Cycle-averaged stenosis pressure gradient (ΔP) and flow velocity were obtained to derive ΔP-v relations from baseline to maximal velocity. For each lesion, we defined v₁ and v₂ as the lowest and highest common flow velocity for ic and iv-derived ΔP-v relations. The equivalence of both adenosine administrations was assessed by the difference in ΔP at v₁ and v₂.

Results: Maximal flow velocity was 56 ± 19 cm/s for ic and 51 ± 15 cm/s for iv, p=NS. The stenosis ΔP-v relations largely overlapped (95% of the velocity range for ic injections; 85% of the flow velocity range for iv infusions). Common flow velocities ranged from v₁= 18 ± 5 cm/s to v₂= 50 ± 15 cm/s. The difference in pressure gradient (ivΔP – icΔP) at v₁ was 0.2 ± 0.7 mmHg and 0.8 ± 3.2 mmHg at v₂ (p=NS), with no trend for differences in ΔP with increasing velocity.

Conclusion: Stenosis ΔP-v relations are not affected by the mode of adenosine administration and comparable hyperemia can be achieved. Ic adenosine injections are preferable, since they are faster and easier to perform and iv infusion tends to induce systemic hemodynamic variability.