Abstract 2106: Quantification of Doppler Flow Velocity-Derived Pulmonary Flow Reserve in Healthy Primates
Background: Pulmonary vascular disease (PVD), characterized by progressive pulmonary microvascular destruction, is only clinically evident late in its course when pulmonary artery pressure (PAP) rises. We hypothesized that changes in pulmonary flow reserve (PFR, maximal hyperemic vs. basal flow) may precede the PAP rise and thus aimed to:
validate invasively-measured Doppler flow-velocity (vdopp) as a marker of pulmonary blood flow and
define the optimal hyperemic agent and dose for vdopp-derived PFR (PFRdopp) assessment, in healthy baboons.
Methods: Eight baboons were anaesthetized and a Doppler-sensing guidewire (DSG) placed in a segmental pulmonary artery. Angiographically-determined vessel diameter (D) and DSG-measured vdopp were obtained at baseline and at increasing intrapulmonary normal saline (NS) infusion rates and boluses. Escalating local doses of adenosine, acetylcholine & papaverine were administered, vdopp obtained and PFRdopp calculated.
Results: NS administration did not change D or vdopp (panels A & B, p≥0.4). Adenosine produced a dose-dependent increase in vdopp maximal at 200μg/kg/min (p<0.0001, panel C), papaverine to 24mg significantly increased vdopp (p<0.0001, panel D) but acetylcholine to 10−l concentration reduced vdopp (p=0.0008). Adenosine and papaverine-derived PFRdopp values were 1.5–2.0.
Conclusions: As D does not vary with NS or hyperemic agent administration, vdopp is a valid marker of pulmonary blood flow. Adenosine and papaverine can be used with a Doppler-flow wire to derive PFR, with normal baboon PFRdopp being 1.5 – 2.0. Thus PFRdopp may be a potential novel marker for investigating early PVD.