Comparison of maximal myocardial blood flow during adenosine infusion with that of intravenous dipyridamole in normal men.
OBJECTIVE
This study compared quantitatively the efficacy of intravenous adenosine and dipyridamole for pharmacologic induction of myocardial hyperemia.


BACKGROUND
Pharmacologic vasodilation is used increasingly for induction of myocardial hyperemia in conjunction with radionuclide imaging of myocardial blood flow. Although both intravenous dipyridamole and adenosine have been used, the magnitude of hyperemia induced by these agents and the hyperemia to baseline blood flow ratios have not been quantified and compared.


METHODS
Twenty normal volunteers were studied with dynamic positron emission tomography (PET) and intravenous nitrogen-13 ammonia. Myocardial blood flow was quantified with a two-compartment tracer kinetic model.


RESULTS
Myocardial blood flow at rest averaged 1.1 +/- 0.2 ml/min per g and increased significantly to 4.4 +/- 0.9 ml/min per g during adenosine and 4.3 +/- 1.3 ml/min per g after dipyridamole administration. Hyperemia to baseline flow ratios averaged 4.3 +/- 1.6 for adenosine and 4.0 +/- 1.3 for dipyridamole. The average flow ratios and the maximal flows achieved were similar for both agents, but there was considerable variation in the individual response to these agents, as indicated by the range of hyperemia to baseline flow ratios (from 2.0 to 8.4 for adenosine and from 1.5 to 5.8 for dipyridamole). In addition, the hyperemic responses to dipyridamole and to adenosine differed by greater than 1 ml/min per g in nine subjects.


CONCLUSIONS
Despite these inter- and intraindividual differences, we conclude that both agents are equally effective in producing myocardial hyperemia.
Chan
S Y
SY
Department of Radiological Sciences, University of California, Los Angeles School of Medicine 90024-1721.
Brunken
R C
RC
Czernin
J
J
Porenta
G
G
Kuhle
W
W
Krivokapich
J
J
Phelps
M E
ME
Schelbert
H R
HR
D000241:Adenosine; D000328:Adult; D003326:Coronary Circulation / Q000187:drug effects*; D004176:Dipyridamole; D005080:Exercise Test / Q000379:methods; D006321:Heart / Q000000981:diagnostic imaging*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009590:Nitrogen Radioisotopes; D014055:Tomography, Emission-Computed
D009590:Nitrogen Radioisotopes; D004176:Dipyridamole; D000241:Adenosine