Assessment of the effects of dobutamine on myocardial blood flow and oxidative metabolism in normal human subjects using nitrogen-13 ammonia and carbon-11 acetate.
The dual purposes of this study with positron emission tomography were to measure the effects of dobutamine on myocardial blood flow and oxidative metabolism, and to compare carbon-11 (C-11) acetate versus nitrogen-13 (N-13) ammonia in quantitating flow in normal subjects. Flow was quantitated with N-13 ammonia at rest and at peak dobutamine infusion (40 micrograms/kg/min) in 21 subjects. In 11 subjects, oxidative metabolism was also estimated at rest and peak dobutamine infusion using the clearance rate of C-11 acetate, k mono (min-1). A 2-compartment kinetic model was applied to the early phase of the C-11 acetate data to estimate flow. The rest and peak dobutamine rate-pressure products were 7,318 +/- 1,102 and 19,937 +/- 3,964 beats/min/mm Hg, respectively, and correlated well (r = 0.77) with rest and peak dobutamine flows of 0.77 +/- 0.14 and 2.25 ml/min/g determined using N-13 ammonia as a flow tracer. Rest and dobutamine flows estimated with C-11 acetate were highly correlated with those determined with N-13 ammonia (r = 0.92). k mono increased from 0.05 +/- 0.01 to 0.18 +/- 0.02 min-1, and correlated highly with the increase in flows (r = 0.91) and rate-pressure products (r = 0.94). Thus, the increase in cardiac demand associated with dobutamine is highly correlated with an increase in supply and oxidative metabolism. C-11 acetate is a unique tracer that can be used to image both flow and metabolism simultaneously.
Department of Medicine, UCLA School of Medicine 90024-1679.
J
J
Krivokapich
S C
SC
Huang
H R
HR
Schelbert
D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D002250:Carbon Radioisotopes; D003326:Coronary Circulation / Q000187:drug effects*; D004280:Dobutamine / Q000494:pharmacology*; D005240:Feasibility Studies; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D009590:Nitrogen Radioisotopes; D010101:Oxygen Consumption / Q000187:drug effects*; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D009590:Nitrogen Radioisotopes; D004280:Dobutamine