Pacing and the non-invasive evaluation of myocardial fatty acid metabolism by means of 17-123I-heptadecanoic acid scintigraphy.
The extent of myocardial non-esterified fatty acid (NEFA) oxidation depends among other things on exogeneous NEFA supply and energy demand. In 6 patients with a multi-programmable pacemaker scintigraphy with 17-123Iodo-heptadecanoic acid (17-123I-HDA) was performed to investigate NEFA metabolism at two levels: at a control level (basal heart rate 69 +/- 6) and at increased pace frequency (104 +/- 5). In both situations the derived time-activity curves, measured during a period of 75 min, were fitted with a monoexponential plus a constant curve: A(t) = A(0).exp (-t In2/T1/2) + C. The half-time value, the uptake measured as the peak activity and the relative size of the oxidation pool were determined. The median of the half-time value did not change: 24 min (range 19-31) in the control heart rate study and 22 min (19-27) during the increased pace frequency study. The median of the uptake increased significantly from 33 cpm/pixel/2 mCi/100 kg (23-34) to 40 cpm/pixel/2 mCi/100 kg (35-42; p less than 0.05 Wilcoxon). The median of the relative size of the oxidation pool increased from 57% (52-62) to 69% (63-71; p less than 0.05). We conclude that during pacing the augmented need for NEFA resulted in a demonstrable increase in uptake and oxidation of 17-123I-HDA. This result suggests that radioiodinated NEFA may be a valuable tool to quantify noninvasively the level of the myocardial NEFA metabolism in the human heart.
Duwel
C M
CM
Department of Cardiology, Free University Hospital, Amsterdam, The Netherlands.
Visser
F C
FC
van Eenige
M J
MJ
Roos
J C
JC
Roos
J P
JP
D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010138:Pacemaker, Artificial; D011877:Radionuclide Imaging
D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D007457:Iodine Radioisotopes; C027252:17-iodoheptadecanoic acid