Low-flow ischaemia has no deleterious effect on the steady-state kinetics of 201Tl and 99mTc sestamibi within myocardial tissue.
OBJECTIVE
This study aimed to specifically analyse the impact of low-flow ischaemia on the ability of myocytes to trap and accumulate Tl and sestamibi (MIBI) within myocardial tissue.


METHODS
In order to reach steady-state conditions for the interstitial/cellular concentration ratios (Ci/Cc) of the tracers and thereby simulate the conditions of cell cultures studies, Tl and MIBI were injected continuously during an 80 min period within the coronary circulation of isolated hearts submitted to normoxia (n=7) or low-flow ischaemia (n=7; >50% reduction in coronary flow). Ci was determined by using interstitial microdialysis and Cc was determined from Ci and myocardial retention values of the tracers.


RESULTS
At the end of the experiments, under steady-state conditions, Ci/Cc was equivalent between low-flow ischaemia and normoxia for both Tl (ischaemia, 0.60 +/- 0.25% vs normoxia, 0.63 +/-0.34%; NS) and MIBI (ischaemia, 1.00 +/- 0.68% vs normoxia, 0.76 +/- 0.32%, NS), whereas tissue concentrations of ATP were more than 4-fold lower in ischaemia than in normoxia (5.1 +/- 3.5 nmol.g vs 22.5 +/- 4.8 nmol.g; P< 0.001).


CONCLUSIONS
In contrast to the published results concerning the effects of anoxia on cell cultures, low-flow ischaemia within myocardial tissue has no deleterious effects on the ability of the cells to accumulate Tl and MIBI under steady-state conditions. This gives definitive evidence of the negligible impact of cellular metabolic disorders in the decrease in Tl or MIBI uptake, which is documented by stress-SPECT within low-flow ischaemic myocardium.
Ayalew
Adey
A
Department of Nuclear Medicine, UPRES Laboratoire EA3447, Faculté de Médecine de Nancy, 54505 Vandoeuvre, France. aayalew@yahoo.com
Maskali
Fatiha
F
Audonnet
Sandra
S
Marie
Pierre-Yves
PY
Menu
Patrick
P
Mertes
Paul-Michel
PM
Olivier
Pierre
P
Franck
Patricia
P
Zannad
Faiez
F
Karcher
Gilles
G
Bertrand
Alain
A
D000818:Animals; D006321:Heart / Q000000981:diagnostic imaging*; D006487:Hemostasis; D066298:In Vitro Techniques; D007700:Kinetics; D008657:Metabolic Clearance Rate; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D011817:Rabbits; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics*; D013793:Thallium / Q000493:pharmacokinetics*
D019275:Radiopharmaceuticals; C027549:thallium chloride; D017256:Technetium Tc 99m Sestamibi; D013793:Thallium