ISSN:
1435-1803
Keywords:
81Rubidium/81mkrypton
;
myocardial perfusion
;
myocardial perfusion reserve
;
isolated rabbit heart
;
Langendorff preparation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Purpose The purpose of the study was to verify that the81Rubidium/81mkrypton (81Rb/81mKr) method allows the quantitative measurement of myocardial perfusion. Principle The potassium analogous cation81Rb is accumulated in the myocardium by the cell membrane-bound Na−K-ATPase. After accumulation an intracellular equilibrium establishes between81Rb and its radioactive daughter nuclide81mKr. The flow-sensitive method evaluates the disturbance of this equilibrium by perfusion which washes out the short-lived diffusable daughter nuclide81mKr while the mother nuclide81Rb remains cell-bound. Methods Isolated rabbit hearts were prepared in a modified Langendorff technique which allowed quantitative collection of the coronary sinus efflux. The myocardium was labeled with pure81Rb by bolus injection into the aortic cannula. Spectroscopic measurements of81Rb and81mKr gamma radiation were performed using a germanium detector. Perfusion was varied in the range between 0 and 4 ml/min/g. The activity ratio81Rb/81mKr was determined and compared with coronary sinus effusion. Results 81Rb/81mKr activity ratio was closely related (r=0.98) to perfusion as described by the predicted equation Rb/Kr=(F/2.96 P)+1. (Rb/Kr=activity ratio between81Rb and81mKr in the myocardium; F=myocardial perfusion (ml/min/g); P=partition coefficient (myocardium/perfusate) for Krypton gas.) The constant P was found to be 1.14±0.06 (mean±SEM). No saturation of this ratio at high flow rates was observed. Conclusion The activity ratio81Rb/81mKr is a valid quantitative measure for myocardial perfusion in isolated hearts. The main limitation of the method before application in man is the correction of the different gamma ray tissue absorption of both nuclides.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00795203
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