Different mechanisms for changes in glucose uptake of the right and left ventricular myocardium in pulmonary hypertension.
In patients with pulmonary hypertension (PH) the right ventricular (RV)-to-left ventricular (LV) ratio of fatty acid uptake is reduced. In animal studies, such a finding was combined with an increased glucose uptake in RV myocardium. The aim of this study was to measure the metabolic rates of glucose uptake for the RV and LV myocardium in patients in relationship to parameters of RV and LV function.


METHODS
Thirty patients with PH underwent PET with (18)F-FDG and SPECT with (99m)Tc-tetrofosmine. The metabolic rate of glucose uptake was determined for RV and LV myocardium using the method of Patlak. A right heart catheter, thermodilution, and Doppler sonography were used to characterize RV and LV function. From these methods, the stroke work of both ventricles and the RV Tei index were calculated.


RESULTS
RV-to-LV ratios of (18)F-FDG-uptake increased with rising pulmonary arteriolar resistance (PAR). With increasing PAR, the metabolic rate of glucose uptake of the left ventricle decreased (r = -0.547; P < 0.01) together with LV stroke work (r = -0.838; P < 0.001). The metabolic rate of glucose uptake of the right ventricle, however, correlated neither with RV stroke work (r = 0.124) nor with PAR (r = 0.189) but with the Tei index (r = 0.78; P < 0.001).


CONCLUSIONS
Increasing right-to-left ratios of glucose uptake with an increasing pressure load in the right ventricle in PH are caused mainly by a significant reduction in the LV metabolic rate of glucose uptake. This is obviously due to a reduced energy demand of the LV myocardium caused by reduced stroke work. An increased metabolic rate of glucose uptake in the right ventricle presumably indicates RV impairment, correlating with the Tei index, which is an established prognostic parameter for cardiac dysfunction and poor survival.
Kluge
Regine
R
Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany.
Barthel
Henryk
H
Pankau
Hans
H
Seese
Anita
A
Schauer
Joachim
J
Wirtz
Hubertus
H
Seyfarth
Hans-Juergen
HJ
Steinbach
Joerg
J
Sabri
Osama
O
Winkler
Joerg
J
D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005947:Glucose / Q000493:pharmacokinetics; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000378:metabolism*; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging* / Q000378:metabolism*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose