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(Circulation. 1999;100:II-187.)
© 1999 American Heart Association, Inc.
Surgery for Congenital Heart Disease |
From the Departments of Cardiac Surgery (I.F., C.S., K.T., H.C.-D., C.M.R., P.J.d.N.), Pediatric Cardiology (A.M.M., S.D.C.), and Anesthesiology (F.X.M.), The Childrens Hospital, Harvard Medical School, Boston, Mass.
Correspondence to Pedro J. del Nido, MD, Department of Cardiac Surgery, Childrens Hospital, Harvard Medical School, 300 Longwood Ave., Boston, MA 02115. E-mail delnido{at}A1.tch.harvard.edu
BackgroundSevere hypertrophy and heart failure are important risk factors in cardiac surgery. Early adaptive changes in hypertrophy include increased ventricular mass-to-cavity volume ratio (M/V ratio) and increased dependence on glucose for energy metabolism. However, glucose uptake is decreased in the late stages of hypertrophy when ventricular dilatation and failure are present. We hypothesized that impaired glucose uptake would be evident early in the progression of hypertrophy and associated with the onset of ventricular dilatation.
Methods and ResultsTen-day-old rabbits underwent banding of the
descending aorta. Development of hypertrophy was followed
by transthoracic echocardiography to
measure left ventricular M/V ratio. Glucose uptake rate, as
determined by 31P-nuclear magnetic resonance spectroscopy
measuring 2-deoxyglucose conversion to 2-deoxyglucose-6-phosphate, was
measured in isolated perfused hearts obtained from banded rabbits when
M/V ratio had increased by 15% from baseline (compensated
hypertrophy) and by 30% from baseline (early-decompensated
hypertrophy). In age-matched control animals, the rate of
glucose uptake was 0.61±0.08 µmol · g of wet
weight-1 · 30 min-1 (mean±SEM). With
a 15% M/V ratio increase, glucose uptake rate remained at control
levels (0.6±0.05 µmol · g of wet
weight-1 · 30 min-1), compared with
hearts with 30% increased M/V ratios, where glucose uptake was
significantly lower (0.42±0.05 µmol · g of wet
weight-1 · 30 min-1;
P
0.05). Glucose transporter protein expression was the
same in all groups.
ConclusionsGlucose uptake rate is maintained during compensated hypertrophy. However, coinciding with severe hypertrophy, preceding ventricular dilatation, and glucose transporter protein downregulation, glucose uptake is significantly decreased. Because of the increased dependence of the hypertrophied hearts on glucose use, we speculate that this impairment may be a contributing factor in the progression to failure.
Key Words: hypertrophy echocardiography glucose metabolism
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