Introduction

The major cause of perinatal brain injury is the acute cerebral hypoxia-ischemia, which mostly occurs by impaired intrapartum gas exchange (1). Cerebral hypoxia in the fetus and newborn increase neonatal morbidity and mortality (2). The most frequently sequelae are mental retardation, cerebral palsy, seizure disorders (1-2), and attention deficit disorder (3) among others. 1HMRS allows noninvasive observations of cerebral Lactate (Lac), Creatine and phosphocreatine (Cr), Choline (Cho) and N-Acetylaspartate (NAA) in newborn infants with and without hypoxic-ischemic brain injury (4-9). Previous investigators have provided data suggesting that Lac is undetectable in the normal neonatal brain at term, but may be found in the brains of both preterm infants and infants who are small for his gestational age (5). 1HMRS is recognized as a noninvasive approach to monitor the human fetal brain since 1994 (10), and has been successful in detecting Lac on lambs fetal brain (11-12) and newborn piglet (15) during hypoxia. In a previous research (14-15), we reported Lac on the Brains of Human Fetuses in High Risk Pregnancies (FHRP) by 1HMRS which brought the possibility of prediction intrauterine hypoxia before the labor. The purpose of the present work was to evaluate the ability of vasodilator to reduce Lac upon administration to mothers with special emphasis on the improvement of the anaerobic pathway observed in FHRP.

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Abbreviations:
¹HMRS: Proton Magnetic Resonance Spectroscopy
MRI: Magnetic Resonance Imaging
Cho: Choline
Cr: Creatine and phosphocreatine
NAA: N-Acetylaspartate
Lac: Lactate
TE: Echo time
TR: Repetition time
RF: Radiofrequency
VOI: Volume of interest
FHRP: Human Fetuses in High Risk Pregnancies
Pi: inorganic phosphorus
ATP: Adenosine Triphosphate

Acknowledgements:
Physicians (Radiologists): H. Ortíz, M. Torcat, G. Zapata.
Anaesthetics: L.Díaz, M. Alliegro, J. Yungano, J. Morales.
MRI & MRS technicians: A. Guitan, J.Guitan, F. Paseta, A. Robaina, N. Isava, R. Cedeño, E. Contreras and M.V. Itriago.
Secretarial assistance: Y. Nazal, R. Velásquez, Y. Soares (CAIBCO)