AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 9, NUMBER 5/6
Sept/Nov 1992
REDUCTION IN THE MIDDLE CEREBRAL ARTERY PULSATILITY INDEX AFTER DECOMPRESSION OF POLYHYDRAMNIOS IN TWIN GESTATION Giancarlo Mart, M.D., Nathan Wasserstrum, M.D., Ph.D., and Brian Kirshon, M.D.
ABSTRACT
Doppler flow velocity profiles of the fetal umbilical (UA) and middle cerebral arteries (MCA) have been assessed via the pulsatility index (PI) and similar measurements.1"3 The amplitude of the PI parallels the magnitude of the corresponding downstream vascular impedance. Fetal stress is accompanied by a rise in PIUA, but a reduction in PIMCA.124-6 xhe reduced PIMCA is thought to reflect a brain-sparing response to inadequate perfusion or oxygenation. It represents an appropriate compensatory decrease in cerebrovascular impedance, and a redistribution of blood flow in favor of the brain.4 This type of change accompanies growth retardation,1'24-6 severe indomethacin-induced constriction of the ductus arteriosus,2 and intravascular transfusion of packed red cells into the isoimmunized fetus.7 Symptomatic polyhydramnios is associated with increased amniotic fluid pressure.89 Therapeutic amniocentesis reduces this pressure.9 In addition to relieving mater-
Downloaded by: Universite Laval. Copyrighted material.
Amniotic fluid decompression was performed for symptomatic polyhydramnios complicating four sets of discordant twin gestations. Doppler ultrasound waveforms of the middle cerebral artery were determined before and after the procedure in seven of the eight fetuses. After amniocentesis, the pulsatility index of the middle cerebral artery (PIMCA) was reduced in all fetuses (p
Sept/Nov 1992
REDUCTION IN THE MIDDLE CEREBRAL ARTERY PULSATILITY INDEX AFTER DECOMPRESSION OF POLYHYDRAMNIOS IN TWIN GESTATION Giancarlo Mart, M.D., Nathan Wasserstrum, M.D., Ph.D., and Brian Kirshon, M.D.
ABSTRACT
Doppler flow velocity profiles of the fetal umbilical (UA) and middle cerebral arteries (MCA) have been assessed via the pulsatility index (PI) and similar measurements.1"3 The amplitude of the PI parallels the magnitude of the corresponding downstream vascular impedance. Fetal stress is accompanied by a rise in PIUA, but a reduction in PIMCA.124-6 xhe reduced PIMCA is thought to reflect a brain-sparing response to inadequate perfusion or oxygenation. It represents an appropriate compensatory decrease in cerebrovascular impedance, and a redistribution of blood flow in favor of the brain.4 This type of change accompanies growth retardation,1'24-6 severe indomethacin-induced constriction of the ductus arteriosus,2 and intravascular transfusion of packed red cells into the isoimmunized fetus.7 Symptomatic polyhydramnios is associated with increased amniotic fluid pressure.89 Therapeutic amniocentesis reduces this pressure.9 In addition to relieving mater-
Downloaded by: Universite Laval. Copyrighted material.
Amniotic fluid decompression was performed for symptomatic polyhydramnios complicating four sets of discordant twin gestations. Doppler ultrasound waveforms of the middle cerebral artery were determined before and after the procedure in seven of the eight fetuses. After amniocentesis, the pulsatility index of the middle cerebral artery (PIMCA) was reduced in all fetuses (p
