title: The maternal cerebral circulation in pre-eclampsia: investigations using Laplace transform analysis of Doppler waveforms.
abstract: OBJECTIVE
  To compare the maternal cerebral circulation in pre-eclampsia and normal pregnancy using an alternative method of Doppler waveform analysis called the Laplace transform analysis, which provides haemodynamic data additional to standard Doppler indices.
  
  
  METHODS
  A prospective cross-sectional study.
  
  
  METHODS
  Department of Obstetrics and Gynaecology, Nottingham University Hospital.
  
  
  METHODS
  The study involved 17 women in the third trimester of a normal pregnancy, 11 with pregnancy-induced hypertension and 26 with pre-eclampsia.
  
  
  METHODS
  Doppler recordings were obtained from the internal and external carotid and middle cerebral arteries, with the measurements in hypertensive women being carried out before any treatment was given. The waveforms were then subjected to Laplace transform analysis which provides information on vessel wall stiffness and upstream and downstream flow conditions.
  
  
  METHODS
  The determination of the Laplace transform analysis parameters, including alpha, the natural frequency of oscillation and real pole, and pulsatility index.
  
  
  RESULTS
  Laplace transform analysis demonstrated a significant increase in vessel wall stiffness in all the arteries in hypertensive pregnancies, but this was more marked in pre-eclampsia. The data were also consistent with, but do not prove, increased downstream resistance in the middle cerebral artery in women with pre-eclampsia but not in those with pregnancy-induced hypertension.
  
  
  CONCLUSIONS
  The Laplace transform analysis of Doppler waveforms yields important physiological information concerning the cerebral circulation in pre-eclampsia, not detected using conventional Doppler indices. The results suggest that both pre-eclampsia and pregnancy-induced hypertension are associated with increased cerebral arterial wall stiffness and that, in addition, there may be cerebral vasoconstriction in pre-eclampsia.
authors.affiliation: Department of Medicine, University of Nottingham.
authors.forename: K J
authors.initials: KJ
authors.lastname: Brackley
authors.forename: M M
authors.initials: MM
authors.lastname: Ramsay
authors.forename: F
authors.initials: F
authors.lastname: Broughton Pipkin
authors.forename: P C
authors.initials: PC
authors.lastname: Rubin
mesh_terms: D000328:Adult; D002342:Carotid Artery, External / Q000000981:diagnostic imaging; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D003430:Cross-Sectional Studies; D004739:England; D005260:Female; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging*; D011225:Pre-Eclampsia / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging*; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D014463:Ultrasonography