3 CEREBRAL AUTOREGULATORY CHANGES IN HYPERTENSIVE STATES ASSESSEDBY BEAT TO BEAT CEREBRAL BLOOD VELOCITY CHANGES KEITH WILLIAMS1,FRANCE GALERNEAU2, MARIA SMALL3, 1Yale University, Obstetrics &Gynecology, New Haven, Connecticut, 2Yale University, Obstetrics andGynecology, New Haven, Connecticut, 3Yale University, New Haven,Connecticut

OBJECTIVE: Recent studies have identified significant changes in cerebralautoregulation in preeclampsia (PET). We chose to examine pulsatilefluctations in in the Middle Cerebral Blood Flow Velocity. (MCBFV) byassessing the beat to beat systolic variation with changes in RR interval andSystolic MCBFV Variability. This study investigates the usefulness as a test ofcerebral autoregulation the beat-to-beat changes in MCBFV with changes inRR intervals.

STUDY DESIGN: Transcranial Doppler monitoring of the middle cerebralartery (MCA) was performed for 2 minutes on 20 normotensive, 10 PET, 5chronic hypertensive and 7 Pregnancy Induced Hypertension (PIH) patientswere assessed. We measured beat-to-beat systolic, diastolic, and meanMCBFV velocity and RR intervals. Offline using software we calculated thebeat-to-beat change in Systolic MCBFV associated with changes RR in eachof the groups. In addition the Systolic MCBFV variability was calculated asthe square root of the mean of the sum of the squares of differences in SystolicMCBFV between adjacent RR intervals. All continuous data was comparedbetween the four groups using ANOVA with Bonferroni correction.

RESULTS: We identified a significant difference the Systolic MCBFVchange with the RR interval among the normotensive PET, Chronic Hyper-tensive and PIH groups (33.6G14.6, vs 16G10.2, vs, 44G14.8, vs31.9G17.8)(P!.004) There was no significant difference in Systolic MCBFVvariability (1.96G63, vs 1.63G.49, vs1.91G.52, vs 1.58G.29)(P!.30).

CONCLUSION: We evaluated cerebral function in various pregnant hyper-tensive states by examining spontaneous fluctuations and rythmicity of RRinterval and systolic MCBFV. Our data suggest that in PET unlike chronichypertension acts to diminish spontaneous beat to beat oscillations inMCBFV. The loss of the dynamic complexity of the variability signal maybe an indication of loss of vessel adaptability to continuously changingenvironmental requirements.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.505

S144 SMFM Abstracts

461 PREGNANCY INDUCED SYMPATHETIC OVERACTIVITY: A COMPARISON OFDIFFERENT HYPERTENSIVE STATES KEITH WILLIAMS1, FRANCE GALERNEAU2,MARIA SMALL3, 1Yale University, Obstetrics & Gynecology, New Haven,Connecticut, 2Yale University, Obstetrics and Gynecology, New Haven,Connecticut, 3Yale University, New Haven, Connecticut

OBJECTIVE: Recent studies have shown that elevated sympathetic outflowin patients might contribute to vasoconstriction in Preeclampsia (PET). Theability to assess Blood Pressure Variability (BPV) and baroreflex sensitivity(BRS) have become powerful techniques for assessing autonomic control incardiac diseases. We questioned whether increased sympathetic activity isassociated with other hypertensive pregnant states including chronic hyper-tension and Pregnancy Induced Hypertension (PIH). The measurement ofsympathetic activity could be helpful in differentiating these conditions.

STUDY DESIGN: We measured continuously beat to beat outputs of Bloodpressure (pilot 9200) for 2 minutes. Time series of systolic as well as systolicbeat-to-beat pressure values and RR intervals were extracted to analyze andassess BRS in 20 normotensive, 10 PET, 5 chronic hypertensive and 7Pregnancy Induced Hypertension (PIH) patients in the third trimester. Wemeasured BRS by the linear spontaneous sequence technique assessingspontaneous sequences of 3 cycles and calculating the linear regression slopebetween BP and RR interval. The BP variability was calculated as the squareroot of the mean of the sum of the squares of differences in Systolic BPbetween adjacent RR intervals. All continuous data was compared betweenthe four groups using ANOVA with Bonferroni correction.

RESULTS: We identified a significant difference in BRS between Normo-tensive, PET, Chr Hypertensive, and PIH patients (13G8.8, vs 4.9G2.5, vs10.4G5.9, vs 9.4G3.6) (P!.034). There was also a significant difference in BPvariability (30.6G16.11, vs16.4G4.2, vs 27.8G16.0, vs 30.8G7.7)(P!.047).The significantly reduced BRS and BPV indicated that increased sympatheticactivity is a significant feature of PET.

CONCLUSION: Women with PET showed an increase in pregnancy inducedsympathetic activity in excess of that seen with chronic hypertension and PIHwith similar blood pressure levels. Non invasive assessment of the autonomicnervous system should be investigated in populations at risk for PET as ascreening tool.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.503

46

462 CEREBRAL CIRCULATORY CHANGES IN DIFFERENT HYPERTENSIVE CONDITIONSKEITH WILLIAMS1, FRANCE GALERNEAU2, MARY SMALL3, 1Yale University,Obstetrics & Gynecology, New Haven, Connecticut, 2Yale University Schoolof Medicine, OB/GYN, New Haven, Connecticut, 3Yale University,Columbia, Connecticut

OBJECTIVE: The cerebral circulatory effects of preeclampsia (PET) leads tosignificant changes in estimated Cerebral Perfusion Pressure (eCPP) andMiddle Cerebral Blood Flow Velocity (MCBFV) variability. We sought tocorrelate beat to beat pulsatile changes in MCBFV with eCPP in differenthypertensive conditions in pregnancy to gain further insight into cerebralautoregulatory control.

STUDY DESIGN: We simultaneously measured beat to beat outputs ofsystolic and diastolic arterial blood pressure and RR intervals (pilot 9200) andbeat to beat, systolic, diastolic, and mean cerebral blood flow (MCBFV)(Ni-colet Vascular TCD) with the patient during supine rest. 20 normotensive, 10preeclampic, 5 chronic hypertensive and 7 Pregnancy Induced Hypertension(PIH) patients were assessed. We calculated the estimated cerebral perfusionpressure according to the following equation. eCPP = Vmean/(Vmean-Vdiastolic) ! (BPmean – BPdiastolic). The Systolic MCBFV variability wascalculated as the square root of the mean of the sum of the squares ofdifferences in Systolic MCBFV between adjacent RR intervals. The change inMCBFV variability per unit change in eCPP was calculated as (SystolicMCBFV/eCPP). All continuous data was compared between the four groupsusing ANOVA with Bonferroni correction.

RESULTS: We identified a significant difference in unit change in MCBFVVariability per unit change in eCPP between the normotensive, PET, chronichypertensive and PIH groups (.374 G.015 vs. 018G.004, vs .035 G.034, vs.022G.017) (P!.016).

CONCLUSION: We assessed beat to beat pulsatile changes in the cerebralcirculation and identified that in preeclampsia cerebral autoregulation resultedin a significantly reduced pulsatile variability of MCBFV per unit change ineCPP with a trend towards a decrease in PIH. The mechanism for this decreasein variability in association with an increase in eCPP in preeclamptic patients islikely protective and results in a reduction in vascular barotrauma associatedwith these pulsatile changes.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.504

464 VASCULAR REACTIVITY AT DIFFERENT SITES IN PREECLAMPSIA-IS THEREA CORRELATION? KEITH WILLIAMS1, INNA LANDRES2, FRANCE GALERNEAU3,MARIA SMALL4, 1Yale University, Obstetrics & Gynecology, New Haven,Connecticut, 2Stanford University, Mountain View, California, 3YaleUniversity, Obstetrics and Gynecology, New Haven, Connecticut, 4YaleUniversity, New Haven, Connecticut

OBJECTIVE: Preeclampsia (PET) is associated with a disordered circulatorychanges in the brain and the peripheral circulation as evidenced by changes inbrachial artery Flow Mediated Vascular Dilation (FMVD) and estimatedCerebral Perfusion Pressure (eCPP). This study investigates whether theperipheral circulatory changes correlate with changes in the central cerebralcirculation.

STUDY DESIGN: 20 normotensive, 10 PET patients were assessed. Trans-cranial Doppler monitoring of the middle cerebral artery in the mother wasperformed and we recorded Mean and Diastolic Blood Presure and Mean andDiastolic Middle Cerebral Blood Flow Velocity (MCBFV). We calculated theeCPP according to the following equation eCPP = Vmean/(Vmean-Vdias-tolic) ! (BPmean – BPdiastolic). Following this FMVD of the brachial arterywas measured post cuff release. We assessed the maximum brachial arterydilatation in each patient. The means were compared between the groups usingstudent t tests and Correlation coefficient between FMVD and eCPP wasmeasured in each of the 2 groups.

RESULTS: eCPP was significantly higher in the PET vs. the normotensivegroup (91.4G15.7 vs 56.9G11.5) P!.001). FMVD was significantly lower inthe PET than the normotensive group (5.0G2.7 vs 8.2G2.9)(P!.022). Therewas poor correlation between FMVD and eCPP in the 2 groups. PET(R=.546), Normotensive (R=.498)

CONCLUSION: Preeclampsia is a multisystem disorder of generalizedvasculopathy with multiple organ systems being affected. This study identifiesthat the peripheral vascular bed (FMVD) and cerebral circulation (eCPP)undergo significant changes in preeclampsia but these changes are independentcomponents of the disease process. Vascular dysfunction occurring in oneorgan system cannot be used to predict dysfunction in another organ system.

0002-9378/$ - see front matterdoi:10.1016/j.ajog.2006.10.506