Sonographic investigation of flow patterns in the perfused human placenta and their modulation by vasoactive agents with enhanced visualization by the ultrasound contrast agent Albunex.
OBJECTIVE
Our objective was to demonstrate sonographically the flow distribution in the circulation of human placentae as well as the sensitivity of the human fetal capillary bed to vasoconstriction and dilatation.


METHODS
Five human full-term placental lobules were maintained in vitro with fetal and maternal flow. Commercial ultrasound scanners were used for imaging. Albunex (1 ml bolus) was administered to the fetal "artery" to monitor patterns of flow. U46619 (1 ml, 10(-6) M; a thromboxane agonist and potent vasoconstrictor) and/or nitroglycerin (a potent vasodilator) were added to the fetal artery.


RESULTS
Following the addition of U46619, mean "fetal pressures" rapidly rose from 23.2 +/- 0.8 to 118 +/- 2. 9 mm Hg (mean +/- standard error of mean; p < 0.001); venous flow rates decreased. As demonstrated by color Doppler imaging, flow markedly changed from a pattern of general distribution throughout the lobule to flow only near the chorionic plate. Color persistence was 94.4 +/- 6.5 seconds with Albunex after nitroglycerin and 39.8 +/- 3.4 seconds with Albunex after injection of U46619 (p < 0.001). Nitroglycerin had no effect when injected by itself but returned "constricted" flow to a "normal" pattern when injected after U46619.


CONCLUSIONS
The contrast medium Albunex improved visualization of the fetal circulation throughout the lobule. Flow in the human placental capillary bed can be regionally manipulated throughout the placental lobule by vasomodulators and monitored by Albunex-enhanced sonographic examination.
Abramowicz
J S
JS
Department of Obstetrics and Gynecology, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642, USA.
Phillips
D B
DB
Jessee
L N
LN
Levene
H
H
Parker
K J
KJ
Miller
R K
RK
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000008:administration & dosage; D000418:Albumins / Q000008:administration & dosage; D001783:Blood Flow Velocity; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007269:Injections, Intra-Arterial; D008863:Microspheres; D005996:Nitroglycerin / Q000008:administration & dosage; D010477:Perfusion; D010920:Placenta / Q000098:blood supply* / Q000000981:diagnostic imaging; D021041:Placental Circulation / Q000187:drug effects*; D011247:Pregnancy; D013931:Thromboxanes / Q000819:agonists; D018615:Ultrasonography, Doppler, Color; D014662:Vasoconstrictor Agents / Q000008:administration & dosage; D014665:Vasodilator Agents / Q000008:administration & dosage
D000418:Albumins; C060687:Albunex; D003287:Contrast Media; D013931:Thromboxanes; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D005996:Nitroglycerin