Article

lock Open Access lock Peer-Reviewed

5

Views

ORIGINAL ARTICLE

Fetal cardiac surgery: hemodynamic characteristics of placenta during extracorporeal circulation

Renato S Assad; Fan-Yen Lee; Kim Berger; Frank I Hanley

DOI: 10.1590/S0102-76381991000100007

ABSTRACT

Decreased placental perfusion and respiratory gas exchange have been observed following experimental fetal cardiopulmonary bypass (CPB). To better characterize placental hemodynamics during CPB, 7 isolated in-situ lamb placentas were placed on a CPB circuit, using umbilical arterial and venous cannulation. Measures were taken to simulate normal placental hemodynamics. Perfusion flow rates were varied randomly from 15 to 300 ml/min/kg fetal wt. during both normothermia and hypothermia. Placental vascular resistance (PVR) remained constant when perfusion pressure and flow were varied above 40 mmHg and 150 ml/min/kg respectively. Below these values, PVR varied inversely. This increase in PVR was more marked when CPB was performed with hypothermia as compared to normothermia. The clinical implications is that decreased placental flow and pressure on CPB may lead to a vicious cycle resulting in further impariment of placental perfusion and respiratory gas exchange. Hypothermia promotes this impairment.

RESUMO

A diminuição da perfusão placentária com conseqüente distúrbio de trocas gasosas ocorre com freqüência após a circulação extracorpórea (CEC) fetal experimental. Com o objetivo de caracterizar a hemodinâmica placentária durante a CEC, foram colocadas em CEC sete placentas de ovelhas, isoladas in situ, através da canulação dos vasos umbilicais. O fluxo da CEC foi alterado de 15 a 300 ml/min/kg de peso fetal, em normotermia e hipotermia. A resistência vascular placentária (RVP) permaneceu constante durante uma pressão de perfusão e fluxo da CEC acima de 40 mmHg e 150 ml/min/kg, respectivamente. Abaixo destes valores, a relação da RVP com estes dois parâmetros foi inversamente proporcional. Um maior aumento da RVP foi observado durante a hipotermia. A implicação clínica destes achados reside no fato de que a diminuição do fluxo e da pressão de perfusão placentária durante a CEC pode conduzir a um ciclo vicioso, resultando em prejuízo adicional da perfusão placentária das trocas gasosas, sendo que a hipotermia agrava ainda mais esta disfunção placentária.
Full text available only in portuguese PDF format.

REFERENCES

1. ASSALI, N. S.; BRINKMAN, C. R.; NUWAYHID, B. - Comparison of maternal and fetal cardiovascular functions in acute and chronic experiments in the sheep. Am. J. Obstet Gynecol., 120: 411-425, 1974.

2. BERMAN Jr., W.; GOODLIN, R. C.; HEYMANN, M. A.; RUDOLPH, A. M. - Relationships between pressure and flow in the umbilical and uterine circulations of the sheep. Circ. Res., 38: 262-266, 1976. [MedLine]

3. BISSONETTE, J. M. & FARREL, R. C. - Pressure-flow and pressure-volume relationships in the fetal placental circulation. J. Appl. Physiol., 35: 355-360, 1973. [MedLine]

4. BRADLEY, S. M.; HANLEY, F. L.; JENNINGS, R. W.; DUNCAN, B. W.; JESTER, J. A.; VERRIER, E. D. - Regional blood flows during cardiopulmonary bypass in fetal lambs: the effect of nitroprusside. Circulation, 82 (Supl. 3): 413, 1990. (Resumo). [MedLine]

5. BRADLEY, S. M.; VERRIER, E. D.; DUNCAN, B. W.; LONGAKER, M. T.; TURLEY, K.; HARRISON, M. R.; HANLEY, F. L. - Cardiopulmonary bypass in the fetal lamb: effect of sodium nitroprusside. Circulation, 80 (Supl. 2): II-220, 1989 (Resumo).

6. CRAWFORD, J. M. - Vascular anatomy of the human placenta. Am. J. Obstet. Gynecol., 84: 1543-1567, 1962. [MedLine]

7. GOETZMAN, B. W.; ITSKOVITZ, J.; RUDOLPH, A. M. - Fetal adaptations to spontaneous hypoxemia and responses to maternal oxygen breathing. Biol. Neonate, 46: 276-284, 1984. [MedLine]

8. GREISS, F. C. - Pressure-flow relationships in the gravid uterine vascular bed. Am. J. Obstet. Gynecol., 96: 41-47, 1966. [MedLine]

9. HEGNAUER, A. H.; SHRIBER, W. J.; HATERIUS, H. O. - Cardiovascular response of the dog to immersion hypothermia. J. Appl. Physiol., 161: 455-465, 1950.

10. IWAMOTO, H. S. & RUDOLPH, A. M. - Effects of angiotensin II on the blood flow and its distribution fetal lambs. Circ. Res., 48: 183-189, 1981. [MedLine]

11. LANDAUER, M.; PHERNETTON, T. M.; RANKIN, J. H. G. - Maternal ovine placental vascular responses to adenosine. Am. J. Obstet. Gynecol., 154: 1152-1155, 1986. [MedLine]

12. LIPSHITZ, J.; AHOKAS, R. A.; REYNOLDS, S. L. - The effect of hydralazine on placental perfusion in the spontaneously hypertensive rat. Am. J. Obstet. Gynecol., 156: 356-359, 1987. [MedLine]

13. PARISI, V. M. & WALSH, S. W. - Arachidonic acid metabolities and the regulation of placental and other vascular tone during pregnancy. Sem. Perinatol., 10: 288-298, 1986.

14. PARISI, V. M. & WALSH, S. W. - Fetal placental vascular responses to prostacyclin after angiotensin ll-induced vasoconstriction. Am. J. Physiol., 257: 102-107, 1989.

15. PARISI, V. M. & WALSH, S. W. - Fetal vascular response to prostacyclin. Am. J. Obstet. Gynecol., 160: 871-875, 1989.

16. PARK, M. K.; HAYASHI, S.; ROBOTHAN, J. L. - Cooling-induced contraction of guinea pig tracheal smooth muscle. Proc. Soc. Exp. Biol., 177: 283-289, 1984.

17. POWER, G. G. & LONGO, L. D. - Sluice flow in the placenta: maternal vascular pressure effect on fetal circulation. Am. J. Physiol., 225: 1490-1496, 1973. [MedLine]

18. RITTENHOUSE, E. A.; HOHRI, H.; DILLARD, D. H.; MERENDINO, K. A. - Deep hypothermia in cardiovascular surgery. Ann. Thorac. Surg., 17: 63-98, 1974. [MedLine]

19. SCHWARTZ, D. B.; PHERNETTON, T. M.; STOCK, M. K.; RANKIN, J. H. G. - Placental vascular responses to 6-keto-prostaglandin E1 in the near-term sheep. Am. J. Obstet. Gynecol., 145: 406-410, 1983. [MedLine]

20. SOUHRADA, J. F.; PRESLEY, D.; SOUHRADA, M. - Mechanisms of the temperature effect on airway smooth muscle. Resp. Physiol., 53: 225-237, 1983.

21. THORNBURG, K. L.; BISSONETTE, J. M.; FABER, J. J. - Absence of fetal placenta waterfall phenomenon in chronically prepared fetal lambs. Am. J. Physiol., 230: 886-892, 1976. [MedLine]

22. VETH, A. F. L. & VAN BEMMEL, J. H. - The role of the placental vascular bed in the fetal response to cord occlusion. In: LONGO, L. D. & RENEAU, D. D. Fetal carciovascular physiology. New York, Garland Publishing, Inc., 1978. p. 579-604.

CCBY All scientific articles published at bjcvs.org are licensed under a Creative Commons license

Indexes

All rights reserved 2017 / © 2020 Brazilian Society of Cardiovascular Surgery DEVELOPMENT BY