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Prenatal Cardiology
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Research paper

Maximal velocity of fetal pulmonary venous blood flow

Oskar Sylwestrzak
,
Maciej Słodki
,
Maria Respondek-Liberska

Prenat Cardio 2019; 9(1): 17-19
Online publish date: 2020/02/10
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Introduction


Colour-coded imaging of fetal pulmonary veins was described for the first time in 1992 by DeVore. Now it is possible to detect the pulmonary veins with their blood flows as early as week 12 of gestation and to trace them in detail as far as the distal end with advancing age [1].
According to Polish Prenatal Cardiology Society and American Ultrasound Institute of Medicine, examination of fetal pulmonary venous blood flow is not compulsory during basic obstetrical ultrasound, but it is an essential part of advanced examination in prenatal cardiology referential centres [2–3].
The purpose of this research was to establish reference ranges for maximal fetal pulmonary venous blood flow velocity for our unit.

Material and methods


The database of fetal ultrasound and echocardiographic examinations performed by experienced fetal cardiologists in the referential centre of prenatal cardiology was analysed retrospectively. Obtained data included: gestational age of pregnancy according to last menstrual period, maximal velocity of blood flow through pulmonary veins (Vmax for PVs), prenatal cardiological diagnosis, extracardiac anomalies, and extracardiac abnormalities. In our centre, visualisation of two PVs is a standard. Vmax for PVs was measured for left and right pulmonary veins at their entrance to the left atrium separately, using the transducer position to obtain almost zero degree for blood flow. A correction angle was not used. The final result was the mean of these two measurements. Healthy fetuses with no evidence of heart defect or any abnormality at the time of examination were selected as a study group. In our database they had labels of normal heart anatomy, no extracardiac malformations, and no extracardiac anomalies. Fetuses with functional or morphological anomalies, oligo- or polyhydramnios, bright spot, arrhythmias, and umbilical cord around the neck and/or 2 vessel cord were excluded. For statistical analysis Statistica 13.1 software was used.

Results


Ultrasound data were collected at 18–39 weeks of gestation in singleton pregnancies. The study group contained 184 healthy fetuses. A scatter graph for their Vmax for PVs during pregnancy was prepared using Pearson correlation (CI 0.95) (Figure 1). The regression equation for Vmax for PVs as a function of gestational age (GA) in days was:
Vmax for PVs (cm/sec) = 0.1 × GA (in days) + 5.5 (r = 0.45, CI 0.95).
The 5th, 10th, 50th, 90th, and 95th percentiles of Vmax for PVs between 18th and 35th week of gestation were calculated. For consecutive percentiles a logarithmic dispersion line was created, and they were combined into a graph (Figure 2).

Discussion


As fetal lung parenchyma develops, so does the pulmonary vasculature. Its development starts by 34 days of gestation. Fetal pulmonary blood flow increases with gestation, from an initial low to almost 50% of the combined ventricular output by term [4]. Only a small amount of blood reaches the fetal pulmonary veins, which is caused by preferential shunting of oxygenated blood from the right to left side of the fetal heart and high vascular resistance in fetal lungs. Nevertheless, visualisation of fetal pulmonary veins connecting to the left atrium plays a crucial role in prenatal cardiology centres (Figure 3).
Many studies show normal fetal pulmonary venous blood flow pattern and velocity [1, 5–7]. Fetal pulmonary venous internal diameters were also evaluated [8]. Considering socio-economic, environmental, and behavioural changes in the contemporary population, it is essential to re-evaluate this data. Normal ranges for pulmonary vein blood flow require continuous elaboration. We estimated ranges of normal Vmax for PVs in our region, for our own centre as a reference value for this and subsequent analyses, but it may be used by other obstetrical/ cardiac centres. According to Paladini et al., normal Vmax for fetal PVs differs from our results marginally [5]. Differences in ranges may be caused by various regions of study or different ultrasound devices used. Pulmonary blood flow velocity and its pattern should always be evaluated during fetal echocardiographic examination in a referential centre. Proper fetal cardio-pulmonary circulation yields better outcomes after delivery.
Haemodynamic changes in the lung veins may occur in utero as early as in the second trimester and could explain reports of chronic changes in the lung veins complicating neonatal or postoperative outcome in some heart anomalies [9]. An abnormal pattern may be seen in anomalous pulmonary venous connection or obstructed left atrium and restrictive foramen ovale [10, 11]. In the case of fetal critical aortic stenosis, a double reverse pattern in the pulmonary veins is associated with a poor prognosis [12]. In the IUGR population and in fetuses of diabetic mothers, we can observe higher pulsatility, which is lower during fetal respiratory movements [13–15]. That is why velocity measurement of blood flow through pulmonary veins is of great value.
Mother hyperoxygenation is considered to be a potential therapy in some cases of prenatal congenital heart defects [16–18]. Such a new way of treatment requires the response of pulmonary veins to a high concentration of oxygen. It is used also in our centre. Nonetheless, its precise role should be carefully evaluated [19].

Conclusions


We present normal ranges for pulmonary vein Doppler flow for the 18th– 36th week of gestation in fetuses with normal heart anatomy, showing a steady increase towards term in statistical analysis. However, the scattered graph of Vmax for PVs suggested that for an individual case the proper interpretation of the calculated values might not be very easy or straightforward.

Conflict of interest


The authors declare no conflict of interest.

REFERENCES


1. Bahlmann F, Gallinat R, Schmidt-Fittschen M, Al Naimi A, Reinhard I, Willruth A. Fetal pulmonary venous blood flow velocities in a normal population and new calculated reference values. Prenat Diagn 2016; 36: 1033-1040.
2. Respondek-Liberska M. [Prenatal USG/ECHO diagnostics. Functional disturbances in cardiovascular system]. 1st Ed. PZWL Wydawnictwo Lekarskie, Warszawa 2019.
3. Respondek-Liberska M. [Prenatal cardiology for obstetricians and pediatric cardiologists]. 1st Ed. Wydawnictwo Czelej, Lublin 2006.
4. Morton SU, Brodsky D. Fetal physiology and the transition to extrauterine life. Clin Perinatol 2016; 43: 395-407.
5. Paladini D, Palmieri S, Celentano E, Guida F, Salviati M, Morra T, et al. Pulmonary venous blood flow in the human fetus. Ultrasound Obstet Gynecol 1997; 10: 27-31.
6. Hong YM, Choi JY. Pulmonary venous flow from fetal to neonatal period. Early Hum Dev 2000; 57: 95-103.
7. Laudy JA, Huisman TW, de Ridder MA, Wladimiroff JW. Normal fetal pulmonary venous blood flow velocity. Ultrasound Obstet Gynecol 1995; 6: 277-281.
8. Dong FQ, Zhang YH, Li ZA, Hou ZZ, He XJ, Guo YZ. Evaluation of normal fetal pulmonary veins from the early second trimester by enhanced-flow (e-flow) echocardiography. Ultrasound Obstet Gynecol 2011; 38: 652-657.
9. Lenz F, Chaoui R. Changes in pulmonary venous Doppler parameters in fetal cardiac defects. Ultrasound Obstet Gynecol 2006; 28: 63-70.
10. Respondek-Liberska M, Janiak K, Moll J, Ostrowska K, Czichos E. Prenatal diagnosis of partial anomalous pulmonary venous connection by detection of dilatation of superior vena cava in hypoplastic left heart. Fetal Diagn Ther 2002; 17: 298-301.
11. Respondek-Liberska M, Sokołowski Ł, Słodki M, Zych-Krekora K, Strzelecka I, Krekora M, et al. Prenatal diagnosis of TAPVC on Monday, delivery of Tuesday and cardiac surgery at Wensday – a model of perinatal care in 3rd trimester in case of fetal/neonatal critical heart defect in tertiary center. Prenat Cardio 2016; 6: 37-42.
12. Sukegawa S, Yamamoto Y, Sato K, Tanaka S, Tanaka T, Mitsuhashi N. Ultrasound evaluation of fetal critical aortic stenosis using the left atrium area/cardiac area ratio and the Doppler patterns in the pulmonary veins. J Med Ultrason 2019; 46: 267-272.
13. Bravo-Valenzuela NJ, Zielinsky P, Huhta JC, Acacio GL, Nicoloso LH, Piccoli A, et al. Dynamics of pulmonary venous flow in fetuses with intrauterine growth restriction. Prenat Diagn 2015; 35: 249-253.
14. Chemello K, Zielinsky P, Nicoloso LH, de Morais MR. Behavior of pulmonary venous flow during fetal respiratory movements. Congenital Heart Dis 2009; 4: 265-268.
15. Zielinsky P, Piccoli AL Jr, Teixeira L, Gus EI, Mânica JL, Satler F, et al. Pulmonary vein pulsatility in fetuses of diabetic mothers: prenatal Doppler echocardiographic study. Arq Bras Cardiol 2003; 81: 604-607, 600-603.
16. Co-Vu J, Lopez-Colon D, Vyas HV, Weiner N, DeGroff C. Maternal hyperoxygenation: a potential therapy for congenital heart disease in the fetuses? A systematic review of the current literature. Echocardiography 2017; 34: 1822-1833.
17. Zarkowska-Szaniawska A, Janiak K, Foryś S, Słodki M, Respondek-Liberska M. Maternal hyperoxygenation test in prediction of fetal lung hypoplasia – preliminary report. Ginekol Pol 2011; 82: 834-839.
18. Zeng S, Zhou J, Peng Q, Deng W, Zhang M, Zhao Y, et al. Sustained maternal hyperoxygenation improves aortic arch dimensions in fetuses with coarctation. Sci Rep 2016; 6: 39304.
19. McHugh A, El-Khuffash A, Bussmann N, Doherty A, Franklin O, Breathnach F. Hyperoxygenation in pregnancy exerts a more profound effect on cardiovascular hemodynamics than is observed in the nonpregnant state. Am J Obstet Gynecol 2019; 220: 397.e1-397.e8.

Division of work:


Oskar Sylwestrzak (ORCID: 0000-0001-9325-7304): collection and/or assembly of data, data analysis and interpretation, writing the article, final approval of article
Maciej Słodki (ORCID: 0000-0002-0160-8013): writing the article, critical revision of the article
Maria Respondek-Liberska (ORCID: 0000-0003-0238-2172): research concept and design, data analysis and interpretation, writing the article, critical revision of the article, final approval of article
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