This study allows us to identify severe early onset of FGR at the end of the second trimester and the beginning of the third. Oxygenated blood from the placenta enters the umbilical vein, then into the ductus venosus, the upper part of the inferior vena cava and into the right atrium. The diameter of the ductus venosus is much smaller than the diameter of the umbilical vein and inferior vena cava, and the blood flow speed in it increases.
A connection has been established between certain changes in blood flow parameters and severe fetal pathology.
To study these vessels, it is necessary that the device has color Doppler mapping functions with a pulse-wave mode.
In the second half, with a physiological flow in the umbilical vein, continuous blood flow is observed at a low speed without pulsation. Ripple is determined in early pregnancy or due to umbilical cord compression or fetal hypoxia. Low-amplitude pulsation is associated with the respiratory movements of the fetus, so measurements are not performed during this period.
Ripple reflects cardiac function rather than vascular resistance in the placenta. When the umbilical cord is compressed, pulsation is observed during systole. Pulsation at the end of the diastole phase is an ominous sign and indicates severe fetal hypoxia.
In the ductus venosus the speed of blood flow is higher. This vessel is located closer to the heart, so blood flow in it reflects the function of the atrium. The shape of the blood flow velocity is a three-phase curve. During fetal hypoxia, the minimum value of the blood flow wave increases due to back pressure caused by atrial contraction. As a result, there is a decrease in blood flow velocity in the late diastole phase, down to zero or negative values.
The inferior vena cava is characterized by a similar three-phase curve, and during atrial contraction, reverse blood flow is often detected here, so the value of Doppler mapping of this vessel is minimal.
- The umbilical cord and umbilical vein are visualized. In order to study the blood flow velocity curve in the umbilical cord vein, a control volume is set on the vessel image, it is checked that the insonation angle is not the smallest, and the blood flow spectrum is recorded.
- The umbilical vein is traced along its entire length from its entry into the anterior abdominal wall to its entry into the liver.
- Using color Doppler scanning, an increase in blood flow velocity is detected in the final section of the umbilical vein, where the immediate continuation of the latter is the narrower ductus venosus.
- The control volume is established on the image of the initial segment of the ductus venosus. In order to obtain a good signal, the direction of the insonation angle is adjusted so that it is less than 30°. The ductus venosus differs from the adjacent inferior vena cava and hepatic veins by its slightly hissing sound.
Protocol Doppler study umbilical cord arteries
Free-floating umbilical cord loop
Setting the reference volume on the umbilical artery image
Subacute insonation angle scanning
Need to remember
- Examination of the umbilical cord artery is the best way to predict the condition of the fetus.
- Of greater clinical importance is the absence of diastolic blood flow in the umbilical cord artery or its reverse direction, rather than various indices.
- A decrease in blood flow velocity in the venous duct during the late diastole phase to zero or negative values indicates fetal hypoxia.
- Pathological pulsation in the umbilical vein, corresponding to the diastolic component of blood flow in the umbilical artery, indicates severe fetal hypoxia.
- The appearance of an early diastolic notch in the uterine arteries during Doppler ultrasound may indicate an increased risk of developing preeclampsia and FGR.
This article is the first part of a series about the heart and blood circulation. Today's material is useful not only for general development, but also to understand what heart defects there are. For a better presentation, there are many drawings, half of them with animation.
Diagram of blood flow in the heart AFTER birth
Deoxygenated blood from the whole body is collected in the right atrium through the superior and inferior vena cava (upper - from the upper half of the body, along the lower - from the lower). From the right atrium, venous blood enters the right ventricle through the tricuspid valve, from where it enters the lungs through the pulmonary trunk (= pulmonary artery).
Scheme: vena cava? right atrium? ? right ventricle? [pulmonary valve] ? pulmonary artery.
Structure of the adult heart(picture from www.ebio.ru).
Arterial blood from the lungs through 4 pulmonary veins (2 from each lung) it is collected in the left atrium, from where through the bicuspid ( mitral) the valve enters the left ventricle and is then released through the aortic valve into the aorta.
Scheme: pulmonary veins? left atrium? [mitral valve] ? left ventricle? [aortic valve] ? aorta.
Pattern of blood flow in the heart after birth(animation).
Superior vena cava - superior vena cava.
Right atrium - right atrium.
Inferior vena cava - inferior vena cava.
Right ventricle - right ventricle.
Left ventricle - left ventricle.
Left atrium - left atrium.
Pulmonary artery - pulmonary artery.
Ductus arteriosus - ductus arteriosus.
Pulmonary vein - pulmonary vein.
Diagram of blood flow in the heart BEFORE birth
For adults, everything is simple - after birth, the blood flows are separated from each other and do not mix. In the fetus, blood circulation is much more complicated, which is due to the presence of the placenta, non-functioning lungs and gastrointestinal tract. The fruit has 3 features:
- open foramen ovale(foramen ovale, “forAmen ovale”),
- open ductus arteriosus(ductus arteriosus, ductus arteriosus)
- and open ductus venosus(ductus venosus, “ductus venosus”).
The foramen ovale connects the right and left atria, the ductus arteriosus connects the pulmonary artery and aorta, and the ductus venosus connects the umbilical vein and the inferior vena cava.
Consider the blood flow in the fetus.
Fetal circulation diagram
(explanations in the text).
Oxygen-enriched arterial blood from the placenta flows through the umbilical vein, which runs in the umbilical cord, to the liver. Before entering the liver, the blood flow is divided, and a significant part of it bypasses the liver along ductus venosus, present only in the fetus, and goes into the inferior vena cava directly to the heart. Blood from the liver itself through the hepatic veins also enters the inferior vena cava. Thus, before flowing into the right atrium, the inferior vena cava receives mixed (venous-arterial) blood from the lower half of the body and the placenta.
Through the inferior vena cava, mixed blood enters the right atrium, from where 2/3 of the blood passes through the open foramen ovale enter the left atrium, left ventricle, aorta and systemic circulation.
Oval hole And ductus arteriosus in the fetus.
Movement of blood through the foramen ovale(animation).
Movement of blood through the ductus arteriosus(animation).
1/3 of the mixed blood entering the inferior vena cava is mixed with all purely venous blood from the superior vena cava, which collects blood from the upper half of the fetal body. Next, from the right atrium, this flow is directed to the right ventricle and then to the pulmonary artery. But the lungs of the fetus do not work, so only 10% of this blood enters the lungs, and the remaining 90% through ductus arteriosus are discharged (shunted) into the aorta, worsening its oxygen saturation. 2 umbilical arteries depart from the abdominal aorta, which in the umbilical cord go to the placenta for gas exchange, and begins new circle blood circulation
Liver The fetus is the only organ of all that receives pure arterial blood from the umbilical vein. Thanks to the “preferential” blood supply and nutrition, by the time of birth the liver has time to grow to such an extent that it takes up 2/3 of the abdominal cavity and in relative terms weighs 1.5-2 times more than an adult.
Arteries to the head and upper body extend from the aorta above the level of the confluence of the ductus arteriosus, so the blood flowing to the head is better oxygenated than, for example, the blood flowing to the legs. Like the liver, the newborn's head is also unusually large and takes up 1/4 of the entire body length(in an adult - 1/7). Brain newborn is 12 - 13% body weight(in adults 2.5%). Probably, young children should be unusually smart, but we cannot guess this due to a 5-fold decrease in brain mass. 😉
Changes in blood circulation after birth
When a newborn takes his first breath, he the lungs expand, vascular resistance in them drops sharply, and blood begins to flow into the lungs instead of the arterial duct, which first becomes empty and then becomes overgrown (scientifically speaking, it becomes obliterated).
After the first inspiration, the pressure in the left atrium increases due to increased blood flow, and the foramen ovale stops functioning and overgrown. The ductus venosus, umbilical vein and terminal sections of the umbilical arteries also become overgrown. Blood circulation becomes the same as in adults.
Heart defects
Congenital
Because heart development is quite complex, this process can be disrupted during pregnancy by smoking, drinking alcohol or taking certain medications. Congenital heart defects are in 1% of newborns. Most often registered:
- defect(non-closure) of the interatrial or interventricular septum: 15-20%,
- incorrect location ( transposition) aorta and pulmonary trunk - 10-15%,
- tetralogy of Fallot- 8-13% (narrowing of the pulmonary artery + malposition of the aorta + ventricular septal defect + enlargement of the right ventricle),
- coarctation(narrowing) of the aorta - 7.5%
- patent ductus arteriosus - 7 %.
Purchased
Acquired heart defects occur in 80% of cases due to rheumatism(as they now say, acute rheumatic fever). Acute rheumatic fever occurs 2-5 weeks after a streptococcal throat infection ( sore throat, pharyngitis). Since streptococci are similar in antigenic composition to the body's own cells, the resulting antibodies trigger damage and inflammation in the circulatory system, which ultimately leads to the formation of heart defects. In 50% of cases the mitral valve is affected(if you remember, it is also called bicuspid and is located between the left atrium and the ventricle).
Acquired heart defects are:
- isolated (2 main types):
- valve stenosis(narrowing of the lumen)
- valve insufficiency(incomplete closure, resulting in reverse blood flow during contraction)
- combined (stenosis and insufficiency of one valve),
- combined (any damage to different valves).
It is worth noting that sometimes combined defects are called combined, and vice versa, because There are no clear definitions here.
The blood circulation of a fetus is significantly different from that of an adult.
The fetus is in the womb, which means it does not breathe with its lungs - the ICC does not function in the fetus, only the BCC works.
The fetus has communications, they are also called fetal jesters, these include:
- foramen ovale (which drains blood from the RA into the LA)
- arterial (Batalov) duct (duct connecting the aorta and pulmonary trunk)
- ductus venosus (this duct connects the umbilical vein to the inferior vena cava)
These communications close over time after birth, and when they are not closed, congenital malformations are formed.
Now we will analyze in detail how blood circulation occurs in a child.
The baby and mother are separated from each other by the placenta; the umbilical cord, which contains the umbilical vein and umbilical artery, goes from it to the baby.
Oxygen-enriched blood travels through the umbilical vein as part of the umbilical cord to the fetal liver; in the fetal liver, the umbilical vein is connected to the inferior vena cava through the DUCT VENOUS. We remember that the inferior vena cava flows into the RA, in which there is an OVAL WINDOW, and through this window blood flows from the RA into the LA, where the blood mixes with a small amount of venous blood from the lungs. Then from the LA through the left interventricular septum into the LV, and then enters the ascending aorta, then through the vessels to the upper part of the body. Collecting in the SVC, the blood of the upper half of the body enters the RA, then into the RV, then into the pulmonary trunk. Let us remember that the ATRERIAL DUCT connects the aorta and the pulmonary trunk, which means that the blood that entered the pulmonary table, for the most part, due to the high resistance in the vessels of the ICC, will not go into the lungs as in an adult, but through the ductus arteriosus into the descending part of the aortic arch. About 10% is thrown into the lungs.
The umbilical arteries carry blood from the fetal tissues to the placenta.
After ligation of the umbilical cord, the ICC begins to function as a result of the expansion of the lungs, which occurs with the child’s first breath.
Closing communications:
- First, the ductus venosus closes by the 4th week, and in its place the round ligament of the liver is formed.
- The ductus arteriosus then closes as a result of vasospasm due to hypoxia for 8 weeks.
- The oval window is the last to close, during the first half of life.
JNA)
see Ductus venosus.
1. Small medical encyclopedia. - M.: Medical encyclopedia. 1991-96 2. First health care. - M.: Great Russian Encyclopedia. 1994 3. Encyclopedic Dictionary of Medical Terms. - M.: Soviet Encyclopedia. - 1982-1984.
See what “Ductus Venous” is in other dictionaries:
- (ductus venosus, PNA, JNA) see List of anat. terms... Large medical dictionary
ductus venosus- (ductus venosus) a vessel connecting the fetus’s umbilical vein with the inferior vena cava. Located in the posterior part of the left longitudinal groove of the liver. After birth, the ductus venosus overgrows, turning into a venous ligament...
thoracic duct- (ductus thoracicus) is the largest lymphatic vessel, 30–40 cm long. It is formed in the upper abdominal cavity from the confluence of the right and left lumbar trunks. According to the length of the thoracic duct, the abdominal, thoracic and cervical parts are distinguished. IN… … Glossary of terms and concepts on human anatomy
One of the two main lymphatic ducts. Lymph passes through it from both lower extremities, from the lower abdomen, the left half of the chest and head, as well as from the left arm. The thoracic duct drains into the left venous angle. Source:… … Medical terms
THORACIC DUCT- (thoracic duct) one of the two main lymphatic ducts. Lymph passes through it from both lower extremities, from the lower abdomen, the left half of the chest and head, as well as from the left arm. The thoracic duct flows into the left venous... ... Explanatory dictionary of medicine
BOTAL DUCT- BOTAL DUCT, ductus arteriosus Bo talli (Leonardo Botallo, 16th century), is a vascular trunk that connects the aortic arch with the pulmonary artery (art. pulmonalis) in the uterine baby and becomes empty after birth. The development of B. p. costs ... Great Medical Encyclopedia
I The thoracic duct (ductus throracicus) is the main lymphatic collector that collects lymph from most of the human body and flows into the venous system. Only the lymph flowing from the right half of the chest, head, neck and right upper... ... passes through the G. p. Medical encyclopedia
Thoracic (lymphatic) duct (ductusthoracicus). Common iliac and lumbar lymph nodes- Front view. internal jugular vein (left); arch of the thoracic duct; the place where the thoracic duct enters the venous angle (the confluence of the internal jugular and subclavian veins; subclavian trunk (lymphatic), left; left brachiocephalic vein; ... ... Atlas of Human Anatomy
right lymphatic duct- (ductus lymphaticus dexter) a short non-permanent vessel formed from the confluence of the right jugular, subclavian, bronchomediastinal trunks and opening into the right venous angle (the junction of the right internal jugular and subclavian veins) ... Glossary of terms and concepts on human anatomy
- (ductus thoracicus, PNA, BNA, JNA) lymphatic vessel through which lymph flows into the venous bed from the legs, pelvis, walls and organs of the abdominal cavity, left arm, left half of the chest, head and neck; formed in the abdominal cavity by the fusion of intestinal... ... Large medical dictionary
- (ductus lymphaticus dexter, PNA) a non-permanent lymphatic vessel formed by the fusion of the right jugular, subclavian, and sometimes bronchomediastinal lymphatic trunks; drains into the right venous angle... Large medical dictionary
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Introduction
Assessment of the umbilical portal venous system (UPVS) has become an important part of antenatal fetal assessment. UPVC abnormalities associated with chromosomal and structural abnormalities, Doppler assessment of ductus venosus flow has become a screening tool for Down syndrome in the first trimester of pregnancy. In addition, recent studies have shown the need to assess blood flow in the fetal liver with intrauterine retention growth.
In the fetus, venous blood flow in the liver is unique, as it is provided by two embryonic and functionally different systems: the umbilical and portal/vitelline systems. From 5 to 10 weeks of pregnancy, a network of anastomoses is formed in the liver between the umbilical and vitelline systems, and the volume of placental blood flow increases, which then flows to the heart through this hepatic system. The intra- and extraportal venous system develops from the right vitelline vein. In the umbilical system, the right umbilical vein regresses, and the portal system directly develops from the left umbilical vein. The ductus venosus, which emerges from the umbilical-portal system, supplies oxygenated blood directly to the fetal heart.
Methods
A prospective study of anatomically normal fetuses was conducted as part of routine antenatal care in a low-risk population. In most cases, studies were performed during fetal sonography at 14–16 weeks and 19–24 weeks or in the third trimester of pregnancy, as part of an assessment of fetal growth.
We excluded fetuses with any abnormal sonographic findings, including the presence of “soft markers” for aneuploidy, in which a normal karyotype was not established. Pregnancies complicated by maternal diseases that could affect fetal development were also excluded. Cases with pathological volume were also excluded. amniotic fluid, associated or not associated with abnormal intrauterine growth of the fetus.
Ultrasound examinations were performed on or equipped with transabdominal 4-8 MHz or transvaginal 5-9 MHz transducers with a 70 Hz high-pass filter.
Only if sonograms with optimal visualization were obtained were the UPVCs included in the study. All examinations were taken in a standard cross-section of the upper abdomen (the section commonly used to measure abdominal circumference). In the section we visualize the stomach and the L-shaped portal sinus (this is the confluence of vessels that originate from the end of the umbilical vein; it was also defined by Mavrides et al. as the vascular space extending from the origin of the inferior branch of the left portal vein to the right portal vein (Fig. 1)). From this perspective, we performed studies by imaging the stomach at a point distal to the transducer to determine the junction of the portal sinus and the main portal vein, which runs on the left side between the stomach and the descending aorta. The connection between the portal vein and the portal sinus was first identified using two-dimensional (2D) ultrasound. After this, color Doppler with high definition flow (HDFlow) was used to achieve the best imaging mode and also to check the direction of blood flow (Fig. 2 a and b). The 3D technique was applied only in cases where the portal sinus and portal vein could not be detected in the same plane in other imaging modes. For 3D HDFlow we used a sample volume angle of 30-35° (Fig. 3). In order to evaluate the intrahepatic branches of the portal system, we adopted the Couinaud liver segmentation system. A longitudinal section was also used to determine the normal course of the umbilical vein and ductus venosus.
Fig.1. Ultrasound images of a normal intrahepatic umbilical vein that connects to the left and right portal veins. On a section measuring the abdominal circumference of a fetus at 23 weeks of gestation. (a) Transverse section used to measure fetal abdominal circumference. (b) Cross-sectional sonogram in the sagittal plane indicated by the dotted line.
Fig.2. On the sonogram we observe the junction of the main portal vein and the bifurcation of the right and left portal branches from the portal sinus in a fetus at 23 weeks of gestation, presented without (a) and with (b, c) HDFlow high-definition flow. Images (a) and (b) show a cross-section of the fetal abdomen. The arrow points to the hepatic artery. Image (c) corresponds to a sagittal section of the main portal vein indicated by the dotted line.
Fig.3. Image of the fetal portal vein at 24 weeks' gestation: normal intrahepatic vascular anatomy is shown in cross section (a). 3D HDFlow allowed visualization of the main portal vein and its branches simultaneously, whereas this was not possible in 2D (b-d).
results
During the study, we studied 208 fruits. The mean gestational age at the time of examination was 25.1 weeks. In a longitudinal section, we noticed that the course of the umbilical vein in the upward direction enters the liver, where it connects with portal system. At the left intrasegmental groove of the liver, it joins the left portal vein, which then courses sharply to the right, creating an L-shaped segment known as the portal segment. The main portal vein bends around the main sulcus on the left. The junction of the main portal vein with the portal sinus is the anatomical point of separation between the right and left branches, and is located downward (Fig. 2 c) and to the right along the base of the ductus venosus. The right portal vein branches into two main branches: the anterior and posterior branches at some distance from the junction of the main portal vein and the portal sinus. Three branches emerge from the left portal vein: two on the left (inferior and superior branches) and one on the right (medial branch) (Fig. 3). During the study period, in only one case (0.4%) were we unable to detect an L-shaped segment of the left portal vein, indicating the absence of a horizontal portion of the left portal vein. In this case, the ductus venosus arises from the right portal vein rather than from the portal sinus (Fig. 4).
Fig.4. A case of development of the umbilical-portal system in a fetus at 23 weeks of gestation (a b). The typical L-shape of the left portal vein cannot be identified (a) and the ductus venosus has a different course (b, arrow) compared to the usual development (c, arrow).
At the confluence of the main portal vein and the portal sinus (Figure 2), we noticed that their confluence angle varied continuously from perpendicular to almost completely parallel to the direction of the lines. Accordingly, three main types of communication between the main portal system and the portal sinus have been classified. The most common type was observed in 140 (67.3%) fetuses. It is a T-shaped connection, with an end-to-side anastomosis between the main portal vein and the portal sinus (Fig. 5). This type of connection showed a wide range of connection angles and varying distances from the branching site of the posterior branch of the right portal vein. The connection ranged from a vertical T-shaped insertion into the portal sinus, far from the bifurcation of the right branch of the right portal vein (Fig. 5 a), to a more acute angle of connection and a shorter distance from this bifurcation (Fig. 5 b and 5 c), forming a cruciform structure consisting of four vessels: the main portal vein, the left portal vein and two branches (anterior and posterior right portal vein) (Fig. 5 d). In 26 fetuses (12.5%), an X-shaped connection was observed between the main portal vein and the portal sinus (Fig. 6), characterized by the formation of a side-to-side anastomosis, which runs almost parallel. In some cases, there is a gap between the main portal vein and the left portal vein, which is an intermediate shape between the second and third type of connection (classified as an H-shape) and is observed in 30 (14.4%) fetuses. In this type, the connections between the main portal vein and the posterior right portal vein were separated from the right portal vein by small vessels (Fig. 7). We also observed different distances between vessels. In the most extreme case, the connection between vessels could not be visualized together in the same plane in greyscale mode. Only in 3D using the HDFlow technique was it possible to demonstrate the thin vessel that connected them (Fig. 7c). In our series, classification of the type of connection between the main portal vein and the portal sinus was not possible in 12 (5.6%) cases, which was mainly explained by the intermediate morphology. Eight of them were between types T and X, and four were between types X and H.
Rice. 5. Variants of anastomosis of the main portal vein and portal sinus end to side in a fetus at 24 weeks of gestation. (a) T-shaped anastomosis. (b) different distances from the branching site of the posterior branch of the right portal vein were noted; in some cases, the left portal vein and the right portal vein branched directly from the main portal vein in a trident-shaped pattern (c). (d) The more acute angle of the connection is an intermediate form between the end-to-side and side-to-side types of anastomoses.
Fig.6. Variants of anastomosis of the main portal vein and portal sinus “side to side” in a fetus at 24 weeks of gestation: X-shaped anastomosis. Sonograms (a) and (b) show the connection with different distances between the main portal vein/posterior branch of the right portal vein complex and the left portal vein/anterior branch of the right portal vein complex. An almost complete gap between each other is shown, which represents an intermediate shape between the X and H shapes. (c) Three-dimensional visualization with high quality 3D HDFlow image flow reconstruction.
Rice. 7. A case of H-shaped anastomosis of the main portal vein and portal sinus in a fetus at 24 weeks of gestation. The main portal vein and the posterior branch of the right portal vein are separated from the left portal vein and the anterior branch of the right portal vein by small vessels connecting them to each other (a and b). (c) The image represents a case in which the main portal vein/anterior branch of the right portal vein and the main portal vein/posterior branch of the right portal vein complexes were so distant from each other that they could only be visualized using the 3D HDFlow.
Conclusion
In this study, we examined the connection between the main portal vein and the portal sinus. The umbilical-portal venous system is a complex of vessels that supply the liver as well as the fetal heart.
We decided to adopt the anatomical nomenclature proposed by Mavrides et al, using the term “portal sinus” for the L-shaped umbilical portion of the left portal vein. The main reason for this was our ability, using 2D and 3D HDF, to easily visualize the inferior branch of the left portal vein as a landmark for the origin of the portal sinus. In addition, this technique allowed us to visualize the main portal vein and its branches simultaneously, which was not possible in 2D (Fig. 3 b–d).
An important feature of our study is the fact that we were able to accurately describe the different anatomical connections between the main portal vein and the portal sinus in a large number of fetuses during pregnancy. Knowledge of these anatomical variations is important in the diagnosis of portal venous system anomalies, such as complete and partial agenesis of the portal vein.
