Congenital Anomalies of the Superior Vena Cava: Embryological Correlation, Imaging Perspectives, and Clinical Relevance.

There is a wide spectrum of congenital anomalies of the superior vena cava, which are more increasingly recognized in cross-sectional imaging. Although some of these anomalies are asymptomatic, others have important clinical and interventional implications. Imaging modalities such as computed tomography and magnetic resonance imaging play an important role in the accurate characterization of these anomalies, which is essential for mapping prior to surgeries or interventions. In this article, we review a wide range of anomalies of the superior vena cava, including the embryological basis, cross-sectional imaging findings, and clinical implications, particularly from an interventional radiology perspective. We also discuss the treatments and complications of these anomalies.

[HISTOGENESIS AND PECULIARITIES OF STRUCTURAL ORGANIZATION OF THE CARDIAC MUSCLE TISSUE IN THE WALLS OF HUMAN CAVAL AND PULMONARY VEINS].

To study the structural organization and histogenesis of the cardiac muscle tissue in the walls of human caval and pulmonary veins, the heart was examined in 3 human embryos (at weeks 6-7 of development) and 20 fetuses (at weeks 9-10, 16, 19, 22 and 24 of development), as well as segments of caval and pulmonary veins of adult men and women (n = 50) located at various distances from the heart. The methods of light and electron microscopy were used in this work. To obtain the isolated cells from the walls of caval and pulmonary veins, the method of tissue alkaline dissociation was used. An immunohistochemical study with the monoclonal antibodies against cardiac troponin T was performed. It was found that the cardiomyocytes in humans were located in the middle and outer tunics of caval and pulmonary veins, where they formed thick layers. In the pulmonary veins of the adult humans, cardiac muscle fibers did not reach the intrapulmonary areas, in the inferior vena cava their layer did not extend beyond the pericardium, in the superior vena cava, its length was 2.5-3.0 cm. The formation of the pulmonary vein orifices occured by sequential inclusion of the wall of the common pulmonary vein, and later--of the right and left pulmonary veins into the wall of the left atrium. During the formation of the orifices of the caval veins, the gradual inclusion of the wall of the venous sinus in the wall of the right atrium was observed, resulting in caval veins opening directly into the cavity of the right atrium. The veins studied were referred to the veins of the muscular type with the strong development of muscular elements containing the myocardial component.

Evaluation of changes in Doppler ultrasonography indices and levels of maternal serum angiogenic factors throughout pregnancy in ewes.

We evaluated the changes in the pulsatility index (PI) and resistance index (RI) of fetal and maternal vessels and maternal serum angiogenic factors throughout pregnancy in 20 Kivircik ewes. They were examined for pregnancy detection on Day 30 after mating. The PI and RI during the pregnancies were followed using Doppler ultrasonography (USG) of the uterine artery, umbilical artery, fetal aorta, and fetal vena cava. Doppler USG was performed every 15 days beginning from the 40th day after mating. Blood samples were collected every 15 days starting from the day of mating. Nitric oxide (NO), vascular endothelial growth factor, basic fibroblast growth factor, and angiopoietin-1 and -2 levels were measured in maternal serum. A gradual decline was observed in the PI and RI of the umbilical artery beginning from Day 75 of pregnancy. Similarly, the RI of the uterine artery decreased on Day 135. Embryonic resorption was detected in two ewes with an increased PI and RI in the uterine artery. A significant and gradual decrease in the maternal serum vascular endothelial growth factor level was observed throughout pregnancy. The maternal serum NO level increased beginning from Day 135 of pregnancy. The results of this study illustrate the progressive changes in the Doppler USG findings of fetomaternal vessels and maternal serum angiogenic factors that occur throughout ewe pregnancy. The umbilical and uterine artery Doppler USG findings and maternal serum NO concentration may be important parameters for evaluation of the course of pregnancy in ewes. The results of this study should be compared with those of further studies that include compromised pregnancies and nonpregnant ewes.

Development of cardiac musculature in the cranial vena cava of rat embryos.

Development of cardiac musculature in the rat cranial vena cava (common cardinal vein or duct of Cuvier) was examined by immunohistochemistry and transmission electron microscopy. Undifferentiated cardiac myocytes were detected in the cranial vena cava wall of rat embryos after 12.5 days post-coitum (dpc). The tunica media of the cranial vena cava was composed of cardiac myocytes after formation of the endothelium. Therefore, the cranial vena cava may be not only a part of the venous system but also of the heart. Myocytes in the cranial vena cava contained developing myofibrils, mitochondria and intercalated discs similar to those found in the myocytes in heart. Striated myofibrils began to differentiate as soon as myocytes appeared in the vena cava wall, and myocytes with differentiating myofibrils occur in the wall as the first component of the tunica media at 12.5 dpc. We concluded that the cardiac musculature in the vena cava is not a secondary extension into the tunica media after birth only in the rat, but a basic structure formed in all mammals during early embryonic development.

Double inferior vena cava and abdominal aortic aneurysm.

Duplicated inferior vena cava was found unexpectedly at the time of resection of abdominal aortic aneurysm. Resection of the aneurysm and preservation of duplicated vena cava was performed. Technical difficulties and embryology of this anomaly are discussed.

Severe cyanosis due to atrial septal defect and an anomalous inferior vena caval valve.

Uncomplicated atrial septal defect is often associated with mild arterial desaturation. A case is reported with severe cyanosis and life-threatening hypoxemia due to an atrial septal defect. Cardiac catheterization revealed normal right heart pressures and an atrial septal defect with shunting of inferior vena caval blood into the left atrium. At surgery an anomalous inferior vena caval valve was found directing inferior vena caval blood into the left atrium. The embryologic basis for this association is discussed. The delayed onset of severe cyanosis may have been contributed to by the thoracic scoliosis.

[Contribution of Doppler exploration of ductus venosus flow]. / Intérêt des dopplers veineux chez le foetus.

Among the different means currently available to assess fetal hypoxia and determine the optimal time for fetal extraction in case of intra-uterine growth retardation (IUGR), Doppler measurement of blood flow in the ductus venosus (DV) is one of the most promising. The DV is one of the three fetal circulation shunts observed in utero. Approximately 55% of the oxygenated blood flowing from the umbilical vein to the foramen ovale and the left cavities short circuits the hepatic circulation via the DV. This oxygenated blood is preferentially directed to the myocardium and the brain. Measurement errors (suprahepatic veins, umbilical veins) can lead to erroneous diagnosis of defective DV. Inversely, there is a normal physiological reverse flow in the suprahepatic veins and the inferior vena cava not present in the DV. In case of fetal hypoxia, the proportion of oxygenated blood increases due to increased flow from the umbilical vein into the DV, increasing the proportion of oxygenated blood delivered to the heart and brain instead of the liver. This corresponds to fetal adaptation to hypoxia and the spectrum of the DV thus normally includes a positive wave. When the fetus is unable to adapt to hypoxia, there is an alteration of the right heart function observable in the DV spectrum with diminished diastolic flow or even zero or reverse flow. Anomalous CV flow is a sign of major deterioration of the fetal status before development of severe anomalies. For many, the short-term variability implies immediate extraction of the fetus. Certain well trained teams combine DV flow with other information such as the biophysical examination of the fetus, the quality of the amniotic fluid, visual and automated growth retardation measurements, and other Doppler measurements for decision making. Doppler measurements of the DV, disclosing IUGR or made during surveillance of IUGR, are theoretically made only if other Doppler findings such as arterial redistribution are abnormal. Doppler assessment of DV flow is not a first intention procedure and only concerns a small high-risk fetal population. Experience and good knowledge of fetal anatomy and the Doppler technique are required (it is easy to confuse the physiological spectrum of the suprahepatic veins with a negative wave corresponding to pathological DV flow).

[Histogenesis and structural organization of the walls of rat venae cavae and pulmonary veins]. / Gistogenez i strukturnaia organizatsiia stenki polykh i legochnykh ven krysy.

Using light and electron microscopic methods, the histogenesis and structural organization of the walls of rat venae cavae and pulmonary veins were studied in prenatal and postnatal periods of development. The special attention was paid to the appearance of the striated myocytes in the walls of these vessels during the process of ontogenesis. The time of initial divergent development of myoblastic differon was established, the stages of differentiation of striated myoblasts and the peculiarities of intercellular junctions were characterized, as well as the innervation and vascularization of the walls of venae cavae and pulmonary veins.

Study of the development of uteroplacental and fetal feline circulation by triplex Doppler.

The objective was to evaluate blood flow in fetal and maternal vessels by Triplex Doppler and its association with development of blood vessels during gestation in the domestic cat. Ten queens were examined weekly from 14 to 63 d after mating. Peak systolic velocity (PSV), end diastolic velocity (EDV), resistance index (RI) and pulsatility index (PI) of uteroplacental, aorta and umbilical fetal arteries and caudal vena cava of the fetus were evaluated. Throughout pregnancy, there was an increase in PSV and EDV in the aorta and umbilical arteries. In the caudal vena cava, there was an increase in PSV, whereas the EDV was constant, with a significant increase on Day 63. Peak systolic velocity and EDV of the uteroplacental artery reduced significantly on Day 63. Resistance index of the umbilical artery progressively decreased. In the aorta, this reduction was detected only on Day 42, with no defined pattern in the caudal vena cava and uteroplacental artery. Pulsatility index of the aorta varied. Although pulsatility increased in the caudal vena cava on Day 35 and remained elevated, pulsatility was significantly reduced in the umbilical artery by Day 63. The pulsatility index of the uteroplacental artery was constant (increased only on Day 63). Triplex Doppler evaluation could be a useful adjunct for prenatal care of pregnant queens, including assessment of vascular gestational development and prediction of gestational age.

Development of the pulmonary vein and the systemic venous sinus: an interactive 3D overview.

Knowledge of the normal formation of the heart is crucial for the understanding of cardiac pathologies and congenital malformations. The understanding of early cardiac development, however, is complicated because it is inseparably associated with other developmental processes such as embryonic folding, formation of the coelomic cavity, and vascular development. Because of this, it is necessary to integrate morphological and experimental analyses. Morphological insights, however, are limited by the difficulty in communication of complex 3D-processes. Most controversies, in consequence, result from differences in interpretation, rather than observation. An example of such a continuing debate is the development of the pulmonary vein and the systemic venous sinus, or "sinus venosus". To facilitate understanding, we present a 3D study of the developing venous pole in the chicken embryo, showing our results in a novel interactive fashion, which permits the reader to form an independent opinion. We clarify how the pulmonary vein separates from a greater vascular plexus within the splanchnic mesoderm. The systemic venous sinus, in contrast, develops at the junction between the splanchnic and somatic mesoderm. We discuss our model with respect to normal formation of the heart, congenital cardiac malformations, and the phylogeny of the venous tributaries.

Magnetic resonance angiography of fetal vessels: feasibility study in the sheep fetus.

PURPOSE: The aim of this study was to perform fetal magnetic resonance angiography (MRA) in utero in a sheep model. MATERIAL AND METHODS: Images of the great vessels, the heart, and the tracheal tree were performed on four pregnant ewes with a 1.5-T scanner (Philips Medical Systems, Best, The Netherlands). MRA was achieved in utero using a nontriggered free-breathing three-dimensional balanced fast field echo (FFE) technique. All obtained MRA images were evaluated in consensus on a three-point scale by two radiologists with 9 and 4 years of experience in fetal MRI, respectively. RESULTS: The fetal heart frequencies were between 130 and 160 bpm. The aorta from the aortic bulb to the bifurcation as well as some of the main aortic branches could be depicted. The pulmonary trunk and arteries, the superior and inferior caval veins, and the subsegmental branches of the trachea could also be visualized. CONCLUSION: The nontriggered MRA of the fetal great vessels with images of the tracheal tree allowed an excellent evaluation of anatomical structures.

Doppler evaluation of maternal and fetal vessels during normal gestation in rabbits.

The aim of this work was to evaluate the hemodynamic changes in the utero-placental arterial vessels in rabbits (Orictolagus cuniculus) throughout pregnancy as well as those in the umbilical cord, aorta, and caudal vena cava of fetuses to establish their normal reference ranges for systolic peak velocity (SPV), end diastolic velocity (EDV), pulsatility index (PI), and resistance index (RI). The blood flow waveforms were monitored every 4 d in 10 rabbits from Day 10 of pregnancy onward by means of color and pulsed wave Doppler ultrasonography using a 5.5-7.5 MHz microconvex transabdominal probe. The utero-placental blood flow was characterized by steep increases and decrease in the SPV with a slow diastolic wave and relatively high EDV, whereas that of the umbilical artery was discontinuous until Day 22 of pregnancy, when a diastolic waveform was also detectable. From Day 10 to 22 of pregnancy, the fetal aorta blood flow was discontinuous, but thereafter a diastolic peak was measurable. The blood flow of the fetal caudal vena cava was characterized by a systolic peak followed by a small diastolic peak. Throughout the gestation, the SPV and the EDV of maternal and fetal vessels increased (alpha<0.05), whereas the PI and the RI decreased (alpha<0.05), except for the utero-placental vessels. This work confirms that the rabbit could also be a valid experimental animal model to study, by Doppler ultrasonography, functional hemodynamic changes of the fetuses and placenta vessels in both normal and pathophysiologic conditions.

[Development of the ascending lumbar and azygos veins in human embryogenesis]. / Razvitie voskhodiashchei poiasnichnoi i neparnoi ven v émbriogenezecheloveka.

The ascending lumbar and azygos veins make a single magistral, but with different topography in the abdominal and thoracic cavities. The former runs more dorsolateral than the sympathetic trunk, and the latter--more ventromedial. These vessels are of different origin in human embryogenesis. The ascending lumbar vein develops from supracardinal veins of the abdominal cavity, that unite the dorsomedial tributaries of the postcardinal vein. The supramesonephral (thoracic) part of the latter makes the azygos vein trunk. Its beginning in the form of a plexus is determined by anastomosing supracardinal, postcardinal and mesocardinal veins. The mesocardinal vein serves as a longitudinal anastomosis for veins, connecting medial tributaries of the postcardinal vein. Differential peculiarities of its basin over the whole length and topographic peculiarities of the ascending lumbar and azygos veins depend on growth specificity of kidneys and adrenals, as well as on other organs in human embryogenesis.

Congenital anomalies of the venae cavae: embryological origin, imaging features and report of three new variants.

Due to the complexity of their developmental stages, the venae cavae may undergo a very large number of congenital anomalies. All the possible abnormalities which, to our knowledge, have been observed in the literature are reported, differentiating those of the superior vena cava and the azygos system, those of the inferior vena cava and the complex anomalies that concern the venous system as a whole. Moreover, we present three new variants: a right double inferior vena cava with azygos continuation of the posterior-medial vein; an agenesis of the superior vena cava with drainage through the azygos and hemiazygos veins to the inferior vena cava; and a double inferior vena cava with hemiazygos and azygos continuation of the left one.

Relationship in the chick of the developing pulmonary vein to the embryonic systemic venous sinus.

Previous studies have shown that the relationship of the systemic venous sinus (sinus venosus) to the developing pulmonary vein are very similar in mice, rats, and man, with the pulmonary vein gaining access to the heart through a persisting segment of the dorsal mesocardium. It has been suggested that this process differs in avian development, with the pulmonary vein being connected to the systemic venous sinus with subsequent transfer to the left atrium. Here we have investigated the anatomical sequence of events in the chick, using serial histological sections and microdissection followed by scanning electron microscopy. We examined a temporal series of chick embryos, ranging from Hamburger and Hamilton stage 15 to stage 30. Although there are some differences in detail, the development of the pulmonary venous connections in the chick was found to be directly comparable to that already described in eutherian mammals. In both mammals and the chick, the dorsal mesocardial connection, which connects the primitive atrium to the posterior thoracic wall, forms a fixed point through which the pulmonary vein gains access to the atrial compartment of the heart, only varying if the connection itself is anomalous. The tributaries of the systemic venous sinus and the primary atrial septal structures develop around the dorsal connection.

In situ morphology of the heart and great vessels in fetal and newborn rats.

Morphology of the cardiac chambers and great vessels of fetal and neonatal rats was studied using the whole body freezing technique and by sectioning through the short axis of the heart with a freezing microtome. Compared to the fetal heart, the neonatal heart showed rapid change 2 to 8 days after birth. The ventricular sinus septum was straight in the fetus and became concave to the left ventricle after birth. The right ventricular wall was as thick as the left in the fetus and became thinner rapidly after birth. At the same time, the right ventricular cavity dilated. The right and left pulmonary arteries and pulmonary veins were small in the fetus and enlarged soon after birth. At the same time, the foramen ovale was closed and the diameters of the inferior vena cava and descending aorta were diminished. One-half-mm thick sections were cut serially and then photographed. Ventricular volumes and masses were calculated from summation of the areas of each chambers. Left ventricular mass per body weight increased rapidly after birth, whereas right ventricular mass per body weight remained constant from 0 to 8 days after birth.