Introduction
Persistent left superior vena cava (PLSVC) is the most prevalent variation in the fetal venous system, occurring in approximately 0.3–0.5% of fetuses (1,2). Notably, approximately 8% of fetuses with PLSVC also exhibit congenital heart disease (1,3). The classification of PLSVC into four distinct types is based on the drainage pathway (1): type I involves drainage of the coronary sinus (CS) to the right atrium (RA) (Figure 1A), type II involves drainage of the CS to the RA with additional flow between the left atrium (LA) and PLSVC (Figure 1B), type III involves drainage directly into the LA (Figure 1C), and type IV involves drainage into the LA via the left pulmonary veins (PVs) and CS atresia (Figure 1D). The most prevalent clinical presentation is type I PLSVC, which does not result in any significant hemodynamic alterations, although isolated widening of the CS is a common finding. In contrast, cardiac arrhythmias and paradoxical embolization are linked with type I and type II. Type II includes drainage into the RA through the CS but includes a short circuit with the LA, resulting in a partial atrial level shunt. The drainage of types II, III, and IV PLSVC into the LA postnatally may result in reduced oxygen saturation in the LA, which could lead to heart failure, hypoxemia, and an elevated risk of cerebral embolism in adult individuals (4). It is encouraging to note that types III and IV PLSVC, which are associated with postnatal oxygenation challenges, are relatively uncommon. The literature contains numerous reports on the diagnosis of type I via prenatal ultrasound, but there are no such reports related to type II, III, or IV. This may be due to the fact that type II, III, and IV are relatively rare; moreover, as type III or IV PLSVC involves drainage directly to the LA or through the left PV to the LA, CS dilatation does not occur. Meanwhile, in type II, drainage occurs into the RA through the CS but involves a short circuit with the LA, resulting in a partial right-to-left shunt and less pronounced dilation of the CS. Overall, type II, III, and IV PLSVC can be easily missed or misdiagnosed.
Figure 1.
Structural presentation of PLSVC classification. (A) Type I PLSVC: the blood in the PLSVC and its drainage into the RA via the dilated CS is present. (B) Type II PLSVC: most of the blood in the PLSVC enters the RA through the dilated CS, whereas some of the blood returns to the LA through the PLSVC. (C) Type III PLSVC: all the blood in the PLSVC drains directly into the LA. (D) Type IV PLSVC: the blood drains into the LA via the LPV with CS atresia. PLSVC, persistent left superior vena cava; RA, right atrium; CS, coronary sinus; LA, left atrium; LPV, left pulmonary vein.
Case presentation
A 28-year-old pregnant woman underwent fetal echocardiography at the department of ultrasound diagnosis in Gansu Provincial Maternity and Child-care Hospital at 26+2 weeks of gestation. Two-dimensional fetal echocardiography revealed a typical complete endocardial cushion defect (Figure 2A; Videos 1) and a persistent right umbilical vein (Figure 2B; Video 2). The PVs did not enter the LA; instead, all four PVs converged into a common PV (Figure 2C; Videos 3,4) and descended through the diaphragm to the portal vein (Figure 2D). High-definition flow (HD-flow) combined with spatiotemporal image correlation (STIC) clearly delineated the common PV and infracardiac total anomalous pulmonary venous connection (TAPVC) (Figure 2E,2F). Although the main pulmonary artery (PA) was not visualized, HD-flow depicted only the left pulmonary artery (LPA) and right pulmonary artery (RPA). Collateral circulation between the descending aorta (DAO) and the LPA/RPA was evident, suggesting type III pulmonary atresia (Figure 3A,3B; Video 5). HD-flow combined with STIC vividly illustrated the collateral circulation between the DAO and the LPA/RPA (Figure 3C,3D). The three-vessel tracheal view revealed a tube-like echo-free structure on the left side of the aorta (Figure 4A; Video 6). Two-dimensional and HD-flow dynamic tracing demonstrated blood flow originating from the left brachiocephalic vein (LBCV), indicative of a PLSVC. The PLSVC descended and ultimately joined the LA, right superior vena cava (RSVC), and inferior vena cava (IVC) into the RA (Figure 4B,4C; Videos 7,8). HD-flow combined with STIC facilitated the visualization of the type III PLSVC (Figure 4D; Video 9).
Figure 2.
Fetus with type III PLSVC complicated by intracardiac and extracardiac abnormalities: (A) A 2D ultrasonographic image displaying the CECD with a single atrioventricular valve. (B) Persistent right umbilical vein in the transverse view of the abdomen. (C) HD-flow showing the formation of the CPV behind the LA in the four-chamber view. (D) HD-flow demonstrating the CPV descending through the diaphragm and converging into the PV. (E,F) HD-flow combined with STIC can be employed to visualize the CPV and infracardiac TAPVC. CECD, complete endocardial cushion defect; LA, left atrium; RA, right atrium; CPV, common pulmonary vein; GB, gallbladder; PRUV, persistent right umbilical vein; STO, stomach; LPV, left pulmonary vein; DAO, descending aorta; RPV, right pulmonary vein; PV, pulmonary vein; VV, vertical vein; IVC, inferior vena cava; LHV, left hepatic vein; MHV, middle hepatic vein; RHV, right hepatic vein; PLSVC, persistent left superior vena cava; 2D, two-dimensional; HD, high-definition; STIC, spatiotemporal image correlation; TAPVC, total anomalous pulmonary venous connection.
Video 1.
Two-dimensional ultrasonography showing a complete endocardial cushion defect.
Video 2.
Two-dimensional ultrasonography showing persistent right umbilical vein.
Video 3.
Two-dimensional ultrasonography showing the left/right pulmonary vein converging into the common pulmonary vein. LPV, left pulmonary vein; CPV, common pulmonary vein; RPV, right pulmonary vein; DAO, descending aorta.
Video 4.
High-definition flow showing the left/right pulmonary vein converging into the common pulmonary vein. LPV, left pulmonary vein; CPV, common pulmonary vein; RPV, right pulmonary vein; DAO, descending aorta.
Figure 3.
Imaging of type III PA using 2D and 3D ultrasonography: (A) A 2D image demonstrating the absence of the MPA, with only the left and right pulmonary arteries visible. (B,C) Visualization of MAPCAs via HD-flow. (D) HD-flow combined with STIC showing MAPCAs between the descending aorta and left/right pulmonary arteries. LPA, left pulmonary artery; RPA, right pulmonary artery; DAO, descending aorta; MAPCA, major aortopulmonary collateral artery; PA, pulmonary atresia; 2D, two-dimensional; 3D, three-dimensional; MPA, main pulmonary artery; HD, high-definition; STIC, spatiotemporal image correlation.
Video 5.
High-definition flow showing the major aortopulmonary collateral arteries between the descending aorta and left/right pulmonary artery. LPA, left pulmonary artery; RPA, right pulmonary artery; MAPCA, major aortopulmonary collateral artery; DAO, descending aorta.
Figure 4.
Prenatal images of type III PLSVC. (A) PLSVC visible on the left side of the aorta in the three-vessel tracheal view. (B,C) 2D ultrasonography and HD-Flow showing the PLSVC draining into the left atrium and the right superior vena cava draining into the right atrium. (D) HD-flow combined with STIC demonstrating drainage of the PLSVC into the LA and confluence of the RSVC into the RA. LV, left ventricle; LSVC, left superior vena cava; AO, aorta; RSVC, right superior vena cava; T, trachea; PLSVC, persistent left superior vena cava; LA, left atrium; RA, right atrium; PLSVC, persistent left superior vena cava; 2D, two-dimensional; HD, high-definition; STIC, spatiotemporal image correlation.
Video 6.
Two-dimensional ultrasonography showing type III persistent left superior vena cava. LV, left ventricle; AO, aorta; LSVC, left superior vena cava; T, trachea; RSVC, right superior vena cava.
Video 7.
Two-dimensional ultrasonography demonstrating the drainage of type III persistent left superior vena cava into the left atrium. LA, left atrium; RA, right atrium; LSVC, left superior vena cava; RSVC, right superior vena cava.
Video 8.
High-definition flow showing the drainage of type III persistent left superior vena cava into the left atrium.
Video 9.
High-definition flow combined with STIC demonstrating the drainage of type III persistent left superior vena cava into the left atrium. LA, left atrium; RA, right atrium; LSVC, left superior vena cava; RSVC, right superior vena cava; STIC, spatiotemporal image correlation.
Following prenatal ultrasonography, the diagnosis and prognosis were discussed with the pregnant woman and her family, who opted for induced labor to terminate the pregnancy. A female infant was delivered with a birth weight of 680 g at 26+5 weeks of gestation. Despite communication with the pregnant woman and her family, they declined to authorize a postmortem examination.
All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.
Discussion
Early diagnosis of PLSVC is important in prenatal care. Fetal echocardiography is valuable for diagnosing most cases of type I PLSVC and offers precise information for prenatal counseling. As the flow in type III or IV PLSVC drains directly to the LA or through the left PV to the LA, CS dilation does not occur, and type III or IV PLSVC can be easily missed or misdiagnosed. The three-vessel tracheal view is particularly crucial for identifying type III PLSVC, although classifying the specific type of PLSVC can pose challenges. Moreover, the use of multisectional observations in this case might have contributed to preventing a missed diagnosis of type III PLSVC.
Combination of HD-flow with STIC can provide three-dimensional visualization of the fetal heart, aorta, and vein, thereby enhancing diagnostic accuracy (5). Furthermore, HD-flow combined with STIC can stereo-display the PLSVC and RSVC, providing an intuitive three-dimensional representation of the PLSVC. This technique also enables the visualization of the routes taken by the RSVC, visually reproducing the spatial positional relationships of the LA and PLSVC, all of which are instrumental in accurately diagnosing type III PLSVC before delivery. In conclusion, combining these two modalities has been shown to enhance the diagnostic process and confidence in the prenatal diagnosis of type III PLSVC.
Finally, it is important to note that type III PLSVC may not only cause hemodynamic changes but can also be associated with severe intracardiac malformations. Moreover, neonates with isolated type III PLSVC require venous catheterization and cardiac surgery. Therefore, prenatal diagnosis of PLSVC is pivotal for prenatal counseling and prognostic evaluation. This, in turn, can help expectant parents readily comprehend the nature of the defect and make informed decisions. The diagnosis of type III PLSVC requires meticulous fetal echocardiography for the detection of potential combinations with other intracardiac malformations. When PLSVC is detected prenatally, a comprehensive evaluation of the fetal structure, particularly of the cardiovascular system, is recommended. If associated structural abnormalities are identified, comprehensive prenatal counseling and assessment of fetal prognosis are advised.
Conclusions
Type I PLSVC is the most common venous variant of this condition and is mostly asymptomatic. Isolated type I PLSVC involves no hemodynamics change in the fetal heart, but when type I PLSVC is discovered in fetuses, the pediatric cardiac surgery expert should be informed in advance, as this condition may cause procedural difficulty or increase the incidence of vascular damage during midline thoracic or cardiac surgery. The prenatal diagnosis of type II, III, and IV PLSVC in fetuses is critical because each type is associated with decreased cardiac oxygenation after birth and needs to be corrected through clinical operation. Thus, accurate prenatal identification of the type of PLSVC, especially of type II, III, and IV, is beneficial to neonatal prognosis and treatment options, as it is vital to achieving a definitive diagnosis in utero.
Supplementary
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Acknowledgments
Funding: This work was supported by the Natural Science Foundation of Gansu Province (No. 23JRRA1391) and the Research Plan for the Health Industry of Gansu Province (No. GSWSKY2021-001).
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.
Footnotes
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-24-1143/coif). The authors have no conflicts of interest to declare.
References
- 1.Azizova A, Onder O, Arslan S, Ardali S, Hazirolan T. Persistent left superior vena cava: clinical importance and differential diagnoses. Insights Imaging 2020;11:110. 10.1186/s13244-020-00906-2 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Poenaru MO, Hamoud BH, Sima RM, Valcea ID, Chicea R, Ples L. Persistent Left Superior Vena Cava Significance in Prenatal Diagnosis-Case Series. J Clin Med 2022;11:4020. 10.3390/jcm11144020 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Bisbee CR, Sherard C, Rajab TK. Left Superior Vena Cava Draining to Left Atrium: A Case Report, Review of the Literature, and Classification. Pediatr Cardiol 2024;45:1838-40. 10.1007/s00246-023-03289-5 [DOI] [PubMed] [Google Scholar]
- 4.Hana D, Wahba D, Schwartzman D, Hamirani YS. Persistent Left Superior Vena Cava Draining Directly Into the Left Atrium With Occluded Coronary Sinus. JACC Case Rep 2023;8:101731. 10.1016/j.jaccas.2022.101731 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Ma B, Wu L, Zhang W. Rare vascular ring of right aortic arch and aberrant left subclavian artery in association with bilateral ductus arteriosus. Ultrasound Obstet Gynecol 2020;55:135-7. 10.1002/uog.20365 [DOI] [PubMed] [Google Scholar]
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