Mondal S, Arasan S, Kumar SS, Pant BP (2024) Commentary on “Absent Right and Persistent Left Superior Vena Cava, Interrupted Inferior Vena Cava: A Case Report”. Clin J Heart Dis 3(1): 1011.

A 29-year-old male underwent incidental detection of ostium secundum Atrial Septal Defect (ASD) with moderate pulmonary hypertension [1]. Subsequent cardiac catheterisation revealed an interrupted Inferior Vena Cava (IVC) and absent right Superior Vena Cava (SVC) (Figure 1).

Figure 1: Schematic depiction of the index case. Note: RA: Right Atrium; RV: Right Ventricle; LA: Left Atrium; LV: Left Ventricle; IVC: Inferior Vena Cava; RSVC: Right Superior Vena Cava; LSVC: Left Superior Vena Cava; CS: Coronary Sinus

Drainage of the upper body occurred via the Persistent Left SVC (PLSVC), while drainage of the lower body occurred through the hemiazygos vein. Consequently, whole-body systemic venous return was achieved solely by the left-sided venous system, via the coronary sinus, except the hepatic veins. Important catheter courses while performing the cardiac catheterisation study have been shown in figure 2.

Figure 2: Catheter and wire courses via important structures have been shown. LSVC: Left Superior Vena Cava; CS: Coronary Sinus; RA: Right Atrium; ASD: Atrial Septal Defect; LA: Left Atrium; PV: Pulmonary Vein; RV: Right Ventricle; RVOT: Right Ventricular Outflow Tract; PA: Pulmonary Artery.

This section will provide a concise overview of the embryonic development of the systemic venous system with clinical implications.

The cardinal veins carry the venous return from the embryo proper (Figure 3, Table 1).

Figure 3: Embryology of the major veins and implications in this case (6 weeks - 7 weeks - 8 weeks -Adult form).

Table 1: Embryonic veins and their corresponding adult derivative and clinical implications.

The anterior cardinal vein is responsible for draining venous blood from the cephalic region (upper body), while the posterior cardinal vein handles venous return from the caudal region (lower body). On each side, anterior and posterior cardinal veins join to form the common cardinal vein. The left and right common cardinal veins are relatively short segments that connect to the sinus venosus. The right anterior and right common cardinal veins form the SVC in the mature circulation [regression of this part in the index case]. The left common cardinal vein and left segment of the sinus venosus form the coronary sinus. The IVC is developmentally more complex and comprises five segments, fusing together to the right of the spine, as their leftward paired counterparts involute [reversed in the index case] [2]. When the IVC is interrupted, one of two major vessels that connect the lower and upper body venous systems generally enlarges to receive the flow and shunt it into the SVC [right system regressed and left hemiazygos system enlarged in the index case]. These are the rightward azygous vein, which runs from the suprarenal segment of the IVC to the SVC, and the leftward hemiazygos vein, which takes a more tortuous course from the leftward lumbar and renal veins up into the thoracic cavity, ultimately turning right to join the azygous vein [it joins the left common cardinal venous system directly in the index case, rather than turning right and joining]. Thus an interrupted IVC generally has either azygous or hemiazygos continuation to the SVC.

The anterior cardinal veins drain the cranial part of the embryo and are connected by a large central anastomosing channel. The segment of the left anterior cardinal vein located proximal (towards the developing heart) to the anastomosis regress [not regressed in the index case, forming the left SVC]. The oblique vein of the left atrium and the coronary sinus, develop from the partially regressed proximal segment of the left anterior cardinal vein [Not regressed in this case, forming part of LSVC joining the Coronary sinus]. The remaining distal (towards the cranium) segment becomes the left internal jugular vein and the anastomosis between the anterior cardinal veins forms the left brachiocephalic vein. The right internal jugular and brachiocephalic veins develop from the distal segment of the right anterior cardinal vein. Erroneous regression on the right side results in absent RSVC. The surgical team opined for closure of OS-ASD without interfering with venous drainage as this would not change the systemic venous drainage to RA through the right ventricle to the pulmonary artery.

In approximately 80-90% of individuals with persistent LSVC, venous drainage occurs into the right atrium via the coronary sinus. This configuration is typically without hemodynamic consequences. However, in the remaining 10-20% of cases, the persistent LSVC may drain into the left atrium (unroofed CS) leading to a right-to-left shunting of blood with systemic desaturation.

Diagnosis of PLSVC typically occurs incidentally during cardiovascular imaging or surgical procedures. Transthoracic Echocardiography (TTE) may reveal a dilated coronary sinus, suggesting the presence of PLSVC. Confirmation of the diagnosis can be achieved through the use of saline contrast (“bubble study”) echocardiography. Approximately 40% of patients with PLSVC may exhibit a concurrent spectrum of cardiac anomalies, like atrial septal defect, bicuspid aortic valve, coarctation of the aorta, coronary sinus ostial atresia, and cor triatriatum [3]. In addition, PLSVC can further complicate the placement of permanent pacemakers and Implantable CardioverterDefibrillators (ICDs). The abnormal venous anatomy can hinder the optimal positioning of these devices and necessitate alternative approaches or techniques to ensure successful implantation and function [4].

A dilated CS should raise suspicion for the presence of a PLSVC. The absence of the right SVC should alert the cardiologist to potential technical difficulties during procedures typically accessed via the upper limb veins. The combined presence of a PLSVC and absent RSVC mandates a comprehensive evaluation for additional systemic venous anomalies and intracardiac defects. Understanding Embryonic Development is Key to Identifying Associated Anomalies.

1. Mondal S, Pant BP, Gopalakrishnan A, Harikrishnan S. Absent right and persistent left superior vena Cava, interrupted Inferior vena cava: A case report. Eur Heart J Case Rep. 2023; 7: ytad345.

2. Oliveira JD, Martins I. Congenital systemic venous return anomalies to the right atrium review. Insights Imaging. 2019; 10: 115.

3. Sarodia BD, Stoller JK. Persistent left superior vena cava: Case report and literature review. Respir Care. 2000; 45: 411–416.

4. Povoski SP, Khabiri H. Persistent left superior vena cava: Review of the literature, clinical implications, and relevance of alterations in thoracic central venous anatomy as pertaining to the general principles of central venous access device placement and venography in cancer patients. World J Surg Oncol. 2011; 9: 173.