Absent Right Superior Vena Cava and Persistent Left Superior Vena Cava: An Incidental Finding

ABSTRACT

A patient with Marfan syndrome undergoing Bentall operation was found to have an absent right superior vena cava and persistent left superior vena cava. The dilation of coronary sinus raised the suspicion of persistent left superior vena cava. The diagnosis was confirmed by agitated saline contrast echocardiography and computed tomography of the chest.

INTRODUCTION

Patients with absent right superior vena cava (RSVC) and persistent left superior vena cava (PLSVC) are generally asymptomatic. However, in a significant minority (about 10%), PLSVC can drain into left atrium and can potentially create a right-to-left shunt and systemic desaturation. The condition is generally diagnosed as an incidental finding during the insertion of a central venous catheter, implantable electronic device, or during cardiovascular imaging/cardiac surgery.[1] The association of this anomaly with Marfan syndrome and aneurysmal dilation of the ascending aorta has not been reported. The clinicians may find technical difficulties with right heart access and should be aware of this condition to avoid possible complications.

CASE REPORT AND IMAGE DESCRIPTION

A 61-year-old male with Marfan syndrome, aneurysm of the sinuses of Valsalva, and aneurysmal dilation of the ascending aorta was admitted for a Bentall operation. Two-dimensional transthoracic echocardiography showed a dilated coronary sinus (CS) [Figure 1a]. Injection of agitated saline into both right and left antecubital veins showed opacification of CS first, followed by the right atrium and right ventricle, suggesting PLSVC [Figure 1b-d, Video 1]. Computed tomography (CT) of the chest showed an absence of RSVC; and both right and left brachiocephalic veins draining into a large PLSVC [Figure 2a]. The PLSVC was draining into the right atrium through CS [Figure 2b]. The surgical procedure, which included ascending aortic cannulation and right atrial cannulation for cardiopulmonary bypass; and the postoperative course were uneventful.

Figure 1.

Transthoracic echocardiography (apical four-chamber view with transducer tilted posteriorly) showing dilated coronary sinus (CS) (a). Injection of agitated saline showed opacification of CS first, followed by right atrium (RA) and right ventricle (RV) (b-d)

Figure 2.

Computed tomogram of the chest showing absent right superior vena cava (SVC) and both right brachiocephalic vein (RBCV) and left brachiocephalic (LBC) vein draining into left SVC (a). Sagittal view (b) showing Left SVC draining into the coronary sinus (CS) and right atrium (RA)

DISCUSSION

RSVC is present in most patients with PLSVC. However, RSVC may be absent in about 0.07-0.13% of the population.[1,2] Regression of the caudal right superior cardinal vein leads to agenesis of RSVC. Failure of closure of the left anterior cardinal vein results in PLSVC.[3] In these patients, both right and left brachiocephalic veins drain into the PLSVC. This anomaly is typically characterized by: (i) PLSVC draining into the right atrium via CS and (ii) left-sided azygos vein draining into the left superior vena cava (SVC). The less common features are (i) additional cardiovascular anomalies such as atrial septal defect, endocardial cushion defect, coarctation of the aorta, bicuspid aortic valve, double aortic arch, and (ii) conduction disturbances.[4] Injection of the contrast material into the right and left antecubital veins will opacify the CS before the right atrium, as happened in our case. Since the patients with absent RSVC are generally asymptomatic, their status should be assessed by echocardiography, contrast echocardiography, venous angiography, CT, or magnetic resonance imaging before invasive medical or surgical procedures. An absent RSVC can pose management difficulties during the following procedures: (i) placement of a central venous catheter/pulmonary artery catheter, (ii) bicaval cannulation for cardiopulmonary bypass, as PLSVC needs to be cannulated separately for adequate venous drainage, (iii) difficulty in the administration of retrograde cardioplegia, (iv) cavopulmonary anastomoses during Glenn or Fontan procedure, (v) implantation of cardiac implantable electronic devices, (vi) venous cannulation for extracorporeal membrane oxygenation, and (vii) orthotopic heart transplantation and endomyocardial biopsies.[5]

In conclusion, an absent RSVC and isolated PLSVC in adult patients is a very rare anomaly. Transthoracic echocardiography, using agitated saline injection into both antecubital veins, is an important diagnostic tool for the accurate diagnosis of this rare congenital anomaly.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.