Absent Right Superior Vena Cava and Persistent Left Superior Vena Cava: The Perioperative Implications

Abstract

A 22-yr-old female patient was admitted for repair of tetralogy of Fallot. Preoperative transthoracic echocardiography revealed large subaortic ventricular septal defect, 50% aortic over-ride, severe valvular and subvalvular pulmonary stenosis, persistent left superior vena cava (PLSVC), and a large coronary sinus (CS). After anesthetic induction, central venous cannulation of the right internal jugular vein was attempted with a 20-guage cannula using Seldinger’s technique. Despite free flow through the cannula, the guidewire could not be advanced beyond 8 cm; therefore, a pediatric (8 cm, 5.5F) triple-lumen catheter was inserted. Intraoperative transesophageal echocardiography (TEE) imaging of the midesophageal (ME) bicaval view with the transducer steered through 90–120° suggested absence of the right superior vena cava (RTSVC) (Figs. 1a and b) (please see video loops available at www.anesthesia-analgesia.com). However, a large PLSVC and CS (Fig. 2) (see video loop) were seen midway between the ME four-chamber and a deep four-chamber view; the probe was slightly rotated counterclockwise. The absent RTSVC was evident on opening the pericardium. After aortic and inferior vena cava cannulation and institution of cardiopulmonary bypass a separate cannula was inserted extrapericardially in the PLSVC. The surgical repair and postoperative course were uneventful. An absent RTSVC is always associated with a PLSVC, with a reported incidence of 0.1% (1). It should be suspected when the chest radiograph does not show its characteristic shadow, particularly with an extra shadow (PLSVC) above the aortic knob (1). On TEE examination, the RTSVC is usually well visualized in the ME bicaval view. Agitated saline administered centrally appears as contrast in the RTSVC and right atrium (RA). With an absent RTSVC, contrast appears in the RA via the CS and can be viewed just below the ME four-chamber view and in bicaval view; however, if the CS is unroofed [absence of common wall between CS and left atrium (LA)], the contrast appears in both the LA and RA. A PLSVC descends along the left paramediastinal structures, anterior to the aortic arch and left pulmonary artery. It then passes inferiorly; in its course receives its tributary the hemiazygos vein, and then descends medially between the left pulmonary veins and left atrial appendage joining the CS in the atrioventricular groove (Fig. 3) causing an enlarged CS. Enlargement of the CS ( 1 cm) may indicate right atrial hypertension, an anomalous systemic venous channel draining through it (e.g., connection of PLSVC, hepatic veins, inferior vena cava), fistulous communication with coronary arteries and total or partial anomalous pulmonary venous connection. A PLSVC can be seen in ME views in the vicinity of the left atrial appendage and left upper pulmonary vein with the probe rotated counterclockwise, and can be traced to its entry into the CS. Occasionally, a PLSVC can be misdiagnosed as descending thoracic aorta, however, it can be differentiated from the descending thoracic aorta by pulse-wave Doppler assessment that shows continuous flow in the PLSVC and pulsatile flow in the descending thoracic aorta. The diagnosis of PLSVC is classically made by injecting contrast into the left-sided brachiocephalic veins and demonstrating contrast appearance in the PLSVC, CS, and RA (in that sequence). In 10% of patients, a PLSVC may drain into the LA either directly or via an unroofed CS; in such a situation, contrast first appears in the LA. Because of the PLSVC draining into the LA (right to left shunt) the arterial blood gas analysis or pulse oximetry will show desaturation. Although, this finding will not help evaluation of cyanotic patients, it can create a diagnostic and management dilemma in patients with acyanotic lesions. This article has supplementary material on the Web site: www.anesthesia-analgesia.org.