Persistent Left Superior Vena Cava with the Absence of the Right Superior Vena Cava and Atrial Appendage: Complex Pacemaker Implantation in a Patient Presenting with a Rare Vascular Anomaly

Abstract

A persistent left superior vena cava (PLSVC) is a commonly observed anatomical anomaly that is frequently detected incidentally via computed tomography (CT) imaging. However, the occurrence of a PLSVC with a right superior vena cava (RSVC) defect, also known as “isolated PLSVC,” is a much rarer anomaly. This peculiar malformation can lead to sinoatrial dysfunction, thus necessitating pacemaker implantation, which requires delicate manipulation due to various anatomical complexities. We herein present a case of a sick sinus syndrome with this rare anomaly, which required special consideration when performing pacemaker lead placement.

Introduction

Persistent left superior vena cava (PLSVC) is a relatively frequent vascular malformation, detected in approximately 0.3% to 0.5% of the population (1). PLSVC without the right superior vena cava (RSVC), also known as “isolated PLSVC” (2), accounts for less than 10% to 20% of PLSVC cases (3,4). Although this anomaly does not cause any hemodynamic problems, poor development of the right atrium sometimes leads to abnormal polarity of the atrial excitation in electrocardiography (ECG) (5) and sinoatrial node dysfunction that may cause pathological sick sinus syndrome (6). Therefore, pacemaker implantation in patients with isolated PLSVC is not an incidental event, but rather a natural progression. When considering transvenous pacemaker implantation, physicians should give special consideration to the unique venous pathway. In this report, we present a strategy for managing a case of this rare malformation.

Case Report

We describe the case of a 71-year-old Japanese man presenting with PLSVC and the absence of the RSVC and right atrial appendage who underwent pacemaker implantation for sick sinus syndrome. At 69 years of age, he reported experiencing fatigue and noticed a reduction in his pulse rate, which declined from 70 bpm to 40 bpm during exercise.

The patient was referred to our cardiology department for pacemaker implantation and was diagnosed with type I sick sinus syndrome. Twelve-lead ECG at his first presentation showed junctional rhythm with a heart rate of 47 bpm (Fig. 1A). An atrial ectopic rhythm originating from the lower right atrium was also recorded, suggesting that this patient's atrioventricular conduction was intact (Fig. 1B). Computed tomography (CT) showed the absence of a SVC and right atrial appendage, while exhibiting the presence of a PLSVC (Fig. 2). This finding suggested that the patient's venous return from the upper body was solely dependent on the PLSVC. Except for these vascular anomalies, we did not identify any other anatomical abnormalities. His cardiac ejection fraction was within the normal range. To avoid any potential limitation in the PLSVC blood flow by dual pacemaker leads, a single-lead pacemaker was implanted via the PLSVC into the right atrium utilizing a thin lead (Capsure Fix Novus 52 cm, Medtronic, Minneapolis, USA) because the atrioventricular conduction was intact. Insertion of the pacemaker lead into the right atrium via the PLSVC proceeded smoothly; however, manipulation of the lead direction within the right atrium was challenging. Initially, we introduced a 25 cm long, 7Fr peel-away sheath (PI0018, Medikit, Tokyo, Japan) from the left subclavian vein through the PLSVC, reaching the ostium of the PLSVC in the right atrium. The atrial lead was then inserted through the sheath, yet attempts to place the lead in the higher right atrium did not succeed due to the absence of the right atrial appendage. Additionally, despite various shapes of the stylet, we were unable to perform a turn up maneuver to the septal wall due to the limited mobility of the lead tip in the right atrium. The lead tip was placed on the lateral wall of the right atrium (Fig. 3A, B). A CT scan was performed after implantation to confirm that the lead was not vertically screwed in and that there was no lateral wall perforation (Fig. 3B). One year after the implantation, we confirmed the patency of the PLSVC by echocardiography (Fig. 3C). As of two years following the intervention, the patient remained asymptomatic and his heart rhythm has been effectively managed by the pacemaker. Importantly, the atrial lead has not resulted in any atrial wall perforation and the lead position has remained unchanged in the chronic phase.

Figure 1.

ECG. A: ECG lead II at first presentation. The arrowheads indicate atrial contractions. B: 12-leads ECG recorded at another time showing an ectopic atrial rhythm with atrioventricular linking.

Figure 2.

The CT images demonstrated the absence of a RSVC and the existence of a PLSVC. (A) 3D reconstructed CT image, anterior view. The ascending aorta and aortic root were fully exposed in the absence of a right atrial appendage. (B) Schematic image of panel A. (C) 2D axial CT image of the patient's mediastinum. The arrowhead indicates the PLSVC. No RSVC was found to exist. Ao: aorta, PA: pulmonary artery, PLSVC: persistent superior vena cava, RA: right atrium, RCA: right coronary artery, RV: right ventricle

Figure 3.

The images of the pacemaker lead via PLSVC. (A) Chest X-ray image. The white arrowheads indicate the pacemaker lead running through the PLSVC. The black arrow indicates the lead tip. (B) 2D axial CT image of the right atrium. The arrow indicates the pacemaker lead. (C) Echocardiographic images one year after the intervention. The left panel depicts the coronary sinus ostium. The right panel shows the color doppler flow from the coronary sinus to the right atrium.

Discussion

We herein present a case of isolated PLSVC that necessitated pacemaker implantation due to sinus node dysfunction. Technically, it is often difficult to place the pacemaker lead via the PLSVC because of its winding path (3). Furthermore, the absence of the right atrial appendage in our patient necessitated careful consideration for lead implantation. Finally, we chose the lateral wall of the right atrium as the tip location, but it required careful attention due to a higher risk of perforation than optimal atrial appendage implantation. The use of a catheter delivery system for cardiac resynchronization therapy or right ventricular septal pacing should be considered if physicians prefer to choose more medial sites in cases similar to this patient (7). However, even with the support of such systems, lead implantation into the atrial septal wall is extremely challenging because it requires a hairpin-like maneuver. Careful observation of the atrio-ventricular conduction is also important for such cases. To avoid occlusion of the PLSVC, we decided to not implant a ventricular lead. Ideally, before making this decision, a more precise evaluation of atrio-ventricular conduction by an electrophysiological study should have been carried out. In addition, it is necessary to track any possible atrio-ventricular conduction delays. In such a situation, lead less pacemaker implantation may be one of the possible treatments.

Author's disclosure of potential Conflicts of Interest (COI).

Kenichi Kamiya: Complimentary user license for Vesalius 3D, PS Tech.