|Number 10-14: Persistent Left SVC Complicating Atrial Fibrillation Ablation|
Number 10-14: Persistent Left SVC Complicating Atrial Fibrillation Ablation
Case from: Vikas K. Rathi1, Robert W.W. Biederman1, June Yamrozik1, Ronald Williams1, William Belden2
Clinical history: A 50 year old male with history of persistent atrial fibrillation and three failed electrical cardioversion attempts in the past 2 years was being evaluated for a pulmonary vein isolation (PVI) procedure. The day prior to ablation he underwent cardiovascular MRI (CMR) to identify the 3D anatomy and location of the pulmonary veins in order to assist the electrophysiologist in the planned PVI procedure.
CMR imaging: The initial cine 2-chamber view demonstrated a markedly dilated coronary sinus (Fig 1). Coronal and sagittal cine images revealed a persistent left superior vena cava (pLSVC) communicating with the coronary sinus which drained into the right atrium (Movies 1 and 2).
An oblique peri-axial image perpendicular to the long-axis of the pLSVC at the level of left pulmonary veins was acquired which demonstrated the pLSVC coursing between the left atrial appendage and the left superior pulmonary vein completely adjacent to the walls of these structure (Movie 3). There was no communication between the pLSVC and the pulmonary veins or left atrial appendage. A 3D MRA demonstrated four pulmonary veins draining into the left atrium (Movie 4). No anomalous pulmonary venous return or sinus venosus defect were seen. He also had a bicuspid aortic valve with mildly dilated ascending aorta and aneurysmal origin of the left subclavian artery (Movies 2 and 3).
Following morphologic and anatomic imaging, the patient underwent 3D magnetic resonance angiography (MRA) with gadolinium chelate (Gd) injected into the right antecubital vein. The first phase acquisition was targeted for pulmonary vein filling and demonstrated four pulmonary veins draining into the left atrium. As expected, the pLSVC was not visualized on first phase images due to the IV administration of Gd in the right antecubital vein and the absence of bridging vein to the left side (common in pLSVC cases) (Movie 4). A second (venous) phase was acquired to demonstrate pLSVC filling (Movie 5)
Movie 4 Movie 5
Electrophysiology Study: A lasso catheter was passed across the interatrial septum and into the left atrium followed by a venogram of the pLSVC which was accessed through the coronary sinus (Movie 6). The lasso catheter was then passed through the coronary sinus into the distal end of the pLSVC. The bipole electrodes LS 1 to 10 on this lasso catheter recorded significant electrical activity originating in the distal LSVC (Fig 2). Since the pLSVC was adjacent to the left atrial wall and the left superior pulmonary vein, the electrical activity within the pLSVC was able to conduct into these structures thereby potentially initiating atrial fibrillation. The pLSVC was rendered electrically inactive after ablation performed within the pLSVC (Fig 3). The electroanatomic map created during the PVI procedure demonstrated ablation lines within the pLSVC, left atrium and pulmonary veins (Movie 7).
Figure 2 - Pre ablation
Figure 3 - Post ablation
Discussion: The major thoracic veins, with their specific electrical properties, have an established role in the genesis and maintenance of atrial fibrillation1,2. The vein of Marshall and pLSVC which drains into the coronary sinus as well as the ligament of Marshall have all been implicated in the cause for premature atrial complexes and initiation of atrial fibrillation3,4. Identification of their presence along with demonstration of electrical activity within such structures is key to successful ablation of atrial fibrillation5.
4. Morgan DR, Hanratty CG, Dixon LJ, et al. Anomalies of cardiac venous drainage associated with abnormalities of cardiac conduction system. Europace. 2002; 4: 281-287.
5. Hsu LF, Jaïs P, Keane D, Wharton JM, Deisenhofer I, Hocini M, Shah DC, Sanders P, Scavée C, Weerasooriya R, Clémenty J, Haïssaguerre M. Atrial fibrillation originating from persistent left superior vena cava. Circulation. 2004 Feb 24;109(7):828-32.
COTW handling editor: Kevin Steel