Pulmonary vein dimensions and variation of branching pattern in patients with paroxysmal atrial fibrillation using magnetic resonance angiography

Pulmonary veins are the most frequent origin of focal and paroxysmal atrial fibrillation. Although radiofrequency ablation has been attempted for the treatment of focal and paroxysmal atrial fibrillation, the anatomy of the pulmonary vein is still not fully understood. To investigate the dimensions and anatomical variation of the pulmonary vein in patients with paroxysmal atrial fibrillation, we performed breath-hold gadolinium enhanced magnetic resonance (MR) angiography using a 1.5 T cardiac MR imager (GE CV/i) in 32 patients with paroxysmal atrial fibrillation (61±8 years old), 11 patients with chronic atrial fibrillation (64±9 years old), and 26 patients with normal sinus rhythm (55±15 years old). Three-dimensional images of the pulmonary veins were thus obtained, and the diameters of the most proximal portion of the left or right superior pulmonary vein and left or right inferior pulmonary vein were measured. Pulmonary vein branching variations were determined by a visual qualitative analysis by two separate readers' agreements, who were blinded to any clinical information. We focused on the existence of a complex-branching pattern draining into the orifice of four pulmonary veins. Patients with either paroxysmal atrial fibrillation or chronic atrial fibrillation showed larger superior pulmonary veins than those with normal sinus rhythm (mean±SD; in the left superior pulmonary vein, 20±3 mm 23±3 mm vs 16±3 mm, P<0.05; in right superior pulmonary vein, 19±4 mm, 19±2 mm vs 16±2 mm, P<0.05). Complex-branching pattern was frequently observed in inferior pulmonary veins in patients with either paroxysmal atrial fibrillation or chronic atrial fibrillation; 25/32 patients with paroxysmal atrial fibrillation, 11/11 patients with chronic atrial fibrillation, compared to 7/26 patients with normal sinus rhythm. Complex-branching patterns were not observed in superior pulmonary veins in any patients in this cohort. In patients with paroxysmal atrial fibrillation or chronic atrial fibrillation, significant pulmonary vein dilation occurred mainly in the superior pulmonary veins, while a complex-branching pattern was frequently observed in the inferior pulmonary veins. These MR angiographic findings might be useful when performing radiofrequency ablation procedures and catheter manipulation for the treatment of paroxysmal atrial fibrillation. (author)