Pulmonary vein mapping
The pulmonary veins are known sources of ectopic atrial beats in patients with chronic atrial fibrillation. These patients are increasingly being treated with radiofrequency ablation in which the radiofrequency current is applied within the left atrium at the level of the ostia of the pulmonary veins. The goal of the treatment is to electrically isolate all the pulmonary veins by creating circumferential lesions at their ostia.
Pulmonary vein mapping prior to performing radiofrequency ablation provides detailed anatomic information which contributes to the success of the procedure. Pulmonary venous anatomy, including variant structures, as well as the relationship between the pulmonary ostia and the left atrium can all be demonstrated prior to the procedure.
Key Points
- With the increasing use of this procedure, variations in the pulmonary vein anatomy have become more appreciated. The right-sided pulmonary veins have demonstrated more variability than those of the left, with the right middle lobe vein draining directly into the left atrium being the most common normal variant.
- Detailed anatomic knowledge prior to performing radiofrequency ablation results in a substantial decrease in overall procedure time as well as reduced fluoroscopic dose to the patient and practitioner.
- Pulmonary vein mapping allows precise measurement of the diameter of the venous ostia, which in turn influences the type of catheter used for ablation.
- There are known complications associated with catheter ablation, such as pulmonary vein stenosis and pulmonary hypertension. MR can accurately demonstrate these lesions and provide noninvasive followup.
Case in Point
56 year old male status post radiofrequency ablation for atrial fibrillation. Follow-up study demonstrated interval development of pulmonary vein stenosis.
For Further Reading
- Marom EM, Herndon JE, Kim YH, McAdams HP. Variations in pulmonary venous drainage to the left atrium: implications for radiofrequency ablation. Radiology. 2004 Mar;230(3):824-9. Epub 2004 Jan 22.
- Robbins IM, Colvin EV, Doyle TP, Kemp WE, Loyd JE, McMahon WS, Kay GN. Pulmonary vein stenosis after catheter ablation of atrial fibrillation. Circulation. 1998 Oct 27;98(17):1769-75.