Left Right Asymmetry, the Pulmonary Vein, and A-Fib

Atrial fibrillation (AF), a common adult cardiac arrhyth-mia, involves abnormal atrial contractions. As every medical student is taught, it is easily diagnosed as an irregularly irregular pulse and loss of organized atrial activity on an ECG. Clinical interest in AF is considerable because AF is the most common adult arrhythmia that increases in prevalence with age, with 5 % of the over 65 population having AF. Moreover, patients with AF have a significantly increased risk of stroke.1 Electrical impulses, critical for a coordinated and physio-logic heartbeat, are normally initiated in the sinoatrial (SA) node. However, in AF the disorganized atrial activity over-rides normal SA node function resulting in irregular conduc-tion of impulses to the ventricles. In the majority of cases, ectopic electrical activity originates in the pulmonary veins.1 In this issue of Circulation Research, Mommersteeg an