Radiofrequency catheter ablation of a concealed atrioventricular accessorypathway associated with a coronary sinus diverticulum

A 31-year-old woman underwent radiofrequency catheter ablation of a conceal ed left posteroseptal accessory pathway associated with a coronary sinus di verticulum. The patient had previously undergone unsuccessful catheter abla tion of the posteroseptal region of the mitral annulus. Coronary sinus veno graphy revealed the presence of the diverticulum near the ostium. An electr ogram in the neck of the diverticulum showed the shortest ventriculoatrial conduction time and a large accessory pathway potential during atrioventric ular reciprocating tachycardia. The pathway was successfully ablated within the neck of the diverticulum. The findings in this case underscore the imp ortance of coronary sinus venography before ablation.