Figure 3b

Radiofrequency ablation (the technique involves heart catheterization with a catheter containing a wire capable of delivering radiofrequency energy to selected areas in the cardiac conductive system) in WPW syndrome. The patient had frequent recurrent supraventricular tachycardias due to WPW syndrome.
A. Standard leads I, II, and V1 demonstrate disappearance of the delta wave from one impulse to the next, 5s after beginning the application of radiofrequency energy (compare successive QRS complexes indicated by arrows).
B. Prior to ablation, the interval between atrial (A) and ventricular (V) activation at the site of the ablation catheter is below 50 ms, and the sharp spike between A and V likely represents activity in the bypass tract.
C. Immediately after ablation, the A-V interval at the site of the ablation catheter (AB) is lengthened to 150 ms, and the accessory pathway spike has disappeared.
D and E. Enlargements of D and E from panels B and C, respectively. (RA= right atrium, AB= ablation catheter, RVA= right ventricular apex.)

Myerburg, R.J., MD, Kessler, K.M., MD, Castellanos, A., MD, Recognition, Clinical Assessment, and Management of Arrhytmias and Conduction Disturbances, Hurst's The Heart, 8th edition, p 705-758.