Dr. Mehdi Razavi at St. Luke's in Houston may be able to help you. you can call him at 713 417 9161. He's pretty sketchy about answerin because he spends a lot of time in the lab.
For an Italian reader I definitely suggest the books of Giuseppe Oreto, "Elettrocardiogramma, un mosaico a 12 tessere" and "I disordini del ritmo cardiaco".
In these books there is an extensive review of the supernormal conduction.