

World Federation of Societies for Paediatric Urology
MD
This edition of Progress in Paediatric Urology is devoted t the current state of the art in Posterior Urethral Valves. Our understanding of urethral valves has evolved dramatically over the years guided by such individuals as Young, Stephens Churchill, and Duckett. But only recently has the paradigm of dynamic interaction, reverberating through all of biology and medicine in recent years, made its way into contemporary thinking about the biology and clinical management of this intriguing urologic entity.
Beginning with his concept of a 'valve bladder syndrome' over 20 years ago, wherein upper tract drainage was found to be critically and complexly linked to the dynamic state of bladder emptying or filling, Mike Mitchell has refocused his well-respected creative thinking on the valve bladder toreemphasize the role of cycling and the ability of valve bladders to remodel themselves I the opportunity and chance to do so is insured by valve ablation without diversion. Ironically, while not the first to espouse the concept of 'cycling' per se, Mitchell, a consummate reconstructive surgeon, has given the bladder the opportunity to shine on its own and demonstrate its enormous reparative potential-a feat, which has been historically overshadowed in past eras where diversion and augmentation dominated therapy of this enigmatic condition. Since then, and particularly on the heels of the seminal report by Close and Mitchell on the remarkable effects of ablation monotherapy, these ideas are also finding their way into the embryonic field of paediatric bladder molecular science.
The infant boys with congenital posterior urethral valves, and the urologists and physicians around the world who care for them, own a debt of gratitude to Mike for persistently championing these concepts over the last two decades. With this in mind, this current volume of Progress in Paediatric Urology id dedicated to Dr. Michael E. Mitchell, MD.
A tribute by Darius J. Bagli, MDCM, FRCSC, FAAP