Doctors at the exclusive Cimeq hospital in western Havana are accustomed to handling the delicate health problems of Cuba's communist elite. It was here last weekend, The Sunday Telegraph has learnt, that they battled for several hours to save the life of the regime's most important patient, Fidel Castro. Unable to stem intestinal bleeding with drugs, the country's top surgeons performed an emergency operation on the veteran leader. To all but a handful of trusted doctors and his closest lieutenants, President Castro's medical condition has been shrouded in mystery, described as a "state secret" in words attributed to the dictator...