MILAN, March 30 Telecom Italia has appointed state-industry veteran Flavio Cattaneo as chief executive to replace Marco Patuano, who resigned over what sources said were clashes over strategy with top investor Vivendi. Milan-born Cattaneo, already a board member at Telecom Italia, takes over as the former state phone monopoly steps up investments in an ultrafast broadband network, a pet project of Prime Minister Matteo Renzi who wants to get Italy up to speed with the rest of Europe.