Venezuelan President Nicolas Maduro looked to the world of digital currency to circumvent U.S.-led financial sanctions, announcing the launch of the “petro” backed by oil reserves to shore up a collapsed economy.The announcement bewildered some followers of cryptocurrencies, which typically are not backed by any government or central banks. Ironically, Venezuela’s currency controls in recent years have spurred a bitcoin fad among tech-savvy Venezuelans looking to bypass controls to obtain dollars or make internet purchases.