Dual-chamber devices monitor the upper and lower heart chambers for an erratic beat and restore normal rhythm.
Regular defibrillators monitor the lower chamber.
St. Jude wasn't expecting approval until the end of the year. The device, called the Photon, will allow St. Jude to gain some market share, however, a smaller model that's still a few months from approval will be more competitive, Faulkner said. They have risen 72 percent this year.