The FTC has authorized a lawsuit to challenge Thoratec Corp.’s proposed $282 million takeover of rival medical device maker HeartWare International Inc.. The Commission claims that the merger would allow Thoratec to maintain its monopoly on the U.S. market of the left ventricular device (LVAD) used to keep patients suffering from end-stage heart failure alive while they await a donor heart, by eliminating HeartWare’s new LVAD, which is the “only significant threat” to Thoratec’s dominance.