Suffering from a broken heart? Thoratec's there for the rebound. The company, a world leader in mechanical circulatory support, makes ventricular assist devices (VAD) for patients suffering late-stage heart failure, including those awaiting a heart transplant. Thoratec offers external and implantable products that provide circulatory support for both acute and long-term needs. Its products are sold under the HeartMate, CentriMag, and Thoratec brands. The company works closely with hospitals and cardiac surgery centers primarily in the US and Europe. St. Jude Medical bought Thoratec for $3.4 billion in late 2015.