The company has also initiated this field action in other countries in recent weeks.

HeartWare in its letters to clinicians and patients said that affected clinical trial controllers exhibit a higher susceptibility to electrostatic discharge (ESD) than newer and commercial controllers.

This recall will not affect new commercial controllers, since the company has made design enhancements to the new controllers to improve immunity to ESD, otherwise it could result in a pump stop, causing serious injury or death.

The company noted that the recall of HeartWare controllers with product codes 1400 and 1401XX distributed during the Advance and Endurance clinical trial periods with serial numbers CON000001 through CON005472 is an expansion of its voluntary Field Safety Corrective Action, FSCA APR2013.

HeartWare provided information to help clinicians and patients in monitoring controller performance and reducing the potential for an ESD event, as part of the 2013 notice.

The firm develops and markets miniaturized implantable heart pumps or ventricular assist devices to treat patients with advanced heart failure.