HeartWare International issued a voluntary recall in the U.S. of older controllers that were distributed during clinical trials.

HeartWare announced that it added the U.S. to its list of countries notified about a vulnerability in older ventricular assist system controllers. Older, but not newer, controllers are susceptible to electrostatic discharge, which potentially could cause the pump to stop.

The company released a notice in 2013 that warned of this risk and advised patients with these devices to avoid dry environments and textiles that are prone to static electricity. After its notice, it received reports of one death and one serious injury that may have been prompted by a pump stopping.

The affected controllers were included in the ADVANCE and ENDURANCE clinical trials under the product codes 1400 and 1401XX. HeartWare estimated that 120 patients in the U.S. may have been implanted with the devices.

As part of the recall, physicians are instructed to track down patients with the recalled controllers, assess risks and determine if a new controller is medically advisable. Replacements should have a serial number CON005473 or higher. HeartWare encouraged clinicians to perform exchanges in a controlled setting.

Patients should not try to exchange recalled controllers. If they have questions, they should contact their physicians or hospital.

The ventricular assist devices were approved in the U.S. in 2012. Framingham, Mass.-based HeartWare has since augmented the design to reduce the risk of electrostatic discharge.