Thoratec Corp., a mini heart pump manufacturing company, released an urgent safety advisory about the use of their pocket controller after four patients died and five others were injured due to the device’s use.

The notice, which included new labeling of their HeartMate II LVAS Pocket System Controller, noted that 2,142 patients were fitted with the device since August, 2012, and many experienced problems during the switch from a backup controller, or older version of the device to a new controller, or the device’s main system.

The controller, which helps operate the company’s ventricular assist device (LVAD), assists the unit in “taking over” for a failing heart.

Almost 5.1 million patients live with heart failure in the US alone, with more and more being added each day, as a growing number of individuals survive heart attacks, high blood pressure, and diabetes. Twenty percent of those with heart failure die within twelve months and the other half don’t make it more than five years.

The Thoratec corp reported that two of the deaths were due to patients changing the controller themselves, and upon inspection, the company could not find any problems with the controllers themselves. Eight of the nine occurred when changing from the pocket controller after the patient was trained on an older model.

“Consumers who have the HeartMate II LVAS Pocket Controller should immediately contact their doctor for retraining on use of the device and to receive updated patient handbook information,” the company said. “All patients using the Pocket Controller and their caregivers should be retrained on the use of the device and be provided with updated Patient Handbook information.”

If you have been fitted with a new pocket controller for the HeartMate II, it is important to understand how to operate the device and monitor yourself for potential warning signs for heart pump malfunctions. If you have any questions regarding operation of the device, consult your medical care provider immediately.