Medtronic (NYSE:MDT) said today that the FDA has classified its recent voluntary field action recall for its HVAD heart pump system controllers as Class I, and the company updated on its steps to correct issues related to the recall.

Class I recall designations, the agency’s most serious classification of recall, are used when there is a reasonable probability that product use could cause serious adverse health consequences or death.

The recall relates to issues with worn alignment guides, internal battery failures and loose power and data connectors, the Fridley, Minn.-based company said. All of the issues could lead to possible injury and death, the company said.

System controllers with serial numbers lower than CON300000 and DC adapters with all serial numbers for product code 1435, were named in the recall.

Medtronic said that it won FDA approval for an updated HVAD controller on April 7, and it began notifying users of the device a week later. The company said the new controller features strengthened power and serial port alignment guides, new internal battery monitoring functionality and redesigned connectors to prevent loosening and vulnerability to exposure damage.

The company said that it has begun to remove current HVAD controllers, with product codes 1400, 1401US and 1407US in select areas. It also released updated guidelines for clinicians with such devices, advising them to update their training on the newly launched controller.

Issues with the implantable heart pump’s controller date back to at least April 2010, when HeartWare said a July 2009 redesign aimed at waterproofing the controllers inadvertently made them airtight and created problems with the controller’s speaker. In February 2015 the company recalled controllers made before the FDA’s 2012 approval of the HVAD pump; further field warnings following in April 2015 and April 2016 detailing a trio of potential issues.