At least 26 heart failure pa­tients have died af­ter try­ing to re­place the con­trol­ler for their HeartMate II blood pumps while out of the hos­pi­tal, according to a news report.

Ab­bott Laboratories is­sued an a­lert for 28,882 HeartMate II con­trol­lers that in­cludes new soft­ware and alarm guides, fol­low­ing re­ports of 70 in­ci­dents in which the de­vice mal­func­tioned af­ter a pa­tient changed out the con­trol­ler at home, the Star Tribune reports.

The in­ci­dents in­clud­ed 26 deaths and 19 in­ju­ries.

“Pa­tients may some­times need to change to their back­up back-up sys­tem con­trol­ler dur­ing the course of ven­tric­u­lar as­sist thera­py. The change should be done quick­ly and in the hos­pi­tal, be­cause it can pres­ent a sig­nifi­cant chal­lenge to pa­tients that are el­der­ly and/or un­trained. For these pa­tients, a slow or im­prop­er … change­over places them at risk of se­ri­ous in­ju­ry or death,” ac­cord­ing to the Food and Drug Administration.

An FDA re­call no­tice says the co­vered de­vices in the re­call were dis­tri­but­ed be­tween July 2012 and De­cem­ber 2016. Dis­tri­bu­tion of the af­fect­ed con­trol­lers was halt­ed in March 2017, the re­call no­tice says.

Ab­bott — which ac­quired Min­ne­so­ta-based St. Jude Medical and its HeartMate II Left Ven­tric­u­lar As­sist De­vice (LVAD) in Jan­u­ar­y — sent out its prod­uct a­lert to doc­tors across the coun­try on March 30.

The FDA is­sued a re­call no­tice classi­fy­ing the Ab­bott com­mu­ni­ca­tion as a Class I re­call, the most se­ri­ous cate­go­ry.

An LVAD is an implantable de­vice that es­sen­tial­ly pumps a per­son’s blood when the heart is too weak to do it on its own.