Robert G Hauser1, Linda M Kallinen Retel. 1. Patient Safety and Advocacy Center, Minneapolis Heart Institute Foundation, Minneapolis, Minnesota. Electronic address: rhauser747@aol.com.
Abstract
BACKGROUND: Conductor fractures may affect the performance of implantable cardioverter-defibrillator leads. During routine surveillance of returned product analyses (RPAs) in the Food and Drug Administration's Manufacturers and User Facility Device Experience database, we found a number of conductor fractures in small diameter implantable cardioverter-defibrillator leads manufactured by St Jude Medical, Inc (SJM, Sylmar, CA). OBJECTIVES: To determine the location and cause of these fractures and to catalog their clinical signs and consequences. METHODS: We searched the FDA's Manufacturers and User Facility Device Experience database on April 11, 2013. SJM provided information and data it collected independently. RESULTS: Our search found 59 leads with fractures in the IS-1 leg. Most fractures were in leads implanted in 2008-2009; no fractures were found in leads implanted after 2010. Outer coil conductor fractures accounted for the majority (51 of 59, 86%). Oversensing and noise were common signs, and 81% of the patients received inappropriate shocks. SJM's RPAs found that the fractures were due to inadequate strain relief and redesigned the IS-1 leg by shortening the crimp bore. Younger age and subpectoral implants appeared to be associated with these fractures. SJM stated the incidence is low (0.040%) and has not seen further fractures of this type in leads with the modified crimp. CONCLUSIONS: SJM's small diameter leads that were manufactured before 2011 are prone to early outer coil fatigue fractures in the IS-1 leg. The failure mechanism appears to have been mitigated by a design change. RPA is important for improving device safety.
BACKGROUND: Conductor fractures may affect the performance of implantable cardioverter-defibrillator leads. During routine surveillance of returned product analyses (RPAs) in the Food and Drug Administration's Manufacturers and User Facility Device Experience database, we found a number of conductor fractures in small diameter implantable cardioverter-defibrillator leads manufactured by St Jude Medical, Inc (SJM, Sylmar, CA). OBJECTIVES: To determine the location and cause of these fractures and to catalog their clinical signs and consequences. METHODS: We searched the FDA's Manufacturers and User Facility Device Experience database on April 11, 2013. SJM provided information and data it collected independently. RESULTS: Our search found 59 leads with fractures in the IS-1 leg. Most fractures were in leads implanted in 2008-2009; no fractures were found in leads implanted after 2010. Outer coil conductor fractures accounted for the majority (51 of 59, 86%). Oversensing and noise were common signs, and 81% of the patients received inappropriate shocks. SJM's RPAs found that the fractures were due to inadequate strain relief and redesigned the IS-1 leg by shortening the crimp bore. Younger age and subpectoral implants appeared to be associated with these fractures. SJM stated the incidence is low (0.040%) and has not seen further fractures of this type in leads with the modified crimp. CONCLUSIONS: SJM's small diameter leads that were manufactured before 2011 are prone to early outer coil fatigue fractures in the IS-1 leg. The failure mechanism appears to have been mitigated by a design change. RPA is important for improving device safety.