Dear Doctor,
Boston Scientific prioritizes patient safety and strives to maintain clear and prompt communication with healthcare professionals. They report a critical incident involving their S-ICD system, which is associated with a device-related patient fatality in May 2017. The incident occurred due to an unusual energy discharge from the device, caused by a memory location corruption from environmental radiation, which led to the failure in arrhythmia detection and treatment, and eventually the patient’s death.
The engineers at Boston Scientific have conducted simulations that replicated the malfunction by deliberately corrupting memory bits on similar model S-ICDs in laboratory conditions. These tests generated results that align with the data from the incident, despite the low likelihood of reoccurrence. Nevertheless, in response to this event, Boston Scientific is proactively developing a software update to prevent such atypical energy discharges. This software, expected to be version V4.04 or higher, is anticipated to be finished in July and communicated to medical professionals following regulatory approvals.
Root Cause Investigation
The investigation into this incident involved thorough analysis of the clinical data and the malfunctioning S-ICD system, along with a review of the device’s software. An immediate initiative was undertaken to work on a software update. The issue was traced back to a transient memory corruption by a single event upset (SEU) caused by environmental radiation. Although all electronic devices with integrated circuits are vulnerable to SEUs, cardiac implantable devices typically have checks to detect and correct such corruptions. However, the limitations of these mechanisms mean not all corruptions are detectable, particularly in scenarios like the one in the reported event where multiple bits were affected in a frequently changing memory location.
Further simulation by Boston Scientific engineers confirmed that the corruption of two particular adjacent bits of memory led to the atypical device behavior observed. Although rigorous simulations were performed, no alternative scenarios leading to the same behavior were discovered, allowing the engineers to conclude definitively that the device malfunction was caused by an SEU impacting those specific memory locations.
Addressing the concerns of the medical community, Boston Scientific offers assurance that the forthcoming software update will mitigate the risk of such incidents and enhance the reliability of the S-ICD systems.
Manual:
Download: Boston Scientific S-ICD Cardiac Rhythm Management Device User Manual
Chat: Powered By VoiceSphere