Left Ventricular Assist Device Malfunctions: It's More Than Just The Pump
Background—Reports of left ventricular assist device (LVAD) malfunction have focused on pump thrombosis. However, the device consists of the pump, driveline and peripherals, all of which are potentially subject to failure.
Methods—Prospectively collected data were reviewed for all LVAD device malfunctions (DM) occurring in rotary LVADs implanted at a single center between April 2004 and May 2016. Durable LVADs included 108 Heartmate II (HMII) and 105 HeartWare ventricular assist devices (HVAD). DM data were categorized according to device type and into categories related to the component that failed: a) controller, b) peripheral components and c) the implantable blood pump or its integral electrical driveline. Pump-related events were analyzed as pump specific (suspected or confirmed thrombosis) or non-pump specific (driveline failure). DM rates were reported as events/1,000 patient-days and Cox proportional hazard models were used for time-to-event analyses. Cumulative rates of malfunction were examined for the main components of each type of LVAD.
Results—Types of DM included controller failure (30%), battery failure (19%) or patient cable failure (14%), while only 13% were due to pump failure. DM's were more common in the HM II device (3.73 per 1000 patient-days vs. 3.06 per 1000 patient-days for the HVAD, p< 0.01). There was a higher rate of pump-specific malfunctions in those implanted with a HM II versus an HVAD (0.55 vs. 0.39 respectively p< 0.01) and peripheral malfunctions (2.32 vs. 1.78 for the HM II and HVAD, respectively; p< 0.01); there was no difference in the incidence of controller DM between the two LVADs. HVAD patients were 90% free of a pump-specific malfunction at 3 years compared with 56% for the HM II (log-rank p< 0.003). Only 74% of the HM II patients were free of pump thrombosis at 3 years compared with 90% of the HVAD patients. Freedom from failure of the integrated driveline was 79% at 3 years for the HMII but 100% for the HVAD (log-rank p< 0.02).
Conclusions—Device malfunction is much broader than pump failure alone and occurs for different components at different rates based upon the type of LVAD.
- Received January 15, 2017.
- Revision received June 5, 2017.
- Accepted June 20, 2017.