Reports on VAD device malfunction (DMF) focus primarily on the pump itself and fail to account for issues with the controller, power supply and other peripheral components. This single center experience with pulsatile (PU) and rotary (ROT) VAD's strives to identify the weakest links in total VAD reliability. DMF's were prospectively collected on all VAD's implanted between 01/2001 to 10/2010 and included: Thoratec PVAD (100 pts=16,383 pt-days), Thoratec Heartmate II (HMII)(73pts=19,934 pt-days), Ventrassist (22 pts=4,096 pt-days) and Heartware (17 pts=1,734 pt-days). DMF's were categorized as to primary pump failure (PF), Controller failure (CONTR), or DMF's due to peripheral component failure (PERPH). 80% of the Heartware, 78% of the Ventrassist and 60 % of the HMII pts had no DMF's while only 40% of the PVAD's did. Due to a more robust observation period, further results are focused on the HM II and PVAD pts. Cumulative DMF's by category are expressed as events/100 pt-days.Device MalfunctionsHMIIPVADCOMPONENT6 MO1 YEAR2 YEARS6 MO1 YEAR2 YEARSPUMP0.010.020.020.040.040.04Controller0.050.080.110.670.730.76Peripherals0.240.310.460.560.660.69Total0.290.420.591.261.411.48Cumulative Events/100 Pt-Days PF is rare but stable over two years for either VAD. CONTR DMF's increase slowly over two years but are 5 to 10 times higher for the PU VAD. CONTR and PERPH DMF's each account for about 50% of DMF's in PU VAD's. PERPH DMF's are the most common issue in ROT VAD's accounting for 82% of DMF's at 6 months and 78% at 2 years. Primary PF is a rare event for both rotary and PU VAD's. CONTR DMF's occur more frequently than PF in either VAD, but are 5 to 10 time more frequent in the PU devices. The most common DMF's in ROT VAD's are due to PERPH components such as drivelines, driveline connectors, batteries and other external components. This implies that more stringent pre-clinical reliability testing of peripheral components is warranted.