In four of our patients implanted with the HeartMate II left ventricular assist device (LVAD), fraying and fracture of the percutaneous lead's internal wires led to pump failure. The patients included two adolescent males (age, 15 and 17 years), one adult male (age, 78 years), and one adult female (age, 49 years). The damage was attributed to patient-related twisting or kinking of the lead. The patients had been supported by the LVAD for 6-18 months before the lead was damaged. In each case, audible and visual alarms were activated, and the pump temporarily continued to function well. The patients were rushed to the hospital, and the pumps were exchanged. All four patients recovered uneventfully and were discharged from the hospital 10-14 days later. They continued to do well on LVAD support for up to 639 days after the initial implant procedure. These events show the importance of educating LVAD patients to avoid excessive twisting or kinking of the device's driveline.