 CUS will be performed 2-3 times weekly in both the low- and standard-threshold groups. CSF will be removed under sterile conditions via VAD taps 10 mlkg over 20 minutes, 0-4 times daily as needed to maintain the CUS ventricular dimensions defined above for each treatment group. Treatment group-specific ventricular size must be achieved within 48-72 hours of VAD placement, and ventricles must be maintained within this range throughout the duration of treatment. 