Medical device for treating decompensated heart failure

Medical device systems and methods for making and using medical device systems are disclosed. An example medical device system includes a control system having a processor (16) and a pump (18), a first expandable member (128, 228, 28A, 28B, 328A) coupled to the processor (16) and configured to be positioned in the superior vena cava (36). The system also includes a second expandable member (129, 229, 28B, 328B) coupled to the processor (16) and configured to be positioned in the inferior vena cava (38). The system also includes a first sensing member (32a) designed to sense a first parameter. The system also includes a second sensing member (32b) designed to sense a second parameter. Additionally, the pump (18) is designed to expand or contract the first expandable member (128, 228, 28A, 28B, 328A), the second expandable member (129, 229, 28B, 328B) or both the first and the second expandable members based on a change in the first parameter, the second parameter or a change in both the first and the second parameters.