A partitioning device for separating a patient's heart chamber into a productive portion and a non-productive portion which is suitable for treating patients with heart disease, particularly congestive heart failure. The partitioning device has a reinforced membrane with outwardly biased members to help seal the periphery of the membrane against the wall of the patient's heart chamber. In one embodiment, the outwardly biased member is an expansive strand that extends between adjacent ribs of an expandable frame which reinforces the membrane. In another embodiment, the outwardly biased member is a hydrophilic body such as foam which swells upon contact with body fluid such as blood in the heart chamber. The reinforced membrane has a central hub with a distally extending support stem with a plurality of feet which extend radially from a centerline axis and preferably have ends that are aligned in a common plane. The ends of the pods which extend radially away from the centerline axis may be interconnected by flexible struts and/or webs.