Abstract: An adjustment clamp suitable for adjusting the tension of a material such as a cardiac support device. The adjustment clamp comprises a pair of interconnected, intersecting arms capable of rotating around a common axis. The arms each comprise a handle, a jaw and a shaft between the handle and jaw. The clamp also includes a latch operably mounted to the handle, wherein the latches of the two arms are capable of engaging each other to secure the clamp at a desired position. In one embodiment, the jaw comprises a flat contact surface. In another embodiment, at least one jaw of one arm comprises a roller assembly. Preferably, the clamp also includes a turning mechanism operably mounted to at least one roller assembly. Methods for using the adjustment claim to increase tension in a material are also described. In a preferred embodiment, the clamp is used to adjust the tension of a cardiac support device.