Progressive cardiac enlargement is a consequence of congestive heart failure (CHF) and a cause of further deterioration. Cardiac restraint devices are intended to interrupt and reverse this process, thereby improving the natural history of CHF. The Paracor restraint device is made from a superelastic nitinol mesh that exerts a small but continuous epicardial force to relieve left ventricular (LV) wall stress and to limit LV dilation. Animal studies have used various heart failure models. The data show the device reduces LV dilation after infarction, preserves LV contractility with rapid pacing, and avoids diastolic constriction in the embolization model. Ten patients in Europe and 10 in the United States have been implanted through a small thoracotomy incision without the use of cardiopulmonary bypass. Changes in LV size, functional status, and exercise performance have been measured, but the detailed data have not yet been presented or published. The device remains experimental, pending completion of additional clinical trials.