A reinforcement region is formed within the myocardium by introducing a delivery device through a vessel wall to a treatment site within a myocardium. A biomaterial is then delivered to the treatment site as the delivery device is withdrawn from the treatment site to form the reinforcement regions. Formation of the reinforcement region may further include introducing a delivery device through a vessel wall to a region within a myocardium such that the delivery device is positioned within the myocardium substantially parallel to a wall of the myocardium. A biomaterial may be delivered into a space formed within the region by the delivery device. The reinforcement region may be formed around an infarct tissue region of a myocardium to reinforce the damaged tissue.