An insertable light-dispensing catheter device, comprising a shaft including a proximal and distal end, a light guide extending through the shaft, and a mirror displaceably extendable from the catheter into a position where the mirror receives and reflects light emitted from the light guide. The mirror can be in the form of a coating on an inflatable balloon; and the balloon, when inflated, can press a patch against a defect (e.g., a ventricular septical defect), while the light cures an adhesive that binds the patch to the structure with the defect, thereby remedying the defect.