A catheter device suitable for shrinking chordae tendineae of the human heart is provided having an energy conduit and a positioning device that facilitates the delivery of thermal energy, including coherent (laser) or non-coherent light, RF, microwave or ultrasound energy, to a predetermined region of the chordae tendineae or other collagen-containing tissue, such as the female urethra or the esophagus near the sphincter. The device comprises a tubular catheter containing an energy conduit, such as a fiber optic cable, adapted for delivering thermal energy to the tissue. The tubular catheter also contain a stabilizing device, disposed at its distal end, such as an asymmetrically shaped balloon or a retractable flexible metal hook. With the distal end of the catheter device positioned within a human heart, application of thermal energy to the chordae tendineae results in a shrinkage of the chordae, providing a treatment for primary mitral valve regurgitation.