1. A study of the fibrosed and often calcareous condition present in the mitral orifice in cases of chronic stenosing rheumatic disease demonstrated that a powerful instrument must be developed if we are to apply surgical relief in the treatment of the disease.
2. An instrument (cardiovalvulotome) is described which actually excises a segment from the mitral orifice and removes this from the blood stream.
3. The efficacy of the instrument has been tested by its use on the stenotic valves of diseased hearts removed at autopsy. Its feasibility has been shown by operations both upon animals and in a single human case.