an improved endocardial catheter includes a plurality of longitudinally extending openings adjacent intermediate portions at its distal end . the catheter is actuable from a retracted or collapsed mode , wherein the sealed openings are arranged around the tubular catheter surface , to an expanded mode . the plurality of longitudinal openings in the catheter wall enable radial expansion of the tubular surface at the distal end so that intermediate portions of the tubular catheter surface are moved to an operative position radially outward from their position in the retracted mode . in the expanded position , the intermediate portions form wings around the distal end , revealing a cavity within the tubular catheter for the release of contrast material or other fluid into endocardial sites through the longitudinal openings .