Abstract
A flow probe for direct measurement of blood flow of the mitral valve was devised. It was useful for acute experiment, particulary concerning pathophysiology of the mitral valve function. Insertion of the probe into the left atrium and fixation to the left atrial wall and thus to the mitral orifice were readily and satisfactorily performed without disturbance of blood flow and valvular function. It must also be emphasized that support with cardiopulmonary bypass was not necessary at the time of insertion of the probe. Effectiveness of the procedure has been confirmed through simultaneous observation of echocardiogram and mitral blood flow of the dog's heart with ruptured chordae tendineae.