A clinical evaluation of the hypothesis that rupture of the left ventricle following mitral valve replacement can be prevented by preservation of the chordae of the mural leaflet.

Experiences with 14 patients undergoing rupture of the left ventricle following mitral valve replacement over a period of 9 years have been described. Three different types have been recognized. Before 1978, most injuries occurred in the atrioventricular groove, apparently resulting from traction that insidiously avulsed the mitral annulus from the underlying left ventricular muscle. Several changes in operative technique, described in the text, were made to prevent this traction avulsion. Following the adoption of these principles, rupture in the atrioventricular groove virtually disappeared. A second type of injury, strut perforation, has been recognized in only one patient, a small 81-year-old female in whom the prosthesis inserted was too large for the ventricular cavity. Translucent obturators were subsequently developed not only to size the left ventricle but also to note the location of the post of the porcine prosthesis before insertion. Further problems of this type have not been seen. The most puzzling, and currently the most significant, problem is a third type of rupture, the mid-ventricular rupture, suggested as Type III by Miller in 1978 and described in detail by Cobbs in 1977 and 1980. The phenomenon seems to be a true spontaneous rupture of a thin left ventricle, usually occurring in small elderly women with mitral valve disease. If the friability of the left ventricle is transiently increased with potassium cardioplegia, such ventricles may spontaneously rupture following division of the chordae to the annulus of the mural leaflet. If this concept is correct, a rupture in some patients can best be prevented by preserving these chordae. It is well realized, of course, that a fortunate narrative experience of 3 1/2 years does not have any statistical value concerning a complication that occurs in 1 to 2% of operations. The experiences are reported, however, because to our knowledge, the untethered loop hypothesis has not been previously evaluated in a large number of consecutive patients operated on. Future comparison of experiences reported by others should make it possible to determine whether or not this concept is correct.