Two cases who underwent emergency operation for papillary muscle rupture complicating acute myocardial infarction were presented. The first case was a 75-year-old female who had suffered myocardial infarction 26 days previously. Operation was performed on the 2nd day after onset of mitral insufficiency. The posterior papillary muscle was partially ruptured and the mitral valve was replaced with a mechanical prosthesis (SJM 25mm). The second case was a 76-year-old female who had suffered myocardial infarction 10 days previously. Emergency operation was performed on the 4th day after onset of mitral insufficiency. The posterior papillary muscle was completely ruptured. Mitral valve replacement with a mechanical prosthesis (Omnicarbon 25mm) was performed. In both cases, recovery from cardiogenic shock was not possible preoperatively even with pharmacologic and circulatory support, but the postoperative courses were uneventful in both cases. We recommend immediate surgical intervention for mitral insufficiency in patients with severe grade regurgitation and cardiogenic shock following acute myocardial infarction.

The present study attempted to define a dynamic muscle contraction against viscosity resistance in which force is proportional to velocity of movement, and to determine its mechanical properties in comparison with isotonic and isokinetic muscle contraction. This dynamic contraction was referred to as the “isoviscous contraction” . A loading mechanism consisting of a directly-driven electromagnetic motor and an electronic control circuit was developed to enable three patterns of dynamic contraction to be performed. The torque, joint angle and joint angular velocity in the three types of dynamic contraction were measured in 8 healthy male volunteers during knee joint extension. The isoviscous contraction was not accompanied by any abrupt change in torque during the movement observed regularly in isotonic and isokinetic contraction. The instructed movement for isoviscous contraction could be performed over a wide range of joint motion at all levels of contraction. In addition to its unique mechanical properties, since the viscosity resistance produces a better damping effect against an abrupt change in torque, isoviscous contraction is considered to be a useful method of rehabilitation training in disabled patients and aged individuals. However, the great inertial force produced by isoviscous contraction corresponding to that in isotonic contraction should be further investigated.