Blunt traumatic rupture of a mitral papillary muscle head.

Severe mitral regurgitation developed in a patient after a lateral-impact motor vehicle accident. The papillary muscle head was disrupted without evidence of other myocardial injury. We hypothesize that a dramatic and sudden increase in intrathoracic pressure may have produced the injury. The patient experienced progressive heart failure and underwent successful mitral valve repair 9 days after the accident.