system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 26-year-old pregnant woman has been detected to have a diastolic murmur in mitral area. Echocardiography reveals mitral valve orifice to be 0.8 cm2. The cause of her murmur is
assistant
The correct answer is  Severe mitral stenosis