This ECG is from a 34 year old female whose chief complaint was shortness of breath with exertion. She recalled having frequent episodes of rather sever throat infections as a child, and the usual child hood diseases. i.e. measles and mumps, but no other serious illnesses. A rumbling diastolic murmur (DRM) with presystolic accentuation and an opening snap (OS), which sounded like a widely split 2nd heart sound, similar to that reproduced here, were localized to the apex and heard best with the patient lying on her left side.