The mitral knock with atrial fibrillation. A possible source of auscultatory confusion.
A 29-year-old woman with atrial fibrillation and severe rheumatic mitral regurgitation initially had a very loud third heart sound with high-frequency components (mitral knock), as well as with a first heart sound of widely varying intensity. After long diastoles a faint first heart sound was heard, with distinct separation from the third heart sound of the preceding cycle; however, on short cycles the loud and high-pitched third heart sound combined with a loud first heart sound to simulate the combination of a first heart sound with an ejection click. Phonoechocardiographic studies clarified the identity of the transients.
D000328:Adult; D001281:Atrial Fibrillation / Q000150:complications* / Q000503:physiopathology; D005260:Female; D006326:Heart Auscultation; D006347:Heart Sounds; D006801:Humans; D008944:Mitral Valve Insufficiency / Q000150:complications* / Q000503:physiopathology; D010701:Phonocardiography