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Updated: Feb 8, 2026

Transesophageal Atrial Burst Pacing for Atrial Fibrillation Induction in Rats
Published on: February 14, 2022
The mitral knock with atrial fibrillation. A possible source of auscultatory confusion
Abstract:
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.
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