Listen for: A dull, low extra sound just after S2, early in diastole: "lub-dub-da", the rhythm of "Ken-tuc-ky". Very low-pitched: use headphones, not a phone speaker.
Usually means: Rapid filling of a large, volume-loaded ventricle. Can be normal in children and young adults; in older adults it suggests heart failure.
References2
- Bickley LS, Szilagyi PG, Hoffman RM, Soriano RP. Bates' Guide to Physical Examination and History Taking. 13th ed. Philadelphia: Wolters Kluwer; 2021. Cardiovascular system chapter.
- Marcus GM, Gerber IL, McKeown BH, et al. Association between phonocardiographic third and fourth heart sounds and objective measures of left ventricular function. JAMA. 2005;293(18):2238-44.