S4

S₄

Symbol for fourth heart sound.

1. Fourth heart sound, which corresponds to atrial contraction during presystole; it is rarely heard in normal hearts.

Abbreviation for fourth heart sound.

Acronym	Definition
S4➣Secondary 4 (various locations)
S4➣Supply Officer (Army)
S4➣Sleep Mode 4 (hibernation computer sleep mode)
S4➣Stainless Sanitary Space System
S4➣Logistics/Embark Office (USMC)
S4➣Supersonicsoundscapes (event promotions/record store)
S4➣NATO SG/2 Shareable (Fire Control) Software Suite

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