S4 Heart Sound Topic Review | Learn the Heart - Healio

The fourth heart sound (S4), also known as the “atrial gallop,” occurs just before S1 when the atria contract to force blood into the left ventricle. BacktoHealio ECGInterpretation QuizzesandCases CardiologyReview LearnTheHeart CardiologyReview TopicReviewsA-Z TopicReviewsA-Z Save S4HeartSoundTopicReview Thefourthheartsound(S4),alsoknownasthe“atrialgallop,”occursjustbeforeS1whentheatriacontracttoforcebloodintotheleftventricle. Iftheleftventricleisnoncompliant,andatrialcontractionforcesbloodthroughtheatrioventricularvalves,aS4isproducedbythebloodstrikingtheleftventricle. Enlarge  CLINICALPEARL:AS4heartsoundoccursduringactiveLVfillingwhenatrialcontractionforcesbloodintoanoncompliantLV. Therefore,anyconditionthatcreatesanoncompliantLVwillproduceaS4,whereasanyconditionthatcreatesanoverlycompliantLVwillproduceaS3heartsound. AS4heartsoundcanbeanimportantsignofdiastolicheartfailureoractiveischemiaandisrarelyanormalfinding.Diastolicheartfailurefrequentlyresultsfromsevereleftventricularhypertrophy,orLVH,resultinginimpairedrelaxation(compliance)oftheLV.Inthissetting,aS4isoftenheard.Also,ifanindividualisactivelyhavingmyocardialischemia,adequateadenosinediphosphatecannotbesynthesizedtoallowforthereleaseofmyosinfromactin;therefore,themyocardiumisnotabletorelax,andaS4willbepresent. Itisimportanttonotethatifapatientisinatrialfibrillation,theatriaarenotcontracting,anditisimpossibletohaveaS4heartsound. CLINICALPEARL:AS4heartsoundisoftenasignofdiastolicheartfailure,anditisrarelyanormalfinding(unlikeaS3). Enlarge                      NormalLVvs.DilatedLV(S3Present) LikeS3,theS4soundislowpitchedandbestheardattheapexwiththepatientintheleftlateraldecubitusposition. BelowiscomparativeinformationforS3andS4. S3–“ventriculargallop” Occursinearlydiastole OccursduringpassiveLVfilling Maybenormalattimes RequiresaverycompliantLV CanbeasignofsystoliccongestiveHF S4–“atrialgallop” Occursinlatediastole OccursduringactiveLVfilling Almostalwaysabnormal RequiresanoncompliantLV CanbeasignofdiastoliccongestiveHF RelatedContent: HeartSoundsTopicReview HeartSoundsQuiz S1HeartSoundTopicReview S2HeartSoundTopicReview S3HeartSoundTopicReview ExtraHeartSounds Readmoreabout heartfailure ischemia Facebook Twitter LinkedIn Email Print Comment ContinueReading RelatedContent Save Save Save We’resorry,butanunexpectederrorhasoccurred. Pleaserefreshyourbrowserandtryagain.Ifthiserrorpersists,[email protected]. Close