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Causes of third heartsound

Etiology of S3
Abnormal increase in transmitral flow
  • Mitral regurgitation
  • VSD
  • PDA
Depression of ventricular function
  • LV dysfunction—LV S3
  • RV dysfunction—RV S3
  • LV S3 and RV S3
LV S3 may be either physiological or pathological
RVS3 is always pathological.
Causes of physiological S3 
  • Children
  • Young adults (< 40 years)
  • Athletes
  • Pregnancy.
  • Pathological 3rd heart sound
  • Pathologic S3 persists in the standing position and is associated with other signs of LV dysfunction.
  • LV S3 - MR, LVF
  • RV S3 - TR, RV
Causes of pathological S3
  • High output states
  • Congenital heart diseasis ASD, VSD,
  • Regurgitant lesions of aortic, mitral, tricuspid valves.
  • Hypertrophic cardiomyopathy
  • ischaemic heart diseases
  • Constrictive pericarditis
  • Systemic hypertension
  • Pulmonary hypertension
Differentiating Features between Right and Left Ventricular S3
RV-S3                                              LVS3
Tncmpid area                                      MItral area
Increas esOn inspiration                  Increases on expiration