Dynamic auscultation

All patients with a new murmur should undergo dynamic auscultation:

• respiration:
  • right sided murmurs are louder during inspiration
  • expiration has the opposite effect
    
    
• Valsalva manoeuvre:
  • this is expiration against a closed glottis
    
    
• squatting:
  • this increases both venous return and peripheral resistance and results in almost all murmurs becoming louder
  • the exception is in hypertrophic, obstructive cardiomyopathy where the dilatation of the left ventricle partially relieves the outflow obstruction