Cardiac murmurs

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Flow Murmur, innocent

Features include: short duration, loudest at left sternal edge, changes with body position, louder at times of higher blood flow (eg. illness, exercise).

Splitting of S2

At expiration, A2 and P2 overlap to produce a single S2. (A2=aortic valve closure, P2=pulmonary valve closure)

In younger people, inspiration delays P2 due to the additional volume of blood drawn into the right heart by the negative intra-thoracic pressure. This is heard as a split S2 on inspiration.

Fixed Splitting of S2

Fixed splitting of S2 is abnormal. ASDs and occasionally VSDs cause fixed splitting: a left to right shunt sends more blood through the pulmonary valve than normal, delaying closure. A split S2 is heard throughout inspiration and expiration.

Grading Cardiac Murmurs

  • Grade 1 - Very faint. Heard in a quiet room by a skilled clinician. May not be heard in all positions.
  • Grade 2 - Quiet, but heard immediately after placing the stethoscope on the chest.
  • Grade 3 - Moderately loud.
  • Grade 4 - Loud with palpable thrill
  • Grade 5 - Very loud, with thrill. May be heard when stethoscope is partly off the chest.
  • Grade 6 - May be heard with stethoscope entirely off the chest.
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