Evaluating the Patient with a Murmur

A murmur is caused by turbulent blood flow.

What are the three main factors which might cause a heart murmur?

The three main factors are:

  • Forward flow through a narrowed outlet
  • Backwards or regurgitant flow through a leaking/ incompetent valve
  • High blood flow in high output states such as anaemia, pregnancy, thyrotoxicosis, sepsis and fever

The presence of a murmur must be evaluated in light of the patient’s overall symptoms, signs and investigation results. Other signs of cardiac disease should be carefully sought.

Many murmurs in asymptomatic patients are innocent. Innocent murmurs are typically short systolic murmurs heard at the left sternal edge (LSE) which vary with respiration and which are decreased by sitting the patient up. There should be no other abnormal sounds or murmurs.