Heart Murmur - Classification

Classification

Murmurs can be classified by seven different characteristics: timing, shape, location, radiation, intensity, pitch and quality.

• Timing refers to whether the murmur is a systolic or diastolic murmur.
• Shape refers to the intensity over time; murmurs can be crescendo, decrescendo or crescendo-decrescendo.
• Location refers to where the heart murmur is usually auscultated best. There are six places on the anterior chest to listen for heart murmurs; each of the locations roughly corresponds to a specific part of the heart. The first five of the six locations are adjacent to the sternum. The six locations are:
  • the 2nd right intercostal space
  • the 2nd to 5th left intercostal spaces
  • the 5th left mid-clavicular intercostal space.
• Radiation refers to where the sound of the murmur radiates. The general rule of thumb is that the sound radiates in the direction of the blood flow.
• Intensity refers to the loudness of the murmur, and is graded according to the Levine scale, from 1 to 6:
  • 1: The murmur is only audible on listening carefully for some time.
  • 2: The murmur is faint but immediately audible on placing the stethoscope on the chest.
  • 3: A loud murmur readily audible but with no palpable thrill.
  • 4: A loud murmur with a palpable thrill.
  • 5: A loud murmur with a palpable thrill. The murmur is so loud that it is audible with only the rim of the stethoscope touching the chest.
  • 6: A loud murmur with a palpable thrill. The murmur is audible with the stethoscope not touching the chest but lifted just off it.
• Pitch may be low, medium or high and is determined by whether it can be auscultated best with the bell or diaphragm of a stethoscope.
• Quality refers to unusual characteristics of a murmur, such as blowing, harsh, rumbling or musical.

The use of two simple mnemonics may help differentiate systolic and diastolic murmurs; PASS and PAID. Pulmonary and aortic stenoses are systolic while pulmonary and aortic insufficiencies (regurgitation) are diastolic. Mitral and tricuspid defects are opposite.