Systolic murmur grading

There’s more to a murmur than you might think. Here is a breakdown of features, grades and diagnosis of systolic heart murmur.

A heart murmur is a sound that can be heard via stethoscope. These whooshing or swishing sounds are caused when blood flow is turbulent as it moves through the heart. A normal heartbeat makes a “lubb-dupp” sound as the valves close, but a heart murmur sounds different. A systolic murmur begins during or after the first heart sound (lubb) and ends before the second (dupp). This differs from a diastolic murmur, which occurs when the cardiac muscle relaxes between beats. Systolic murmur may be congenital or acquired.

Murmur grading ranges

  • Grade 1 is a murmur that can only be heard with extra effort by the clinician.
  • Grade 2 is faint, but audible.
  • Grade 3 is moderately loud.
  • Grade 4 is very loud.
  • Grade 5 is extremely loud and is audible with one edge of the stethoscope touching the chest wall.
  • Grade 6 is audible with the stethoscope just removed from the chest wall.

Features of systolic murmur

There are two types of systolic murmur:

  • Ejection murmurs – These start in the semilunar valves and may be functional or organic.
  • Regurgitant murmurs – These occur when heart valves don’t close properly, and blood leaks backward. These typically start in the atrioventricular valves. All regurgitant systolic murmurs are organic.

There are seven clinical features in all systolic murmurs:

  • Intensity (loudness) — the intensity is graded; see intensity ranges below.
  • Frequency (pitch) — the velocity of blood at the murmur site determines the frequency; the higher the velocity, the higher the pitch of the murmur.
  • Quality — the tone of the murmur can be blowing, honking or harsh, for example.
  • Duration — describes how long the murmur lasts during the heartbeat.
  • Configuration — refers to the “shape” of the murmur as it gets louder and softer.
  • Primary location — is the point of maximum intensity.
  • Site(s) of radiation — exist if the murmur radiates.

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Causes of systolic heart murmur

  • Aortic stenosis: Narrowing in the aortic valve, which lets blood pass from the heart to the aorta
  • Atrial septal defect: A hole in the atrial septum which is the wall separating the upper chambers (atria)
  • Hypertrophic obstructive cardiomyopathy: A genetic heart condition where the septum between the ventricles thickens
  • Pulmonic stenosis: Narrowing in the pulmonary valve that connects the heart and lungs

Symptoms of systolic heart murmurs

Some people who have heart murmurs don’t have noticeable symptoms. Depending on the cause of the heart murmur, the patient may have:

  • A bluish tint to the skin
  • Chronic (long-lasting) cough
  • Fainting (syncope)
  • Fatigue
  • Fluid retention and swelling (edema) in the legs
  • Unexplained lightheadedness or dizziness
  • Shortness of breath (dyspnea)

Innocent heart murmur doesn’t require treatment. Abnormal heart murmurs often are addressed pharmacologically.

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