Grading diastolic murmurs

Diastolic murmurs are graded on a scale of 1 to 4, while systolic murmurs are graded on a scale of 1 to 6. Often, grade 1 systolic/diastolic murmurs are not discernible to inexperienced clinicians, while grade 4 diastolic or grade 6 systolic murmurs are heard even without the stethoscope on the chest and may actually be visible.

The intensity of a murmur is primarily determined by the volume/velocity of blood flowing through a defect and the distance between the stethoscope and the lesion. For example, a very thin patient with severe aortic stenosis with a high pressure gradient across the valve (thus high velocity of blood flow) will have a loud murmur. Conversely, the exact same valvular lesion in a morbidly obese person or a person with severe COPD and a widened anterior-posterior chest diameter may be inaudible.

Grading diastolic murmurs

Intensity

Description

Grade 1

Barely audible

Grade 2

Audible, but soft

Grade 3

Easily audible

Grade 4

Loud