Systolic Murmurs - Auscultation Course

Lesson #1: Innocent Murmur

This recording is of an innocent murmur. Innocent murmurs are generated by normal blood flow within the heart. Blood flow turbulence creates vibrations in the heart's tissues which are then transmitted to the chest wall.

Benign, innocent murmurs are very common in children. This type of murmur is associated with non-cardiac conditions such as pregnancy, hyperthyroidism, exercise, and anemia in adults. When these conditions are treated appropriately, the systolic murmur disappears.

Use the stethoscope bell or diaphragm, auscultating over the pulmonic area. Listen for increasing sound intensity with inspiration. Innocent murmurs usually appear in early systole with low-to-mid-range-frequencies of 100-250Hz. The murmur is fairly short in duration. In this recording S1 and S2 are normal. Diastole is silent.

Lesson #2: Aortic Sclerosis

This aortic sclerosis murmur is fairly loud, heard early in systole. When viewing the waveform, notice the diamond-shaped appearance. Regular vibrations of this murmur provide a musical quality (cooing).

It is caused by turbulent blood flow into the aorta. Diastole is silent and S1 and S2 are normal.

Lesson #3: Mild Aortic Stenosis

Aortic stenosis has a murmur characterized by an aortic ejection click in early systole, followed by a diamond-shaped systolic murmur that ends mid-way through systole. The murmur has a mid-frequency pitch. As the condition worsens, the murmur frequency increases.

The first heart sound is normal. The second heart sound is physiologically split. The aortic component of the second heart sound is louder than normal.

The anatomy video shows thickened aortic valve leaflets with decreased movement. The left ventricle wall thickness is increased.

Lesson #4: Severe Aortic Stenosis

In severe aortic stenosis, there is a diamond-shaped systolic murmur continuing through systole. The murmur is loud and higher pitched than a mild aortic stenosis murmur.

S1 is normal. S2 is louder than normal. In fact, you are hearing only the accentuated pulmonic component of S2 due to heart failure on the left side. The aortic ejection click heard in mild cases of valvular aortic stenosis is gone. A fourth heart sound can often be heard in late diastole. This is caused by the increased left ventricular wall thickness and stiffness.

Calcification of the aortic valve leaflets is a cause of this murmur. When viewing the cardiac animation, look for a greatly thickened left ventricular wall and the almost totally immobile aortic leaflets.

Lesson #5: Mitral Regurgitation

A mitral regurgitation murmur is a rectangular murmur that continues throughout all systole. It has a mid-frequency pitch. S1 is normal. S2 is single. There is a third heart sound gallop in diastole.

The murmur is generated by turbulent blood flow through the incompetent mitral valve leaflets into the left atrium. Both the left ventricle and the left atrium are enlarged.

Lesson #6: Mitral Valve Prolapse

The mitral valve prolapse murmur is medium pitched with a diamond shaped waveform. This murmur begins immediately after a mid systolic click and continues to the end of systole.

The intensity of the murmur increases and its starting point begins earlier in systole as left ventricular volume decreases (going from supine to standing). The intensity of the murmur and its starting position move later in systole as the volume increases (by raising the legs while in the supine position). The mid-systolic click also moves in tandem with the murmur.

On the cardiac animation video, observe that the murmur is caused by the prolapse of the posterior mitral valve leaflet. The murmur is illustrated by turbulent flow from the left ventricle into the left atrium.

Lesson #7: Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy associated murmur is an early peaking, harsh, diamond shaped, systolic murmur. It begins at the onset of systole and stops well before S2. A fourth heart sound gallop is also present in diastole. View the waveform to see these features.

Observe that S1 intensity has increased due to a hyperdynamic left ventricle. S2 is single.

On the anatomy video, observe that the contraction of the left ventricle is strong and occurs in a reduced amount of time. Anatomically, the septal wall is very much thicker than the rest of the ventricle, but this is not shown in the animation.

The strong contraction of the left ventricle causes the anterior leaflet to be sucked into the ventricle, blocking the flow into the aorta and causing an aortic murmur. At the same time turbulent flow from the left ventricle to the left atrium causes a second murmur. Since the two murmurs occur at the same time, you hear a single murmur.

You can hear the difference between the two murmurs by moving the stethoscope head the aortic to the mitral valve area. First, you will hear the diamond shaped aortic murmur and later the rectangular pansystolic murmur.