Pulmonary Stenosis Ejection Murmurs

1. Where is the classic "pulmonary area"? What is wrong with this term?

ANS: The classic pulmonary area is the second left interspace. Pulmonary events, however, may be best heard anywhere along the left sternal border (or even in the epigastrium in patients with chronic obstructive pulmonary disease).

2. Where is the best place for hearing the murmur of (a) valvular PS and (b) infundibular PS?

ANS: a. Valvular PS: best at the second left interspace.

b. Infundibular PS: best at the third or fourth left interspace.

3. What is the relation between the peak of the crescendo of the PS murmur and the severity of the obstruction?

ANS: The later the peak, the more severe is the obstruction.

4. Why is it that while in AS the murmur rarely peaks much beyond mid-systole, in PS the peak may go beyond mid-systole?

ANS: The right ventricle (RV) is shaped like a teapot, with a main chamber, namely, the inflow tract (also known as the RV sinus), and a thick, high spout, which is the outflow tract or infundibulum.

The outflow tract of the RV is a tubular structure made up mostly of muscle, called the crista supraventricularis, which separates the tricuspid from the pulmonary valves.

The inflow and outflow tract contract asynchronously in a peristaltic fashion, the inflow tract first, then the infundibular or outflow tract. The worse the obstruction at the valve, the later the outflow tract contracts relative to the inflow tract [7]. It is the late contraction of this RV outflow tract that apparently produces the late peak of the crescendo.

The LV, on the other hand, has no distinct muscular outflow tract. The anterior mitral leaflet and its chordae and papillary muscles form the posterolateral wall of a merely functional outflow tract, which is not anatomically independent enough to contract more than slightly asynchronously. (See figure on page 208.)

There is no infundibulum in the LV because the mitral and aortic valves are in direct continuity.

Anterolateral papillary muscle and chordae

Septum

Outflow tract

Anterolateral papillary muscle and chordae

Septum

Outflow tract

l. ventricle

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