Global Right Ventricular Contractile
Function
Measurement of RV function is more difficult than LV function
because of the complex shape of the right ventricle, its large surface area relative
to its volume, and its tendency to change shape with changes in loading. Normally,
inward motion of the free wall of the right ventricle contributes most to RV ejection;
however, some ejection is contributed by contraction of the RV outflow tract and
by descent of the base of the heart. Thus, the four-chamber and ME RV inflow-outflow
cross sections are the most useful for assessing RV function because they reveal
the free wall best. In the four-chamber cross section, a normal right ventricle
will appear smaller than a normal left ventricle (intracavitary area roughly two
thirds of the LV cavity area) because it is crescent shaped and partially wrapped
around the left ventricle. In the ME RV inflow-outflow cross section, the crescent
shape of the right ventricle should be most apparent.
Although subtle RV dysfunction is hard to diagnose with TEE, severe
dysfunction is not. The hallmarks are severe hypokinesis or akinesis of the RV free
wall, enlargement of the right ventricle to exceed that of the apparent size of the
left ventricle, a change in the shape of the right ventricle from crescent to round,
and a flattening or bulging of the intraventricular septum to the left. These signs
may be accompanied by tricuspid regurgitation secondary to tricuspid annular dilation.
With very severe RV failure caused by RV pressure overload, RV dilation can be so
great that it "tamponades" the left ventricle.
