Incidence of Doppler regurgitant flow velocities during normal pregnancy

Abstract

The incidence of regurgitant flow velocities were determined using colour flow mapping and pulse Doppler in 107 pregnant women, 55 of whom were less than 28 weeks gestation. The results were compared with 51 non-pregnant controls. The incidence of tricuspid regurgitant velocities increased from 42% in the control group to 67% at greater than or equal to 28 weeks gestation with a median peak regurgitant velocity of 1.7 ms-1. The incidence of pulmonary regurgitant velocities increased from 50% in the control group to 96% at greater than or equal to 28 weeks gestation with a median peak regurgitant velocity of 1.1 m s-1. Mitral and aortic regurgitant velocities were recorded in 27% and 2% of non-pregnant controls respectively. No statistically significant increase in left sided regurgitant velocities was evident during pregnancy. The increase in incidence of right heart regurgitant velocities may be secondary to the dilatation of the respective value orifices due to the volume loading of pregnancy.

Physiological remodeling of the mitral valve during pregnancy

“…One important difference between human pregnancy and heart failure, however, is that mitral regurgitation becomes significant in heart failure (23) but not in pregnancy (7,46). The results of the present study raise the intriguing possibility that the reversal of extensibility (i.e., an increase back to NP properties) of the enlarged leaflets in LP contributes to the maintenance of coaptation.…”

“…The results of the present study raise the intriguing possibility that the reversal of extensibility (i.e., an increase back to NP properties) of the enlarged leaflets in LP contributes to the maintenance of coaptation. This may be the mechanism under which mitral regurgitation is largely uncommon in pregnancy, despite the large increase in valve orifice area (7,46). That is, with volume loading and valve orifice expansion, the mitral leaflet may not maintain coaptation simply due to its functional reserve but by adaptive remodeling and tissue growth that increases the size and alters the material properties of the leaflet.…”

“…It is interesting that, despite the large increase in valve orifice area, mitral regurgitation is relatively uncommon in pregnancy (7,46). One possible explanation for this is that the mitral valve has a large "functional reserve," with a total leaflet area that is at least 1.5 times larger than that of the annulus (15).…”