Left ventricular torsional mechanics in uncomplicated pregnancy

Alterations in left ventricular (LV) twist (torsion) and untwist have been described for a variety of physiologic and pathologic conditions. Little information is available regarding changes in these parameters during normal pregnancy.

Pregnancy is associated with significant changes in LV torsional mechanics.

Left ventricular twist and untwist was measured in 32 pregnant females (mean gestation 199 ± 48 d) and 23 nonpregnant controls using speckle-tracking echocardiography.

Left ventricular ejection fraction (68 ± 5% vs 66 ± 5%) was similar between the groups (P not significant). There was a significant increase in peak LV twist from nonpregnant controls (9.4 ± 3.7 degrees) to second-trimester (12.0 ± 4.2 degrees) and third-trimester subjects (12.6 ± 5.9 degrees, all P<0.05). Peak LV twist velocity was also increased in second- and third-trimester groups compared with controls (94 ± 24 degrees/sec and 93 ± 30 vs 64 ± 21 degrees/sec, respectively, both P<0.05). Both peak untwist velocity and time to peak untwist velocity were not significantly different between groups (P not significant). Multiple regression analysis indicate that only systolic blood pressure (r = 0.394, P = 0.005) was an independent predictor for increased LV torsion.

There are significant changes in LV torsional indices during the course of pregnancy, whereas untwist parameters remain unchanged. Blood pressure is independently associated with increased torsion during pregnancy.