Left Ventricular Torsional Mechanics in Uncomplicated Pregnancy

Abstract

Background: 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. Hypothesis: Pregnancy is associated with significant changes in LV torsional mechanics. Methods: Left ventricular twist and untwist was measured in 32 pregnant females (mean gestation 199 ± 48 d) and 23 nonpregnant controls using speckle-tracking echocardiography.Results: 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. Conclusions: 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. IntroductionPregnancy is associated with reversible adaptations in maternal systolic and diastolic left ventricular (LV) function. 1,2 Prior studies have shown increased preload and cardiac output, 3 -5 decreased systemic vascular resistance, 2,6 and increased LV mass and wall thickness 7 during pregnancy. Changes in LV fractional shortening are less well-defined, with the literature offering conflicting data. 8 -10 Little information is available concerning alterations in LV torsion (LV Tor ), the helical twisting motion of the LV about its longitudinal long axis. 11 Speckle-tracking echocardiography (STE) is a noninvasive method that allows for rapid, objective quantification of LV Tor . 12 Numerous studies have demonstrated that STE can accurately quantify differences in LV Tor associated with various pathophysiologic conditions. 13 -16 We used STE to measure LV Tor in healthy pregnant women and nonpregnant controls.

Shortness of Breath During Pregnancy: Could a Cardiac Factor Be Involved?

“…Recently, using this echocardiographic technique, a small decrease in LV segmental longitudinal systolic and diastolic function, as well as changes in torsion and peak LV twist velocity, in hearts of women with otherwise normal pregnancies were reported . Thus, in the current study we employed indexes derived from both TDI and speckle tracking techniques, in addition to the more traditional methods, to study cardiac function in a unique group of patients to whom these methods have not yet been applied: those with significant SOB with no other known systemic or obstetric problem and no obvious reason on clinical investigation.…”

Factors Influencing the Twisting and Untwisting Properties of the Left Ventricle during Normal Pregnancy

“…Yoon et al 12 reported significant changes in torsion and peak LV twist velocity in the 2nd and 3rd trimester compared with nonpregnant controls, while another study by Tzemos et al 11 found that torsion increased significantly during pregnancy in women with a bicuspid aortic valve and valve stenosis, as well as in pregnant women without valve pathology, compared with nonpregnant controls. Moreover, values of twist and peak systolic twisting rate in the 3rd trimester were significantly greater than in control subjects.…”

“…12 Peak untwisting rate has been described as a more sensitive, load-independent marker of diastolic function as it largely occurs during isovolumic relaxation time. To our knowledge, this is the first time that an enhanced peak untwisting rate during pregnancy has been described.…”

“…3 The ensuing increased vascular capacitance during pregnancy leads to an increase in blood volume combined with increased plasma renin activity, and therefore an increase in preload. [10][11][12][13] The aim of this study was to investigate the changes in LV strain and rotational properties during the three trimesters of normal pregnancy and to examine the factors that drive the twisting and untwisting motion during pregnancy. Heart rate also increases from the first few weeks of gestation until the 3rd trimester.…”

“…[6][7][8][9] So far, only sparse data are available concerning the factors that influence twisting and untwisting changes during normal pregnancy. [10][11][12][13] The aim of this study was to investigate the changes in LV strain and rotational properties during the three trimesters of normal pregnancy and to examine the factors that drive the twisting and untwisting motion during pregnancy.…”