BackgroundCardiovascular disease in pregnancy is the leading cause of maternal mortality in North America. Although transthoracic echocardiography (TTE) is the most widely used imaging modality for the assessment of cardiovascular function during pregnancy, little is known on the role of cardiovascular magnetic resonance (CMR). The objective of the Cardiac Hemodynamic Imaging and Remodeling in Pregnancy (CHIRP) study was to compare TTE and CMR in the non-invasive assessment of maternal cardiac remodeling during the peripartum period.MethodsBetween 2010–2012, healthy pregnant women aged 18 to 35 years were prospectively enrolled. All women underwent TTE and CMR during the third trimester and at least 3 months postpartum (surrogate for non-pregnant state).ResultsThe study population included a total of 34 women (mean age 29 ± 3 years). During the third trimester, TTE and CMR demonstrated an increase in left ventricular end-diastolic volume from 95 ± 11 mL to 115 ± 14 mL and 98 ± 6 mL to 125 ± 5 mL, respectively (p < 0.05). By TTE and CMR, there was also an increase in left ventricular (LV) mass during pregnancy from 111 ± 10 g to 163 ± 11 g and 121 ± 5 g to 179 ± 5 g, respectively (p < 0.05). Although there was good correlation between both imaging modalities for LV mass, stroke volume, and cardiac output, the values were consistently underestimated by TTE.ConclusionThis CMR study provides reference values for cardiac indices during normal pregnancy and the postpartum state.

Abstract-Chlamydia pneumoniae infection has been linked with atherosclerosis. However, the mechanism responsible for the atherogenic effects of C pneumoniae remains unclear. Heat shock proteins (HSPs) have been found in atherosclerotic lesions. HSPs of HSP70 and HSP90 families are involved in the regulation of cell cycle progression and cell proliferation. We assessed the hypothesis that HSP60 is induced in vascular cells infected with C pneumoniae and stimulates cell proliferation. Rabbit vascular smooth muscle cells (VSMCs) and human umbilical vein endothelial cells (HUVECs) were infected with C pneumoniae. Western blot analysis demonstrated the induction of endogenous HSP60 expression in C pneumoniae-infected VSMCs. C pneumoniae infection significantly increased the number of VSMCs, and the mitogenic effect correlated with the expression level of endogenous HSP60. In contrast to VSMCs, C pneumoniae infection had no effect on the expression level of HSP60 and did not stimulate cell proliferation in HUVECs. Exogenous addition of recombinant chlamydial HSP60 had no mitogenic effect on VSMCs and HUVECs. However, overexpression of HSP60 within VSMCs by infection with adenovirus encoding human HSP60 resulted in a significant increase in cell numbers compared with uninfected VSMCs. These results suggest that overexpression of endogenous HSP60 may be a central intracellular event responsible for the mitogenic effects induced by C pneumoniae infection. In addition to C pneumoniae, other infectious agents and atherogenic risk factors may also stimulate VSMC proliferation and contribute to the lesion formation through the induction of HSP60.

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