Publications

Optical mapping is a high-resolution fluorescence imaging technique, which provides highly detailed visualizations of the electrophysiological wave phenomena, which trigger the beating of the heart. Recent advancements in optical mapping have demonstrated that the technique can now be performed with moving and contracting hearts and that motion and motion artifacts, once a major limitation, can now be overcome by numerically tracking and stabilizing the heart's motion. As a result, the optical measurement of electrical activity can be obtained from the moving heart surface in a co-moving frame of reference and motion artifacts can be reduced substantially. The aim of this study is to assess and validate the performance of a 2D marker-free motion tracking algorithm, which tracks motion and non-rigid deformations in video images. Because the tracking algorithm does not require markers to be attached to the tissue, it is necessary to verify that it accurately tracks the displacements of the cardiac tissue surface, which not only contracts and deforms, but also fluoresces and exhibits spatio-temporal physiology-related intensity changes. We used computer simulations to generate synthetic optical mapping videos, which show the contracting and fluorescing ventricular heart surface. The synthetic data reproduces experimental data as closely as possible and shows electrical waves propagating across the deforming tissue surface, as seen during voltage-sensitive imaging. We then tested the motion tracking and motion-stabilization algorithm on the synthetic as well as on experimental data. The motion tracking and motion-stabilization algorithm decreases motion artifacts approximately by 80% and achieves sub-pixel precision when tracking motion of 1-10 pixels (in a video image with 100 by 100 pixels), effectively inhibiting motion such that little residual motion remains after tracking and motion-stabilization. To demonstrate the performance of the algorithm, we present optical maps with a substantial reduction in motion artifacts showing action potential waves propagating across the moving and strongly deforming ventricular heart surface. The tracking algorithm reliably tracks motion if the tissue surface is illuminated homogeneously and shows sufficient contrast or texture which can be tracked or if the contrast is artificially or numerically enhanced. In this study, we also show how a reduction in dissociation-related motion artifacts can be quantified and linked to tracking precision. Our results can be used to advance optical mapping techniques, enabling them to image contracting hearts, with the ultimate goal of studying the mutual coupling of electrical and mechanical phenomena in healthy and diseased hearts.

OBJECTIVES

Hypertension and obesity are common cardiometabolic risk factors in reproductive age women. The association of hypertensive disorders of pregnancy with later-life cardiovascular disease is well-established, however, it is unknown how obesity and hypertensive disorders of pregnancy converge to accelerate development of hypertension in the postpartum period. The aim of this study was to characterize rates of sustained hypertension at one year postpartum using the new American Heart Association/American College of Cardiology Guidelines among overweight and obese women with a normotensive pregnancy or hypertensive disorder of pregnancy.

STUDY DESIGN

315 early pregnant women were enrolled prospectively and followed up to 12 months after delivery (mean 7.0 ± 1.8 months). At a postpartum research visit, we measured blood pressure and collected blood samples to measure cystatin C and high sensitivity C-reactive protein.

RESULTS

A total of 254 women had a normotensive pregnancy, 39 had gestational hypertension (12.4%) and 22 had preeclampsia (7.0%). 91 women had hypertension at the postpartum study visit (28.9%). After adjustment for maternal age, BMI, lactation and time postpartum, preeclampsia was associated with an aOR 2.35 (95%CI 1.63-3.41) of development of sustained hypertension and an aOR 3.23 (95%CI 1.56-6.68) of hypertension with abnormal biomarkers compared to women with normotensive pregnancies.

CONCLUSIONS

We demonstrate a high prevalence of hypertension and abnormal biomarkers associated with hypertensive disorders of pregnancy among overweight and obese women. Our findings support the need for structured follow up and risk reduction in overweight and obese women with hypertensive disorders of pregnancy as early as the first year postpartum.