Longitudinal fractional shortening and its relation to diastolic cardiac function

Assessment of cystatin C in pediatric sickle cell disease and β-thalassemia as a marker of subclinical cardiovascular dysfunction: a case-control study

Cardiovascular complications represent the main determinant of survival in patients with hemoglobinopathies. Serum cystatin C is a well-known marker of nephropathy in sickle cell disease (SCD) and β-thalassemia patients that has recently emerged as a strong predictor of cardiovascular dysfunction in patients with and without kidney disease. We performed a case control study to determine the role of cystatin C as a predictor of subclinical cardiovascular dysfunction in SCD and β-thalassemia patients. We enrolled 40 SCD patients with a mean age of 12.4 years, 40 β-thalassemia patients with a mean age of 11.4 years and 40 age and sex-matched controls. We assessed hematological profile, serum ferritin, urinary albumin-creatinine ratio (UACR), serum cystatin C, echocardiography and carotid intima media thickness (CIMT). UACR, cystatin C and CIMT were higher in SCD and β-thalassemia patients compared to controls (p < .001). Significantly higher cystatin C levels were observed in SCD and β-thalassemia patients with nephropathy or left ventricular systolic dysfunction (shortening fraction <30%, or ejection fraction <55%; p < .001). Moreover, SCD patients with pulmonary hypertension had significantly higher cystatin C levels. Cystatin C levels were positively correlated with CIMT in SCD (p = .02) and β-thalassemia patients (p < .001) while negatively correlated with ejection fraction and shortening fraction (p < .001). The cutoff values of cystatin C ≥ 16.03 and ≥ 13.2 (ng/mL) could detect subclinical cardiac dysfunction risk among SCD and β-thalassemia patients respectively. Cystatin C appears to be a promising marker for subclinical cardiovascular dysfunction in SCD and β-thalassemia patients.

Sensitivity analysis of a strongly-coupled human-based electromechanical cardiac model: Effect of mechanical parameters on physiologically relevant biomarkers

The human heart beats as a result of multiscale nonlinear dynamics coupling subcellular to whole organ processes, achieving electrophysiologically-driven mechanical contraction. Computational cardiac modelling and simulation have achieved a great degree of maturity, both in terms of mathematical models of underlying biophysical processes and the development of simulation software. In this study, we present the detailed description of a human-based physiologically-based, and fully-coupled ventricular electromechanical modelling and simulation framework, and a sensitivity analysis focused on its mechanical properties. The biophysical detail of the model, from ionic to whole-organ, is crucial to enable future simulations of disease and drug action. Key novelties include the coupling of state-of-the-art human-based electrophysiology membrane kinetics, excitation-contraction and active contraction models, and the incorporation of a pre-stress model to allow for pre-stressing and pre-loading the ventricles in a dynamical regime. Through high performance computing simulations, we demonstrate that 50% to 200% - 1000% variations in key parameters result in changes in clinically-relevant mechanical biomarkers ranging from diseased to healthy values in clinical studies. Furthermore mechanical biomarkers are primarily affected by only one or two parameters. Specifically, ejection fraction is dominated by the scaling parameter of the active tension model and its scaling parameter in the normal direction ( k ort 2 ); the end systolic pressure is dominated by the pressure at which the ejection phase is triggered ( P ej ) and the compliance of the Windkessel fluid model ( C ); and the longitudinal fractional shortening is dominated by the fibre angle ( ϕ ) and k ort 2 . The wall thickening does not seem to be clearly dominated by any of the considered input parameters. In summary, this study presents in detail the description and implementation of a human-based coupled electromechanical modelling and simulation framework, and a high performance computing study on the sensitivity of mechanical biomarkers to key model parameters. The tools and knowledge generated enable future investigations into disease and drug action on human ventricles.

Placental Growth Factor as an Indicator of Maternal Cardiovascular Risk After Pregnancy

BACKGROUND

Angiogenic placental growth factor (PlGF) concentrations rise during pregnancy, peaking at the end of midpregnancy. Low PlGF concentrations during pregnancy are associated with pregnancy complications with recognized later-life cardiovascular risk. We hypothesized that low PlGF concentrations, especially in midpregnancy, identify not only a subset of women at risk for pregnancy complications but also women with greater cardiovascular risk factor burden after pregnancy regardless of pregnancy outcome.

METHODS

In a population-based prospective cohort study of 5475 women, we computed gestational age-adjusted multiples of the medians of early pregnancy and midpregnancy PlGF concentrations. Information on pregnancy complications (preeclampsia, small for gestational age, and spontaneous preterm birth) was obtained from hospital registries. Six years after pregnancy, we measured maternal systolic and diastolic blood pressures, cardiac structure (aortic root diameter, left atrial diameter, left ventricular mass, and fractional shortening), carotid-femoral pulse wave velocity, and central retinal arteriolar and venular calibers. Blood pressure was also measured 9 years after pregnancy.

RESULTS

Women were on average 29.8 (SD, 5.2) years of age in pregnancy, were mostly European (55.2%), and 14.8% developed a pregnancy complication. Quartile analysis showed that especially women with midpregnancy PlGF in the lowest quartile (the low-PlGF subset) had a larger aortic root diameter (0.40 mm [95% CI, 0.08-0.73]), left atrial diameter (0.34 mm [95% CI, -0.09 to 0.78]), left ventricular mass (4.6 g [95% CI, 1.1-8.1]), and systolic blood pressure (2.3 mm Hg [95% CI, 0.93-3.6]) 6 years after pregnancy than women with the highest PlGF. Linear regression analysis showed that higher midpregnancy PlGF concentrations were associated with a smaller aortic root diameter (-0.24 mm [95% CI, -0.39 to -0.10]), smaller left atrial diameter (-0.75 mm [95% CI, -0.95 to -0.56]), lower left ventricular mass (-3.9 g [95% CI, -5.5 to -2.3]), and lower systolic blood pressure (-1.1 mm Hg [95% CI, -1.7 to -0.46]). These differences persisted after the exclusion of women with complicated pregnancies.

CONCLUSIONS

Women with low PlGF in midpregnancy have a greater aortic root diameter, left atrial diameter, and left ventricular mass and higher systolic blood pressure 6 and 9 years after pregnancy compared to women with higher PlGF, including women with uncomplicated pregnancies. The pathophysiological implications of lower PlGF concentrations in midpregnancy might provide insight into the identification of pathways contributing to greater cardiovascular risk factor burden.

Echocardiography without electrocardiogram using nonlinear dimensionality reduction methods

PURPOSE

The aim of this study is to evaluate the efficiency of a new automatic image processing technique, based on nonlinear dimensionality reduction (NLDR) to separate a cardiac cycle and also detect end-diastole (ED) (cardiac cycle start) and end-systole (ES) frames on an echocardiography system without using ECG.

METHODS

Isometric feature mapping (Isomap) and locally linear embeddings (LLE) are the most popular NLDR algorithms. First, Isomap algorithm is applied on recorded echocardiography images. By this approach, the nonlinear embedded information in sequential images is represented in a two-dimensional manifold and each image is characterized by a symbol on the constructed manifold. Cyclicity analysis of the resultant manifold, which is derived from the cyclic nature of the heart motion, is used to perform cardiac cycle length estimation. Then, LLE algorithm is applied on extracted left ventricle (LV) echocardiography images of one cardiac cycle. Finally, the relationship between consecutive symbols of the resultant manifold by the LLE algorithm, which is based on LV volume changes, is used to estimate ED (cycle start) and ES frames. The proposed algorithms are quantitatively compared to those obtained by a highly experienced echocardiographer from ECG as a reference in 20 healthy volunteers and 12 subjects with pathology.

RESULTS

Mean difference in cardiac cycle length, ED, and ES frame estimation between our method and ECG detection by the experienced echocardiographer is approximately 7, 17, and 17 ms (0.4, 1, and 1 frame), respectively.

CONCLUSION

The proposed image-based method, based on NLDR, can be used as a useful tool for estimation of cardiac cycle length, ED and ES frames in echocardiography systems, with good agreement to ECG assessment by an experienced echocardiographer in routine clinical evaluation.

Diastolic function assessed by cardiac MRI using longitudinal left ventricular fractional shortening

INTRODUCTION

Diastolic dysfunction contributes significantly to diastolic heart failure. We examined the use of cardiac magnetic resonance imaging (CMR) using midwall longitudinal fractional shortening (MLFS) in the evaluation of transthoracic echocardiogram (TTE)-evidenced diastolic dysfunction.

METHODS

A total of 80 patients with CMR within 6 months of TTE and normal ejection fraction were identified. MLFS was calculated as percentage change in distance from the anterior mitral leaflet base to the apical endocardium in systole and diastole.

RESULTS

MLFS of grade II/III [0.14 (0.12-0.16)] was significantly lower than that of grade 0/I [0.20 (0.19-0.21)], P=.001. MLFS detected age-related changes with grade 0 [0.22 (0.21-0.23)] significantly lower than grade I [0.18 (0.16-0.20)], P=.001.

CONCLUSION

TTE-evidenced diastolic dysfunction can be reliably identified by CMR using MLFS.

Clinicopathological and radiological study of Egyptian β-thalassemia intermedia and β-thalassemia major patients: relation to complications and response to therapy

The clinico epidemiological characteristics, frequency of complications, and response to various therapeutic modalities in 80 Egyptian β-thalassemia intermedia (β-TI) patients were compared with 70 β-thalassemia major (β-TM) patients. β-Thalassemia intermedia patients had a higher incidence of left atrium dilatation, right ventricular dilatation and pulmonary hypertension, whereas, β-TM patients showed a higher incidence of left ventricular (LV) dilatation, restrictive LV filling and impaired LV contractility, with an overall higher incidence of heart disease (p <0.001). Short stature, delayed puberty, osteoporosis, bone fractures, diabetes mellitus and viral hepatitis was frequently observed in β-TM patients compared with β-TI patients (p <0.05). Administration of hydroxyurea (HU) alone was associated with significant improvement in hematological parameters and quality of life for β-TI patients. In conclusion, the risk of complications still burdens the life of Egyptian thalassemia patients and their frequency varies between β-TI and β-TM. We provide evidence that calls for the use of HU in β-TI patients.

Diastolic cardiac function is synonymous with long-axis systolic function: a novel concept in cardiac function

AIMS

There has been recent speculation on the relationship between diastolic cardiac function and long-axis cardiac function. The goal of this study was to obtain conclusive evidence regarding the relationship between these parameters.

METHODS

Echocardiography and cardiac magnetic resonance imaging were performed consecutively in 33 subjects. Longitudinal fractional shortening and fractional shortening of the left ventricular wall length were measured in each procedure and the relationships with diastolic cardiac function were assessed.

RESULTS

Diastolic cardiac function and long-axis systolic function in each procedure were significantly correlated. Spearman coefficients for correlations between longitudinal fractional shortening measured echocardiographically and diastolic cardiac function parameters were 0.76 (P < 0.0001) for E/A, -0.77 (P < 0.0001) for E/e', 0.87 (P < 0.0001) for e', and 0.91 (P < 0.0001) for e'/a'.

CONCLUSIONS

Long-axis cardiac function correlates well with diastolic cardiac function. e'/a' showed a strong correlation with longitudinal fractional shortening and is a good candidate for use as an index for assessment of long-axis cardiac function.