Acute and chronic cardiac adaptations in adults born preterm

- What is the topic of this review? Studies using cardiovascular magnetic resonance imaging and echocardiography to investigate cardiac alterations at rest and during exercise-induced physiological stress in adults born preterm. - What advances does it highlight? People born preterm have a greater long-term cardiovascular risk, which may be explained in part by their cardiac structural and functional alterations. They have potentially adverse alterations in left and right ventricular structure and function that worsens with blood pressure elevation; an impaired myocardial functional reserve; and an increase in diffuse myocardial fibrosis that may drive their lower diastolic function. Preterm birth accounts for more than 10% of births worldwide and associates with a long-term increase in cardiovascular disease risk. The period around preterm birth is a rapid and critical phase of cardiovascular development, which might explain why changes in multiple components of the cardiovascular system have been observed in individuals born preterm. These alterations include reduced microvascular density, increased macrovascular stiffness, and higher systolic and diastolic blood pressure. Cardiac alterations have been observed in people born preterm as early as neonatal life and infancy, with potentially adverse changes in both left and right ventricular structure and function extending into adulthood. Indeed, studies using cardiovascular magnetic resonance imaging and echocardiography have demonstrated that preterm-born individuals have structural cardiac changes and functional impairments. Furthermore, myocardial tissue characterization by cardiovascular magnetic resonance imaging has demonstrated an increase in left ventricular diffuse myocardial fibrosis in young adults born preterm, and under acute physiological stress, their myocardial functional reserve assessed by echocardiography is reduced. The preterm heart is also more susceptible to chronic systolic blood pressure elevation, with a significantly greater increase in left ventricular mass as systolic blood pressure rises observed in preterm-born compared to term-born young adults. Given these known, potentially adverse acute and chronic cardiac adaptations in the preterm-born population, primary prevention strategies are needed to reduce long-term cardiovascular disease risk in this subgroup of the population

Conformal Standard Model with an extended scalar sector

We present an extended version of the Conformal Standard Model (characterized by the absence of any new intermediate scales between the electroweak scale and the Planck scale) with an enlarged scalar sector coupling to right-chiral neutrinos. The scalar potential and the Yukawa couplings involving only right-chiral neutrinos are invariant under a new global symmetry SU(3)$_N$ that complements the standard U(1)$_{B-L}$ symmetry, and is broken explicitly only by the Yukawa interaction, of order $10^{-6}$, coupling right-chiral neutrinos and the electroweak lepton doublets. We point out four main advantages of this enlargement, namely: (1) the economy of the (non-supersymmetric) Standard Model, and thus its observational success, is preserved; (2) thanks to the enlarged scalar sector the RG improved one-loop effective potential is everywhere positive with a stable global minimum, thereby avoiding the notorious instability of the Standard Model vacuum; (3) the pseudo-Goldstone bosons resulting from spontaneous breaking of the SU(3)$_N$ symmetry are natural Dark Matter candidates with calculable small masses and couplings; and (4) the Majorana Yukawa coupling matrix acquires a form naturally adapted to leptogenesis. The model is made perturbatively consistent up to the Planck scale by imposing the vanishing of quadratic divergences at the Planck scale (`softly broken conformal symmetry'). Observable consequences of the model occur mainly via the mixing of the new scalars and the standard model Higgs boson.Comment: version accepted for publication in the JHEP, 41 pages, 1 figur

Understanding the preterm human heart: what do we know so far?

Globally, preterm birth affects more than one in every 10 live births. Although the short-term cardiopulmonary complications of prematurity are well known, long-term health effects are only now becoming apparent. Indeed, preterm birth has been associated with elevated cardiovascular morbidity and mortality in adulthood. Experimental animal models and observational human studies point toward changes in heart morphology and function from birth to adulthood in people born preterm that may contribute to known long-term risks. Moreover, recent data support the notion of a heterogeneous cardiac phenotype of prematurity, which is likely driven by various maternal, early, and late life factors. This review aims to describe the early fetal-to-neonatal transition in preterm birth, the different structural and functional changes of the preterm human heart across developmental stages, as well as potential factors contributing to the cardiac phenotype of prematurity

Physical activity modification in youth with congenital heart disease: a comprehensive narrative review

Congenital heart disease (CHD) affects nearly 1% of births. As survival rates have dramatically improved, the majority of individuals with CHD now live into adulthood. As these patients age, they become prone to a large range of complications, such as chronic heart failure and acquired cardiovascular disease. Promotion of a healthy and active lifestyle from childhood onwards has been suggested as a sustainable and effective strategy to enhance cardiovascular health, improve quality of life and reduce immediate and long-term risk in people with CHD. Well-established physical activity consensus statements for youth with CHD have now been published. In this article, we review how increasing physical activity in youth with CHD may offer immediate and long-term cardiovascular benefits, what is known about physical activity in children with CHD, describe the unique factors that contribute to achieving sufficient and insufficient physical activity levels and summarize the evidence of trials on physical activity promotion in youth with CHD. Furthermore, we discuss some of the challenges that need to be addressed by further research regarding the optimal strategy, timing and format of physical activity intervention programmes in children and adolescents with CHD. IMPACT: Congenital heart disease (CHD) affects nearly 1% of births, with the majority of individuals with CHD now living into adulthood due to improved survival. As CHD patients age, they become prone to a large range of cardiovascular complications. This article discusses how and why increasing physical activity in youth with CHD may offer immediate and long-term cardiovascular benefits, the barriers to achieving sufficient physical activity levels and the evidence from trials on physical activity promotion in youth with CHD. The optimal strategy, timing and format of physical activity intervention programmes in children and adolescents with CHD are discussed

Effects from the charm scale in K+ -> pi+ nu nubar

We consider contributions to the rare decay K+ -> pi+ nu nubar which become nonlocal at the charm scale. Compared to the leading term, such amplitudes are suppressed by two powers of mK/mc and could potentially give corrections at the level of 15%. We compute the leading coefficients of the subleading dimension eight operators in the effective theory below the charm mass. The matrix elements of these operators cannot all be calculated from first principles and some must be modeled. We find that these contributions are likely to be small, but the estimate is sufficiently uncertain that the result may be as large as the existing theoretical uncertainty from other sources.Comment: 9 pages, 3 figures; Eq. (15) fixed, all results and conclusions unaltere

Constraint algebra in LQG reloaded : Toy model of a U(1)^{3} Gauge Theory I

We analyze the issue of anomaly-free representations of the constraint algebra in Loop Quantum Gravity (LQG) in the context of a diffeomorphism-invariant gauge theory in three spacetime dimensions. We construct a Hamiltonian constraint operator whose commutator matches with a quantization of the classical Poisson bracket involving structure functions. Our quantization scheme is based on a geometric interpretation of the Hamiltonian constraint as a generator of phase space-dependent diffeomorphisms. The resulting Hamiltonian constraint at finite triangulation has a conceptual similarity with the "mu-bar"-scheme in loop quantum cosmology and highly intricate action on the spin-network states of the theory. We construct a subspace of non-normalizable states (distributions) on which the continuum Hamiltonian constraint is defined which leads to an anomaly-free representation of the Poisson bracket of two Hamiltonian constraints in loop quantized framework.Comment: 60 pages, 6 figure

Symplectic charges in the Yang-Mills theory of the normal conformal Cartan connection: applications to gravity

It is known that a source-free Yang-Mills theory with the normal conformal Cartan connection used as the gauge potential gives rise to equations of motion equivalent to the vanishing of the Bach tensor. We investigate the conformally invariant presymplectic potential current obtained from this theory and find that on the solutions to the Einstein field equations, it can be decomposed into a topological term derived from the Euler density and a part proportional to the potential of the standard Einstein-Hilbert Lagrangian. The pullback of our potential to the asymptotic boundary of asymptotically de Sitter spacetimes turns out to coincide with the current obtained from the holographically renormalized gravitational action. This provides an alternative derivation of a symplectic structure on scri without resorting to holographic techniques. We also calculate our current at the null infinity of asymptotically flat spacetimes and in particular show that it vanishes for variations induced by the BMS symmetries. In addition, we calculate the Noether currents and charges corresponding to gauge transformations and diffeomorphisms.Comment: 29 pages, 0 figure