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Leveraging cutting-edge numerical methodologies, we study the ground state of the two-dimensional spin-polarized Fermi gas in an optical lattice. We focus on systems at high density and small spin polarization, corresponding to the parameter regime believed to be most favorable to the formation of the elusive Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid phase. Our systematic study of large lattice sizes, hosting nearly 500 atoms, provides strong evidence of the stability of the FFLO state in this regime, as well as a high-accuracy characterization of its properties. Our results for the density correlation function reveal the existence of density order in the system, suggesting the possibility of an intricate coexistence of long-range orders in the ground state. The ground-state properties are seen to differ significantly from the standard mean-field description, providing a compelling avenue for future theoretical and experimental explorations of the interplay between spin imbalance, strong interactions, and superfluidity in an exotic phase of matter.

From flow without dissipation of energy to the formation of vortices when placed within a rotating container, the superfluid state of matter has proven to be a very interesting physical phenomenon. Here we present the key mechanisms behind superfluidity in fermionic systems and apply our understanding to an exotic system found deep within the universe -- the superfluid found deep within a neutron star. A defining trait of a superfluid is the pairing gap, which the cooling curves of neutron stars depend on. The extreme conditions surrounding a neutron star prevent us from directly probing the superfluid's properties, however, we can experimentally realize conditions resembling the interior through the use of cold atoms prepared in a laboratory and simulated on a computer. Experimentalists are becoming increasingly adept at realizing cold atomic systems in the lab that mimic the behavior of neutron stars and superconductors. In their turn, computational physicists are leveraging the power of supercomputers to simulate interacting atomic systems with unprecedented accuracy. This paper is intended to provide a pedagogical introduction to the underlying concepts and the possibility of using cold atoms as a tool that can help us make significant strides towards understanding exotic physical systems., 11 pages, 8 figures

We determine the spin and charge orders in the ground state of the doped two-dimensional (2D) Hubbard model in its simplest form, namely with only nearest-neighbor hopping and on-site repulsion. At half-filling, the ground state is known to be an anti-ferromagnetic Mott insulator. Doping Mott insulators is believed to be relevant to the superconductivity observed in cuprates. A variety of candidates have been proposed for the ground state of the doped 2D Hubbard model. A recent work employing a combination of several state-of-the-art numerical many-body methods, established the stripe order as the ground state near $1/8$ doping at strong interactions. In this work, we apply one of these methods, the cutting-edge constrained-path auxiliary field quantum Monte Carlo method with self-consistently optimized gauge constraints, to systematically study the model as a function of doping and interaction strength. With careful finite size scaling based on large-scale computations, we map out the ground state phase diagram in terms of its spin and charge order. We find that modulated antiferromagnetic order persists from near half-filling to about $1/5$ doping. At lower interaction strengths or larger doping, these ordered states are best described as spin-density waves, with essentially delocalized holes and modest oscillations in charge correlations. When the charge correlations are stronger (large interaction or small doping), they are best described as stripe states, with the holes more localized near the node in the antiferromagnetic spin order. In both cases, we find that the wavelength in the charge correlations is consistent with so-called filled stripes in the pure Hubbard model., Comment: 12 pages, 12 figures

We perform extensive auxiliary-field quantum Monte Carlo (AFQMC) calculations for the three-band Hubbard (Emery) model in order to study the ground-state properties of Copper-Oxygen planes in the cuprates. Employing cutting-edge AFQMC techniques with a self-consistent gauge constraint in auxiliary-field space to control the sign problem, we reach supercells containing around 500 atoms to capture collective modes in the charge and spin orders and characterize the behavior in the thermodynamic limit. The self-consistency scheme interfacing with generalized Hartree-Fock calculations allows high accuracy in AFQMC to resolve small energy scales, which is crucial for determining the complex candidate orders in such a system. We present detailed information on the charge order, spin order, momentum distribution, and localization properties as a function of charge-transfer energy for the the under-doped regime. In contrast with the stripe and spiral orders under hole-doping, we find that the corresponding 1/8 electron-doped system exhibits purely antiferromagnetic order in the three-band model, consistent with the asymmetry between electron and hole-doping in the phase diagram of cuprates., 15 pages, 16 figures

We study the superconducting pairing correlations in the ground state of the doped Hubbard model -- in its original form without hopping beyond nearest neighbor or other perturbing parameters -- in two dimensions at intermediate to strong coupling and near optimal doping. The nature of such correlations has been a central question ever since the discovery of cuprate high-temperature superconductors. Despite unprecedented effort and tremendous progress in understanding the properties of this fundamental model, a definitive answer to whether the ground state is superconducting in the parameter regime most relevant to cuprates has proved exceedingly difficult to establish. In this work, we employ two complementary, state-of-the-art many-body computational methods, constrained path (CP) auxiliary-field quantum Monte Carlo (AFQMC) and density matrix renormalization group (DMRG) methods, deploying the most recent algorithmic advances in each. Systematic and detailed comparisons between the two methods are performed. The DMRG is extremely reliable on small width cylinders, where we use it to validate the AFQMC. The AFQMC is then used to study wide systems as well as fully periodic systems, to establish that we have reached the thermodynamic limit. The ground state is found to be non-superconducting in the moderate to strong coupling regime in the vicinity of optimal hole doping., Close to the published version

The primary work presented in this paper focuses on the calculation of density–density dynamical correlations in an attractive two-dimensional Fermi gas in several physically interesting regimes, including the strongly correlated BEC–BCS crossover regime. We use state-of-the-art dynamical BCS theory, and we address the possibility to renormalize the interaction strength, using unbiased Quantum Monte Carlo results as an asset to validate the predictions. We propose that a suitable interplay between dynamical BCS theory, which is computationally very cheap and yields results directly in real time domain, and Quantum Monte Carlo methods, which are exact but way more demanding and limited to imaginary time domain, can be a very promising idea to study dynamics in many-body systems. We illustrate the idea and provide quantitative results for a few values of the interaction strength in the cold gas.

Interfacing unbiased quantum Monte Carlo simulations with state-of-art analytic continuation techniques, we obtain exact numerical results for dynamical density and spin correlations in the attractive Hubbard model, describing a spin-balanced two-dimensional cold Fermi gas on an optical lattice. We focus on half-filling, where on average one fermion occupies each lattice site, and the system displays an intriguing supersolid phase: a superfluid with a checkerboard density modulation. The coexistence of $U(1)$ broken symmetry and the density modulations makes this regime very challenging and interesting for the calculation of dynamical properties. We compare our unbiased results with state-of-the-art Generalized Random Phase Approximation calculations: both approaches agree on a well-defined low-energy Nambu-Goldstone collective mode in the density correlations, while the higher energy structures appear to differ significantly. We also observe an interesting high-energy spin mode. We argue that our results provide a robust benchmark for Generalized Random Phase Approximation techniques, which are widely considered to be the method of choice for dynamical correlations in Fermi gases. Also, our calculations yield new physical insight in the high-energy behavior of the dynamical structure factor of the attractive Hubbard model, which is a well known prototype lattice model for superconductors and is a fertile field to target the observation of collective modes in strongly correlated systems., Comment: 12 pages, 6 figures, post-print version

We introduce an efficient and numerically stable technique to make use of a BCS trial wave function in the computation of correlation functions of strongly correlated quantum fermion systems. The technique is applicable to any projection approach involving paths of independent-fermion propagators, for example in mean-field or auxiliary-field quantum Monte Carlo (AFQMC) calculations. Within AFQMC, in the absence of the sign problem, the methodology allows the use of a BCS reference state which can greatly reduce the required imaginary time of projection, and improves Monte Carlo sampling efficiency and statistical accuracy for systems where pairing correlations are important. When the sign problem is present, the approach provides a powerful generalization of the constrained-path AFQMC technique which usually uses Slater determinant trial wave functions. As a demonstration of the capability of the methodology, we present benchmark results for the attractive Hubbard model, both spin-balanced (no sign problem) and with a finite spin polarization (with sign problem)., Comment: 13 pages, 5 figures

The three-band Hubbard model is a fundamental model for understanding properties of the Copper-Oxygen planes in cuprate superconductors. We use cutting-edge auxiliary-field quantum Monte Carlo (AFQMC) methods to investigate ground state properties of the model in the parent compound. Large supercells combined with twist averaged boundary conditions are studied to reliably reach the thermodynamic limit. Benchmark quality results are obtained on the magnetic correlations and charge gap. A key parameter of this model is the charge-transfer energy $\Delta$ between the Oxygen p and the Copper d orbitals, which appears to vary significantly across different families of cuprates and whose ab initio determination is subtle. We show that the system undergoes a quantum phase transition from an antiferromagnetic insulator to a paramagnetic metal as $\Delta$ is lowered to 3 eV., Comment: 5 pages, 4 figures

The Copper-Oxygen planes in cuprates have been at the center of the search for a theory of high-temperature superconductivity. We conduct an extensive study of the ground state of the three-band Hubbard (Emery) model in the underdoped regime. We focus on the magnetic and charge orders, and present results from generalized Hartree-Fock (GHF) calculations. The ground-state properties at the thermodynamic limit are challenging to pin down because of sensitivity to computational details including the shapes and sizes of the supercells. We employ large-scale computations with various technical improvements to determine the orders within GHF. The ground state exhibits a rich phase diagram with hole doping as the charge transfer energy is varied, including ferromagnetic domain walls embedded in an antiferromagnetic background, spin spirals, and nematic order., Comment: 12 pages, 10 figures

This chapter provides a self-contained review of the foundations of probability theory, in order to fix notations and introduce mathematical objects employed in the remaining chapters. In particular we stress the notions of measurability, related to what it is actually possible to observe when performing an experiment, and statistical independence. We present several tools to deal with random variables; in particular we focus on the normal random variables, a cornerstone in the theory of random phenomena. We conclude presenting the law of large numbers and the central limit theorem.

In this chapter we introduce the art of sampling of random variables. Sampling a random variable X, for example real valued, means using a random number generator to generate n real numbers \((x_1,\ldots ,x_n)\), realizations of a sample \((X_1,\ldots ,X_n)\) of independent and identically distributed random variables sharing the same law as X. The ability of sampling is crucial to deal with integrals in high dimensions, appearing in quantum mechanics and in statistical physics, and gives the possibility to simulate physical systems. We first introduce simple tools to sample random variables, that can be used only in quite special situations. In the last part of the chapter, we will introduce and discuss a very general sampling technique, relying on the Metropolis theorem.

In this chapter we introduce the basic notions of stochastic calculus, starting from the Brownian motion. Stochastic processes describe time-dependent random phenomena, generalizing the usual deterministic evolution. The description of the latter requires the notions of differential and integral, which need to be properly extended to stochastic properties. Stochastic calculus is the branch of mathematics dealing with this important topic. The reason why traditional calculus is not suitable for stochastic processes is revealed by the Brownian motion. Since \(Var(B_t) = t\), implying that \(B_t\) “scales” as \(\sqrt{t}\), its trajectories are not differentiable in the usual sense. The stochastic calculus allows us to introduce generalized notions of differential and integral, notwithstanding this difficulty. Moreover, it allows to write differential equations involving stochastic processes, providing thus a powerful generalization of ordinary differential equations to study phenomena evolving in time in a non deterministic way.

In this chapter we present applications of probability theory within the science of extracting information from data: mathematical statistics. We present, on a rigorous basis, the theory of statistical estimators and some of the most widely employed hypothesis tests. Finally, we briefly discuss linear regression, a mandatory topic for physicists.

In this chapter we deal with conditional probability. After having sketched the elementary definitions, we introduce the advanced notion of conditional expectation of a random variable with respect to a given \(\sigma \)-field. The intuitive meaning of the conditional expectation is the best prediction we can do about the values taken by the random variable, once we have observed the family of events inside the \(\sigma \)-field. The conditional expectation is widely used in the theory of stochastic processes we will present in the following chapters.

Response functions are central objects in physics. They provide crucial information about the behavior of physical systems, and they can be directly compared with scattering experiments involving particles like neutrons, or photons. Calculations of such functions starting from the many-body Hamiltonian of a physical system are challenging, and extremely valuable. In this paper we focus on the two-dimensional (2D) ultracold Fermi atomic gas which has been realized experimentally. We present an application of the dynamical BCS theory to obtain response functions for different regimes of interaction strengths in the 2D gas with zero-range attractive interaction. We also discuss auxiliary-field quantum Monte Carlo (AFQMC) methods for the calculation of imaginary-time correlations in these dilute Fermi gas systems. Illustrative results are given and comparisons are made between AFQMC and dynamical BCS theory results to assess the accuracy of the latter., 16 pages, 4 figures

The term analytic continuation emerges in many branches of Mathematics, Physics, and, more generally, applied Science. Generally speaking, in many situations, given some amount of information that could arise from experimental or numerical measurements, one is interested in extending the domain of such information, to infer the values of some variables which are central for the study of a given problem. For example, focusing on Condensed Matter Physics, state-of-the-art methodologies to study strongly correlated quantum physical systems are able to yield accurate estimations of dynamical correlations in imaginary time. Those functions have to be extended to the whole complex plane, via analytic continuation, in order to infer real-time properties of those physical systems. In this Review, we will present the Genetic Inversion via Falsification of Theories method, which allowed us to compute dynamical properties of strongly interacting quantum many--body systems with very high accuracy. Even though the method arose in the realm of Condensed Matter Physics, it provides a very general framework to face analytic continuation problems that could emerge in several areas of applied Science. Here we provide a pedagogical review that elucidates the approach we have developed., 18 pages, 3 figures. This is an Accepted Manuscript of an article published by Taylor & Francis in Advances in Physics X on 19 Feb 2017 (online), available online: http://www.tandfonline.com/doi/full/10.1080/23746149.2017.1288585

We study the response of one-dimensional liquid $^4$He to weak perturbations relying on the dynamical structure factor, $S(q,\omega)$, recently obtained via ab-initio techniques [Phys. Rev. Lett. 116, 135302 (2016)]. We evaluate the drag force, $F_v$, experienced by an impurity moving along the system with velocity $v$ and the static response function, $\chi(q)$, describing the density modulations induced by a periodic perturbation with wave vector $q$., Comment: 7 pages, 2 figures

We compute the zero-temperature dynamical structure factor of one-dimensional liquid ^{4}He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model.

An otherwise healthy 47-year-old man presented to the emergency department in cardiogenic shock after suffering a massive myocardial infarction due to left main occlusion. He was initially supported by extracorporeal membrane oxygenation and subsequently was converted to paracorporeal support with a Levitronix left ventricular assist device. He experienced multiple postoperative complications including renal failure, respiratory failure, retroperitoneal hematoma requiring suspension of anticoagulation, and fungal bloodstream infection precluding transition to an implantable device. He was reconditioned and successfully underwent orthotopic heart transplant 183 days after presentation. A discussion of the relevant issues is included.

Aims No drug has been proven efficacious to prevent the post-pericardiotomy syndrome (PPS), but colchicine seems safe and effective for the treatment and prevention of pericarditis. The aim of the COlchicine for the Prevention of the Post-pericardiotomy Syndrome (COPPS) trial is to test the efficacy and safety of colchicine for the primary prevention of the PPS. Methods and results The COPPS study is a multicentre, double-blind, randomized trial. On the third post-operative day, 360 patients (mean age 65.7 ± 12.3 years, 66% males), 180 in each treatment arm, were randomized to receive placebo or colchicine (1.0 mg twice daily for the first day followed by a maintenance dose of 0.5 mg twice daily for 1 month in patients ≥70 kg, and halved doses for patients

Background Left ventricular assist devices (LVADs) are increasingly used as bridges to transplantation or as destination therapy. As sicker and older patients are more frequently considered for mechanical support, general surgical problems are expected to increase in these patients. Methods Anesthesia records and clinical charts were reviewed for 11 recipients of LVADs undergoing 12 general surgical procedures between January 1988 and March 2007. Results Eight patients underwent major surgical procedures: 1 intracranial hematoma drainage, 1 right hemicolectomy with ileocolostomy, 1 splenectomy, 1 surgical repair of an iliac-femoral artery pseudoaneurysm, 2 cholecystectomies, 1 pyelolithotomy, and 1 coil embolization of a femoral side-branch disruption. Four patients underwent minor surgical procedures. The mean duration of LVAD support before surgery was 58.7 ± 45.6 days. All patients survived the procedures. Conclusion Noncardiac surgery in LVAD recipients is feasible, without significant morbidity or mortality. Intraoperative coagulation management has a key role in safely performing these procedures.

A Jastrow wave function (JWF) and a shadow wave function (SWF) describe a quantum solid with Bose--Einstein condensate; i.e. a supersolid. It is known that both JWF and SWF describe a quantum solid with also a finite equilibrium concentration of vacancies x_v. We outline a route for estimating x_v by exploiting the existing formal equivalence between the absolute square of the ground state wave function and the Boltzmann weight of a classical solid. We compute x_v for the quantum solids described by JWF and SWF employing very accurate numerical techniques. For JWF we find a very small value for the zero point vacancy concentration, x_v=(1.4\pm0.1) x 10^-6. For SWF, which presently gives the best variational description of solid 4He, we find the significantly larger value x_v=(1.4\pm0.1) x 10^-3 at a density close to melting. We also study two and three vacancies. We find that there is a strong short range attraction but the vacancies do not form a bound state., Comment: 19 pages, submitted to J. Low Temp. Phys

ObjectivePatients with bicuspid aortic valve are at increased risk for aortic complications.MethodsA total of 115 consecutive patients with bicuspid aortic valve disease underwent surgery of the ascending aorta. We classified the cusp configuration by 3 types: fusion of left coronary and right coronary cusps (type A), fusion of right coronary and noncoronary cusps (type B), and fusion of left coronary and noncoronary cusps (type C). Histopathologic changes in the ascending aortic wall were graded (aortic wall score).ResultsWe observed type A fusion in 85 patients (73.9%), type B fusion in 28 patients (24.3%), and type C fusion in 2 patients (1.8%). Patients with type A fusion were younger at operation than patients with type B fusion (51.3 ± 15.5 years vs 58.7 ± 7.6 years, respectively; P = .034). The mean ascending aorta diameter was 48.9 ± 5.0 mm and 48.7 ± 5.7 mm in type A and type B fusion groups, respectively (P = .34). The mean aortic root diameter was significantly larger in type A fusion (4.9 ± 6.7 mm vs 32.7 ± 2.8 mm; P < .0001). The aortic wall score was significantly higher in type A fusion than in type B fusion (P = .02). The prevalence of aortic wall histopathologic changes was significantly higher in type A fusion. Moreover, there were no statistically significant differences between type A and type B fusion in terms of prevalence of bicuspid aortic valve stenosis, regurgitation, or mixed disease.ConclusionIn diseased bicuspid aortic valves, there was a statistically significant association between type A valve anatomy and a more severe degree of wall degeneration in the ascending aorta and dilatation of the aortic root at younger age compared with type B valve anatomy.

Background: Long-term implantable continuous axial-flow pumps are increasingly used in bridging heart failure patients to heart transplant. Compared to pulsatile left ventricular assist devices (LVADs), they offer smaller dimensions, less surgical trauma and less thromboembolisms. However concerns still remain about the long-term effects of continuous-flow on patients’ outcome. The aim of this study was to review our mechanical bridge to transplant experience to compare pre- and post-transplant outcomes between pulsatile and continuous-flow LVAD recipients. Methods: Thirty-six patients with a continuous-flow device (Micromed DeBakey, Houston, TX or InCor Berlin Heart, Berlin, Germany — group A) were compared with 41 patients supported with a pulsatile device (Novacor W , WorldHeart, Oakland, CA — group B). Results: Mean age (48.6 12.4 vs 47.2 12.5) and LVAD duration (119.3 115.4 vs 128.3 198.3) were similar in the two groups. Group A recipients were smaller compared to group B (mean body surface area = 1.77 0.18 vs 1.93 0.16; p < 0.001). Idiopathic dilated cardiomyopathy was not significantly greater between the two groups (78% vs 58.3%; p = 0.085). Successful bridging to transplantation was similar in group A compared to group B (52.8% vs 63.4%; p = non significant). On-VAD mortality was similar between the two groups (A vs B = 33.3% vs 36.6%; p = non significant). Thirtyday mortality after HTx in group A was 10.5% compared to 7.7% in group B (p = non significant). First year post-transplant incidence of treated rejections(36.8%vs46%;p = nonsignificant)asthemeannumberofrejection/patient(0.38 0.5vs0.53 0.83;p = nonsignificant)weresimilar in group A compared to group B. Conclusions: In our experience, when compared to pulsatile LVAD, continuous-flow pumps are similarly effective in transplant rate and post-transplant outcome. # 2008 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

We address the calculation of dynamical correlation functions for many fermion systems at zero temperature, using the auxiliary-field quantum Monte Carlo method. The two-dimensional Hubbard hamiltonian is used as a model system. Although most of the calculations performed here are for cases where the sign problem is absent, the discussions are kept general for applications to physical problems when the sign problem does arise. We study the use of twisted boundary conditions to improve the extrapolation of the results to the thermodynamic limit. A strategy is proposed to drastically reduce finite size effects relying on a minimization among the twist angles. This approach is demonstrated by computing the charge gap at half-filling. We obtain accurate results showing the scaling of the gap with the interaction strength $U$, connecting to the scaling of the unrestricted Hartree-Fock method at small $U$ and Bethe Ansatz exact result in one dimension at large $U$. A new algorithm is then proposed to compute dynamical Green functions and correlation functions which explicitly varies the number of particles during the random walks in the manifold of Slater determinants. In dilute systems, such as ultracold Fermi gases, this algorithm enables calculations with much more favorable complexity, with computational cost proportional to basis size or the number of lattice sites., Comment: Published version. 13 pages, 11 figures

The zero-temperature dynamical structure factor $S(q,\omega)$ of one-dimensional hard rods is computed using state-of-the-art quantum Monte Carlo and analytic continuation techniques, complemented by a Bethe Ansatz analysis. As the density increases, $S(q,\omega)$ reveals a crossover from the Tonks-Girardeau gas to a quasi-solid regime, along which the low-energy properties are found in agreement with the nonlinear Luttinger liquid theory. Our quantitative estimate of $S(q,\omega)$ extends beyond the low-energy limit and confirms a theoretical prediction regarding the behavior of $S(q,\omega)$ at specific wavevectors $\mathcal{Q}_n=n 2 \pi/a$, where $a$ is the core radius, resulting from the interplay of the particle-hole boundaries of suitably rescaled ideal Fermi gases. We observe significant similarities between hard rods and one-dimensional $^4$He at high density, suggesting that the hard-rods model may provide an accurate description of dense one-dimensional liquids of quantum particles interacting through a strongly repulsive, finite-range potential., Comment: 13 pages, 9 figures

Oxidative stress plays a role in the progression of chronic heart failure (CHF), but whether and how ischaemic heart disease (IHD) or non-IHD aetiology may account for differential redox alterations is currently unclear. We assessed the relation between thiol redox state and lipid peroxidation, as a marker of oxidative stress, in patients with CHF of ischaemic or non-ischaemic origin.Blood reduced glutathione, plasma total and reduced cysteine, cysteinylglycine, homocysteine, glutathione, plasma alpha-tocopherol, ascorbic acid, and free malondialdehyde were assessed in 43 CHF heart transplant candidates (24 IHD and 19 non-IHD) and 30 controls matched for age, gender and number of atherosclerotic risk factors.Reduced cysteine was increased in CHF patients compared with controls. The highest levels were found in IHD versus non-IHD patients versus controls. Malondialdehyde levels were significantly higher in IHD patients than in controls, whereas antioxidant vitamins did not differ among the three groups.Specific abnormalities in the thiol pattern are associated with heart failure aetiology in CHF patients. Our findings point to the possible role of reduced cysteine in the progression of chronic IHD to heart failure status, as an additional pro-oxidant stimulus for worsening oxidative stress.

Background Left ventricular assist device (LVAD) implantation has proven effective as a bridge to transplantation in end-stage heart failure patients (ESHFPs), although survival during device support is critical. Oxidative stress has been implicated in the development of heart failure, but the influence of redox state on in-hospital post-LVAD outcome has not been clarified. Methods and Results In this report we describe the oxidant/anti-oxidant profiles of 15 ESHFPs before LVAD placement, 5 of whom did not survive to 1 month, and in 30 subjects without cardiac disease, representing the control group. Conclusions Preliminary findings suggest that adequate activity of the GPx-1–based anti-oxidant system before device placement is associated with patient survival up to 1 month, despite comparable baseline oxidative stress in patients who both survived and died (within 2 weeks post-LVAD).

Prosthetic ring annuloplasty is considered the gold standard technique for mitral valve repair, but it has been associated with some drawbacks. Suture annuloplasty is less expensive and may have some physiopathologic advantages. We reviewed the literature to assess clinical results of mitral suture annuloplasty. Thirteen series, each reporting more than 50 patients and published in the last 10 years, were included in the analysis. They comprised 1,648 patients with cumulative follow-up of 5,607 patient-years. Our review suggests that suture annuloplasty is a safe procedure, but a trend toward recurrence of annular dilatation with time was reported. In selected cases, suture annuloplasty is effective, and its mid-term clinical results are encouraging and compare well with those of prosthetic ring repair series. The quality of the results varies according to the particular annuloplasty technique used and to the mitral valve pathology treated. Recent technical modifications have been found to decrease the incidence of repair failure and promise to improve the reproducibility of the procedure. Further investigations are warranted to better assess the long-term results of suture annuloplasty, and to determine whether its theoretical functional advantages translate into a real clinical benefit.

Cardiogenic shock (CS) occurs in 7% to 10% of cases after acute myocardial infarction and remains the most common cause of death in these patients. Despite aggressive treatment regimens such as fibrinolysis and percutaneous transluminal coronary angioplasty, mortality rates from CS remain extremely high. It has been shown that intra-aortic balloon pumping can result in initial hemodynamic stabilization. However, in the majority of studies, death was merely delayed. In recent years, efforts have been made to develop ventricular devices (LVAD) capable of providing complete short-term hemodynamic support. Seventeen major studies of LVAD support for CS complicating acute myocardial infarction are reported in the literature, with a mean weaning and survival rate of 58.5% and 40%, respectively. Patients considered in these studies are difficult to compare in terms of demographic and anatomic data, but taking these considerations into account, LVAD support seems to give no survival improvement in these patients compared with early reperfusion alone or associated with intra-aortic balloon pumping. Data emerging from experimental studies of acute myocardial infarction supported with LVAD are intriguing. In this review, we report the LVAD experience in the CS setting, starting from percutaneous extracorporeal support up to bridge therapy with implantable devices.

Background Aminothiols have a critical function as intracellular redox buffers and constitute furthermore an important extracellular redox system. Lipid peroxidation is increased in chronic heart failure (CHF), but the contribution of each thiol to oxidative stress in this syndrome has not been evaluated. Aim To assess the correlation between blood and plasma concentrations of aminothiols and lipid peroxidation as marker of oxidative stress in CHF patients. Methods Blood reduced glutathione (GSH), plasma total and reduced cysteine, cysteinylglycine, homocysteine, GSH, α-tocopherol, ascorbic acid, and free malondialdehyde (MDA) were assessed in samples obtained from 26 CHF heart transplant candidates and 26 age- and gender-matched controls with atherosclerotic risk factors and no history of cardiovascular disease. Results are expressed as median and interquartile range (I–III). Results MDA levels were significantly higher in CHF patients than in controls [1.03 (0.56–1.60) μM vs. 0.70 (0.40–0.83) μM, p =0.006]. Blood reduced GSH concentrations were significantly higher [662 (327–867) μM vs. 416 (248–571) μM, p =0.016], while α-tocopherol levels were significantly lower [15 (13–19) μM vs. 21 (17–32) μM, p =0.001] in CHF patients than in controls. By multivariate logistic regression analysis, the only independent predictors of lipid peroxidation, as expressed by MDA levels ≥1.00 μM, were increased blood GSH concentrations (OR 1.003 per unit, 95% CI 1.001 to 1.006, p =0.008), ischemic (OR 20, 95% CI 2.6 to 155, p =0.004) and non ischemic CHF etiology (OR 11, 95% CI 1.3 to 99, p =0.026). Conclusions Abnormalities in intracellular GSH cycling are associated to increased lipid peroxidation in CHF.

Cardiac allograft vasculopathy (CAV) is a major cause of mortality and morbidity after heart transplantation. Proliferation signal inhibitors (PSIs) have been demonstrated to slow the progression of CAV in de novo heart transplant recipients, but limited evidence is available regarding their efficacy in patients with established CAV. This manuscript describes the case of a patient in whom everolimus was introduced eight years after transplant, replacing azathioprine. The patient was known to have CAV since the fourth post-transplant year, and had suffered an anterior myocardial infarction 7.5 years after transplant. This was treated with primary percutaneous transluminal coronary angioplasty plus stenting of an occluded mid left anterior descending artery. After a few weeks on everolimus, the patient developed pneumonia, followed by acute, reversible renal failure and reversible leukopenia. This was due to improper management of immunosuppressive agents and concomitant medications, despite recommendations regarding drug-drug interactions. The patient recovered and subsequently remained stable, with mild reduced left ventricular ejection fraction (48-45%), and New York Heart Association functional class I-II up to three years. Control coronary angiography one year after starting everolimus was unchanged, showing good patency of the stent and stable diffuse CAV. An increasing number of long-term heart transplant recipients are at risk of clinical manifestations of CAV, and PSIs appear to have promise in reducing this risk. Favorable data from small studies and case reports are currently being investigated in large clinical trials.

Advances in immunosuppressive therapies in the past decade have improved short-term survival following heart transplantation, but cardiac allograft vasculopathy (CAV) has remained a major cause of mortality and morbidity in the long-term. CAV is often underdiagnosed by coronary angiography; intravascular ultrasound (IVUS) is currently the gold standard for diagnosis of CAV, with an increase in maximal intimal thickness of ≥0.5 mm from baseline to one year post-transplant representing a risk factor for the incidence of cardiac events during follow-up. Non-invasive tests such as stress echocardiography or scintigraphy evaluate the impact of CAV on myocardial function and/or perfusion. They provide useful prognostic information and may serve as screening tests for selecting patients who need invasive evaluation. The need for effective strategies to prevent CAV, and control its progression once established, is of utmost importance to improve long-term survival and quality of life after heart transplantation. Proliferation signal inhibitors (PSIs) have been demonstrated to slow the development of CAV and to reduce the rate of cardiac events in de novo heart transplant recipients. In maintenance patients, palliation of the disease with percutaneous revascularization is being attempted with increasing frequency, with satisfactory short-term success and possible but unproven long-term benefit. A pilot, single-center, randomized study with sirolimus versus standard care suggests that PSIs may also be effective in limiting the progression of established CAV, validating the need for this hypothesis to be explored in larger trials.

OBJECTIVE Left ventricular assist devices (VADs) are an accepted therapy to bridge patients with end-stage heart failure to heart transplantation. The DeBakey VAD, a continuous axial flow pump weighing 93 g, has been introduced into clinical practice as a bridge to transplant. METHODS Starting from April 2000,17 patients (12 males, five females, mean age 44.3 +/- 12.8 years; 11 dilated idiopathic cardiomyopathy, five ischaemic cardiomyopathy, one pulsatile device failure) with end-stage heart failure were implanted with a DeBakey VAD as a bridge to transplantation at our institution. Before implant, all patients suffered from severe heart failure (New York Heart Association functional class IV) despite optimal medical therapy and were put on the waiting list for heart transplantation. Mean cardiac index was 1.59 +/- 0.51 l/min/m2. RESULTS Fourteen patients were successfully transplanted after 99 +/- 117 days of assistance (range 11-443 days). Two patients died during assistance of multiorgan failure, one patient is still on VAD. No patient needed additional right ventricular mechanical support. Left ventricular/left VAD thrombosis occurred in one patient who was successfully treated conservatively. No clinical elevation of plasma free haemoglobin was detected. Neither device, driveline, abdominal pocket infection nor device failure occurred. CONCLUSIONS In our experience with the continuous axial flow DeBakey VAD, a high success rate was obtained associated with a low risk of complications. All the patients tolerated continuous blood flow for extended periods that makes this device a valuable alternative to pulsatile VADs as a bridge to transplantation.

ATP acts as a neurotransmitter via seven P2X receptor-channels for Na(+) and Ca(2+), and eight G-protein-coupled P2Y receptors. Despite evidence suggesting roles in human heart, the map of myocardial P2 receptors is incomplete, and their involvement in chronic heart failure (CHF) has never received adequate attention. In left myocardia from five to nine control and 5-12 CHF subjects undergoing heart transplantation, we analyzed the full repertoire of P2 receptors and of 10 "orphan" P2Y-like receptors. All known P2Y receptors (i.e. P2Y(1,2,4,6,11,12,13,14)) and two P2Y-like receptors (GPR91 and GPR17) were detected in all subjects. All known P2X(1-7) receptors were also detected; of these, only P2X(6) was upregulated in CHF, as confirmed by quantitative real time-PCR. The potential significance of this change was studied in primary cardiac fibroblasts freshly isolated from young pigs. Exposure of cardiac fibroblasts to ATP or its hydrolysis-resistant-analog benzoylATP induced apoptosis. TNFalpha (a cytokine implicated in CHF progression) exacerbated cell death. Similar effects were induced by ATP and TNFalpha in a murine cardiomyocytic cell line. In cardiac fibroblasts, TNFalpha inhibited the downregulation of P2X(6) mRNA associated to prolonged agonist exposure, suggesting that, by preventing ATP-induced P2X(6) desensitization, TNFalpha may abolish a defense mechanism meant at avoiding Ca(2+) overload and, ultimately, Ca(2+)-dependent cell death. This may provide a basis for P2X(6) upregulation in CHF. In conclusion, we provide the first characterization of P2 receptors in the human heart and suggest that the interaction between TNFalpha and the upregulated P2X(6) receptor may represent a novel pathogenic mechanism in CHF.

A 45-year-old male with dilatative cardiomyopathy was supported with an Incor (Berlin-Heart AG) axial flow magnetically levitated bearings pump. Due to constant anemization in late follow-up, gastrointestinal bleeding was suspected and a PillCamtrade mark Capsule Endoscopy (Given Imaging) was performed. No interference between the devices was detected and full small bowel visualization was achieved.

Impella Recover 100 is an intravascular microaxial blood pump designed for short-term circulatory support in conditions of reduced left ventricular function. Two-dimensional echocardiography is a consolidated tool to study and monitor patients undergoing circulatory support. Three-dimensional (3D) echocardiography is emerging as a source of more accurate analysis in heart morphology and function. We described the use of 3D echocardiography in a patient who underwent Impella recover 100 support for postcardiotomy shock. 3D echocardiography allowed complete visualization of the pump and provided excellent intraoperative assessment of the complex spatial location into the left ventricle.

The aim of this study was to suggest a protocol for serial echocardiographic evaluations in patients undergoing circulatory support by a new miniaturized electric axial pump, the Impella® recover 100 (IR 100). IR 100 is implanted through the ascending aorta into the left ventricle drawing blood from the left ventricle to the aorta. Methods and results: This protocol has been applied in eight patients receiving twelve IR 100 implants. Before implantation echocardiography was useful to rule out anatomic contraindications. During and after implantation echocardiography provided informations for correct positioning and evaluation of left ventricular filling necessary to optimize pump performance. During assistance it gave important informations to assess left and right ventricular function. Conclusion: Echocardiography has pivotal role in IR 100 management before, during and after implantation.