Heart valves

Infective endocarditis (IE) is a severe disease. Pathogen isolation is fundamental so as to treat effectively and reduce morbidity and mortality. Blood and valve culture and histopathology (HP) are routinely employed for this purpose. Valve HP is the gold standard for diagnosis. To determine the sensitivity and specificity of clinical criteria for IE (the modified Duke and the St Thomas' minor modifications, STH) of blood and valve culture compared to valve HP, and to evaluate antibiotic treatment duration. Prospective case series of patients, from 2006 to 2014 with surgically treated IE. Statistical analysis was done by the R software. There were 136 clinically definite episodes of IE in 133 patients. Mean age ± SD was 43 ± 15.6 years and IE was left sided in 81.6 %. HP was definite in 96 valves examined, which were used as gold standard. Sensitivity of blood culture was 61 % (CI 0.51, 0.71) and of valve culture 15 % (CI 0.07, 0.26). The modified Duke criteria were 65 % (CI 0.55, 0.75) sensitive and 33 % specific, while the STH's sensitivity was 72 % (CI 0.61, 0.80) with similar specificity. In multivariate analysis and logistic regression, the only variable with statistical significance was duration of antibiotic therapy postoperatively. Valve HP had high sensitivity and valve culture low sensitivity in the diagnosis of IE. The STH's criteria were more sensitive than the modified Duke criteria. Valve HP should guide duration of postoperative antibiotic treatment.

It is generally agreed that physiological levels of melatonin, a hormone secreted by the pineal gland, are important in protecting against oxidative stress-induced tissue damage. We investigated the effects that pinealectomy and the administration of exogenous melatonin have on the brains, testes, duodena and stomachs of rats. Pinealectomized (Px) and sham-operated (non-Px) rats were used. We evaluated structural changes, and catalase (CAT), reduced glutathione (GSH), super oxide dismutase (SOD) and malondialdehyde (MDA) levels. The rats were divided into the following five groups (eight rats in each group): sham (non-Px), Px+ vehicle, Px+ melatonin (10 mg/kg given daily intraperitoneally for a week), melatonin and ethyl alcohol. The antioxidant levels in the tissue of Px rats were significantly lower than in those of the sham group. Administering melatonin significantly increased antioxidant levels (p < 0.05). The Px rats also showed a significant increase in MDA levels when com...

To validate the use of pulsed Doppler tissue imaging that measures myocardial wall velocities and to define the characteristics of these velocities in normal subjects, we obtained and compared the anteroseptal and posterior wall velocities in 24 volunteers with pulsed Doppler tissue imaging and digitized M-mode echocardiography. We also studied the relation between velocity components and hemodynamic events timed by standard Doppler flows. There was an excellent correlation between Doppler and M-mode-derived velocities (r = 0.95, p < 0.001), with higher reproducibility for Doppler (r = 0.99) than for M-mode (r = 0.95, p < 0.001). Biphasic velocities that were uniformly present during isovolumic contraction and relaxation were attributed to geometric changes due to asynchronous contraction and ventricular interdependence. We conclude that wall velocities obtained by pulsed Doppler tissue imaging are accurate and reproducible. This method may prove useful for studying the contractile and elastic properties of the myocardium.

Theoretical models of the human heart valves are useful tools for understanding and characterizing the dynamics of healthy and diseased valves. Enabled by advances in numerical modeling and in a range of disciplines within experimental biomechanics, recent models of the heart valves have become increasingly comprehensive and accurate. In this paper, we first review the fundamentals of native heart valve physiology, composition and mechanics in health and disease. We will then furnish an overview of the development of theoretical and experimental methods in modeling heart valve biomechanics over the past three decades. Next, we will emphasize the necessity of using multiscale modeling approaches in order to provide a comprehensive description of heart valve biomechanics able to capture general heart valve behavior. Finally, we will offer an outlook for the future of valve multiscale modeling, the potential directions for further developments and the challenges involved.

Collagen is the main load bearing protein in many soft tissues, and in cardiovascular tissues in particular. In many tissues collagen has a specific architecture that is crucial for the biomechanical function of the tissue. Typical examples are the hammock-shaped collagen architecture in heart valves and a helical pattern in arteries. One of the objectives in cardiovascular tissue engineering is the reconstitution of this architecture. It is hypothesized that the architecture is mediated by mechanical stimulation. Computational models were developed to predict the mechanoregulation of the collagen architecture. This review recapitulates the key modeling assumptions and results achieved to date.

Conventional replacement therapies for heart valve disease are associated with significant drawbacks. The field of tissue engineering has emerged as an exciting alternative in the search for improved heart valve replacement structures. One of the principles behind this concept is the transplantation of living elements, embedded in a suitable scaffold material, to the diseased site where the structure becomes integrated with patients' tissue to restore natural function. Significant progress has been made in the last ten years in the development of a living artificial heart valve alternative (LAHVA), with the identification of potential replacement sources for valve cells, scaffolds to maintain the cells in a three-dimensional environment, and signals to promote tissue development. This review addresses the need for a tissue-engineered alternative to current prostheses and provides a detailed account of normal heart valve structure--the blueprint for LAHVA fabrication. The research efforts to create a viable LAHVA, including recent developments, are discussed. Particular attention is focused on the choice of cell source for LAHVA construction, the use of biodegradable natural and synthetic polymeric scaffolds as extracellular matrix derivatives, and exogenous stimulation of tissue growth. The critical challenges involved in LAHVA development and possible future areas of investigation are also discussed.

Transthoracic Doppler echocardiography continues to play a predominant role in the evaluation of patients with valvular heart disease. Current efforts in the research arena have been focused on improving the accuracy of techniques, as well as in further describing the shortcomings. Accurate quantitation of valvular regurgitation continues to be a major stumbling block. However, more sophisticated techniques are being successfully applied to obviate some of the limitations of color flow imaging. Transesophageal echocardiography has provided a new window and clarity of resolution that greatly facilitates evaluation of valvular heart disease in cases where the transthoracic approach is limited, particularly in patients with prosthetic valves.

The traditional transthoracic and transesophageal echocardiographic examination have proven to be useful imaging tools for studying cardiac morphology, pathology, and function. Recently, catheter-based ultrasound transducers have been available for intravascular ...

There are numerous examples of fluid–structure interactions (FSIs) within the human body. In all cases, a computer model capable of simulating the phenomenon can aid in the understanding of organ function, failure, and implant design or improvement. In the current paper, two approaches are examined for use in simulating the FSI problem of the dynamics of tissue heart valves. Valve leaflets have nonlinear anisotropic material properties, and undergo complex deformation. Their motion affects—and is affected by—the surrounding blood. This two-way coupling necessitates a robust algorithm in order to overcome numerical stiffness, convergence challenges, and stability issues. A locally refined Cartesian mesh, sharp interface method has been developed for the fluid flow solution. In the structural domain, the valve leaflet is represented in a Lagrangian fashion and moves based on its experimentally determined material properties. In computing leaflet motion, the anisotropic, nonlinear material properties of the valve leaflet are incorporated using a finite element solver, which calculates the leaflet deformation and stresses based on the stress imparted by the surrounding fluid. Two FSI algorithms have been studied in the context of a sharp-interface Cartesian grid setting, and each has been validated with benchmark results. The two approaches are compared, and ultimately one is selected as most appropriate for simulating tissue heart valves. In the selected approach, a strongly coupled, partitioned method is used in which subiterations of the fluid and structure solutions are performed at each time step. During the subiterations, the leaflet motion is used as a boundary condition on the fluid, and the fluid stresses act as a boundary condition on the leaflet. In this way, continuity is ensured and two-way coupling is achieved. The selected approach has overcome the challenges faced by previous simulations reported in the literature, and a robust FSI solution is achieved using physiologic Reynolds numbers, realistic material properties, highly resolved grids, and a dynamic simulation. This approach has the advantage of handling both thin and volumetric embedded objects in a unified fashion, and of treating rigid and deformable structures in the same way, thus allowing a spectrum of potential applications.

Little information exists on the clinical characteristics and factors related to hospital mortality in patients with active infective endocarditis referred for surgery. Between January 1, 2003 and December 31, 2006, 86 patients (56 males, 30 females, mean age 59.2 years) with active infective endocarditis were referred to our Department (2.8% of overall hospitalizations). The relation of several clinical, laboratory and echocardiographic findings at admission with hospital mortality was evaluated. A native valve (NVE) was involved in 50/86; the other 30 had a prosthetic valve endocarditis (PVE). Six had pacemaker endocarditis. The aortic valve was involved more frequently than the mitral valve, both in NVE and PVE. The tricuspid valve was involved in four drug addicts; 51% of patients were in NYHA class III-IV. Staphylococci and streptococci were isolated in 69% of patients (39% vs 30%). Blood cultures were negative in 24%. Overall hospital mortality has been 11.6%. Two patients die...

We report clinical, neuroimaging and immunological findings in seven women with antiphospholipid antibodies (APLA) and cerebral ischemia. Two patients had systemic lupus erythematosus (SLE) and five had the antiphospholipid syndrome (APS). Autopsies were done in 3 women who died acutely with focal neurological deficits. Evidence for cerebral embolism was found in all patients: a) pathology demonstrated multiple cerebral infarctions and cerebral emboli from underlying non-bacterial thrombotic endocarditis (NBTE) in the patients who died. b) Three patients had thickened mitral valves and embolic cerebral occlusions were identified with cerebral angiography. c) In one patient, echocardiography detected a thrombus on the posterior leaflet of a prolapsing mitral valve at the time of ictus. Our data provide further evidence to implicate valvular endothelium in the genesis of cerebral ischemia in some patients with APLA.

We present an algorithm for obtaining the heart rate from the signal of a single, contact-less sensor recording the mechanical activity of the heart. This vital parameter is required on a beat-to-beat basis for applications in sleep analysis and heart failure disease management. Our approach bundles information from various sources for first robust estimates. These estimates are further refined in a second step. An unambiguous comparison with the ECG RR-intervals taken as reference is possible for 98.5% of the heart beats. In these cases, a mean absolute error of 17 ms for the inter-beat interval lengths has been achieved, over a test corpus of 20 whole nights.

Tissue neovascularization is a major event in the development and dissemination of inflammatory diseases, such as infective endocarditis (IE). Although the molecular triggers which allow vascular ingrowth in the aforementioned avascular regions are not well understood, they may represent potential prophylactic or therapeutic targets. Thus, an investigation was conducted to determine whether the expression of chondromodulin-1 (Chm-1), an anti-angiogenic protein, is dysregulated in mitral valves in a rabbit model of IE, and whether Chm-1 transcripts are differentially expressed in various heart tissues. Five groups of animals (seven per group) were studied: group I was untreated controls; group II received (intravenously) 6x10(6) colony-forming units of Staphylococcus aureus; group III underwent mitral valve surgery; and groups IV and V underwent surgery and received S. aureus (as per group II), with tissues sampled at 6 and 12 h after surgery, respectively). Mitral valve surgery was ...

The pattern of expression and distribution of extracellular matrix (ECM) components in human cardiac leaflets was analyzed. Additionally, interstitial cells (ICs) from the four different leaflets were isolated and studied. Immunohistochemistry and immunocytochemistry were used for localization, and flow cytometric analysis to quantify the expression of specific markers on these ICs; the synthesis and expression of ECM components was assessed. Elastin was found predominantly on the inflow layer, but fine fibers were also present in the central and outflow layers. Collagen I was predominantly on the outflow layer but permeated throughout the leaflets. Collagen III was expressed ubiquitously. Proteoglycan expression was throughout the leaflet, but was predominant in the central layer. Fibronectin and vitronectin were expressed strongly in the inflow layer, moderately in the central layer, and weakly in the outflow layer. Biglycan expression was ubiquitous, with strong filamentous stran...

A pentacuspid pulmonary valve is a rare
congenital anomaly. The present report describes a case of
pentacuspid pulmonary valve encountered during the autopsy
of a 50-year-old man with a ruptured abdominal aortic aneurysm.
The pentacuspid pulmonary valve had three relatively
equal cusps and two smaller cusps. In this case, a tricuspid
aortic valve was identiWed with normal structure and no
evidence of heart failure was found clinically or pathologically.

 Using various microscopical techniques we studied the development of the atrioventricular valves in human hearts between 5 and 19 weeks of development. Within the atrioventricular cushions two different layers could be recognized that remained present in all ages studied. The atrial layer, being present at the side of the atrioventricular orifice, was positive for laminin while the ventricular layer, that was connected to the myocardium, was positive for fibronectin and collagen III. Fate-mapping of these two layers, morphometrics, and scanning electron microscopy, supplemented with in vivo labeling of cushion tissue in chicken hearts have lead to new insights in the process of valve development. The cushions became freely movable prevalvular leaflets by delamination of ventricular myocardium underneath the cushion tissue. This myocardium gradually retracted towards annulus and papillary muscles and finally disappeared, resulting in fibrous, non-myocardial valves. The atrial layer of the cushions remained present as a jelly-like surface on the valve leaflets while the ventricular layer of the cushions became the compact fibrous tissue of the leaflets and the chords. Chordal development was first visible at 10 weeks of development when gaps were formed in the ventricular layer of the cushions on top of the papillary muscles. These gaps enlarged into the interchordal spaces while the cushion tissue in between the gaps lengthened to form the chords. We conclude that the leaflets as well as the chords of the atrioventricular valves are derived from atrioventricular cushion tissue. Myocardium is only important for loosening of the leaflets while keeping connection with the developing papillary muscles. Errors in delamination or retraction of myocardium or remodeling of cushion tissue into chords form the basis for various congenital valve anomalies.