Pathological Mineralization of Cardiac Valves: Causes and Mechanism

OBJECTIVE

Mechanism of calcification of cardiac valves was investigated through a comparative characterization of structure, morphology, and size of hydroxyapatite (HAP) crystals formed in mineral deposit on cardiac valves, bone tissue, and crystals synthesized from aqueous solutions under definite conditions.

METHODS

All deposits on cardiac valves and bone samples were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDS) in a Philips XL30 FEG microscope to evaluate their overall view and structure, to estimate the sizes of particles, and to carry out the chemical analysis. High resolution transmission electron microscopy (HRTEM) and electron micro diffraction was done for precise phase identification of individual crystals and measurements of their sizes.

RESULTS

Mineral deposit on cardiac valves contained hydroxyapatite crystals (HAP) crystals with lengths from a few nanometers to a few hundred nanometers. Similar to the HAP precipitation in aqueous solutions, crystals in deposit were randomly oriented relative to each other and without the substrate effect on their orientation. Octacalcium phosphate (OCP) phase was also detected in the form of large (up to a few microns) crystals. The quantity of the OCP crystals was quite low in comparison with the amount of the HAP crystals. HAP crystals in bone samples were no more than 20 nm in length and textured in the HAP [0001] direction along collagen fibers. The HAP crystals from cardiac valves and bones were of uniform thickness comparable with the crystallographic unit cell.

CONCLUSIONS

Mass crystallization model and hemodynamics in heart and arteries determine the mechanism of pathological calcification through the mediation of hydroxyapatite nanocrystals perpetually circulating with the bloodstream.

Third heart sound: genesis and clinical importance

Auscultation of third heart sound has been performed for more than a century, an interest that not only persists today, but also has experienced renewed emphasis. Sophisticated study of the third heart sound by current investigative techniques has underscored the value of clinical detection with the time-honored stethoscope. This review re-examines the mechanisms of genesis of third heart sound in regard to the hemodynamic and echocardiographic aspects, and its clinical importance.

Functional and morphological cardiac changes in myeloproliferative disorders (clinical study)

PURPOSE

Cardiac involvement is not well defined in myeloproliferative disorders (MPD). The purpose of this study was to evaluate the cardiac involvement by transthoracic echocardiography in MPD.

MATERIALS AND METHODS

The study groups were 36 patients (mean age: 58+/-15 years, 20 female and 16 male) with MPD and 30 age-matched healthy controls. MPD group included 15 essential thrombocythemia (ET), eight chronic phase chronic myelogenous leukemia (CML), seven idiopathic myelofibrosis (MF) and six polcythemia vera patients.

RESULTS

Valvular regurgitations were present in 14 patients (39%) and eight controls (27%), (P>0.05). Mitral regurgitation (MR) was more prominent in CML compared to controls (P=0.044). The rates of annular calcifications, valvular thickening, and vegetation like lesions were not different between MPD and control groups. Pulmonary hypertension (PHT) was present in six (17%) patients, but none of the controls (P=0.021). The rates of PHT in CML and MF were significantly higher than controls (P<0.05). The rate of PHT was not different in-between MPD patients with and without thromboembolic events, however, in MPD cases with thromboembolic events PHT was more common compared to controls (P=0.037).

CONCLUSION

This study showed that valvular lesions were not more prevalent in MPD. PHT was the most prominent cardiac pathology in MPD (especially in CML, MF and thromboembolic events subgroups) compared to controls. Further evaluation of the cardiac changes in MPD subgroups with extended studies including trans-oesophageal echocardiography and longer follow-up periods would be appropriate.

Intermediate outcomes of atrioventricular valvuloplasty in lateral tunnel Fontan patients

BACKGROUND AND AIM OF THE STUDY

Lateral tunnel Fontan operation patients with atrioventricular valve (AVV) regurgitation have an increased incidence of Fontan failure (death, take-down or transplant). The outcomes of patients undergoing AVV repair during Fontan palliation were reviewed to determine the optimal technique and timing of repair.

METHODS

Hospital records for all patients with AVV regurgitation at the time of their Fontan procedure were reviewed retrospectively. Patients with staged single-ventricle palliation culminating in a lateral tunnel Fontan operation who had their first AVV repair at the Children's Hospital, Boston, were included. AVV regurgitation was graded by semi-quantitative color Doppler echocardiography on a scale of 1 to 4, as was ventricular dysfunction.

RESULTS

Among 859 lateral tunnel Fontan patients, 27 (3%) had a total of 30 AVV repairs (18 tricuspid, six mitral, six common AVV). Of the 27 first-time AVV repairs (16 TV, six MV, five CAVV), six were performed pre-Fontan, and 21 at or after Fontan. The median age at the first AVV repair was 3 years (range: 0.6-9.4 years). Preoperatively, the median echocardiographic severity of AVV regurgitation was grade 3 (range: 2-4). At median follow up of 1.2 years (range: 0-9.5 years) the severity of AVV regurgitation was reduced significantly to median grade 2 (range: 0-4; p <0.001). No patient with initial AVV repair at the time of Fontan underwent reoperation for AVV regurgitation. In all cases, ventricular function was maintained or improved, with preoperative median systemic ventricular function grade 1.5 (range: 1 to 4) versus postoperative grade 1 (range: 1-4; p = NS). There were no Fontan failures in the intermediate term.

CONCLUSION

AVV regurgitation and ventricular systolic function can be maintained or improved in the intermediate term following AVV repair in single-ventricle patients.

Dynamic and reversible changes of interstitial cell phenotype during remodeling of cardiac valves

BACKGROUND AND AIM OF THE STUDY

The roles of cardiac valvular interstitial cells (VIC) in extracellular matrix remodeling in fetal development, adaptation and response to injury are largely unknown.

METHODS

The phenotype of VIC was studied in health (normal adult human and sheep), development (fetal human and sheep), disease (human mitral valves with myxomatous degeneration), adaptation (clinical pulmonary to aortic valve autografts) and tissue-engineered heart valves matured in vitro and remodeled in vivo. Cell phenotype was assessed using expression of vimentin (V), alpha-smooth muscle actin (SMA, A), matrix metalloproteinase (MMP)-13/collagenase-3 (M), and SMemb (S).

RESULTS

VIC in normal adult valves were predominantly quiescent fibroblasts immunoreactive to vimentin (89.7 +/- 2.5%), but not MMP-13 or SMemb, with only 2.5 +/- 0.4% of alpha-SMA-positive cells ('normal/quiescent' phenotype: V+/A-/M-/S-). In contrast, fetal VIC were mostly activated myofibroblasts ('developing/activated' phenotype: V+/A+/M+/S+), with 62.1 +/- 5.0% of cells staining positive for alpha-SMA. VIC in myxomatous valves, short-term autografts and engineered valves in vitro were also activated myofibroblasts with coexpression of vimentin, alpha-SMA (36.2 +/- 3.7%, 19.3 +/- 2.4%, and 60.3 +/- 9% positive cells, respectively), strong MMP-13 activity indicative of collagen remodeling, and SMemb ('remodeling/activated' phenotype: V+/A+/M+/S+). In contrast, VIC in long-term pulmonary autografts and engineered valve explants had a mostly fibroblast-like phenotype, with sparse alpha-SMA expression (6.0 +/- 1% and 5.4 +/- 1.0% positive cells) (V+/A-/M-/S-).

CONCLUSION

Most VIC in normal valves were quiescent with a fibroblast-like phenotype. VIC in developing, diseased, adapting and engineered valves adjust to a dynamic environment through VIC activation and secretion of proteolytic enzymes mediating extracellular matrix remodeling ('developing/ remodeling/activated' phenotype), followed by a normalization of phenotype.

Design and manufacture of a polyvinyl alcohol (PVA) cryogel tri-leaflet heart valve prosthesis

Although current artificial heart valves are life sustaining medical devices, improvements are still necessary to address deficiencies. Bioprosthetic valves have a compromised fatigue life, while mechanical valves have better durability but are prone to thromboembolic complications. A novel, one-piece, tricuspid valve, consisting of leaflets, stent and sewing ring, made entirely from the hydrogel, polyvinyl alcohol cryogel (PVA-C), has been developed and demonstrated. This valve has three thin leaflets attached to a cylindrical stent. In order to approximate the complex shape of the surface of the natural heart valve leaflets, two different geometries have been proposed: revolution about an axis of a hyperboloid shape and revolution about an axis of an arc subtending (joining) two straight lines. The parameters of both geometries were examined based on a compromise between avoiding sharp curvature of leaflets and minimization of the central opening of the valve when closed. The revolution of an arc subtending two straight lines was selected as the preferred geometry since it has the benefit of a smaller central opening when the value of the maximum curvature for the leaflets is the same for each valve geometry. A cavity mold has been designed and constructed to form the PVA-C heart valve. The three leaflets were formed and integrated into the stent and sewing ring in a single process. Prototype heart valves were manufactured in the mold from a solution of PVA and water, by controlled freezing and thawing cycles.

Effects of valve characteristics on the accuracy of the Bernoulli equation: a survey of data submitted to the U.S. FDA

BACKGROUND AND AIM OF THE STUDY

In 1988, valve manufacturers petitioned the U. S. Food & Drug Administration (FDA) to replace catheter with Doppler ultrasound measurements of pressure gradient (delta P) in clinical studies. Manufactures agreed to submit bench data validating the Bernoulli equation used to calculate delta P = delta P = K(Vd2 - Vp2), where K = constant, Vd = distal Doppler velocity, and Vp = proximal Doppler velocity. Previous studies suggest that K may vary from the idealized 4.0, which could lead to incorrect valve assessment and clinical errors.

METHODS

Variation in K-values in marketing application data submitted to the FDA was assessed. Pulse duplicator data included four bileaflet valves, two stented bioprostheses, and seven stentless bioprostheses, sized from 19 to 33 mm. Effects of valve type, valve size, blood-mimicking fluid used, and distal pressure tap position (DPTP) were evaluated via an analysis of variance.

RESULTS

K-values varied from 2.50 to 7.40 (n = 90). K was found to be dependent on valve type (p < 0.0001), blood-mimicking fluid (p < 0.0001) and DPTP (p < 0.0001), but not valve size. At DPTP = 30 mm, K = 3.43 +/- 0.56, 5.15 +/- 0.81, and 4.81 +/- 1.02, for bileaflet, stented and stentless valves, respectively. K averaged 10% less using the 100-mm DPTP, due to pressure recovery. Variations due to blood-mimicking fluid were likely related to the fluid density.

CONCLUSION

Variations due to DPTP and fluid used are consistent with physical mechanisms of pressure recovery and fluid density. Results from previous studies have suggested that effects of valve type on K are also real. The magnitude of these effects appeared to be +/- 25%. Extrapolation to patients is difficult, but clinicians should be aware that Doppler measurements may vary by similar amounts. Doppler pressure gradients should be interpreted qualitatively and moderated by other diagnostic measures of valve performance.

Heart valve tissue engineering

Valvular heart disease is a significant cause of morbidity and mortality world-wide. Classical replacement surgery involves the implantation of mechanical valves or biological valves (xeno- or homografts). Tissue engineering of heart valves represents a new experimental concept to improve current modes of therapy in valvular heart surgery. Various approaches have been developed differing either in the choice of scaffold (synthetic biodegradable polymers, decellularised xeno- or homografts) or cell source for the production of living tissue (vascular derived cells, bone marrow cells or progenitor cells from the peripheral blood). The use of autologous bone marrow cells in combination with synthetic biodegradable scaffolds bears advantages over other tissue engineering approaches: it is safe, it leads to complete autologous prostheses and the cells are more easily obtained in the clinical routine. Even though we demonstrated the feasibility to construct living functional tissue engineered heart valves from human bone marrow cells, so far their general potential to differentiate into non-hematopoietic cell lineages is not fully exploited for tissue engineering applications.

An In Vivo Method for Measuring Turbulence in Mechanical Prosthesis Leakage Jets

This work introduces a method for the in vivo measurement and analysis of turbulence within the leakage of a mechanical heart valve. Several analysis techniques were applied to ultrasound measurements acquired within the atrium of a pig, and error associated with these techniques was analyzed. The technique chosen applies cyclic averaging to mean and maximum velocity measurements within small, normalized phase windows to calculate Reynolds normal stresses in the direction of the ultrasound beam. Maximum shear stresses are estimated from these normal stresses using an analytical technique. The stresses observed were smaller than those reported from previous in vitro simulations.

Cardiac and ocular pathologies in a mouse model of mucopolysaccharidosis type VI

Mucopolysaccharidosis type VI (MPS VI) is a lysosomal storage disease caused by a deficiency of arylsulfatase B (ASB) which has its function in the sequential degradation of glycosaminoglycans (GAG). Targeted disruption of the ASB gene resulted in a mouse model of MPS VI that has been closely investigated for skeletal and chondral dysplasia. As ocular and cardiac impairment are also clinically important manifestations of the MPS VI syndrome, the present study was initiated for detailed biochemical, histologic and functional analysis of cornea, optic nerve and heart in ASB-deficient mice. Biochemical evidence for GAG-storage could be obtained for liver, kidney, spleen and myocardium as well as for heart valves, cornea and optic nerve from ASB-deficient mice. In MPS VI mice, histology revealed structural impairment of corneal stroma and epithelium as well as a thickening of the heart valves. According to histologic investigations, the optic nerve appeared not to be altered. However, GAG-storage in the dura mater could be demonstrated in MPS VI mice. Heart function was assessed by echocardiography. While the dimensions of MPS VI hearts were not altered, these hearts clearly showed decreased myocardial contraction and a 50% reduction of cardiac output. In addition, insufficiencies in the mitral and aortic valves were detected. Thus, ASB-deficient mice resemble the phenotype of human MPS VI not only in the skeletal but also in the ocular and cardiac symptoms. To our knowledge, these in vivo evaluations of heart function represent the first respective investigation of a MPS VI animal model and should provide a valuable measure for therapy studies in the MPS VI mouse.

Impulsive-Motion Model for Computing the Closing Motion of Mechanical Heart-Valve Leaflets

The speed of mechanical heart-valve leaflets is known to be an important quantity for predicting cavitation, yet no simple computational means exists for predicting the leaflet speed. In this study, a model for simulating the motion of heart-valve leaflets in rigid test systems is presented. The input for the simulations is the ventricular pressure trace, readily measured in heart-valve tests. The model is based upon an impulsive-motion approximation, wherein the motion within the system is produced by rapid acceleration at the boundary, e.g., by a moving piston. A set of quasisteady, linear equations for the pressure field that are decoupled from the leaflet equation of motion is derived. The pressure field and leaflet moment are computed without the need to treat moving boundaries. Model predictions of closing time compared favorably with those measured in a 1994 cavitation study. Computed values of leaflet tip speed were also compared with those of a previous study, at the same value of average pressure slope. The model values were in agreement with measured speeds, given the limitations of using the average pressure slope as a metric for comparison.

Measurement of the closing behavior of the björk-shiley monoleaflet mechanical heart valve with an electrohydraulic total artificial heart

When cavitation occurs near a material surface of a mechanical heart valve (MHV), pits on the surface of the MHV and hemolysis are caused. Therefore, it is very important to investigate the possibility of the occurrence of cavitation in an MHV. To study the possibility of cavitation occurrence in a 25 mm Björk-Shiley monoleaflet, we analyzed the closing behavior of these valves. The closing event of these valves in the mitral and aortic positions was simulated in an electrohydraulic total artificial heart with a stroke volume of 100 ml. Tests were conducted under physiologic pressures at heart rates of 50, 60, 70, and 80 beats/min with cardiac outputs of 4.8, 5.9, 7.0, and 8.1 l/min, respectively. The disk-closing behavior was measured by a laser displacement sensor. The closing behaviors were investigated with various cardiac outputs and gravity direction. The maximum velocities of the aortic valve ranged from 0.8 to 0.9 m/s, and for the mitral valve ranged from 1.48 to 1.6 m/s. In aortic position valves, the maximum closing velocities were less than the reported cavitation thresholds, but the maximum closing velocities of the mitral valve were similar to the cavitation threshold. Therefore, we suggest that there should be the possibility of cavitation occurrence in the mitral valve of an electrohydraulic total artificial heart.

Cardiac valve replacement in human immunodeficiency virus-infected patients

BACKGROUND

Valve replacement in human immunodeficiency virus (HIV)-infected patients is being performed with increasing frequency, but the early and late results in these immunocompromised patients are not known.

METHODS

A 10-year retrospective clinical review was undertaken; patients and their physicians were contacted for follow-up clinical status.

RESULTS

Twenty-two HIV-infected patients underwent valve replacement between 1990 and 1999, with no operative or hospital deaths. Mean patient age was 37.6 years; 15 were men. Indications for operation were heart failure in 59% (13/22) and sepsis in 91% (20/22). There were 12 aortic valve replacements, seven mitral valve replacements, and three double valve replacements. Mechanical valves were used in 11, bioprostheses in seven, and homografts in four. Follow-up information was available in 20 of 22 patients (84%). At mean follow-up of 5 years, there were 10 late deaths, due to: intracerebral hemorrhage (2), heart failure (2), unknown cause (2), renal failure (1), AIDS (1), sepsis (1) and endocarditis (1). Of the 20 patients with active preoperative endocarditis, 4 (20%) developed recurrent endocarditis; freedom from recurrent endocarditis was 83% at 1 year. Intravenous drug abuse was reported in 16 patients; survival among these patients was 94% at 1 month and 50% at 5 years. Recurrent endocarditis was only seen in patients with continued intravenous drug abuse.

CONCLUSIONS

Valve replacement in HIV-infected patients has low operative risk, but late results are poor when HIV infection is associated with intravenous drug abuse, probably due to immunocompromise and continued high-risk behavior.

Physical activity, heart and ageing: a morpho-functional study by Echo-Color-Doppler in sedentary and non sedentary healthy subjects

Several papers have shown that in young people sports activity is associated with a higher prevalence of cardiac valves incompetence, that can be detected, though to a lesser extent, even in healthy subjects randomly selected from the population. Aim of the present study was to analyse the effects of physical activity not only in young subjects but even in the elderly, with particular reference to valve competence, by using the Echo-Color-Doppler. The study cohort was represented by 80 healthy young subjects, 40 men and 40 women, aged between 20 and 25 years, each group subdivided into two subgroups, sedentary and non sedentary, and 80 healthy elderly subjects, 40 men and 40 women, aged between 65 and 91 years, again divided into sedentary and non sedentary. Valve incompetence was more frequent in the elderly if compared to young subjects (P<0.001) and in non sedentary if compared to sedentary subjects (P<0.01), while no significant difference was found between males and females. Worth of interest the fact that in young subjects valve incompetence was more frequent in non sedentary if compared to sedentary subjects (P<0.001), while in the elderly no significant difference was found between sedentary and non sedentary subjects. This original datum may be explained both by the natural higher prevalence of valve incompetence in the elderly, and by the kind of physical activity usually performed by the elderly, i.e. endurance activity.

Trileaflet valve for VAD use with purged sinus

Clinical applications of ventricle assist devices continue to be problematic due to thromboembolic complications. The problem originates mainly at the valves, which are usually made of an antithrombogenic material, such as cross-linked bovine pericardium. However, wherever the blood flow is stagnant or forms a recirculation region, a thrombus is likely to form. A similar blood flow is found in the space between the housing of the valve and the leaflets, the so-called valve sinus. Consequently, thrombi are often generated in this region. The novel valve design presented in this article avoids the formation of stagnant flow in the valve sinus during systole by a purge flow. This flow is taken from the main flow through the valve and is directed into each sinus region. The effect is achieved by perforation of the valve sinus with a small orifice at the bottom of the sinus. The purge flow effect is investigated with the computational fluid dynamics (CFD) method. The simulation shows that the purge flow effectively increases flow in the valve sinuses.

Serum levels of carbohydrate antigen 125 in patients with chronic heart failure: relation to clinical severity, hemodynamic and Doppler echocardiographic abnormalities, and short-term prognosis

OBJECTIVES

The aim of this study was to evaluate the serum levels of carbohydrate antigen 125 (CA125) in patients with congestive heart failure (CHF).

BACKGROUND

CA125 is a glycoprotein produced by serosal epithelium, found to be increased in ovarian cancer.

METHODS

Serum levels of CA125 were obtained in 286 patients (122 males and 164 females; age 69 +/- 13 years) with CHF (left ventricular ejection fraction 30 +/- 11%). A non-invasive evaluation was obtained by Doppler echocardiography; right heart catheterization was performed in 88 patients. An attempt to adjust medical therapy to maximally tolerated doses was done, and CA125 was repeated after 18 days (range 7 to 40) in 80 patients. The mean follow-up duration was 6 +/- 3 months in 240 patients.

RESULTS

The mean value of CA125 was 68 +/- 83 U/ml (range 3 to 537): 71 +/- 85 in men and 56 +/- 64 U/ml in women (p = NS). CA125 above the normal value (<35 U/ml) was found in 152 (53%) of 286 patients; it was higher in patients with advanced New York Heart Association (NYHA) functional class (n = 140 in class I/II: 15 +/- 9 U/ml; n = 63 in class III: 57 +/- 18 U/ml; n = 83 in class IV: 167 +/- 94 U/ml; p < 0.005). CA125 was related to the deceleration time of early filling on transmitral Doppler (r = -0.63, p < 0.05) and to pulmonary artery wedge pressure (r = 0.66, p < 0.05) and right atrial pressure (r = 0.69, p < 0.05). During 6 +/- 3 months of follow-up, a combined end point of mortality and CHF hospitalization was observed in 16 of 127 patients with CA125 <35 U/ml, compared with 70 of 113 patients with CA125 >35 U/ml (p < 0.01). After medical treatment optimization, NYHA class decreased by more than one grade in 56 of 80 patients and was unchanged or increased in 24 patients: CA125 decreased from 125 +/- 98 to 53 +/- 61 U/ml (p < 0.001) in the former and changed from 130 +/- 81 to 153 +/- 61 U/ml (p = NS) in the latter.

CONCLUSIONS

Our data suggest that CA125 is related to CHF severity and short-term prognosis. Furthermore, fluctuations of CA125 serum levels over time may reflect changes induced by therapy. Therefore, measurements of CA 125 serum levels might be proposed for the serial assessment of CHF patients.

[Changes in the cardiac valvular apparatus in patients with end-stage chronic renal failure on long-term programmed hemodialysis]

AIM

To examine the specific features of development of cardiac valvular diseases, biochemical changes in the blood composition, and changes in the density of bone tissue in patients with chronic renal failure (CRF) treated with programmed hemodialysis.

MATERIALS AND METHODS

118 patients with CRF (Group 1 patients (n = 69) aged 18-40 years and Group 2 patients (n = 49) aged 55-73 years) were examined.

RESULTS

Mitral valvular prolapse or disease mainly developed in Group 1 patients having profound phophorous and calcium metabolic changes and significantly elevated concentrations of blood parathyroid hormone; developed aortic valvular disease and calcium salt-impregnated cardiac tissues were observed in Group 2 patients.

CONCLUSION

The revealed regularities occur in chronic renal failure regulated by programmed hemodialysis and they are risk factors for chronic heart failure in elderly patients in particular.

Fate of stentless bioprostheses on right side of the heart

Newly developed stentless bioprostheses have shown good midterm results in the aortic position, but few data are available on their use at the right side of the heart. Four types of stentless bioprosthesis were used for right-side reconstruction of congenital heart anomalies in 50 patients (3 Baxter-Edwards Prima, 27 Medtronic Freestyle, 14 Cryolife Ross, and 6 Medtronic Contegra). Mean age was 9.03 +/- 6.25 years. Serial Doppler echocardiographic studies were performed to evaluate transvalvular pressure gradients. The hospital mortality was 6%. Reoperation was required in 3 patients in the early postoperative period because of left ventricular outflow tract obstruction, endocarditis, or tricuspid insufficiency. Measurements from 34 patients were available for statistical analysis. Clinical follow-up was complete in 43 of the 47 hospital survivors; the mean follow-up period was 16.6 +/- 16 months. Four patients died during follow-up; 93% of the survivors have an unrestricted lifestyle. Although peak transvalvular conduit gradients increased in all types of conduit, no reoperation has yet been performed for conduit stenosis. The newly developed stentless bioprostheses may be a useful alternative for right-side reconstruction of congenital heart anomalies.

Application of FFT analyzed cardiac Doppler signals to fuzzy algorithm

Doppler signals, recorded from the output of tricuspid, mitral, and aorta valves of 60 patients, were transferred to a personal computer via 16-bit sound card. The fast Fourier transform (FFT) method was applied to the recorded signal from each patient. Since FFT method inherently cannot offer a good spectral resolution at highly turbulent blood flows, it sometimes leads to wrong interpretation of cardiac Doppler signals. In order to avoid this problem, firstly six known diseased heart signals such as hypertension, mitral stenosis, mitral failure, tricuspid stenosis, aorta stenosis, aorta insufficiency were introduced to fuzzy algorithm. Then, the unknown heart diseases from 15 patients were applied to the same fuzzy algorithm in order to detect the kinds of diseases. It is observed that the fuzzy algorithm gives true results for detecting the kind of diseases.

Plasma von Willebrand factor and soluble p-selectin as indices of endothelial damage and platelet activation in 1321 patients with nonvalvular atrial fibrillation: relationship to stroke risk factors

BACKGROUND

Epidemiological studies have identified clinical and echocardiographic factors associated with increased stroke risk in atrial fibrillation (AF), but mechanisms linking these factors to stroke in AF are incompletely understood. We hypothesized that stroke risk factors may be associated with increased endothelial damage/dysfunction and platelet activation among patients with AF.

METHODS AND RESULTS

We measured plasma levels of von Willebrand factor (vWF, a marker of endothelial damage/dysfunction) and soluble P-selectin (sP-sel, a marker of platelet activation) by ELISA in 1321 participants in the Stroke Prevention in Atrial Fibrillation (SPAF) III study and related these indices to the presence of stroke risk factors and cardiovascular disease. Age (P<0.001), prior cerebral ischemia (P<0.01), recent heart failure (P<0.001), diabetes (P<0.001), and body mass index (P<0.001) were independently associated with increased vWF (r(2) adjusted=9%). Independent associates of increased sP-sel were diabetes (P=0.01), peripheral vascular disease (P<0.001), and current smoking (P=0.01), whereas prior cerebral ischemia (P=0.002) and female sex (P<0.001) were associated with reduced sP-sel (r(2) adjusted=4%). Using prospectively validated stroke risk stratification criteria, we observed a significant stepwise increase in vWF from low- to moderate- to high-risk groups (r(2) adjusted=3%, P<0.001), whereas sP-sel remained constant (P= 0.24).

CONCLUSIONS

Four recognized risk factors for stroke in AF (advancing age, prior cerebral ischemia, recent heart failure, and diabetes) were independently associated with raised plasma vWF (or endothelial damage/dysfunction), whereas only 1 (diabetes) was associated with increased sP-sel (platelet activation). Further longitudinal studies are now needed to confirm relationships between endothelial damage/dysfunction, platelet activation, and stroke in AF.

Spectral characteristics of mechanical heart valve closing sounds

BACKGROUND AND AIMS OF THE STUDY

In-vivo evaluation of cavitation is based on the registration of high-frequency pressure fluctuations that represent a mixture of both cavitation and valve closing sounds, and are difficult to separate. In order to extract the cavitation signal, a high-pass filter removing the closing sound is applied. Importantly, the cut-off frequency should be chosen based on the valve's resonance pattern. This could be determined in a cavitation-free, air-operated set-up. As air and water/blood have different physical properties that could influence resonance frequencies, it is necessary to correlate the frequency content of the closing sounds recorded in air to represent expected findings in fluid. The study aim was to characterize the impact of the surrounding media on resonance frequency of a sound source, and to develop a method capable of evaluating the spectral characteristics of mechanical heart valves.

METHODS

Five different valves were investigated. An in-vitro set-up was developed where the valves were operated in an airflow-controlled setting without cavitation. The valve closing sounds were recorded and a spectral analysis was performed. The resonance frequency of a simple sound source was also recorded in water and air in order to evaluate the impact of the surrounding media.

RESULTS

Resonance frequencies from the sound source measured in air increased 14% compared with corresponding measurements in water. These data were used to correct findings from the five valves that showed different spectral characteristics in air. The frequency at which 97.5% of the signal energy was contained ranged from 40.9 to 65.8 kHz.

CONCLUSION

Using an airflow in-vitro model, it was possible to determine the frequency signature of different mechanical heart valves. This might provide the information needed to design the optimal high-pass filter when evaluating cavitation.

Cardiac involvement in Wilson disease

BACKGROUND

Wilson disease is an inherited autosomal recessive disorder of copper metabolism resulting in pathological accumulation of copper in the liver, brain and other tissues. One of the reported manifestations is cardiac involvement.

METHODS

We studied 42 patients with Wilson disease (19 men and 23 women, mean age 34 +/- 10 y) and 42 age- and sex-matched healthy volunteers. All subjects underwent complete echocardiographic examination; 24 h ECG Holter monitoring was performed in 23 Wilson disease patients.

RESULTS

In comparison to healthy subjects, patients with Wilson disease had increased thickness of the interventricular septum (9.5 +/- 1.4 vs 8.6+/-1.1 mm, p < 0.01) and left ventriclular (LV) posterior wall (9.1 +/- 1.3 vs 8.2 +/- 1.0 mm, p < 0.01). While the two groups did not differ in LV mass index, relative LV wall thickness was significantly increased in Wilson disease patients compared to control subjects (0.39 +/- 0.06 vs 0.34 +/- 0.04 p < 0.001). Concentric LV remodelling was present in 9 patients (21%) and LV hypertrophy in one patient. Systolic LV function showed a nonsignificant trend towards lower values in Wilson disease patients (EF 62 +/- 5% vs 64 +/- 50%, p = 0.06). Diastolic filling and the frequency of valvular abnormalities were comparable in both groups. The established echocardiographic abnormalities did not correlate with the type of Wilson disease manifestation, the presence of the His1069Gln mutation, laboratory parameters or the duration and type of therapy. Twenty-four-hour ECG Holter monitoring detected ECG abnormalities in 10 patients (42%), the most frequent findings being runs of supraventricular tachycardias and frequent supraventricular ectopic beats.

CONCLUSIONS

Cardiac involvement in Wilson disease patients was mild, characterized by LV parietal thickening with an increased prevalence of concentric LV remodelling and a relatively high frequency of benign supraventricular tachycardias and extrasystolic beats.

Advances towards understanding heart valve response to injury

BACKGROUND

Composed of endocardial endothelial, valvular interstitial, cardiac muscle, and smooth muscle cells (SMC), heart valves are prone to various pathologic conditions the morphology of which has been well described. The morphology of diseased valves suggest that the "response to injury" process occurs in these valves, and is associated with an accumulation of interstitial cells and matrix, valvular inflammation and calcification, conditions that lead to dysfunction. The purpose of this study is to describe the current knowledge of the regulation of the valvular "response to injury" process, since we feel that this paradigm is essential to understanding valve disease.

METHODS

The pertinent literature relating to the cell and molecular biology of valvular repair, and specifically interstitial cell function in valve repair, is reviewed.

RESULTS

The cell and molecular biology of valve interstitial cells are poorly understood. Molecules regulating some of the aspects of the "response to injury" process have been studied, however, the signal transduction pathways, gene activation, and interactions of bioactive molecules with each other, with cells, and with the matrix have not been characterized. Initial studies identify the cell and molecular biology of interstitial cells to be an important area of research. Agents that have been studied include nitric oxide (NO) and FGF-2 and several matrix-related proteins including osteopontin. The present review suggests several directions for future study and a working model of valvular repair is presented.

DISCUSSION

The regulation of the "response to injury" process in the human heart valve is still largely unknown. The cell and molecular events and processes that occur in heart valve function and repair remain poorly understood. These events and processes are vital to our understanding of the pathobiology of heart valve disease, and to the successful design of tissue engineered replacement valves.

Cell proliferation in carcinoid valve disease: a mechanism for serotonin effects

BACKGROUND AND AIM OF THE STUDY

Elevated serum serotonin is associated with carcinoid heart disease, the hallmark of which is valvular thickening. Yet, the mechanistic role of serotonin in carcinoid heart disease is poorly understood. We postulated that serotonin has a direct mitogenic effect on cardiac valvular subendocardial cells, and that this effect is mediated by serotonin receptors.

METHODS

The dose-dependent proliferative effects of serotonin (10(-8) to 10(-4)M) on cultured porcine aortic valve cells via a [3H]thymidine assay were determined in vitro. Serotonin receptor antagonist studies in culture were also performed using methiotepin, a 5HT1b antagonist, and ketanserin, a 5HT2 receptor antagonist, to determine the mechanism of serotonin action. The ex-vivo proliferation level in human carcinoid (n = 26) and normal valves (n = 10) was compared using proliferating cell nuclear antigen (PCNA) staining, a marker for proliferation. Identification and localization of specific 5HT receptor was assessed by immunostaining for serotonin receptors in the valves.

RESULTS

Serotonin increased valvular proliferation in vitro in a dose-dependent manner (10-fold increase) (p <0.001), and this mitogenic effect was inhibited by methiotepin but not ketanserin. In human carcinoid heart valves the level of proliferation was 35-fold higher than in normal human valves (p <0.001). 5HT1b receptors were found only in the carcinoid valves, and not in the normal valves.

CONCLUSION

Serotonin is a powerful mitogen for valvular subendocardial cells. The mitogenic effect is at least partly mediated via 5HT1b receptors. Subendothelial cell proliferation is significantly elevated in human carcinoid valves in vivo. The data suggest a mechanism whereby serotonin may contribute to valvular proliferation in carcinoid heart disease.