Annular Valve Research Articles

Test of a Novel Moving Magnet Actuated Seat Valve for Digital Displacement Fluid Power Machines

The emerging digital displacement (DD) fluid power technology requires a new class of high-performance valves that can operate in harsh high-pressure conditions. To overcome the switching performance limitations of solenoids and to avoid the mechanical complexity of moving coil actuators, a novel electronically-controlled moving magnet actuated (MMA) annular seat valve is proposed, designed, built, and tested rigorously in the laboratory. The actuator is energized using one coil only, it has bidirectional force capability and it utilizes magnetic latching to keep it open instead of a spring. The annular seat valve has two metering edges; the static pressure drop is 0.11/0.31 bar at −142/108 L/min, respectively. The valve closing time is 4–6 ms depending on the flow rate. The MMA valve is tested experimentally in both standalone test rigs besides in situ tests in a fully operational DD prototype machine. Measurements provided for pumping and motoring operation at 800 r/min/100 bar demonstrate that the proposed MMA valve topology is a promising candidate for energy-efficient digital displacement machines. Key characteristics include little power consumption, good switching performance, and a simple mechanical design.

LEFT HEART DIASTOLIC DYSFUNCTION PARAMETERS IN ASSOCIATION WITH PULMONARY FUNCTION VARIABLES IN COPD

SESSION TITLE: Obstructive Lung Diseases 2 SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/10/2018 01:00 PM - 02:00 PM PURPOSE: COPD is a leading cause for morbidity and mortality worldwide. Though it is primarily a pulmonary disease, COPD affects other body systems including the cardiovascular system. Few studies have found an association between COPD and left heart diastolic dysfunction. The aim of this study is to look for an association between parameters of diastolic dysfunction, and parameters of pulmonary function test (PFT) among patients with COPD. METHODS: This is a cross-sectional analysis performed in a community-based teaching hospital. Patients with working diagnosis of COPD, who underwent PFT during the years 2016 and 2017, were initially-screened. A total of 182 individuals were identified. We then included the patients who had; 1) forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) ratio < 70%, and 2) an echocardiography performed not more than two years from the most recent PFT. Patients were excluded if any one of the following was identified; 1) age < 18 years old, 2) mitral stenosis, repair, or replacement, 3) moderate annular mitral valve calcification or worse, 4) moderately severe mitral regurgitation or worse, 5) left ventricular assistant device, 6) left bundle branch block, 7) ventricular-paced rhythm, 8) ejection fraction (EF) < 50%. We included the following cardiac variables; EF, tricuspid regurgitation (TR) velocity, average e/e’, septal e’, and lateral e’. PFT variables (as percentage predicted) were; post-bronchodilator FEV1, post-bronchodilator FVC, total lung capacity (TLC), residual volume (RV), and functional residual capacity (FRC). Correlation between each cardiac parameter and each PFT variable was estimated using Pearson correlation coefficient. Two-tailed t-test was used to calculate p-values. RESULTS: From the 182 initially-screened individuals, a total of 24 were identified. 66.7% (n=16) were females, and with mean age of 66.2 ± 8.2 years. After performing statistical analysis, there was a significant association between FRC and TR velocity with correlation coefficient of 0.44 (p =0.033). Moreover, there was a trend, but not a significant association, between RV and TR velocity with correlation coefficient of 0.38 (p = 0.067). CONCLUSIONS: Among patients with COPD, FRC and RV, parameters for air-trapping, are associated with TR velocity, a parameter for diastolic dysfunction. CLINICAL IMPLICATIONS: One of the theories which attempts to explain left heart diastolic dysfunction in patients with COPD is that auto-PEEP effect due to air-trapping would cause reduction in preload, which then stresses the left ventricle, leading to tachycardia with subsequent diastolic dysfunction. In our study, the association between FRC and TR velocity, along with the trend between RV and TR velocity would support this theory. This could help in predicting patients with COPD who might have unidentified left heart diastolic dysfunction. DISCLOSURES: No relevant relationships by Ali Alkhayat, source=Web Response No relevant relationships by Faeq Kukhon, source=Web Response No relevant relationships by Taro Minami, source=Web Response No relevant relationships by Ahmed Mohamed, source=Web Response No relevant relationships by Fatima Zeba, source=Web Response

Flow Characteristics and Sizing of Annular Seat Valves for Digital Displacement Machines

Flow Characteristics and Sizing of Annular Seat Valves for Digital Displacement Machines

Relation of Serum Vitamin D to Risk of Mitral Annular and Aortic Valve Calcium (from the Multi-Ethnic Study of Atherosclerosis)

Serum 25-hydroxyvitamin D [25(OH)D] concentration has been identified as a possible modifiable risk factor for cardiovascular disease (CVD). We hypothesized that serum 25(OH)D concentration would be associated with calcifications of the left-sided heart valves, which are markers of CVD risk. Aortic valve calcium (AVC) and mitral annular calcium (MAC) were quantified from cardiac computed tomography scans performed on 5,530 Multi-Ethnic Study of Atherosclerosis participants at the baseline examination (2000 to 2002) and at a follow-up visit at either Examination 2 (2002 to 2004) or Examination 3 (2004 to 2005). 25(OH)D was measured from serum samples collected at the baseline examination. Using relative risk regression, we evaluated the multivariable-adjusted risk of prevalent and incident AVC and MAC in this ethnically diverse population free of clinical CVD at baseline. The mean age of participants was 62 ± 10years; 53% were women, 40% white, 26% black, 21% Hispanic, and 12% Chinese. Prevalent AVC and MAC were observed in 12% and 9% of study sample, respectively. There were no significant associations between 25(OH)D and prevalent AVC or MAC. Over a mean follow-up of 2.5years, 4% developed incident AVC and 5% developed incident MAC. After adjusting for demographic variables, each 10ng/ml higher serum 25(OH)D was associated with a 15% (relative risk 0.85, 95% confidence interval 0.74 to 0.98) lower risk of incident MAC but not AVC. However, this association was no longer significant after adjusting for lifestyle and CVD risk factors. Results suggest a possible link between serum 25(OH)D and the risk for incident MAC, but future studies with longer follow-up are needed to further test this association.

IMPACT OF DIFFERENT CALCIUM LOCATIONS OF MITRAL ANNULUS AND AORTIC VALVE CUSPS ON RISK OF CONDUCTION DISTURBANCES AFTER TRANSCATHETER AORTIC VALVE IMPLANTATION

Background: The impact of the presence and severity of mitral annular (MAC) and aortic valve calcifications on the risk of new conduction system disorders (CSD) after transcatheter aortic valve implantation (TAVI) remains unclear. Methods: Consecutive patients with severe symptomatic aortic valve

Abstract WP240: Association Between Mitral and Annular Calcification or Aortic Valve Calcification and Complex Aortic Atheroma in Ischemic Stroke Patients

Background and aims: The aim of this study was to investigate the prevalence of mitral annular calcification (MAC) and aortic valve calcification (AVC) according to the presence or absence of complex aortic atheroma (CAA), using transesophageal echocardiography (TEE) data. Methods: This study included 130 (mean age 59.5 years; male 68.5%) consecutive patients who admitted in our hospital with acute ischemic stroke and underwent transesophageal echocardiography (TEE) for determination of stroke etiology during hospitalization. Stroke subtypes were classified with TOAST criteria. Embolic stroke with undetermined source (ESUS) was defined on the basis of the Cryptogenic Stroke/ESUS International Working Group criteria. MAC and AVC were defined as focal areas of high echogenicity of mitral valve annulus and aortic leaflet, respectively. CAA was assessed by TTE and defined as ≥4 mm and/or ulceration and/or mobile plaques. Comparisons were made between patients with and without CAA (CAA and non-CAA group, respectively) with regard to clinical and echocardiological findings. Results: Of the 130 patients, 26 (20.0%) had CAA. The patients in the CAA and non-CAA groups showed significant differences in age (mean, 69.5 vs. 57.0, P &lt; 0.001), hypertension (88.5% vs. 44.2%, P &lt; 0.001), chronic kidney disease (46.2% vs. 22.1%, P = 0.013), diabetes mellitus (61.5% vs. 23.1%, P &lt; 0.001), hyperlipidemia (69.2% vs. 37.5%, P = 0.004), MAC (23.1% vs. 2.9%, P &lt; 0.001), AVC (19.2% vs. 5.8%, P = 0.022), and MAC or/and AVC (34.6% vs. 7.7%, P &lt; 0.001). When restricted to ESUS patients, there were significant differences in age (mean, 65.0 vs. 53.3, P = 0.042), hypertension (mean, 80.0% vs. 43.6%, P = 0.040), history of coronary artery disease (40.0% vs. 2.6%, P &lt; 0.001), diabetes mellitus (60.0% vs. 12.8%, P = 0.001), hyperlipidemia (80.0% vs. 30.8%, P = 0.004), AVC (37.5% vs. 6.8%, P = 0.012), and MAC or/and AVC (34.6% vs. 7.7%, P = 0.030) between the 2 groups, whereas the prevalence of MAC was not different between CAA and non-CCA groups (12.5% vs. 2.3%, P = 0.16). Conclusions: Stroke patients with CAA frequently have concurrent MAC and/or AVC, which may prompt an effort to detect CAA for patients with MAC and /or AVC in transthoracic echocardiography.

Relation Between Epicardial Adipose and Aortic Valve and Mitral Annular Calcium Determined by Computed Tomography in Subjects Aged ≥65 Years

Epicardial adipose tissue (EAT) has been linked to coronary artery calcium deposits and atherosclerotic disease. Mitral annular (MAC) and aortic valve calcium (AVC) have also been associated with atherosclerosis. This study examined the possible relation between EAT thickness and valvular calcium deposits. We included 294 patients aged ≥65 years who had noncontrast computed tomography scans of the chest. Mean age was 76 ± 7years; 47% were men. Using reconstructed images, EAT thickness was measured at various locations. MAC and AVC were quantified by Agatston technique. The sum of AVC and MAC was reported as the grand total score (GTS). Subjects were divided into 2 groups based on the value of GTS; GTS= 0, no cardiac calcification and GTS ≥1, cardiac calcification group. Epicardial fat (left and right atrioventricular grooves and superior interventricular groove) was significantly greater in the cardiac calcification group compared with the no cardiac calcification (all values, p <0.05). After adjusting for clinical variables including BMI, EAT at the superior interventricular groove remained significantly associated with total calcium. Left atrioventricular groove EAT demonstrated a trend toward an association with total calcium, but this did not reach statistical significance. In conclusion, epicardial fat is associated with calcium deposits of the mitral annulus and aortic valve.

PT184 Permanent Pacemaker Implantation and Calcification of Annular and Aortic Valve Evaluated by Biopse in Patients Underwent Aortic Valve Replacement

PT184 Permanent Pacemaker Implantation and Calcification of Annular and Aortic Valve Evaluated by Biopse in Patients Underwent Aortic Valve Replacement

MITRAL ANNULAR CALCIFICATION AND RISK OF STROKE IN SEVERE AORTIC STENOSIS: A PROPENSITY SCORE ANALYSIS

Mitral annular calcification (MAC) & aortic valve sclerosis/stenosis (AS) are both known to be associated with increased risk of ischemic stroke. The independent association of MAC with stroke in the presence of severe AS is largely unknown, which we wanted to explore in this study. We

The Structural Impact of Aortic Valve Replacement on Mitral Regurgitation

Background: Structural changes to the mitral annulus occur following aortic valve replacement (AVR) for severe aortic stenosis which may influence functional mitral regurgitation (MR). Methods: A retrospective review of 44 patients who underwent open AVR for aortic stenosis at a single center from 2010-2013 was performed. Patients undergoing concomitant aortic root surgery or with severe MR were excluded. MR was evaluated with preoperative and postoperative transthoracic echocardiograms. Univariate and multivariable analyses were performed to assess for factors associated with postoperative MR improvement and worsening. Results: Prior to AVR, none had severe MR, 5% (2 patients) had moderate, 9% (4 patients) mild-to-moderate, 46% (20 patients) mild, and 23% (9 patients) trace MR. Of patients with pre-operative MR, 44% (16 patients) experienced improvement of MR. Six patients had worsening of MR and the remaining 22 patients had no change. Cases of more severe MR were more likely to improve compared with mild or trace MR (P = 0.04). MR worsening was significantly more likely in patients with bicuspid aortic valves (83% vs. 24%; P = 0.004), and with larger aortic annulus diameters (P = 0.03). MR worsening was less frequent in cases of mitral annular calcification (0% vs 42%; P = 0.04) and left atrial enlargement (17% vs 65%; P = 0.03). Logistic regression analysis revealed negative predictors for MR improvement were mitral annular calcification (P = 0.04) and larger aortic annulus diastolic diameter (P = 0.05). Conclusion: Structural factors such as aortic annular size, mitral annular calcification and valve morphology may impact MR following AVR and should be investigated further as potential targets of surgical therapy.

Distribution of Mitral Annular and Aortic Valve Calcium as Assessed by Unenhanced Multidetector Computed Tomography

Aging is associated with calcium deposits in various cardiovascular structures, but patterns of calcium deposition, if any, are unknown. In search of such patterns, we performed quantitative assessment of mitral annular calcium (MAC) and aortic valve calcium (AVC) in a broad clinical sample. Templates were created from gated computed tomography (CT) scans depicting the aortic valve cusps and mitral annular segments in relation to surrounding structures. These were then applied to CT reconstructions from ungated, clinically indicated CT scans of 318 subjects, aged ≥65 years. Calcium location was assigned using the templates and quantified by the Agatston method. Mean age was 76 ± 7.3 years; 48% were men and 58% were white. Whites had higher prevalence (p = 0.03) and density of AVC than blacks (p = 0.02), and a trend toward increased MAC (p = 0.06). Prevalence of AVC was similar between men and women, but AVC scores were higher in men (p = 0.008); this difference was entirely accounted for by whites. Within the aortic valve, the left cusp was more frequently calcified than the others. MAC was most common in the posterior mitral annulus, especially its middle (P2) segment. For the anterior mitral annulus, the medial (A3) segment calcified most often. In conclusion, AVC is more common in whites than blacks, and more intense in men, but only in whites. Furthermore, calcium deposits in the mitral annulus and aortic valve favor certain locations.

TCT-91 Comparison of Portico® and CoreValveTM Self-expanding Transcatheter Heart Valves for the Treatment of Failed Surgical Aortic Bioprosthesis: Insights from the Valve in Valve International Data (VIVID) Registry

Portico® (St. Jude Medical) and CoreValve™ (Medtronic) are both nitinol based self-expanding transcatheter heart valves with unique features enabling device retrievability for Portico and supra annular valve position for CoreValve systems. In this study, we sought to investigate the effect of the

Abstract 716: Echocardiographic Evidence of Systemic Atherosclerosis and Long-Term Outcomes in Patients with Non-Hemorrhagic Stroke

Background: Echocardiography is routinely performed for evaluation of cardiac embolic causes in patients with non-hemorrhagic stroke. However, added value of echocardiographic evidence for systemic atherosclerosis in patients with known peripheral disease and non-hemorrhagic stroke has not been well established. Material and Methods: Retrospective chart review was performed in 517 consecutive patients treated for non-hemorrhagic stroke at a single academic medical center. Complete transthoracic echocardiograms were reviewed for presence of mitral annular calcifications, valve sclerosis, or aortic atherosclerosis. Long-term outcomes were ascertained through the National Death Index. This study was approved by the institutional IRB. Results: The study cohort included 48% females. Coronary artery disease (CAD) was present in 27%, hypertension in 62%, diabetes in 20%, dyslipidemia in 38%, peripheral vascular disease (PVD) in 4%, and end-stage renal disease in 5%. Echocardiographic evidence of systemic atherosclerosis was noted in 43%. We observed 28% mortality at the mean follow-up length of 46+/-20 months. Mortality was significantly increased in older patients, and in patients with histories of end-stage renal disease (p=0.048), PVD (p&lt;0.001), diabetes (p=0.05), hypertension (p=0.027), and CAD (p=0.012). Echocardiographic evidence of systemic atherosclerosis was associated with a 2-fold increase in mortality (20 vs. 40%, p&lt;0.0001). In multivariate logistic regression analysis, when adjusted for recorded end-points, the echocardiographic evidence of systemic atherosclerosis was not predictive of adverse outcomes. Only age (HR 1.9, 95%CI 1.6-2.4, p&lt;0.0001), diabetes (HR 1.9, 95% CI 1.1-3.3, p=0.029), and PVD (HR 5.1, 95%CI 1.8-14.4, p=0.0024) were associated with increased mortality. Conclusions: In patients with non-hemorrhagic stroke, systemic evidence of atherosclerosis suggested by transthoracic echocardiography is not associated with worse long-term prognosis. This should not preclude providers from performing an echocardiographic evaluation if clinically indicated. The question of diagnostic utility for post stroke transthoracic echocardiography is an important topic and warrants further study.

Magnetorheological energy absorber with dual concentric annular valves

For semi-active shock and vibration mitigation systems using magnetorheological energy absorbers, fail-safe performance is of particular significance if electric power is lost. At the same time, the minimization of the field-off damping force of the magnetorheological energy absorbers at high speed is also important because the damping force due to the viscous damping force at high speed becomes too excessive, and thus, the controllable dynamic range is rapidly reduced. In this article, a fail-safe magnetorheological energy absorber with dual concentric annular valves and an inner-set permanent magnet is proposed to decrease the field-off damping force while keeping an appropriate dynamic range for improving shock and vibration mitigation performance. In the magnetorheological energy absorber, the dual concentric annular valves are configured so as to decrease the baseline damping force, and magnetic activation methods using the electromagnetic coil winding and the permanent magnet are used to maintain appropriate magnetic intensity in these concentric annular valves. An initial field-on damping force is produced by the magnetic field bias generated from the inner-set permanent magnet in consideration of the failure of the electric power supply. The initial field-on damping force of the magnetorheological energy absorbers can be increased (or decreased) by applying positive (or negative) current to the electromagnetic coil winding, and thus, bidirectional controllable damping performance could be realized. After establishing the analytical damping force model of the magnetorheological energy absorber using a Bingham-plastic nonlinear fluid model, its working principle and magnetic properties are analytically validated and analyzed via electromagnetic finite element analysis. The performance of the magnetorheological energy absorber is also theoretically compared with that of a conventional magnetorheological energy absorber with a single valve with the constraint of an identical volume under different excitation velocities.

Integral characteristics of a porous gas axial bearing

A flat axial bearing with pressurized gas supply through an annular flow valve made from anisotropic porous material is considered. The differential equation for the pressure in the lubricant layer adjacent to the porous wall is numerically solved using the Runge-Kutta method, with two boundary conditions taken into account. One of these, which is integral, has remained out of sight in the porous support analysis until recently. An algorithm for calculating the lifting force and rigidity of support as well as mass rate of gas flow through this support is presented. The optimization of support is performed, and conclusions are drawn as to its influence on different factors.

Catheter ablation related mitral valve injury: the importance of early recognition and rescue mitral valve repair.

An increasing number of catheter ablations involve the mitral annular region and valve apparatus, increasing the risk of catheter interaction with the mitral valve (MV) complex. We review our experience with catheter ablation-related MV injury resulting in severe mitral regurgitation (MR) to delineate mechanisms of injury and outcomes. We searched the Mayo Clinic MV surgical database over a 19-year period (1993-2012) and the electrophysiologic procedures database over a 23-year period (1990-2013) and identified 9 patients with catheter ablation related MV injury requiring clinical intervention. Indications for ablation included atrial fibrillation (AF) [n = 4], ventricular tachycardia (VT) [n = 3], and left-sided accessory pathways [n = 2]. In all 4 AF patients, a circular mapping catheter entrapped in the MV apparatus was responsible for severe MR. In all 3 VT patients, radiofrequency energy delivery led to direct injury to the MV apparatus. In the 2 patients with accessory pathways, both mechanisms were involved (1 per patient). Six patients required surgical intervention (5 MV repair, 1 catheter removal). One patient developed severe functional MR upon successful endovascular catheter disentanglement that improved spontaneously. Two VT patients with persistent severe postablation MR were managed nonsurgically, 1 of whom died 3 months postprocedure. Circular mapping catheter entrapment and ablation at the mitral annulus are the most common etiologies of MV injury during catheter ablation. Close surveillance of the MV is needed during such procedures and early surgical repair is important for successful salvage if significant injury occurs.

The Potential of FDG PET/CT for Early Diagnosis of Cardiac Device and Prosthetic Valve Infection Before Morphologic Damages Ensue

Diagnosis of cardiac mechanical device or prosthesis valve infection, and more importantly accurate localization of the infection site, such as defibrillator pocket, pacemaker lead, annular or peri-annular valve ring abscesses remain clinically challenging. Inconclusive diagnosis can lead to delayed antibiotic therapy, device extraction or surgical intervention, which may have dire consequences to the patient. Among patients with suspected cardiac mechanical device or prosthetic valve infection, recent publications advocate the use of (18)F-fluoro-2-deoxyglucose positron emission tomography computed tomography (FDG PET/CT), particularly when anatomy based imaging studies, such as echocardiography or CT, are uncertain or negative. A potential advantage of FDG PET/CT is in its detection of inflammatory cells early in the infection process, before morphologic damages ensue. However, there are many unanswered questions in the literature. There is a need for standardization amongst the various imaging studies, such as dietary preparation, duration and timing of image acquisition, image processing with and without CT attenuation correction, and more importantly image interpretation criteria. The answer for these issues awaits well designed, prospective studies.

Optimum design of seat region in valves suitable for digital displacement machines

Digital displacement fluid power is an upcoming technology setting new standards for the achievable efficiency in variable displacement fluid power pumps and motors. In the present work, an annular seat valve suitable for use in digital displacement units is considered, and the valve geometry is optimised considering both the mechanical strength during pressure loading and fluid flow restriction in the open valve state. Material stresses are modelled using finite element (FE) analysis including non-linear material behaviour, contact elements and fluid pressure penetrating load, closely reflecting the actual load of the seat valve connected to a fluid pressure chamber. Valve pressure losses are modelled using computational fluid dynamics (CFD). On basis of an overall physical size requirement and material specification, optimum valve geometry and stroke length are given as function of a defined normalised flow coefficient directly related to the machine efficiency.

The Research on Working Performance of Annular Valve Spring Based on Solidworks

According to the problem of cylindrical helical compression springs deformation and fracture in the process of using. come up with a Solution that use conical helical spring instead of it, validate the improvement measure with relevant simulation and test analysis, draw a conclusion that the working performance of conical helical spring is better than the cylinder, this paper has some guiding effect on the selection of Annular valve spring.

Design optimization of magnetorheological fluid valves using response surface method

A new design optimization methodology for the optimal design of a single-coil annular magnetorheological valve constrained in a specific volume inside a magnetorheological damper has been presented in this article. The methodology combines the finite element model, with the design of experiments and response surface techniques in order to develop approximate response surface functions for the magnetic field intensity across the activation length of a magnetorheological valve orifice with respect to identified design variables. The accuracy of the developed response surface functions over the entire design space has been verified. The developed analytical response functions have then been used in Bingham plastic model, which is based on the steady behavior of a magnetorheological fluid in order to derive the field-dependent performance functions of the magnetorheological damper, which can be effectively used in the design optimization problems. The design optimization problem has been formulated for single- and multiobjective performance functions using sequential quadratic programming technique and the genetic algorithm to find the global optimum geometrical parameters of the magnetorheological valve. Finally, a proportional–integral–derivative controller has been designed to evaluate the closed-loop performance of the optimally designed magnetorheological valve confined in a magnetorheological damper used in a quarter-car suspension model.