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1.
Int J Phytoremediation ; 23(10): 1013-1020, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33470122

RESUMEN

Remediation in this study employs the use of green plants and their extracts in enhancing the remediation process of polluted soils. GC-MS & FTIR techniques were employed in determining the constituents of the soil during the investigation. 60 ml of the extracts were applied on 1 by 2 ft segments of hydrocarbon polluted site and observed for two months. The results show that plant extract A significantly reduced the TPHs and PAHs to 5,450 and 126.2 mg/kg, respectively, as compared to those of extract B whose TPH and PAH values are 10,432 and 362.3 mg/kg, respectively. Both plant extracts reduced the total petroleum hydrocarbon compounds significantly when compared to the standard reference PAH and PAHs (4,500 mg/kg and 50 mg/kg respectively). The microbial plate count for the three media shows that the plant based surfactant had a synergy with the identified bacteria in enhancing Phytoremediation of the crude oil polluted site. Novelty statement: This study examined the application of two plant-based surfactants for remediation. These natural surfactants significantly reduced the petroleum hydrocarbon compounds present in the soil within the in-situ observation window. These Herbaceous plant family extracts have a great advantage as an eco-friendly alternative to synthetic surfactants, and they also exhibited an anti-fungi characteristic. The two biodegradable plant-based surfactants also significantly reduced the time that it could have taken for a remediation process.


Asunto(s)
Petróleo , Contaminantes del Suelo , Biodegradación Ambiental , Hidrocarburos , Plantas , Suelo , Microbiología del Suelo , Contaminantes del Suelo/análisis , Tensoactivos
2.
Circulation ; 136(17): 1598-1609, 2017 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-28724752

RESUMEN

BACKGROUND: Transcatheter heart valve (THV) thrombosis has been increasingly reported. In these studies, thrombus quantification has been based on a 2-dimensional assessment of a 3-dimensional phenomenon. METHODS: Postprocedural, 4-dimensional, volume-rendered CT data of patients with CoreValve, Evolut R, and SAPIEN 3 transcatheter aortic valve replacement enrolled in the RESOLVE study (Assessment of Transcatheter and Surgical Aortic Bioprosthetic Valve Dysfunction With Multimodality Imaging and Its Treatment with Anticoagulation) were included in this analysis. Patients on anticoagulation were excluded. SAPIEN 3 and CoreValve/Evolut R patients with and without hypoattenuated leaflet thickening were included to study differences between groups. Patients were classified as having THV thrombosis if there was any evidence of hypoattenuated leaflet thickening. Anatomic and THV deployment geometries were analyzed, and thrombus volumes were computed through manual 3-dimensional reconstruction. We aimed to identify and evaluate risk factors that contribute to THV thrombosis through the combination of retrospective clinical data analysis and in vitro imaging in the space between the native and THV leaflets (neosinus). RESULTS: SAPIEN 3 valves with leaflet thrombosis were on average 10% further expanded (by diameter) than those without (95.5±5.2% versus 85.4±3.9%; P<0.001). However, this relationship was not evident with the CoreValve/Evolut R. In CoreValve/Evolut Rs with thrombosis, the thrombus volume increased linearly with implant depth (R2=0.7, P<0.001). This finding was not seen in the SAPIEN 3. The in vitro analysis showed that a supraannular THV deployment resulted in a nearly 7-fold decrease in stagnation zone size (velocities <0.1 m/s) when compared with an intraannular deployment. In addition, the in vitro model indicated that the size of the stagnation zone increased as cardiac output decreased. CONCLUSIONS: Although transcatheter aortic valve replacement thrombosis is a multifactorial process involving foreign materials, patient-specific blood chemistry, and complex flow patterns, our study indicates that deployed THV geometry may have implications on the occurrence of thrombosis. In addition, a supraannular neosinus may reduce thrombosis risk because of reduced flow stasis. Although additional prospective studies are needed to further develop strategies for minimizing thrombus burden, these results may help identify patients at higher thrombosis risk and aid in the development of next-generation devices with reduced thrombosis risk.


Asunto(s)
Válvulas Cardíacas/cirugía , Hemodinámica , Modelos Cardiovasculares , Trombosis/fisiopatología , Reemplazo de la Válvula Aórtica Transcatéter/efectos adversos , Femenino , Humanos , Masculino , Trombosis/etiología
3.
Am J Physiol Heart Circ Physiol ; 310(11): H1801-7, 2016 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-27106040

RESUMEN

Acute aortic regurgitation (AR) post-chronic aortic stenosis is a prevalent phenomenon occurring in patients who undergo transcatheter aortic valve replacement (TAVR) surgery. The objective of this work was to characterize the effects of left ventricular diastolic stiffness (LVDS) and AR severity on LV performance. Three LVDS models were inserted into a physiological left heart simulator. AR severity was parametrically varied through four levels (ranging from trace to moderate) and compared with a competent aortic valve. Hemodynamic metrics such as average diastolic pressures (DP) and reduction in transmitral flow were measured. AR index was calculated as a function of AR severity and LVDS, and the work required to make up for lost volume due to AR was estimated. In the presence of trace AR, higher LVDS had up to a threefold reduction in transmitral flow (13% compared with 3.5%) and a significant increase in DP (2-fold). The AR index ranged from ∼42 to 16 (no AR to moderate AR), with stiffer LVs having lower values. To compensate for lost volume due to AR, the low, medium, and high LVDS models were found to require 5.1, 5.5, and 6.6 times more work, respectively. This work shows that the LVDS has a significant effect on the LV performance in the presence of AR. Therefore, the LVDS of potential TAVR patients should be assessed to gain an initial indication of their ability to tolerate post-procedural AR.


Asunto(s)
Insuficiencia de la Válvula Aórtica/fisiopatología , Estenosis de la Válvula Aórtica/fisiopatología , Ventrículos Cardíacos/fisiopatología , Hemodinámica/fisiología , Modelos Cardiovasculares , Rigidez Vascular/fisiología , Válvula Aórtica/fisiopatología , Humanos , Resistencia Vascular/fisiología , Función Ventricular Izquierda/fisiología
4.
J Emerg Med ; 50(6): 881-6, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27221019

RESUMEN

BACKGROUND: Although subgaleal hemorrhage can present very soon after delivery with catastrophic consequences, subaponeurotic or subgaleal fluid collections are rare and clinically distinct causes of infant scalp swelling that present weeks to months after birth. Their exact etiology remains uncertain; however, they are frequently associated with instrumental and traumatic delivery. AIM & METHODS: To characterize 11 subaponeurotic fluid collections that presented to the Temple Street Children's University Hospital Emergency Department (TSCUHED) from July 2013 to July 2015 by a retrospective chart review. CASE REPORT: Eleven infants were identified with delayed subaponeurotic fluid collections. Of note, all infants were either successful vacuum delivery or failed vacuum delivery with subsequent forceps delivery or emergency caesarean section. All infants were otherwise well at presentation, and resolution of the scalp swelling occurred within weeks to months. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This condition follows a benign course and conservative management is the treatment of choice.


Asunto(s)
Hemorragia/diagnóstico , Hemorragia/etiología , Cuero Cabelludo/lesiones , Factores de Tiempo , Extracción Obstétrica por Aspiración/normas , Parto Obstétrico/normas , Edema/diagnóstico , Edema/etiología , Servicio de Urgencia en Hospital/organización & administración , Hemorragia/terapia , Humanos , Lactante , Recién Nacido , Irlanda , Estudios Retrospectivos , Cuero Cabelludo/anomalías
5.
J Cardiovasc Magn Reson ; 17: 51, 2015 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-26112155

RESUMEN

BACKGROUND: The development of clinically applicable fluid-structure interaction (FSI) models of the left heart is inherently challenging when using in vivo cardiovascular magnetic resonance (CMR) data for validation, due to the lack of a well-controlled system where detailed measurements of the ventricular wall motion and flow field are available a priori. The purpose of this study was to (a) develop a clinically relevant, CMR-compatible left heart physical model; and (b) compare the left ventricular (LV) volume reconstructions and hemodynamic data obtained using CMR to laboratory-based experimental modalities. METHODS: The LV was constructed from optically clear flexible silicone rubber. The geometry was based off a healthy patient's LV geometry during peak systole. The LV phantom was attached to a left heart simulator consisting of an aorta, atrium, and systemic resistance and compliance elements. Experiments were conducted for heart rate of 70 bpm. Wall motion measurements were obtained using high speed stereo-photogrammetry (SP) and cine-CMR, while flow field measurements were obtained using digital particle image velocimetry (DPIV) and phase-contrast magnetic resonance (PC-CMR). RESULTS: The model reproduced physiologically accurate hemodynamics (aortic pressure = 120/80 mmHg; cardiac output = 3.5 L/min). DPIV and PC-CMR results of the center plane flow within the ventricle matched, both qualitatively and quantitatively, with flow from the atrium into the LV having a velocity of about 1.15 m/s for both modalities. The normalized LV volume through the cardiac cycle computed from CMR data matched closely to that from SP. The mean difference between CMR and SP was 5.5 ± 3.7%. CONCLUSIONS: The model presented here can thus be used for the purposes of: (a) acquiring CMR data for validation of FSI simulations, (b) determining accuracy of cine-CMR reconstruction methods, and


Asunto(s)
Ventrículos Cardíacos/anatomía & histología , Hemodinámica , Imagen por Resonancia Cinemagnética/instrumentación , Modelos Anatómicos , Modelos Cardiovasculares , Contracción Miocárdica , Fantasmas de Imagen , Función Ventricular Izquierda , Presión Arterial , Fenómenos Biomecánicos , Gasto Cardíaco , Frecuencia Cardíaca , Humanos , Fotogrametría , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Reología , Elastómeros de Silicona , Factores de Tiempo
6.
J Biomech Eng ; 137(12): 121007, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26502376

RESUMEN

The mitral valve (MV) is a bileaflet valve positioned between the left atrium and ventricle of the heart. The annulus of the MV has been observed to undergo geometric changes during the cardiac cycle, transforming from a saddle D-shape during systole to a flat (and less eccentric) D-shape during diastole. Prosthetic MV devices, including heart valves and annuloplasty rings, are designed based on these two configurations, with the circular design of some prosthetic heart valves (PHVs) being an approximation of the less eccentric, flat D-shape. Characterizing the effects of these geometrical variations on the filling efficiency of the left ventricle (LV) is required to understand why the flat D-shaped annulus is observed in the native MV during diastole in addition to optimizing the design of prosthetic devices. We hypothesize that the D-shaped annulus reduces energy loss during ventricular filling. An experimental left heart simulator (LHS) consisting of a flexible-walled LV physical model was used to characterize the filling efficiency of the two mitral annular geometries. The strength of the dominant vortical structure formed and the energy dissipation rate (EDR) of the measured fields, during the diastolic period of the cardiac cycle, were used as metrics to quantify the filling efficiency. Our results indicated that the O-shaped annulus generates a stronger (25% relative to the D-shaped annulus) vortical structure than that of the D-shaped annulus. It was also found that the O-shaped annulus resulted in higher EDR values throughout the diastolic period of the cardiac cycle. The results support the hypothesis that a D-shaped mitral annulus reduces dissipative energy losses in ventricular filling during diastole and in turn suggests that a symmetric stent design does not provide lower filling efficiency than an equivalent asymmetric design.


Asunto(s)
Prótesis Valvulares Cardíacas , Ventrículos Cardíacos/anatomía & histología , Válvula Mitral/anatomía & histología , Válvula Mitral/fisiología , Modelos Cardiovasculares , Función Ventricular Izquierda/fisiología , Biomimética/métodos , Velocidad del Flujo Sanguíneo , Simulación por Computador , Diseño Asistido por Computadora , Análisis de Falla de Equipo , Humanos , Modelos Anatómicos , Diseño de Prótesis , Volumen Sistólico/fisiología
7.
ACS Omega ; 8(46): 43771-43791, 2023 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-38027312

RESUMEN

There is a lack of information about the detailed characterization of biomass of Nigerian origin. This study presents a comprehensive characterization of six biomass, groundnut shells, corncob, cashew leaves, Ixora coccinea (flame of the woods), sawdust, and lemongrass, to aid appropriate selection for bio-oil production. The proximate, ultimate, calorific value and compositional analyses were carried out following the American Standard for Testing and Materials (ASTM) standards. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and X-ray fluorescence were employed in this study for functional group analyses, thermal stability, and structural analyses. The H/C and O/C atomic ratios, fuel ratio, ignitability index, and combustibility index of the biomass samples were evaluated. Groundnut shells, cashew leaves, and lemongrass were identified as promising feedstocks for bio-oil production based on their calorific values (>20 MJ/kg). Sawdust exhibited favorable characteristics for bio-oil production as indicated by its higher volatile matter (79.28%), low ash content (1.53%), low moisture content (6.18%), and high fixed carbon content (13.01%). Also, all samples showed favorable ignition and flammability properties. The low nitrogen (<0.12%) and sulfur (<0.04%) contents in the samples make them environmentally benign fuels as a lower percentage of NOx and SOx will be released during the production of the bio-oil. These results are contributions to the advancement of a sustainable and efficient carbon-neutral energy mix, promoting biomass resource utilization for the generation of energy.

8.
Ir J Med Sci ; 189(1): 327-332, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31197576

RESUMEN

BACKGROUND: Throughout the developed world, the introduction of rotavirus vaccination has led to reductions in the incidence and severity of acute gastroenteritis (AGE) in young children and consequently to reductions in paediatric emergency department (PED) attendances with AGE. Rotavirus vaccination was added to the Irish National Immunisation Schedule in November 2016. AIMS: To assess the impact of vaccine introduction on citywide PED attendances and hospital admissions with all-cause AGE during rotavirus season. METHODS: In an observational study, a retrospective search was performed of electronic records in three independent PEDs in Dublin. Weekly presentations and admissions with AGE in the first 30 weeks (gastroenteritis season) of the years 2012-2018 were counted and stratified by age. RESULTS: Median weekly presentations in 2017-2018, 126 (interquartile range (IQR) 103-165) were significantly lower than in 2012-2016, 160 (IQR 128-214) (p < 0.001). A reduction in presentations was seen across the three hospitals and in those aged less than 5 years. In one PED, median admissions in 2017-2018 were 10 (IQR 7-13) in comparison with nine (IQR 7-13) in 2012-2016, (p = 0.463). The emergency department AGE presentations to hospital ward admission rate was 6.7:1. CONCLUSION: A reduction in PED presentations with AGE is demonstrated post-rotavirus vaccine introduction into the Irish National Immunisation Schedule. No significant change in paediatric hospital admissions was demonstrated.


Asunto(s)
Gastroenteritis/prevención & control , Medicina de Urgencia Pediátrica/normas , Infecciones por Rotavirus/prevención & control , Vacunas contra Rotavirus/uso terapéutico , Rotavirus/patogenicidad , Adolescente , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Estudios Retrospectivos , Vacunas contra Rotavirus/farmacología
9.
BMJ Open Qual ; 8(3): e000445, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31523725

RESUMEN

Infection is the most frequent indication for non-scheduled admission to paediatric hospitals, leading to high levels of empiric antibiotic prescribing. Antibiotic prescribing in line with local guidelines, improves patient outcomes, reduces adverse drug events and helps to reduce the emergence of antimicrobial resistance. We undertook an improvement project at Temple Street Children's University Hospital targeting documentation of indication and compliance with empiric antibiotic prescribing guidelines among medical admissions via the emergency department (ED). Results of weekly audits of empiric antibiotic prescribing were fed back to prescribers. Front-line ownership techniques were used to empower prescribers to generate ideas for change, such as regular discussion of antibiotic prescribing issues at weekly clinical meetings, antibiotic 'spot quiz', updates to prescribing guidelines, improved access and promotion of a prescribing app, laminated guideline summary cards, and reminders and guideline summaries at a point of prescribing in ED. Documentation of indication and guideline compliance increased from a median of 30% in December 2014 to 100% in March 2015, and was sustained at 100% to September 2016, then 90% to December 2017. The intervention was associated with improvements in non-targeted indicators of prescribing quality, an overall reduction in antimicrobial consumption in the hospital, and a €105 000 reduction in annual antimicrobial acquisition costs. We found that a simple, paper-based, data collection system was effective, provided opportunities for a point-of-care interaction with prescribers, and facilitated weekly data feedback. We also found that using a pre-existing weekly clinical meeting to foster prescriber ownership of the data, allowing prescribers to identify possible tests of change, and exploiting the competitive nature of doctors, led to a rapid and sustained improvement in prescribing quality. Awareness of local prescribing processes and culture are essential to delivering improvements in antimicrobial stewardship.

10.
J R Soc Interface ; 16(154): 20190063, 2019 05 31.
Artículo en Inglés | MEDLINE | ID: mdl-31113333

RESUMEN

The recent unexpected discovery of thrombosis in transcatheter heart valves (THVs) has led to increased concerns of long-term valve durability. Based on the clinical evidence combined with Virchow's triad, the primary hypothesis is that low-velocity blood flow around the valve could be a primary cause for thrombosis. However, due to limited optical access in such unsteady three-dimensional biomedical flows, measurements are challenging. In this study, for the first time, we employ a novel single camera volumetric velocimetry technique to investigate unsteady three-dimensional cardiovascular flows. Validation of the novel volumetric velocimetry technique with standard planar particle image velocimetry (PIV) technique demonstrated the feasibility of adopting this new technique to investigate biomedical flows. This technique was used to quantify the three-dimensional velocity field in the vicinity of a validated, custom developed, transparent THV in a bench-top pulsatile flow loop. Large volumetric regions of flow stagnation were observed in the neo-sinus throughout the cardiac cycle, with stagnation defined as a velocity magnitude lower than 0.05 m s-1. The volumetric scalar viscous shear stress quantified via the three-dimensional shear stress tensor was within the range of low shear-inducing thrombosis observed in the literature. Such high-fidelity volumetric quantitative data and novel imaging techniques used to obtain it will enable fundamental investigation of heart valve thrombosis in addition to providing a reliable and robust database for validation of computational tools.


Asunto(s)
Prótesis Valvulares Cardíacas , Modelos Cardiovasculares , Diseño de Prótesis , Estrés Mecánico , Trombosis/fisiopatología , Velocidad del Flujo Sanguíneo , Humanos , Flujo Pulsátil , Trombosis/etiología
11.
Ann Biomed Eng ; 45(2): 405-412, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-27164838

RESUMEN

Valve-in-valve transcatheter aortic valve replacement (VIV-TAVR) has proven to be a successful treatment for high risk patients with failing aortic surgical bioprostheses. However, thrombus formation on the leaflets of the valve has emerged as a major issue in such procedures, posing a risk of restenosis, thromboembolism, and reduced durability. In this work we attempted to understand the effect of deployment position of the transcatheter heart valve (THV) on the spatio-temporal flow field within the sinus in VIV-TAVR. Experiments were performed in an in vitro pulsatile left heart simulator using high-speed Particle Image Velocimetry (PIV) to measure the flow field in the sinus region. The time-resolved velocity data was used to understand the qualitative and quantitative flow patterns. In addition, a particle tracking technique was used to evaluate relative thrombosis risk via sinus washout. The velocity data demonstrate that implantation position directly affects sinus flow patterns, leading to increased flow stagnation with increasing deployment height. The particle tracking simulations showed that implantation position directly affected washout time, with the highest implantation resulting in the least washout. These results clearly demonstrate the flow pattern and flow stagnation in the sinus is sensitive to THV position. It is, therefore, important for the interventional cardiologist and cardiac surgeon to consider how deployment position could impact flow stagnation during VIV-TAVR.


Asunto(s)
Prótesis Valvulares Cardíacas , Modelos Cardiovasculares , Seno Aórtico/fisiopatología , Seno Aórtico/cirugía , Reemplazo de la Válvula Aórtica Transcatéter , Velocidad del Flujo Sanguíneo , Humanos
12.
Ann Biomed Eng ; 45(5): 1305-1314, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-28091966

RESUMEN

An incompetent aortic valve (AV) results in aortic regurgitation (AR), where retrograde flow of blood into the left ventricle (LV) is observed. In this work, we parametrically characterized the detailed changes in intra-ventricular flow during diastole as a result of AR in a physiological in vitro left-heart simulator (LHS). The loss of energy within the LV as the level of AR increased was also assessed. The validated LHS consisted of an optically-clear, flexible wall LV and a modular AV holder. Two-component, planar, digital particle image velocimetry was used to visualize and quantify intra-ventricular flow. A large coherent vortical structure which engulfed the whole LV was observed under control conditions. In the cases with AR, the regurgitant jet was observed to generate a "kinematic obstruction" between the mitral valve and the LV apex, preventing the trans-mitral jet from generating a coherent vortical structure. The regurgitant jet was also observed to impinge on the inferolateral wall of the LV. Energy dissipation rate (EDR) for no, trace, mild, and moderate AR were found to be 1.15, 2.26, 3.56, and 5.99 W/m3, respectively. This study has, for the first time, performed an in vitro characterization of intra-ventricular flow in the presence of AR. Mechanistically, the formation of a "kinematic obstruction" appears to be the cause of the increased EDR (a metric quantifiable in vivo) during AR. EDR increases non-linearly with AR fraction and could potentially be used as a metric to grade severity of AR and develop clinical interventional timing strategies for patients.


Asunto(s)
Insuficiencia de la Válvula Aórtica/fisiopatología , Ventrículos Cardíacos/fisiopatología , Modelos Cardiovasculares , Obstrucción del Flujo Ventricular Externo/fisiopatología , Animales , Fenómenos Biomecánicos , Velocidad del Flujo Sanguíneo , Porcinos
13.
J Biomech ; 49(4): 618-23, 2016 Feb 29.
Artículo en Inglés | MEDLINE | ID: mdl-26895781

RESUMEN

Diastolic fluid dynamics in the left ventricle (LV) has been examined in multiple clinical studies for understanding cardiac function in healthy humans and developing diagnostic measures in disease conditions. The question of how intraventricular filling vortex flow pattern is affected by increasing heart rate (HR) is still unanswered. Previous studies on healthy subjects have shown a correlation between increasing HR and diminished E/A ratio of transmitral peak velocities during early filling (E-wave) to atrial systole (A-wave). We hypothesize that with increasing HR under constant E/A ratio, E-wave contribution to intraventricular vortex propagation is diminished. A physiologic in vitro flow phantom consisting of a LV physical model was used for this study. HR was varied across 70, 100 and 120 beats per minute (bpm) with E/A of 1.1-1.2. Intraventricular flow patterns were characterized using 2D particle image velocimetry measured across three parallel longitudinal (apical-basal) planes in the LV. A pair of counter-rotating vortices was observed during E-wave across all HRs. With increasing HR, diminished vortex propagation occurred during E-wave and atrial systole was found to amplify secondary vorticity production. The diastolic time point where peak vortex circulation occurred was delayed with increasing HR, with peak circulation for 120bpm occurring as late as 90% into diastole near the end of A-wave. The role of atrial systole is elevated for higher HR due to the limited time available for filling. Our baseline findings and analysis approach can be applied to studies of clinical conditions where impaired exercise tolerance is observed.


Asunto(s)
Función Atrial , Frecuencia Cardíaca/fisiología , Hemodinámica , Modelos Cardiovasculares , Sístole/fisiología , Función Ventricular Izquierda , Humanos
14.
Ann Thorac Surg ; 101(5): 1759-65, 2016 May.
Artículo en Inglés | MEDLINE | ID: mdl-26806168

RESUMEN

BACKGROUND: Durability and hemodynamic performance are top considerations in selecting a valve for valve replacement surgery. This study was conducted in order to evaluate the long-term mechanical durability and hydrodynamic performance of the Carpentier-Edwards PERIMOUNT Magna Ease Bioprostheses, through 1 billion cycles (equivalent to 25 years). METHODS: In vitro valve hydrodynamic performance, durability, and quantitative flow visualization were conducted in accordance with ISO 5840:2005 heart valve standard. The study valves were subjected to accelerated valve cycling to an equivalent of 25 years of wear. Hydrodynamic evaluations at intervals of 100 million cycles (2.5 years) were performed on the study valves. New uncycled Magna Ease valves were used as hydrodynamic controls in this study. A quantitative assessment of the fluid motion downstream of the control and study valves was performed using particle image velocimetry. The results between the test and control valves were compared to assess valve performance after an equivalent of 25 years of wear. RESULTS: All study valves met the ISO 5840 requirements for effective orifice area, 1.81 ± 0.06 cm(2) and 2.06 ± 0.17 cm(2), and regurgitant fraction, 1.11% ± 0.87% and 2.5% ± 2.34%, for the 21 mm and 23 mm study valves, respectively. The flow characterization of the control valves and the billion-cycle valves demonstrated that the valves exhibited similar flow characteristics. The velocity and shear stress fields were similar between the control and study valves. CONCLUSIONS: The Magna Ease valves demonstrated excellent durability and hydrodynamic performance after an equivalent of 25 years of simulated in vitro wear. All study valves successfully endured 1 billion cycles of simulated wear, 5 times longer than the standard requirement for a tissue valve as stipulated in ISO 5840.


Asunto(s)
Bioprótesis , Prótesis Valvulares Cardíacas , Humanos , Hidrodinámica , Estrés Mecánico
15.
JACC Cardiovasc Interv ; 9(15): 1618-28, 2016 08 08.
Artículo en Inglés | MEDLINE | ID: mdl-27491613

RESUMEN

OBJECTIVES: The purpose of this study was to optimize hemodynamic performance of valve-in-valve (VIV) according to transcatheter heart valve (THV) type (balloon vs. self-expandable), size, and deployment positions in an in vitro model. BACKGROUND: VIV transcatheter aortic valve replacement is increasingly used for the treatment of patients with a failing surgical bioprosthesis. However, there is a paucity in understanding the THV hemodynamic performance in this setting. METHODS: VIV transcatheter aortic valve replacement was simulated in a physiologic left heart simulator by deploying a 23-mm SAPIEN, 23-mm CoreValve, and 26-mm CoreValve within a 23-mm Edwards PERIMOUNT surgical bioprosthesis. Each THV was deployed into 5 different positions: normal (inflow of THV was juxtaposed with inflow of surgical bioprosthesis), -3 and -6 mm subannular, and +3 and +6 mm supra-annular. At a heart rate of 70 bpm and cardiac output of 5.0 l/min, mean transvalvular pressure gradients (TVPG), regurgitant fraction (RF), effective orifice area, pinwheeling index, and pullout forces were evaluated and compared between THVs. RESULTS: Although all THV deployments resulted in hemodynamics that would have been consistent with Valve Academic Research Consortium-2 procedure success, we found significant differences between THV type, size, and deployment position. For a SAPIEN valve, hemodynamic performance improved with a supra-annular deployment, with the best performance observed at +6 mm. Compared with a normal position, +6 mm resulted in lower TVPG (9.31 ± 0.22 mm Hg vs. 11.66 ± 0.22 mm Hg; p < 0.01), RF (0.95 ± 0.60% vs. 1.27 ± 0.66%; p < 0.01), and PI (1.23 ± 0.22% vs. 3.46 ± 0.18%; p < 0.01), and higher effective orifice area (1.51 ± 0.08 cm(2) vs. 1.35 ± 0.02 cm(2); p < 0.01) at the cost of lower pullout forces (5.54 ± 0.20 N vs. 7.09 ± 0.49 N; p < 0.01). For both CoreValve sizes, optimal deployment was observed at the normal position. The 26-mm CoreValve, when compared with the 23-mm CoreValve and 23-mm SAPIEN, had a lower TVPG (7.76 ± 0.14 mm Hg vs. 10.27 ± 0.18 mm Hg vs. 9.31 ± 0.22 mm Hg; p < 0.01) and higher effective orifice area (1.66 ± 0.05 cm(2) vs. 1.44 ± 0.05 cm(2) vs. 1.51 ± 0.08 cm(2); p < 0.01), RF (4.79 ± 0.67% vs. 1.98 ± 0.36% vs. 0.95 ± 1.68%; p < 0.01), PI (29.13 ± 0.22% vs. 6.57 ± 0.14% vs. 1.23 ± 0.22%; p < 0.01), and pullout forces (10.65 ± 0.66 N vs. 5.35 ± 0.18 N vs. 5.54 ± 0.20 N; p < 0.01). CONCLUSIONS: The optimal deployment location for VIV in a 23 PERIMOUNT surgical bioprosthesis was at a +6 mm supra-annular position for a 23-mm SAPIEN valve and at the normal position for both the 23-mm and 26-mm CoreValves. The 26-mm CoreValve had lower gradients, but higher RF and PI than the 23-mm CoreValve and the 23-mm SAPIEN. In their optimal positions, all valves resulted in hemodynamics consistent with the definitions of Valve Academic Research Consortium-2 procedural success. Long-term studies are needed to understand the clinical impact of these hemodynamic performance differences in patients who undergo VIV transcatheter aortic valve replacement.


Asunto(s)
Válvula Aórtica/cirugía , Bioprótesis , Prótesis Valvulares Cardíacas , Hemodinámica , Reemplazo de la Válvula Aórtica Transcatéter/instrumentación , Válvula Aórtica/fisiopatología , Valvuloplastia con Balón , Humanos , Modelos Anatómicos , Modelos Cardiovasculares , Diseño de Prótesis , Reemplazo de la Válvula Aórtica Transcatéter/efectos adversos
18.
Thromb Res ; 134(1): 63-7, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24821370

RESUMEN

Low circulating protein C (PC) levels have been observed in sepsis, especially in patients with Neisseriae Meningitides infections. Poor clinical outcome and high limb amputation rates have been associated in infected patients with low circulating PC levels. Published studies using activated PC replacement therapy patients with sepsis have shown reduced mortality rates, however, its use has been associated with severe bleeding events. Paediatric sepsis studies using non-activated plasma-derived PC (Ceprotin®) are lacking. We present a retrospective study in children with sepsis who were treated with Ceprotin® focusing on amputation rate post treatment. Thirty subjects were identified. Median age at diagnosis was 2 years. Twenty-one (70%) were treated for Nesseria Meningitides and one (3%) for Streptococcus-A ß-haemolyticus, another 8 (26%) patients with malignancies were treated for neutropenic sepsis. Following Ceprotin® administration, a significant increase in leukocyte count (p=0.004), neutrophil count (p=0.001) and PC (pretreatment=13%, posttreatment=88.5%; p=0.0001) was seen. Prothrombin time (pretreatment =30.3 seconds, posttreatment =16.5; p=0.000) and activated partial thromboplastin time (pretreatment =61.8 sec, postreatment =42.6 sec; p=0.000) were significantly reduced, while fibrinogen levels were significantly elevated (pretreatment =1.9 g/dL, posttreatment =4.4 g/dL; p=0.000). The median time between admission to intensive care and Ceprotin® administration was 10 hrs. Limb amputation rate was reduced (16-23% versus 30-50% from previous studies) and there were no haemorrhagic events observed. This study demonstrates the safe administration of non-activated plasma-derived PC concentrate in patients with sepsis who are coagulopathic and it associated with a reduction in amputation rates.


Asunto(s)
Amputación Quirúrgica/métodos , Proteína C/metabolismo , Sepsis/sangre , Sepsis/cirugía , Adolescente , Niño , Preescolar , Femenino , Humanos , Lactante , Recuento de Leucocitos , Masculino , Meningitis Meningocócica/sangre , Meningitis Meningocócica/tratamiento farmacológico , Neisseria meningitidis/aislamiento & purificación , Estudios Retrospectivos , Sepsis/tratamiento farmacológico , Sepsis/microbiología
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