INTRODUÇÃO: Instabilidade hemodinâmica é uma condição comum nos pacientes críticos e usualmente associada aos quadros de choque. O débito cardíaco (DC) é o principal determinante da oferta de oxigênio, e uma importante variável a ser monitorizada nestes pacientes. A diferença arterio-venosa central de dióxido de carbono (△pCO2), é um índice que mostrou-se correlacionar inversamente com o DC em diversos estudos. OBJETIVOS: O objetivo deste estudo é avaliar o valor prognóstico do △pCO2 (utilizando uma amostra venosa central) em uma série heterogênea de pacientes com instabilidade hemodinâmica. MÉTODOS: Estudo prospectivo observacional conduzido em uma UTI geral de 18 leitos do Complexo Hospitalar da Santa Casa de Porto Alegre. Variáveis hemodinâmicos, coleta de gasometria arterial e venosa central, e lactato, foram realizadas na admissão e após 6, 12, 18 e 24 horas. A gravidade da doença foi avaliada pelo escore APACHE II e a a severidade da disfunção orgânica pelo escore SOFA. RESULTADOS: 60 pacientes foram analisados. A mortalidade ao fim de 28 dias foi de 43% (26/60). Não se observou diferença entre os valores médios de △pCO2 entre sobreviventes e óbitos em 28 dias. O tempo de permanência na UTI foi maior entre os pacientes com um △pCO2 “alargado”. Os valores médios de saturação venosa central de oxigênio (SvcO2) foram maiores no subgrupo de pacientes com △pCO2 normal. CONCLUSÃO: Este estudo mostrou que o △pCO2, em pacientes com instabilidade hemodinâmica, está relacionado com desfecho secundários importantes como uma maior permanência em UTI. A explicação fisiológica para isso deve-se a uma maior redução no fluxo sanguíneo (como sugerido por uma SvcO2 mais baixa) causando uma oferta inadequada de oxigênio na fase aguda da doença, resultando em maior tempo de recuperação. / BACKGROUND: Hemodynamic instability is a common condition in critically ill patients and is usually associated with shock. Cardiac output (CO) is the major determinant of oxygen supply and an important variable to be monitored in these patients. The venousarterial difference of partial pressure of carbon dioxide (△pCO2) ,is an index that have shown to be inversely correlate with the CO in several studies. OBJECTIVES: This study aims to evaluate the prognostic value of the △pCO2 (using a central venous sample) in a heterogeneous series of critically ill patients with hemodynamic instability. METHODS: A prospective observational clinical study was conducted in a 18-bed general ICU of the Santa Casa de Porto Alegre Hospital Complex. Hemodynamic measurements, collection of arterial and central venous blood gases, and lactate were performed on admission and after 6 , 12, 18 and 24 hours.The severity of patient’s disease was evaluated by the APACHE II score and the level of organic disfunction was evaluated by the SOFA score. RESULTS: A total of 60 patients were analyzed. The mortality rate at 28 days was 43% (26/60). There was no difference observed in mean △pCO2 between deaths and survivors after 28 days.The ICU stay was longer among patients with “enlarged” △pCO2.Mean central venous oxygen saturation values were higher in patients with normal △pCO2. CONCLUSION: This study showed that the △pCO2 in patients with hemodynamic instability is correlated with important secondary outcomes like higher ICU stay. The physiologic explanation is a reduction on blood flow (as suggested by lower ScvO2) causing a inadequate oxygen tissue delivery in the acute phase of the disease, resulting in a greater recovery time.

O treinamento de caminhada (TC) é recomendado para o tratamento de indivíduos com claudicação intermitente (CI) porque melhora a capacidade de caminhada. Além disso, seria interessante que o TC também promovesse modificações benéficas no sistema cardiovascular, pois os eventos cardiovasculares são a principal causa de morte nestes indivíduos. No entanto, os efeitos cardiovasculares do TC em indivíduos com CI foi pouco estudado. Assim, o objetivo deste estudo foi verificar o efeito do TC sobre o risco, a função e a regulação cardiovasculares em indivíduos com CI. Quarenta e dois indivíduos com CI foram divididos de forma aleatória em 2 grupos: controle (GC, n=20, sessões de 30 min de alongamento) e treinamento de caminhada (GT, n=22, 15 séries de 2 min de caminhada em intensidade correspondente à frequência cardíaca (FC) do limiar de dor intercalados por 2 min de repouso passivo). Nos dois grupos, a intervenção foi realizada 2 vezes/semana durante 12 semanas consecutivas. No início e ao final do estudo, os indivíduos realizaram as seguintes avaliações: glicemia e perfil lipídico de jejum; índice de massa corporal; capacidade de caminhada; consumo de oxigênio no 1º estágio e no pico do teste de esforço; índice tornozelo-braço (ITB) de repouso; janela isquêmica após teste ergoespirométrico; pressão arterial (PA) em repouso (auscultatória) e de 24 horas (oscilométrica); débito cardíaco (DC - reinalação de CO2); FC (ECG); volume sistólico (VS); resistência vascular (RV) sistêmica, do antebraço e da perna (plestismografia); componentes de alta (AF) e baixa (BF) frequência da variabilidade da FC; e sensibilidade barorreflexa espontânea (SBR). Mudanças significantes (P<0,05) ao longo do tempo e entre os grupos foram verificadas pela análise de variância ANOVA de dois fatores para medidas repetidas. O TC aumentou significantemente a capacidade de caminhada (&Delta;=+302±85m) e a SBR (&Delta;=+2.13±1.07 ms/mmHg), e diminuiu o VO2) no 1º estágio do teste (&Delta;=-1,8±0,4ml.kg-1.min-1), a janela isquêmica (&Delta;=- 0,40±0,38mmHg.min.m-1), a PA média (&Delta;=-5±2mmHg), a variabilidade da PA média de 24h (&Delta;=-0,8±0,2mmHg), o DC (&Delta;=-0.37±0.24L/min), a FC (&Delta;=- 4±2bpm), a RV do antebraço (&Delta;=-8.5±2.8 U) e a razão BF/AF (&Delta;=-1.24±0.99). A glicemia, o perfil lipídico, o índice de massa corporal, o VO2) pico, o ITB de repouso e a RV sistêmica e da perna não foram modificadas pelo TC. Não houve mudança em nenhuma variável no GC. Em conclusão, o TC melhorou a capacidade de caminhada, a economia de caminhada e a janela isquêmica. Além disso, o TC melhorou a função (PA, DC, FC e RV antebraço) e a regulação (BF/AF e SBR) cardiovasculares em indivíduos com CI. Estas alterações fornecem suporte adicional para a utilização do TC no tratamento de indivíduos com CI / Walking training (WT) is recommended for the treatment of patients with intermittent claudication (IC) because it improves walking capacity. Moreover, it would be interesting that WT also promotes beneficial changes on cardiovascular system, since cardiovascular events are the main causes of death in these patients. Nevertheless, the effects of WT on cardiovascular system in patients with IC have been poorly studied. Thus, the objective of this study was to investigate the effects of WT on cardiovascular risk, function and regulation in patients with IC. Forty-two IC patients were randomly divided into 2 groups: Control (CG, n=20, 30 min of stretching exercises) and walking training (TG, n=22, 15 sets of 2:2-min walk:rest at the heart rate (HR) of pain threshold). In both groups, the intervention was performed twice/week for 12 consecutive weeks. At the beginning and end of the study, the following measured were done: fasting glycemia and lipid profile; body mass index; walking capacity; VO2 at the first stage and the peak of a treadmill test; ankle brachial index (ABI); ischemic window after maximal test; resting (auscultatory) and 24-hour (oscillometric) blood pressure (BP); cardiac output (CO - CO2 rebreathing); heart rate (HR - ECG); stroke volume (SV); systemic, forearm and leg vascular resistance (VR - plethysmography); low- (LF) and high-frequency (HF) components of HR variability; and spontaneous baroreflex sensitivity (SBS). Significant changes (P<0.05) over time and between groups were assessed by 2-way ANOVA for repeated measures. WT significantly increased walking capacity (&Delta;=+302±85m) and SBS (&Delta;=+2.13±1.07 ms/mmHg), and decreased VO2 at the first stage of treadmill test (&Delta;=-1.8±0.4ml.kg-1.min-1), ischemic window (&Delta;=-0.40±0.38mmHg.min.m-1), mean BP (&Delta;=-5±2mmHg), ambulatory mean BP variability (&Delta;=-0,8±0,2 mmHg), CO (&Delta;=-0.37±0.24 L/min), HR (&Delta;=- 4±2bpm), forearm VR (&Delta;=-8.5±2.8 U) and LF/HF (&Delta;=-1.24±0.99). Glycemia, lipid profile, body mass index, VO2 peak, ABI, systemic and leg VR were unchanged following WT. There was no significant change for any variable in CG. In conclusion, WT enhanced walking capacity, walking economy and ischemic window. In addition, WT improved cardiovascular function (BP, CO, HR and forearm VR) and autonomic regulation (LF/HF, SBS) in patients with IC. These changes provide further support for the use of regular WT in treating patients with IC

Submitted by Nadir Basilio (nadirsb@uninove.br) on 2016-05-17T20:28:42Z No. of bitstreams: 1 Fabio Spacassassi.pdf: 735389 bytes, checksum: 05a5852fd59601a5f2553e9da68da954 (MD5) / Made available in DSpace on 2016-05-17T20:28:42Z (GMT). No. of bitstreams: 1 Fabio Spacassassi.pdf: 735389 bytes, checksum: 05a5852fd59601a5f2553e9da68da954 (MD5) Previous issue date: 2015-06-30 / A day-to-day activity as a professional firefighter leads you to a physical and psychological risk constantly. These stressful situations may cause to this professional a physiological disorder that chronically can lead to the onset of other cardiovascular diseases. Our proposal was the identification of the type of stress and its symptoms, and the hemodynamic and metabolic alterations that can effect from daily routine experiences throughout its operational career. The study compared a group of firefighters GB (n = 52), working in the operational business for over 5 years, with a control group, CO (n = 52), representing the general population. These two groups were composed by healthy volunteers who concluded a clinical evaluation before applying the tests. Data were matched by age, sex and race and calculated by weight, height, body mass index and anthropometric measurements of neck circumference, waist circumference, hip circumference and waist-hip ratio. The autonomic evaluation was performed by the frequency meter Polar device (model RS800) through the heart rate variability evaluated in time (SDNN, RMSSD and variance) and frequency (HF, LF and HF / LF) domain. The stress rate was performed by psychosocial adjustment scale Holmes-Rahe via a score that classifies the probability of potential professional illness. The hemodynamic evaluation was performed by non-invasive indirect technique with Hypertension Diagnosis Incorporation (H.D.I), with the variables systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), pulse pressure, cardiac output (CO), impedance, systemic vascular resistance (SVR) and elasticity index of large and small arteries. Commercial kits were used for biochemical data (total cholesterol, triglycerides, HDL-C, LDL-C, creatinine, uric acid, urea and glucose). It was verified that the autonomic assessment indexes SDNN (39.5 ± 3.0 ms), VARR (1734.4 ± 238.9 ms2) and RMSSD (23.5 ± 2.4 ms) were significantly lower (p<0.05) in GB than CO: SDNN (59.9 ± 5.6 ms), VARR (4108.3 ± 752.4 ms2), RMSSD (45.1 ± 7.8 ms), and higher for GB LF/HF (3.6 ± 0.4) than CO (2.3 ± 0.2). For the stress perception there was no difference between groups. The Hemodynamic data was significantly higher (p<0.05) for the GB with SBP (131.1 ± 1.8 seg/cm5), FC (81.2 ± 1.6 bpm), SVR (1234 ± 23.8 seg/cm5), impedance (125.0 ± 5.9 seg/cm5) and DC (5.7 ± 0.09 L/min ) in relation to CO which showed systolic blood pressure (125 ± 16.8 mmhg), FC (71.1 ± 1.4 bpm), SVR (1141 ± 32.5 seg/cm5), impedance (104.5 ± 3.9 seg/cm5), DC (5.0 ± 0.1 L/min) and biochemistry profile with significantly higher (p<0.05) values for the GB in CT (203 ± 4.9 mg/dL), HDL (47.6 ± 1.4 mg/dL), creatinine (1.1 ± 0.09 mg/dL) and glucose (99.0 ± 2.4 mg/dL) than CO with CT (163.5 ± 4.5 mg/dL), HDL (39.8 ± 1.5 mg/dL), creatinine (1,0 ± 0,02 mg/dL) and glucose (89,8 ± 1,1 mg/dL). Through the results it was concluded that the autonomic balance was worst in the firefighter than in control group. The results of anthropometric, hemodynamic and metabolic profile also were worst in the firefighters. It suggests a possible susceptibility for cardiovascular disease development in firefighters. / O bombeiro tem em sua rotina diária situações que o coloca em risco físico e psicológico constantemente. Essas situações são agentes estressores que fazem com que este profissional seja suscetível a alterações de ordem fisiológicas, que de forma crônica podem levar ao aparecimento de doenças como as de origem cardiovascular. A nossa proposta foi identificar se o estresse pode resultar em alterações autonômicas, hemodinâmicas e metabólicas em bombeiros. Foi feita a comparação de um grupo de bombeiros denominado GB (n=52), que trabalha na atividade operacional há mais de 5 anos, com um grupo controle, denominado CO (n=52), representando a população em geral. Os dois grupos foram voluntários sadios que passaram por uma avaliação clínica antes da aplicação de todos os testes. Os dados foram pareados pela idade, sexo e raça e realizado medida de peso, altura, índice de massa corpórea, circunferência cervical, circunferência abdominal, circunferência do quadril e relação cintura-quadril. A avaliação autonômica foi feita pelo aparelho frequencímetro Polar (modelo RS800), por meio da avaliação da variabilidade da frequência cardíaca no domínio do tempo (SDNN, RMSSD e Variância) e da frequência (HF, LF e relação HF/LF). A percepção do estresse foi realizada pela escala de reajustamento psicossocial Holmes-Rahe por um escore que classifica a probabilidade de adoecimento do profissional. A avaliação hemodinâmica foi realizada pela técnica indireta não invasiva com o Hypertension Diagnosis Incorporation (H.D.I), pelas variáveis pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), pressão arterial média (PAM), frequência cardíaca (FC), pressão de pulso, débito cardíaco (DC), impedância, resistência vascular sistêmica (RVS) e índice de elasticidade de pequenas e grandes artérias. Os dados bioquímicos para o perfil metabólico (colesterol total, triglicérides, HDL-colesterol, LDL-coleserol, creatinina, ácido úrico, ureia e glicose) foram feitos por Kits comerciais. Os índices de SDNN (39,5 ± 3,0 ms), VARR (1734,4 ± 238,9 ms2) e RMSSD (23,5 ± 2,4 ms) na avaliação autonômica foram significativamente menores (p<0,05) no GB do que o CO: SDNN (59,9 ± 5,5 ms), VARR (4108,3 ± 752,4 ms2) e RMSSD (45,1 ± 7,8 ms). O componente LF/HF foi maior no GB (3,6 ± 0,4) do que no CO (2,3 ± 0,2). Em relação a percepção do estresse não houve diferença entre os grupos. Os dados hemodinâmicos: PAS (131,1 ± 1,8 mmHg), FC (81,2 ± 1,6 bpm), RVS (1.234 ± 23,8 seg/cm5), impedância (125.0 ± 5,9 seg/cm5) e DC (5,7 ± 0,1 L/min) foram significativamente maiores (p<0,05) para o GB em relação ao CO: PAS (125 ± 16,8 mmHg), FC (71,1 ± 1,4 bpm), RVS (1.141 ± 32,5 seg/cm5), impedância (104,5 ± 3,9 seg/cm5) e DC (5,1 ± 0,1 L/min). Em relação aos dados bioquímicos, os valores de colesterol total (203 ± 4,9 mg/dL), HDL (47,6 ± 1,4 mg/dL), creatinina (1,1 ± 0,09 mg/dL) e glicose (99,1 ± 2,4 mg/dL) foram significativamente maiores (p<0,05) no GB em relação ao CO: colesterol total (163,5 ± 4,5 mg/dL), HDL (39,8 ± 1,5 mg/dL), creatinina (1,0 ± 0,02 mg/dL) e glicose (89,8 ± 1,1 mg/dL). Os dados obtidos mostram um pior balanço autonômico, sobretudo no domínio do tempo, no GB. Os dados antropométricos, hemodinâmicos e o perfil metabólico também são piores no GB do que o CO. Os resultados obtidos nesse estudo apontam para uma possibilidade de maior risco cardiovascular nos bombeiros quando comparados com o grupo controle.

Infinite-Dimensional Systems (IDSs) which have been made possible by recent advances in mathematical and computational tools can be used to model complex real phenomena. However, due to physical, economic, or stringent non-invasive constraints on real systems, the underlying characteristics for mathematical models in general (and IDSs in particular) are often missing or subject to uncertainty. Therefore, developing efficient estimation techniques to extract missing pieces of information from available measurements is essential. The human brain is an example of IDSs with severe constraints on information collection from controlled experiments and invasive sensors. Investigating the intriguing modeling potential of the brain is, in fact, the main motivation for this work. Here, we will characterize the hemodynamic behavior of the brain using functional magnetic resonance imaging data. In this regard, we propose efficient estimation methods for two classes of IDSs, namely Partial Differential Equations (PDEs) and Fractional Differential Equations (FDEs). This work is divided into two parts. The first part addresses the joint estimation problem of the state, parameters, and input for a coupled second-order hyperbolic PDE and an infinite-dimensional ordinary differential equation using sampled-in-space measurements. Two estimation techniques are proposed: a Kalman-based algorithm that relies on a reduced finite-dimensional model of the IDS, and an infinite-dimensional adaptive estimator whose convergence proof is based on the Lyapunov approach. We study and discuss the identifiability of the unknown variables for both cases. The second part contributes to the development of estimation methods for FDEs where major challenges arise in estimating fractional differentiation orders and non-smooth pointwise inputs. First, we propose a fractional high-order sliding mode observer to jointly estimate the pseudo-state and input of commensurate FDEs. Second, we propose a modulating function-based algorithm for the joint estimation of the parameters and fractional differentiation orders of non-commensurate FDEs. Sufficient conditions ensuring the local convergence of the proposed algorithm are provided. Subsequently, we extend the latter technique to estimate smooth and non-smooth pointwise inputs. The performance of the proposed estimation techniques is illustrated on a neurovascular-hemodynamic response model. However, the formulations are efficiently generic to be applied to a wide set of additional applications.

Objectives: Adequate organ perfusion, as well as appropriate blood pressure levels at the time of unclamping, is crucial for early and long-term graft function and outcome in simultaneous pancreas–kidney transplantation (SPKT). However, the optimal intraoperative mean arterial pressure (MAP) level has not well been defined. Methods: From a prospectively collected database, the medical data of 105 patients undergoing SPKT at our center were retrospectively analyzed. A receiver operating characteristic (ROC) analysis was preliminarily performed for optimal cut-off value for MAP at reperfusion, to predict early pancreatic graft function. Due to these results, we divided the patients according to their MAP values at reperfusion into <91 mmHg (n = 47 patients) and >91 mmHg (n = 58 patients) groups. Clinicopathological characteristics and outcomes, as well as early graft function and long-term survival, were retrospectively analyzed. Results: Donor and recipient characteristics were comparable between both groups. Rates of postoperative complications were significantly higher in the <91 mmHg group than those in the >91 mmHg group (vascular thrombosis of the pancreas: 7 (14%) versus 2 (3%); p = 0.03; pancreatitis/intraabdominal abscess: 10 (21%) versus 4 (7%); p = 0.03; renal delayed graft function (DGF): 11 (23%) versus 5 (9%); p = 0.03; postreperfusion urine output: 106 ± 50 mL versus 195 ± 45 mL; p = 0.04). There were no significant differences in intraoperative volume repletion, central venous pressure (CVP), use of vasoactive inotropic agents, and the metabolic outcome. Five-year pancreas graft survival was significantly higher in the >91 mmHg group (>91 mmHg: 82% versus <91 mmHg: 61%; p < 0.01). No significant differences were observed in patient and kidney graft survival at 5 years between both groups. Multivariate Cox regression analysis affirmed MAP < 91 mmHg as an independent prognostic predictor for renal DGF (HR 3.49, 1.1–10.8, p = 0.03) and pancreas allograft failure (HR 2.26, 1.0–4.8, p = 0.01). Conclusions: A MAP > 91 mmHg at the time point of reperfusion was associated with a reduced rate of postoperative complications, enhancing and recovering long-term graft function and outcome and thus increasing long-term survival in SPKT recipients.

No description available.

No description available.

The ability to maintain balance is based on various processes of motor control in complex neural networks of subcortical and cortical brain structures. However, knowledge on brain processing during the execution of whole-body balance tasks is still limited. In the present study, we investigated brain activity during slacklining, a task with a high demand on balance capabilities, which is frequently used as supplementary training in various sports disciplines as well as for lower extremity prevention and rehabilitation purposes in clinical settings. We assessed hemodynamic response alterations in sensorimotor brain areas using functional near-infrared spectroscopy (fNIRS) during standing (ST) and walking (WA) on a slackline in 16 advanced slackliners. We expected to observe task-related differences between both conditions as well as associations between cortical activity and slacklining experience. While our results revealed hemodynamic response alterations in sensorimotor brain regions such as primary motor cortex (M1), premotor cortex (PMC), and supplementary motor cortex (SMA) during both conditions, we did not observe differential effects between ST and WA nor associations between cortical activity and slacklining experience. In summary, these findings provide novel insights into brain processing during a whole-body balance task and its relation to balance expertise. As maintaining balance is considered an important prerequisite in daily life and crucial in the context of prevention and rehabilitation, future studies should extend these findings by quantifying brain processing during task execution on a whole-brain level.

No description available.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Bioprosthetic heart valves (BHVs) for transcatheter aortic valve implantation (TAVI) have been rapidly developing over the last decade since the first valve replacement using the TAVI technique. TAVI is a minimally invasive valve replacement procedure offering lifesaving treatment to patients who are denied open heart surgery. The biomedical engineering research group at Stellenbosch University designed a 19 mm balloon expandable BHV for TAVI in 2007/8 for testing in animal trials. In the current study the valve was enlarged to 23 mm and 26 mm diameters. A finite element analysis was performed to aid in the design of the stents. New stencils were designed and manufactured for the leaflets using Thubrikar‟s equations as a guide. The 23 mm valve was manufactured and successfully implanted into two sheep. Fluid structure interaction (FSI) simulations constitute a large portion of this thesis and are being recognized as an important tool in the design of BHVs. Furthermore, they provide insight into the interaction of the blood with the valve, the leaflet dynamics and valve hemodynamic performance. The complex material properties, pulsating flow, large deformations and coupling of the fluid and the physical structure make this one of the most complicated and difficult research areas within the body. The FSI simulations, of the current valve design, were performed using a commercial programme called MSC.Dytran. A validation study was performed using data collected from a cardiac pulse duplicator. The FSI model was validated using leaflet dynamics visualisation and transvalvular pressure gradient comparison. Further comparison studies were performed to determine the material model to be used and the effect of leaflet free edge length and valve diameter on valve performance. The results from the validation study correlated well, considering the limitations that were experienced. However, further research is required to achieve a thorough validation. The comparative studies indicated that the linear isotropic material model was the most stable material model which could be used to simulate the leaflet behaviour. The free edge length of the leaflet affects the leaflet dynamics but does not greatly hinder its performance. The hemodynamic performance of the valve improves with an increase in diameter and the leaflet dynamics perform well considering the increased surface area and length. Many limitations in the software prevented more accurate material models and flow initiation to be implemented. These limitations significantly restricted the research and confidence in the results. Further investigation regarding the implementation of FSI simulations of a heart valve using the commercial software is recommended. / AFRIKAANSE OPSOMMING: Bio-prostetiese hartkleppe (Bioprosthetic Heart Valves - BHVs) wat gebruik word vir transkateter aortaklep-inplantings (Transcatheter Aortic Valve Implantation - TAVI) het geweldig vinnige ontwikkeling getoon in die afgelope tien jaar sedert die eerste klepvervanging wat van die TAVI prosedure gebruik gemaak het. TAVI is ʼn minimaal indringende klepvervangingsprosedure wat lewensreddende behandeling bied aan pasiënte wat ope-hart sjirurgie geweier word. Die Biomediese Ingenieurswese Navorsingsgroep (BERG) by Stellenbosch Universiteit het in 2007/8 ʼn 19 mm ballon-uitsetbare BHV vir TAVI ontwerp vir eksperimente met diere, en hierdie tesis volg op die vorige projekte. In die huidige studie is die klep vergroot na 23 mm en 26 mm in deursnee. ʼn Eindige element analise is gedoen om by te dra tot die ontwerp van die rekspalke vir die klep. Nuwe stensils is ontwerp en vervaardig vir die klepsuile, deur gebruik te maak van Thubrikar se vergelykings. Die 23 mm klep is vervaardig en suksesvol in twee skape ingeplant. Vloeistruktuur interaksie (Fluid Structure Interaction (FSI)) simulasies vorm ‟n groot deel van die tesis en word gesien as ʼn noodsaaklike hulpmiddel in die ontwerp van BHVs. Die simulasies verskaf ook insig in die interaksie van die bloed met die klep, die klepsuil-dinamika en die klep se hemodinamiese werkverrigting. Die komplekse materiaal eienskappe, polsende vloei, grootskaalse vervorming, die verbinding van die vloeistof en die fisiese struktuur maak van hierdie een van die mees gekompliseerde voorwerpe om te simuleer. Die FSI simulasies van die huidige ontwerp, is uitgevoer deur van kommersiële sagteware, MSC.Dytran, gebruik te maak. ʼn Geldigheidstudie wat data gebruik het vanaf die hartklop-nabootser, is uitgevoer. Die FSI model word geverifieer deur klepsuil dinamika visualisering en ʼn vergelyking van die drukgradiënt gebruik te maak. Verdere vergelykende studies is uitgevoer om te bepaal watter materiaal model om te gebruik, asook die uitwerking van die klepsuil-vrye rand en klepdeursnee op die klep se werkverrigting. Die resultate van die studie korreleer goed, in ag genome die beperkings wat ervaar is. Verdere navorsing is egter nodig vir ʼn volledige geldigheidstudie. Vergelykende studies het getoon dat die liniêre isotropiese materiaalmodel die meer stabiele materiaalmodel is wat kan gebruik word om klepsuilgedrag te simuleer. Die vrye-rand lengte van die klepsuil affekteer die dinamika van die klepsuil, maar belemmer nie die werkverrigting grootliks nie. Die hemodinamiese werkverrigting van die klep verbeter met die toename in deursnee en die klepsuil-dinamika vertoon goed in ag genome die verhoogde oppervlak area en lengte. Die vele beperkings in die sagteware het die implementering van meer akkurate materiaalmodelle verhoed. Hierdie beperkings het ʼn verminderde vertroue in die resultate tot gevolg gehad. Verdere ondersoek rakende die implementering van die FSI simulasies van ʼn hartklep deur kommersieel beskikbare sagteware te gebruik, word aanbevel.