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1.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(5): 737-744, 2019 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-31631621

RESUMO

This study aims to explore the effect of aortic sinus diameter on aortic valve opening and closing performance in the case of no obvious disease of aortic valve and annulus and continuous dilation of aortic root. A total of 25 three-dimensional aortic root models with different aortic sinus and root diameters were constructed according to the size of clinical surgical guidance. The valve sinus diameter DS is set to 32, 36, 40, 44 and 48 mm, respectively, and the aortic root diameter DA is set to 26, 27, 28, 29 and 30 mm, respectively. Through the structural mechanics calculation with the finite element software, the maximum stress, valve orifice area, contact force and other parameters of the model are analyzed to evaluate the valve opening and closing performance under the dilated state. The study found that aortic valve stenosis occurs when the DS = 32 mm, DA = 26, 27 mm and DS = 36 mm, DA = 26 mm. Aortic regurgitation occurs when the DS = 32, 36 and 40 mm, DA = 30 mm and DS = 44, 48 mm, DA = 29, 30 mm. The other 15 models had normal valve movement. The results showed that the size of the aortic sinus affected the opening and closing performance of the aortic valve. The smaller sinus diameter adapted with the larger root diameter and the larger sinus diameter adapted with the smaller root diameter. When the sinus diameter is 40 mm, the mechanical performance of the valve are good and it can well adapt with the relatively large range of aortic root dilation.


Assuntos
Aorta/anatomia & histologia , Insuficiência da Valva Aórtica/fisiopatologia , Estenose da Valva Aórtica/fisiopatologia , Valva Aórtica/fisiologia , Humanos
2.
Clin Interv Aging ; 14: 1379-1386, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31447550

RESUMO

Background: Both aortic valve stenosis and aortic stiffness are moderators of arterio ventricular coupling and independent predictors of cardiovascular morbidity and mortality. Studies on the effect of transcatheter aortic valve implantation (TAVI) on aortic functional properties are limited. We performed a study to investigate the possible short-term changes in aortic stiffness and other aortic functional properties after TAVI in older patients. Methods: TAVI Care&Cure is an observational ongoing study including consecutive patients undergoing a TAVI procedure. Central and peripheral hemodynamic measurements were measured non invasively 1 day before (T-1) and 1 day after (T+1) TAVI using a validated oscillometric method using a brachial cuff (Mobil-O-Graph). Results: 40 patients were included. Mean aortic valve area at baseline was 0.76±0.24 cm2. Indices of severity of aortic valve stenosis improved significantly. Systolic blood pressure (SBP) dropped by 8.5%, from 130.3±22.9 mmHg to 119.5±15.8 mmHg (p=0.005). Diastolic blood pressure (DBP) dropped by 13.1% from 74.8±14.5 mmHg to 65.0±11.3 mmHg (p<0.001). The arterial pulse wave velocity (aPWV) decreased from 12.05±1.99 m/s to 11.6±1.56 m/s (p=0.006). Patients with high aPWV at baseline showed a significantly larger reduction in SBP in comparison to patients with low aPWV: - 20.3 mmHg (-14.1%) vs - 3.1 mmHg (-2.6%), respectively (p=0.033). The same trend was found for the DBP: -16.2 (-20.4%) vs -4.5 mmHg (-6.3%) for high vs low aPWV at baseline (p=0.037). Conclusion: We found short-term changes in blood pressure and aortic stiffness after TAVI. The amplitude of the changes was the largest in patients with elevated aortic stiffness at baseline.


Assuntos
Estenose da Valva Aórtica/fisiopatologia , Estenose da Valva Aórtica/cirurgia , Valva Aórtica/fisiologia , Pressão Sanguínea/fisiologia , Substituição da Valva Aórtica Transcateter/métodos , Rigidez Vascular/fisiologia , Idoso , Idoso de 80 Anos ou mais , Aorta , Feminino , Próteses Valvulares Cardíacas , Implante de Prótese de Valva Cardíaca , Hemodinâmica , Humanos , Masculino , Análise de Onda de Pulso , Índice de Gravidade de Doença , Fatores de Tempo , Resultado do Tratamento
3.
Georgian Med News ; (290): 63-68, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31322517

RESUMO

Little is known about the gender differences of left ventricular (LV) remodeling in patients with aortic valve calcification (AVC). The aim was to assess gender differences of structure functional changes and LV myocardial remodeling in patients with AVC depending on the type of valve lesion. 293 patients (131 men) with revealed AVC by transthoracic echocardioscopy without aortic stenosis and 76 patients (50 men) without AVC were examined. Men had normal geometry of LV more often than women (15.7% vs. 4.4 % in isolated AVC and 11.9% vs. 2.8 % in combined lesion of aortic valve (AV) and mitral valves ring (MVR), р<0.052), and eccentric hypertrophy was registered more often in man with combined AV and MVR lesion (38.1% vs. 15.5 % in women with combined AV and MVR lesion and vs. 20.2 % in men with isolated AVC, р<0.029). LV systolic function was worse in men with combined valves lesion (ejection fraction was 54.0 (48.0; 65.0) vs. 66.0 (60.0; 71.0) % in women with combined valves lesion and vs. 63.0 (55.0; 70.0) % in men with isolated AVC, р<0.022). Men with combined valves lesion also had a larger right ventricle (RV) size (RV index was 1.3 (1.2; 1.5) vs. 1.2 (1.1; 1.4) cm/m2 in women with combined valves lesion and vs. 1.2 (1.1; 1.4) cm/m2 in men with isolated AVC, р<0.036) and had tricuspid regurgitation more often (76.2% vs. 56.3 % in women with combined valves lesion and vs. 58.4 % in men with isolated AVC, р<0.029). Women had higher peak aortic jet velocity (1.5 (1.4; 1.7) vs. 1.4 (1.2; 1.6) m/s in man, р<0.0001). Dominating models of LV remodeling in women were concentric, mainly concentric hypertrophy (61.5% vs. 31.5 % in men in groups with isolated AVC and 64.8% vs. 31.0 % in combined valves lesion groups, р<0.001). Also women had a higher left auricle index than men (2.3 (2.0; 2.5) vs. 2.1 (1.9; 2.4) cm/m2, р<0.015). There were revealed differences in distribution of LV remodeling types depending on the gender and the type of valve lesion.


Assuntos
Estenose da Valva Aórtica/patologia , Estenose da Valva Aórtica/cirurgia , Valva Aórtica/patologia , Calcinose/sangue , Função Ventricular Esquerda/fisiologia , Remodelação Ventricular , Idoso , Idoso de 80 Anos ou mais , Valva Aórtica/fisiologia , Valva Aórtica/cirurgia , Biomarcadores/sangue , Calcinose/complicações , Calcinose/patologia , Calcinose/fisiopatologia , Calcinose/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Sexuais
4.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(2): 199-205, 2019 Apr 25.
Artigo em Chinês | MEDLINE | ID: mdl-31016935

RESUMO

Valve transplantation is often used in the treatment of aortic valve insufficiency. However, after surgery, the reconstructed aortic roots have an expansion phenomenon, in which the lack of valve height causes the aortic valve to close again. In this paper, the effects of different aortic valve height design on valve opening and closing performance were studied. The optimal surgical plan was obtained by in vitro numerical simulation, providing technical support and theoretical basis. In this paper, six groups of three-dimensional geometric models with a valve height increment of ± 0.5 mm were established with a root diameter of 26.0 mm and a valve height of 14.0 mm. Through the structural mechanics calculation and analysis of the parameters such as maximum stress, valve area and contact force of the model, reasonable geometrical dimensions are obtained. The study found that the maximum stress values of the six groups of models ranged from 640 to 690 kPa, which was consistent with the results of the literature; the three-group models with valve heights of 13.5 mm, 14.0 mm, and 14.5 mm were within a reasonable range. The contact force value of the 6 groups of leaflets increased with the increase of valve height. Studies have shown that the height of the aortic valve has an effect on the aortic valve closure performance. A valve height that is too small or too large will reduce the aortic systolic valve area and affect the aortic function.


Assuntos
Insuficiência da Valva Aórtica/cirurgia , Valva Aórtica/fisiologia , Próteses Valvulares Cardíacas , Valva Aórtica/cirurgia , Humanos , Modelos Cardiovasculares
5.
Proc Inst Mech Eng H ; 233(5): 544-553, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30922162

RESUMO

This study was aimed at assessing the robustness of a fixed-grid fluid-structure interaction method (Multi-Material Arbitrary Lagrangian-Eulerian) to modelling the two-dimensional native aortic valve dynamics and comparing it to the Arbitrary Lagrangian-Eulerian method. For the fixed-grid method, the explicit finite element solver LS-DYNA was utilized, where two independent meshes for the fluid and structure were generated and the penalty method was used to handle the coupling between the fluid and structure domains. For the Arbitrary Lagrangian-Eulerian method, the implicit finite element solver ADINA was used where two separate conforming meshes were used for the valve structure and the fluid domains. The comparison demonstrated that both fluid-structure interaction methods predicted accurately the valve dynamics, fluid flow, and stress distribution, implying that fixed-grid methods can be used in situations where the Arbitrary Lagrangian-Eulerian method fails.


Assuntos
Valva Aórtica/fisiologia , Hidrodinâmica , Fenômenos Mecânicos , Modelos Biológicos , Fenômenos Biomecânicos , Análise de Elementos Finitos
7.
J Card Surg ; 34(5): 318-322, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30900354

RESUMO

BACKGROUND: The fate of the spared bicuspid aortic valve in patients undergoing ascending aortic aneurysm surgery is relatively unknown. Our institutional policy has been to replace all aortic valves with significant abnormalities, as evidenced by intraoperative transesophageal echocardiography or direct visual inspection. In this study, we elaborate our experience regarding the long-term fate of preserved bicuspid aortic valves after ascending aortic aneurysm extirpation. MATERIALS AND METHODS: From 2000 to 2018, 407 consecutive ascending aortic aneurysm patients with concomitant bicuspid aortic valves underwent surgery by a single surgeon at our institution. Among these, 23 (5.65%) patients did not have their valve replaced, forming the study group. Postoperative and preoperative echocardiograms were compared to determine changes in valve function. RESULTS: Follow-up was complete in 100% of patients. The average time between preoperative and postoperative echocardiograms was 4.50 ± 4.09 years (0.19-15.63). Aortic stenosis or regurgitation changed from none to mild in 5 (21.7%) of patients, with an average echocardiographic interval follow-up of 3.08 years, and from none to severe in 2 (8.7%), with an interval of 11.7 years. One patient required reoperation, including aortic valve replacement, during follow-up. CONCLUSION: Bicuspid aortic valves free of aortic stenosis or insufficiency before surgery and "healthy" appearing at surgery can safely be preserved.


Assuntos
Aorta/cirurgia , Aneurisma Aórtico/cirurgia , Valva Aórtica/anormalidades , Doenças das Valvas Cardíacas , Tratamentos com Preservação do Órgão/métodos , Procedimentos Cirúrgicos Vasculares/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Aneurisma Aórtico/diagnóstico por imagem , Valva Aórtica/fisiologia , Ecocardiografia Transesofagiana , Feminino , Seguimentos , Humanos , Período Intraoperatório , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Resultado do Tratamento
8.
BMJ Case Rep ; 12(2)2019 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-30798276

RESUMO

This 37-year-old man presented with left sided facial warmth and numbness associated with new sudden-onset right hemiparesis. The patient first developed sudden numbness of his left lip and warmth in left ear which travelled to the rest of left face. His past medical history was significant for hypertension, Hodgkin lymphoma treated with radiation therapy at the age of 10, and sleeve gastrectomy for obesity 1 year ago complicated by bilateral ischaemic cerebral infarctions with residual left hemiparesis. No acute infarcts were found on MRI. Transesophageal echocardiography revealed a complex atheroma near the sinotubular junction in ascending aorta.


Assuntos
Valva Aórtica/fisiologia , Doenças das Valvas Cardíacas/diagnóstico , Paresia/etiologia , Acidente Vascular Cerebral/diagnóstico , Adulto , Anticolesterolemiantes/uso terapêutico , Valva Aórtica/diagnóstico por imagem , Aspirina/uso terapêutico , Ecocardiografia Transesofagiana , Inibidores do Fator Xa/uso terapêutico , Doenças das Valvas Cardíacas/tratamento farmacológico , Doenças das Valvas Cardíacas/fisiopatologia , Humanos , Masculino , Paresia/fisiopatologia , Rivaroxabana/uso terapêutico , Rosuvastatina Cálcica/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento
9.
Biomed Mater ; 14(3): 035014, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30769335

RESUMO

INTRODUCTION: Calcific aortic valve disease (CAVD) is the most common acquired heart valve disease with complex underlying pathomechanisms that are yet not fully understood. Three-dimensional (3D) cell culture models as opposed to conventional two-dimensional (2D) techniques may reveal new aspects of CAVD and serve as a transitional platform between conventional 2D cell culture and in vivo experiments. METHODS: Here we report on fabrication and characterization of a novel 3D hydrogel derived from cell-free native aortic valves. A detailed analysis containing protein composition, rheological behavior, cytotoxic and proliferative effects as well as results of 3D cell culture experiments are presented. Moreover, this aortic valve derived hydrogel (AVdH) is compared to commercially available biological extracellular matrix (ECM) components to evaluate and classify AVdH with respect to other currently used ECM solutions, i.e. Collagen type I and Matrigel®. RESULTS: On the biochemical level, a complex composition of native proteins was detected. Using different techniques, including mass spectrometry with Gene Ontology network and enrichment analysis, different fundamental biological functions of AVdH were identified, including peptidase-, peptidase inhibitor-, growth- and binding activity. No cytotoxic effects were detected and AVdH showed positive effects on cell growth and proliferation in vitro when compared to Collagen type I and Matrigel®. CONCLUSION: These results suggest AVdH as an organotypic ECM supporting sophisticated 3D cell culture model studies, while mimicking the native environment of the aortic valve to a greater level for enhanced in vitro analyses.


Assuntos
Valva Aórtica/fisiologia , Materiais Biomiméticos , Técnicas de Cultura de Células , Hidrogéis/química , Engenharia Tecidual/métodos , Animais , Valva Aórtica/patologia , Estenose da Valva Aórtica/terapia , Calcinose/terapia , Proliferação de Células , Sistema Livre de Células , Colágeno/química , Combinação de Medicamentos , Matriz Extracelular/química , Doenças das Valvas Cardíacas/terapia , Cinética , Laminina/química , Proteoglicanas/química , Reologia , Ovinos , Software
10.
Mater Sci Eng C Mater Biol Appl ; 97: 632-643, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30678950

RESUMO

The original intention for building a tissue-engineered heart valve (TEHV) was to simulate a normal heart valve and overcome the insufficiency of the commonly used heart valve replacement in the clinic. The endothelialization of the TEHV is very important as the endothelialized TEHV can decrease platelet adhesion and delay the valvular calcification decline process. In this work, we encapsulated vascular endothelial growth factor (VEGF) into polycaprolactone (PCL) nanoparticles. Then, through the Michael addition reaction, PCL nanoparticles were introduced onto the decellularized aortic valve to prepare a hybrid valve. The encapsulation efficiency of the PCL nanoparticles for VEGF was up to 82%, and the in vitro accumulated release rate was slow without an evident initial burst release. In addition, the hybrid valve had a decreased hemolysis ratio and possessed antiplatelet adhesion capacity, and it was able to promote the adhesion and proliferation of endothelial cells, covering the surface with a dense cell layer to accelerate endothelialization. An experiment involving the subcutaneous implant in SD rats showed that at week 8, lots of blood capillaries were formed in the hybrid valve. Mechanics performance testing indicated that the mechanical property of the hybrid valve was partly improved. Taken together, we applied a nano-drug controlled release system to fabricate TEHV, and provide an approach for the biofunctionalization of the TEHV scaffold for accelerating endothelialization.


Assuntos
Valva Aórtica/química , Portadores de Fármacos/química , Nanopartículas/química , Engenharia Tecidual , Fator A de Crescimento do Endotélio Vascular/química , Animais , Valva Aórtica/fisiologia , Valva Aórtica/transplante , Plaquetas/citologia , Plaquetas/fisiologia , Próteses Valvulares Cardíacas , Células Endoteliais da Veia Umbilical Humana , Humanos , Adesividade Plaquetária , Poliésteres/química , Coelhos , Ratos , Ratos Sprague-Dawley , Regeneração , Propriedades de Superfície , Suínos , Fator A de Crescimento do Endotélio Vascular/metabolismo
11.
Clin Calcium ; 29(2): 157-163, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-30679395

RESUMO

Intimal and medial calcification are increased with type 1 and type 2 diabetes, metabolic syndrome, chronic kidney disease, and ageing. There are several biological mechanisms through which vascular calcification increases all-cause mortality and atherosclerotic plaque rupture. Arterial medial calcification increases arterial stiffness that causes systolic hypertension and diastolic dysfunction and heart failure. In contrast, arterial intimal calcification is strongly associated with atherosclerotic plaque burden, predicting adverse arterial events. In particular, micro-calcifications within the fibrous caps are through to increase local stress and risk of plaque rupture. While vascular calcification has originally through to be a passive process, it has become increasingly clear that calcification of both intimal and medial layers is an active and tightly regulated process in which dynamic phenotypic changes of vascular smooth muscle cells plays a major role. Interestingly, the driving factors for medial and intimal calcification differ. Whilst uremia and senescence, high serum calcium and phosphate levels drives medial calcification, inflammation and oxidative stress are critical for intimal calcification. Despite the different drivers and environmental cues, the medial and intimal arterial calcification shares common intracellular signaling cascades to promoter cellular reprogramming and phenotypic switching. Recent studies employing new technologies demonstrate that calcifying extracellular vesicles(EVs)that have specific mineralization-promoting cargos such as tissue nonspecific alkaline phosphatase(TNAP), annexins Ⅱ and Ⅵ, are released from vascular smooth muscle, macrophages, and valvular interstitial cells, and serve as calcifying foci. Recent study identified a specific trafficking protein, sortilin, as a key player in the formation of calcifying EVs secreted by vascular smooth muscle cells. Research on aortic valve calcification using spatiotemporal multi-omics identified many secreted and structural matrix proteins not previously implicated in valvular calcification, and revealed that inflammation is likely to be a significant contributor regardless of the layers and stages of the aortic stenosis progression. Increased understanding of the precise molecular mechanisms of phenotypic switching of vascular smooth muscle offers the best chance to identify the potential drug targets for vascular calcification.


Assuntos
Estenose da Valva Aórtica , Valva Aórtica/fisiologia , Diabetes Mellitus Tipo 2 , Músculo Liso Vascular/fisiologia , Calcificação Vascular , Células Cultivadas , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Calcificação Vascular/metabolismo
12.
Clin Calcium ; 29(2): 207-213, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-30679402

RESUMO

Advances in CT scan revealed that the presence of calcified plaque by coronary CT and aortic calcification and aortic valve calcification by aortic CT are related to subsequent cardiovascular events. In particular, coronary calcification has many evidence related to cardiovascular events as a surrogate marker of plaque in atherosclerotic coronary arteries. From now on, by identifying atherosclerosis by calcium scanning with CT, it is necessary to consider drug treatment and lifestyle improvement, etc. for prevention of cardiovascular disease.


Assuntos
Estenose da Valva Aórtica , Valva Aórtica/fisiologia , Calcinose , Placa Aterosclerótica , Tomografia Computadorizada por Raios X/métodos , Calcificação Vascular , Calcinose/metabolismo , Humanos , Fatores de Risco
13.
IEEE J Biomed Health Inform ; 23(3): 1032-1040, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-29993702

RESUMO

Accurate detection of fiducial points in a seismocardiogram (SCG) is a challenging research problem for its clinical application. In this paper, an automated method for detecting aortic valve opening (AO) instants using the dorso-ventral component of the SCG signal is proposed. This method does not require electrocardiogram (ECG) as a reference signal. After preprocessing the SCG, multiscale wavelet decomposition is carried out to get signal components in different wavelet subbands. The subbands having possible AO peaks are selected by a newly proposed dominant-multiscale-kurtosis- and dominant-multiscale-central-frequency-based criterion. The signal is reconstructed using selected subbands, and it is emphasized using the weights derived from the proposed relative squared dominant multiscale kurtosis. The Shannon energy followed by autocorrelation coefficients is computed for systole envelope construction. Finally, AO peaks are detected by a Gaussian-derivative-filtering-based scheme. The robustness of the proposed method is tested using clean and noisy SCG signals from the combined measurement of ECG, breathing, and SCG database. Evaluation results show that the method can achieve an average sensitivity of 94%, a prediction rate of 90%, and a detection accuracy of 86% approximately over 4585 analyzed beats.


Assuntos
Valva Aórtica/fisiologia , Testes de Função Cardíaca/métodos , Processamento de Sinais Assistido por Computador , Acelerometria/métodos , Algoritmos , Eletrocardiografia , Frequência Cardíaca/fisiologia , Humanos
14.
J Thorac Cardiovasc Surg ; 157(2): 455-465, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30139642

RESUMO

OBJECTIVES: This study applied advanced 4-dimensional flow magnetic resonance imaging processing to assess differences in aortic flow dynamics after valve sparing root replacement, with and without reconstruction of the Valsalva sinuses. METHODS: We enrolled patients after valve sparing root replacement with a straight tubular prosthesis (n = 10) or with a prosthesis with Valsalva neosinuses (n = 10); age-matched subjects without cardiovascular diseases served as controls (n = 10). 4-Dimensional flow magnetic resonance imaging acquisitions were performed on a 3.0T magnetic resonance imaging unit. In-house processing was used to segment the aortic lumen and extract the volumetric 4-dimensional flow velocity field. Velocity flow streamlines were computed to compare the amount of rotational flow and wall shear stress. Occurrence of abnormal wall shear stress (WSS) was estimated within the descending aorta of each surgical group. RESULTS: Physiologic-like sinus vortices were visible in the aortic root when using the prosthesis with neosinuses, whereas straight tubular graft revealed localized intrados malrotations (P = .003 for organized vortical structures vs neosinuses graft and P < .001 vs control). In the ascending aorta, recreation of the sinuses resulted in significantly lower velocity and WSS than in the straight tubular graft (P < .001) and controls (P < .001), these alterations were attenuated in the mid-descending aorta. Incidence of abnormal WSS was markedly higher in the straight tube grafts than neosinus of Valsalva grafts. CONCLUSIONS: Re-creation of the sinuses of Valsalva during valve-sparing root replacement is associated with more physiologic flow and significantly lower WSS in the aortic root. Lower WSSs in the distal thoracic aorta is a novel finding with potential implications on distal aortic remodeling.


Assuntos
Aorta/fisiologia , Aorta/cirurgia , Velocidade do Fluxo Sanguíneo/fisiologia , Implante de Prótese Vascular , Adulto , Idoso , Aorta/diagnóstico por imagem , Valva Aórtica/fisiologia , Implante de Prótese Vascular/efeitos adversos , Implante de Prótese Vascular/métodos , Implante de Prótese Vascular/estatística & dados numéricos , Estudos de Casos e Controles , Feminino , Humanos , Imagem Tridimensional , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Tratamentos com Preservação do Órgão
15.
Artif Organs ; 43(3): 222-228, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30155903

RESUMO

Left ventricular assist devices (LVADs) restore cardiovascular circulatory demand at rest with a spontaneous increase in pump flow to exercise. The relevant contribution of cardiac output provided by the LVAD and ejected through the aortic valve for exercises of different intensities has been barely investigated in patients. The hypothesis of this study was that different responses in continuous recorded pump parameters occur for maximal and submaximal intensity exercises and that the pump flow change has an impact on the oxygen uptake at peak exercise (pVO2 ). Cardiac and pump parameters such as LVAD flow rate (QLVAD ), heart rate (HR), and aortic valve (AV) opening were analyzed from continuously recorded LVAD data during physical exercises of maximal (bicycle ergometer test) and submaximal intensities (6-min walk test and regular trainings). During all exercise sessions, the LVAD speed was kept constant. Cardiac and pump parameter responses of 16 patients for maximal and submaximal intensity exercises were similar for QLVAD : +0.89 ± 0.52 versus +0.59 ± 0.38 L/min (P = 0.07) and different for HR: +20.4 ± 15.4 versus +7.7 ± 5.8 bpm (P < 0.0001) and AV-opening with 71% versus 23% of patients (P < 0.0001). Multi-regression analysis with pVO2 (R2  = 0.77) showed relation to workload normalized by bodyweight (P = 0.0002), HR response (P = 0.001), AV-opening (P = 0.02), and age (P = 0.06) whereas the change in QLVAD was irrelevant. Constant speed LVADs provide inadequate support for maximum intensity exercises. AV-opening and improvements in HR show an important role for higher exercise capacities and reflect exercise intensities. Changes in pump flow do not impact pVO2 and are independent of AV-opening and response in HR. An LVAD speed control may lead to adequate left ventricular support during strenuous physical activities.


Assuntos
Débito Cardíaco/fisiologia , Exercício/fisiologia , Insuficiência Cardíaca/cirurgia , Coração Auxiliar , Idoso , Valva Aórtica/fisiologia , Teste de Esforço , Feminino , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/reabilitação , Ventrículos do Coração/fisiopatologia , Ventrículos do Coração/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
16.
J Thorac Cardiovasc Surg ; 157(1): 126-132, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30557939

RESUMO

OBJECTIVE: Aortic valve repair is currently in transition from surgical improvisation to a reproducible operation and an option for many patients with aortic regurgitation. Our research efforts at improving reproducibility include development of methods for intraoperatively testing and visualizing the valve in its diastolic state. METHODS: We developed a device that can be intraoperatively secured in the transected aorta allowing the aortic root to be pressurized and the closed valve to be inspected endoscopically. Our device includes a chamber that can be pressurized with crystalloid solution and ports for introduction of an endoscope and measuring gauges. We show use of the device in explanted porcine hearts to visualize the aortic valve and to measure leaflet coaptation height in normal valves and in valves that have undergone valve repair procedures. RESULTS: The procedure of introducing and securing the device in the aorta, pressurizing the valve, and endoscopically visualizing the closed valve is done in less than 1 minute. The device easily and reversibly attaches to the aortic root and allows direct inspection of the aortic valve under conditions that mimic diastole. It enables the surgeon to intraoperatively study the valve immediately before repair to determine mechanisms of incompetence and immediately after the repair to assess competence. We also show its use in measuring valve leaflet coaptation height in the diastolic state. CONCLUSIONS: This device enables more relevant prerepair valve assessment and also enables a test of postrepair valve competence under physiological pressures.


Assuntos
Insuficiência da Valva Aórtica/cirurgia , Valva Aórtica/cirurgia , Anuloplastia da Valva Cardíaca/instrumentação , Monitorização Intraoperatória/instrumentação , Animais , Valva Aórtica/patologia , Valva Aórtica/fisiologia , Insuficiência da Valva Aórtica/fisiopatologia , Anuloplastia da Valva Cardíaca/métodos , Humanos , Monitorização Intraoperatória/métodos , Suínos
17.
J Vis Exp ; (141)2018 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-30531712

RESUMO

The ultimate solution for patients with end-stage heart failure is organ transplant. But donor hearts are limited, immunosuppression is required, and ultimately rejection can occur. Creating a functional, autologous bio-artificial heart could solve these challenges. Biofabrication of a heart comprised of scaffold and cells is one option. A natural scaffold with tissue-specific composition as well as micro- and macro-architecture can be obtained by decellularizing hearts from humans or large animals such as pigs. Decellularization involves washing out cellular debris while preserving 3D extracellular matrix and vasculature and allowing "cellularization" at a later timepoint. Capitalizing on our novel finding that perfusion decellularization of complex organs is possible, we developed a more "physiological" method to decellularize non-transplantable human hearts by placing them inside a pressurized pouch, in an inverted orientation, under controlled pressure. The purpose of using a pressurized pouch is to create pressure gradients across the aortic valve to keep it closed and improve myocardial perfusion. Simultaneous assessment of flow dynamics and cellular debris removal during decellularization allowed us to monitor both fluid inflow and debris outflow, thereby generating a scaffold that can be used either for simple cardiac repair (e.g. as a patch or valve scaffold) or as a whole-organ scaffold.


Assuntos
Coração Artificial , Coração/fisiologia , Pressão , Engenharia Tecidual/métodos , Tecidos Suporte , Animais , Valva Aórtica/citologia , Valva Aórtica/fisiologia , Matriz Extracelular/fisiologia , Coração Artificial/normas , Humanos , Perfusão , Suínos , Tecidos Suporte/normas
18.
Cardiovasc Eng Technol ; 9(4): 739-751, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30406610

RESUMO

PURPOSE: The understanding of the optimum function of the healthy aortic valve is essential in interpreting the effect of pathologies in the region, and in devising effective treatments to restore the physiological functions. Still, there is no consensus on the operating mechanism that regulates the valve opening and closing dynamics. The aim of this study is to develop a numerical model that can support a better comprehension of the valve function and serve as a reference to identify the changes produced by specific pathologies and treatments. METHODS: A numerical model was developed and adapted to accurately replicate the conditions of a previous in vitro investigation into aortic valve dynamics, performed by means of particle image velocimetry (PIV). The resulting velocity fields of the two analyses were qualitatively and quantitatively compared to validate the numerical model. In order to simulate more physiological operating conditions, this was then modified to overcome the main limitations of the experimental setup, such as the presence of a supporting stent and the non-physiological properties of the fluid and vessels. RESULTS: The velocity fields of the initial model resulted in good agreement with those obtained from the PIV, with similar flow structures and about 90% of the computed velocities after valve opening within the standard deviation of the equivalent velocity measurements of the in vitro model. Once the experimental limitations were removed from the model, the valve opening dynamics changed substantially, with the leaflets opening into the sinuses to a much greater extent, enlarging the effective orifice area by 11%, and reducing greatly the vortical structures previously observed in proximity of the Valsalva sinuses wall. CONCLUSIONS: The study suggests a new operating mechanism for the healthy aortic valve leaflets considerably different from what reported in the literature to date and largely more efficient in terms of hydrodynamic performance. This work also confirms the crucial role that numerical approaches, complemented with experimental findings, can play in overcoming some of the limitations inherent in experimental techniques, supporting the full understanding of complex physiological phenomena.


Assuntos
Valva Aórtica/anatomia & histologia , Valva Aórtica/fisiologia , Hemodinâmica , Modelos Cardiovasculares , Modelagem Computacional Específica para o Paciente , Fenômenos Biomecânicos , Humanos , Análise Numérica Assistida por Computador , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Estresse Mecânico
19.
J Biomech ; 81: 145-148, 2018 11 16.
Artigo em Inglês | MEDLINE | ID: mdl-30340762

RESUMO

We report a patient-specific case of bicuspid aortic valve with fusion of right and left coronary leaflets (R-L type I BAV), moderate aortic valve deficiency and ascending thoracic aortic aneurysms (ATAA) who was treated by only ascending aorta replacement preserving the BAV. The flow eccentricity, the helicity intensity (h2), the circumferential time averaged wall shear stress (TAWSScircumferential), the cumulative viscous energy loss at the systolic peak (EL') and the pulse wave velocity (PWV) were calculated by combining 4D flow MRI and CFD analysis before (Stage I) and after (Stage II) the surgical procedure. CFD analyses assumed rigid walls, a non-Newtonian behavior for the blood and MRI measured patient-specific blood flow profiles as inlet boundary conditions. Stage II results showed suppression of recirculation in the ascending aorta, loss of jet flow impingement onto the aortic wall, maximum TAWSScircumferential decrease (from 6.69 Pa in Stage I to 6 Pa in Stage II), reduction of flow helicity (from 10.97 in Stage I to 8.47 in Stage II) and EL' (from 15.8 mW in Stage I to 11.2 mW in Stage II). However, Floweccentricity and PWV were found higher in Stage II due to the diameter reduction (Floweccentricity = 0.60 in Stage I and Floweccentricity = 0.91 in Stage II; PWV = 3.80 m/s in Stage I and PWV = 9.37 m/s in Stage II). Our work has permitted to compute for the first time the hemodynamic alterations obtained after restoration of normal ascending aorta and sinotubular junction geometry even preserving an R-L type I BAV with still acceptable function.


Assuntos
Aorta Torácica/fisiologia , Aneurisma da Aorta Torácica/fisiopatologia , Aneurisma da Aorta Torácica/cirurgia , Valva Aórtica/anormalidades , Valva Aórtica/fisiologia , Doenças das Valvas Cardíacas , Hemodinâmica/fisiologia , Humanos , Imagem por Ressonância Magnética , Pessoa de Meia-Idade , Análise de Onda de Pulso , Estresse Mecânico , Procedimentos Cirúrgicos Vasculares
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