Improved Prediction of the Collagen Fiber Architecture in the Aortic Heart Valve

2004 ◽  
Vol 127 (2) ◽  
pp. 329-336 ◽  
Author(s):  
Niels J. B. Driessen ◽  
Carlijn V. C. Bouten ◽  
Frank P. T. Baaijens
Keyword(s):  
Aortic Valve ◽  
Biaxial Loading ◽  
Fiber Architecture ◽  
Native Valve ◽  
Mechanical Conditioning ◽  
Collagen Remodeling ◽  
Principal Stretch ◽  
Aortic Heart Valve ◽  
Living Tissues ◽  
Insight Into

Living tissues show an adaptive response to mechanical loading by changing their internal structure and morphology. Understanding this response is essential for successful tissue engineering of load-bearing structures, such as the aortic valve. In this study, mechanically induced remodeling of the collagen architecture in the aortic valve was investigated. It was hypothesized that, in uniaxially loaded regions, the fibers aligned with the tensile principal stretch direction. For biaxial loading conditions, on the other hand, it was assumed that the collagen fibers aligned with directions situated between the principal stretch directions. This hypothesis has already been applied successfully to study collagen remodeling in arteries. The predicted fiber architecture represented a branching network and resembled the macroscopically visible collagen bundles in the native leaflet. In addition, the complex biaxial mechanical behavior of the native valve could be simulated qualitatively with the predicted fiber directions. The results of the present model might be used to gain further insight into the response of tissue engineered constructs during mechanical conditioning.

Mechanical equilibrium determines the fractal fiber architecture of aortic heart valve leaflets

1994 ◽  
Vol 266 (1) ◽  
pp. H319-H328 ◽  
Author(s):  
C. S. Peskin ◽  
D. M. McQueen
Keyword(s):  
Aortic Valve ◽  
Aortic Wall ◽  
Equation Of Motion ◽  
The Self ◽  
Fiber Architecture ◽  
Fiber Structure ◽  
Aortic Heart Valve ◽  
Vortex Lines ◽  
Fractal Character ◽  
Braided Structure

In this work, the structure of the aortic valve is derived from its function, which (in the closed-valve configuration) is to support a uniform pressure load. It is assumed that this load is transferred to the aortic wall by a one-parameter family of fibers under tension. The equation of equilibrium for this fiber structure turns out to be equivalent to the equation of motion of vortex lines in the self-induction approximation. The method of Buttke (J. Comput. Phys. 76:301–326, 1988) is used to solve these equations and, hence, to determine the fiber architecture of the aortic leaflets. Because of a singularity at the center of the aortic valve, the computed fiber architecture has a fractal character with increasing complexity at progressively smaller scales. The computed fiber architecture resembles the branching braided structure of the collagen fibers that support the real aortic valve.

scholarly journals Corynebacterium jeikeium native valve infective endocarditis case report: a confirmed microbiological and pathological diagnosis from heart valvular tissue

2020 ◽  
Author(s):  
Wentzel Bruce Dowling ◽  
Johan Koen
Keyword(s):  
Infective Endocarditis ◽  
Aortic Valve ◽  
Penicillin G ◽  
Peripheral Vascular ◽  
Native Valve ◽  
Valve Tissue ◽  
Case Summary ◽  
Duke Criteria ◽  
G Prior ◽  
Initial Blood

Abstract Background The Modified Duke criteria is an important structured schematic for the diagnosis of infective endocarditis (IE). Corynebacterium jeikeium is a rare cause of IE that is often resistant to standard IE anti-microbials. We present a case of C. jeikeium IE, fulfilling the Modified Duke pathological criteria. Case summary A 50-year-old male presented with left leg peripheral vascular disease with septic changes requiring amputation. Routine echocardiography post-amputation demonstrated severe aortic valve regurgitation with vegetations that required valve replacement. Two initial blood cultures from a single venepuncture showed Streptococcus mitis which was treated with penicillin G prior to surgery. Subsequent aortic valve tissue cultured C. jeikeium with suggestive IE histological valvular changes and was successfully treated on a prolonged course of vancomycin. Discussion This is the first C. jeikeium IE case diagnosed on heart valvular tissue culture and highlights the importance for the fulfilment of the Modified Duke criteria in diagnosing left-sided IE. Mixed infection IE is rare, and this case possibly represents an unmasking of resistant C. jeikeium IE following initial treatment of penicillin G.

The Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Oleksandr Barannyk ◽  
Peter Oshkai
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Aortic Root ◽  
Reynolds Shear Stress ◽  
Prosthetic Heart Valve ◽  
Flow Characteristics ◽  
Aortic Pressure ◽  
Valve Prosthesis ◽  
Aortic Heart Valve ◽  
Valve Diseases

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted in the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases were classified into two clinical categories and were correlated with the corresponding changes in aortic root geometry while keeping the aortic base diameter fixed. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output, and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, while keeping the diameter of the orifice constant, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.

scholarly journals Label-free optical biomarkers detect early calcific aortic valve disease in a wild-type mouse model

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ishita Tandon ◽  
Shelby Johns ◽  
Alan Woessner ◽  
Jessica Perez ◽  
Delaney Cross ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Early Detection ◽  
Mouse Model ◽  
Osteogenic Differentiation ◽  
Aortic Valve Disease ◽  
Valve Disease ◽  
Label Free ◽  
Calcific Aortic Valve Disease ◽  
Collagen Remodeling ◽  
Positive Expression

Abstract Background Calcific aortic valve disease (CAVD) pathophysiology is a complex, multistage process, usually diagnosed at advanced stages after significant anatomical and hemodynamic changes in the valve. Early detection of disease progression is thus pivotal in the development of prevention and mitigation strategies. In this study, we developed a diet-based, non-genetically modified mouse model for early CAVD progression, and explored the utility of two-photon excited fluorescence (TPEF) microscopy for early detection of CAVD progression. TPEF imaging provides label-free, non-invasive, quantitative metrics with the potential to correlate with multiple stages of CAVD pathophysiology including calcium deposition, collagen remodeling and osteogenic differentiation. Methods Twenty-week old C57BL/6J mice were fed either a control or pro-calcific diet for 16 weeks and monitored via echocardiography, histology, immunohistochemistry, and quantitative polarized light imaging. Additionally, TPEF imaging was used to quantify tissue autofluorescence (A) at 755 nm, 810 nm and 860 nm excitation, to calculate TPEF 755–860 ratio (A860/525/(A755/460 + A860/525)) and TPEF Collagen-Calcium ratio (A810/525/(A810/460 + A810/525)) in the murine valves. In a separate experiment, animals were fed the above diets till 28 weeks to assess for later-stage calcification. Results Pro-calcific mice showed evidence of lipid deposition at 4 weeks and calcification at 16 weeks at the valve commissures. The valves of pro-calcific mice also showed positive expression for markers of osteogenic differentiation, myofibroblast activation, proliferation, inflammatory cytokines and collagen remodeling. Pro-calcific mice exhibited lower TPEF autofluorescence ratios, at locations coincident with calcification, that correlated with increased collagen disorganization and positive expression of osteogenic markers. Additionally, locations with lower TPEF autofluorescence ratios at 4 and 16 weeks exhibited increased calcification at later 28-week timepoints. Conclusions This study suggests the potential of TPEF autofluorescence metrics to serve as a label-free tool for early detection and monitoring of CAVD pathophysiology.

Valve-in-Valve TAVR: State-of-the-Art Review

2019 ◽  
Vol 14 (4) ◽  
pp. 299-310 ◽  
Author(s):  
J. James Edelman ◽  
Jaffar M. Khan ◽  
Toby Rogers ◽  
Christian Shults ◽  
Lowell F. Satler ◽  
...  
Keyword(s):  
High Risk ◽  
Aortic Valve ◽  
Transcatheter Aortic Valve Replacement ◽  
State Of The Art ◽  
Native Valve ◽  
Reoperative Surgery ◽  
Transcatheter Aortic Valve ◽  
Structural Valve Deterioration ◽  
Valve In Valve ◽  
Coronary Obstruction

An increasing number of surgically implanted bioprostheses will require re-intervention for structural valve deterioration. Valve-in-valve transcatheter aortic valve replacement (ViV TAVR) has become an alternative to reoperative surgery, currently approved for high-risk and inoperable patients. Challenges to the technique include higher rates of prosthesis–patient mismatch and coronary obstruction, compared to native valve TAVR. Herein, we review results of ViV TAVR and novel techniques to overcome the aforementioned challenges.

scholarly journals A Rare Case of Aortic Valve Thrombosis in Patient with Idiopathic Hypereosinophilic Syndrome

2015 ◽  
Vol 2015 ◽  
pp. 1-3
Author(s):  
Elisabetta Grolla ◽  
Michele Dalla Vestra ◽  
Luca Bonanni ◽  
Ada Cutolo ◽  
Fausto Rigo
Keyword(s):  
Aortic Valve ◽  
Hypereosinophilic Syndrome ◽  
Organ System ◽  
Idiopathic Hypereosinophilic Syndrome ◽  
Thromboembolic Complications ◽  
Native Valve ◽  
Prosthetic Valves ◽  
Common Causes ◽  
Valve Thrombosis ◽  
Cardiac Ventricles

Idiopathic hypereosinophilic syndrome (HES) is characterized by persistent eosinophilia and eosinophil-mediated organ-system damage. Cardiac thrombosis and thromboembolic complications represent common causes of morbidity and mortality and usually involve cardiac ventricles or mitral and prosthetic valves, while the involvement of the aortic valve is extremely rare in HES. Here we report peculiar multimodality images of an atypical case of extended thrombosis of the aortic valve, complicated by myocardial ischemia and asymptomatic cerebral ischemia, likely due to thrombus embolization, occurring in a 48-year-old man with HES. Prompt anticoagulant and steroid therapy lead to rapid and complete resolution of the thrombotic lesions, allowing preserving the native valve and preventing further embolic events.

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