Pediatric tri-tube valved conduits made from fibroblast-produced extracellular matrix evaluated over 52 weeks in growing lambs

2021 ◽  
Vol 13 (585) ◽  
pp. eabb7225
Author(s):  
Zeeshan H. Syedain ◽  
Bee Haynie ◽  
Sandra L. Johnson ◽  
Matthew Lahti ◽  
James Berry ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Heart Valves ◽  
Systolic Pressure ◽  
Valve Design ◽  
Pressure Drops ◽  
The Third ◽  
Collagenous Matrix ◽  
Valved Conduit ◽  
Bioprosthetic Valves

There is a need for replacement heart valves that can grow with children. We fabricated tubes of fibroblast-derived collagenous matrix that have been shown to regenerate and grow as a pulmonary artery replacement in lambs and implemented a design for a valved conduit consisting of three tubes sewn together. Seven lambs were implanted with tri-tube valved conduits in sequential cohorts and compared to bioprosthetic conduits. Valves implanted into the pulmonary artery of two lambs of the first cohort of four animals functioned with mild regurgitation and systolic pressure drops <10 mmHg up to 52 weeks after implantation, during which the valve diameter increased from 19 mm to a physiologically normal ~25 mm. In a second cohort, the valve design was modified to include an additional tube, creating a sleeve around the tri-tube valve to counteract faster root growth relative to the leaflets. Two valves exhibited trivial-to-mild regurgitation at 52 weeks with similar diameter increases to ~25 mm and systolic pressure drops of <5 mmHg, whereas the third valve showed similar findings until moderate regurgitation was observed at 52 weeks, correlating to hyperincrease in the valve diameter. In all explanted valves, the leaflets contained interstitial cells and an endothelium progressing from the base of the leaflets and remained thin and pliable with sparse, punctate microcalcifications. The tri-tube valves demonstrated reduced calcification and improved hemodynamic function compared to clinically used pediatric bioprosthetic valves tested in the same model. This tri-tube valved conduit has potential for long-term valve growth in children.

scholarly journals Bioprosthetic Heart Valves: Impact of Implantation on Biomaterials

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Pooja Singhal ◽  
Adriana Luk ◽  
Jagdish Butany
Keyword(s):  
Heart Disease ◽  
Heart Valves ◽  
Prosthetic Heart Valves ◽  
Bioprosthetic Heart Valves ◽  
Modes Of Failure ◽  
Mechanical Valves ◽  
Different Types ◽  
Patient Groups ◽  
Bioprosthetic Valves

Prosthetic heart valves are commonly used in the treatment of valvular heart disease. Mechanical valves are more durable than the bioprosthetic valves; however, the need for long-term anticoagulant therapy renders them unsuitable for some patient groups. In this paper we discuss the different types and models of bioprosthesis, and in particular, pericardial bioprosthesis. We also discuss the preimplantation preparation processes, as well as their postimplantation changes and modes of failure.

Failure and Hydrodynamic Function Testing of Explanted Pericardial and Porcine Bioprosthetic Valves

1989 ◽  
Vol 203 (2) ◽  
pp. 65-70 ◽  
Author(s):  
J Fisher ◽  
T J Spyt ◽  
D J Wheatley
Keyword(s):  
Host Tissue ◽  
Pressure Drops ◽  
Tissue Ingrowth ◽  
And Function ◽  
Hydrodynamic Function ◽  
Function Testing ◽  
Open Position ◽  
Bioprosthetic Valves ◽  
Increased Pressure

The long-term durability and function of cardiac bioprostheses can be affected by both calcification and mechanical failure of the tissue. The mechanisms of failure and hydrodynamic function of 66 explanted bioprostheses have been studied. The majority of porcine valves were heavily calcified with leaflet tears adjacent to the calcification at the commissures. These tears caused prolapsed leaflets and regurgitation of between 30 and 70 per cent. Only three porcine valves had tissue failure in the absence of calcification. The majority of pericardial valves failed due to leaflet tears at the edge of the frame in the absence of macroscopic calcification. These tears also produced prolapsed leaflets and large regurgitation in hydrodynamic tests. Three pericardial valves were heavily calcified and stenotic without leaflet tears. Leaflet dynamics in the pericardial valves were affected by host tissue ingrowth which produced increased pressure drops across the valves, an asymmetrical open position and leaflet flutter. In the absence of calcification and leaflet tears, there was little change in the function of explanted porcine valves.

Laura’s Students One and Seven Years Later

2018 ◽  
Author(s):  
Marilyn Watson
Keyword(s):  
School District ◽  
Life Skills ◽  
Adopted Child ◽  
The Third

In the third year, Laura took a leave through November to help settle her newly adopted child. Her students missed her and, when she returned, some seemed to have reverted to their original untrusting selves. Soon, their trust in Laura and in themselves was restored. Would that trust remain? Seven years later, I interviewed 9 of the 14 students still in the school district. All remembered Laura and the class fondly. Eight had detailed memories of their interactions with Laura, and the life skills and attitudes they learned in her class. Of the six students who were judged insecurely attached when they entered Laura’s class, four appeared successful and confident and two were currently failing most of their courses. Possible causes for the long-term success of some students and failure of others are discussed.

GA: Armani’s Giorgio Armani

2018 ◽  
Author(s):  
Paul Brooker ◽  
Margaret Hayward
Keyword(s):  
Final Section ◽  
The Body ◽  
Body Shop ◽  
The Third ◽  
Haute Couture ◽  
Fashion Designer ◽  
The Body Shop ◽  
The Uk ◽  
Career Woman

The Armani high-fashion example illustrates the importance of adaptive rational methods in his founding and developing of an iconic high-fashion firm. Armani adapted stylistically to fashion’s new times in the 1970–80s by creating a new style catering for the career woman. His stylistic adaptation is compared with that of another famous Italian fashion designer, Versace, who instead modernized haute couture fashion and created a succession of glamourous styles. Both leaders exploited the same opportunity but in different ways. The third section compares these leaders’ legacies in the 1990s–2000s and assesses from a long-term perspective how capably they had used adaptive rational methods. The final section shifts the focus from fashion to the cosmetics industry and from Italy to the UK. Anita Roddick used adaptive rational methods to establish The Body Shop corporation in the 1970s–80s. However, she then abandoned rational methods with dire results for her corporation in the 1990s.

scholarly journals Extended analytical formulae for the perturbed Keplerian motion under low-thrust acceleration and orbital perturbations

2021 ◽  
Vol 133 (3) ◽  
Author(s):  
Marilena Di Carlo ◽  
Simão da Graça Marto ◽  
Massimiliano Vasile
Keyword(s):  
Gravitational Perturbation ◽  
Low Thrust ◽  
Orbital Elements ◽  
Third Body ◽  
The Third ◽  
Orbital Perturbations ◽  
Analytical Formulae ◽  
Numerical Orbit ◽  
Body Potential

AbstractThis paper presents a collection of analytical formulae that can be used in the long-term propagation of the motion of a spacecraft subject to low-thrust acceleration and orbital perturbations. The paper considers accelerations due to: a low-thrust profile following an inverse square law, gravity perturbations due to the central body gravity field and the third-body gravitational perturbation. The analytical formulae are expressed in terms of non-singular equinoctial elements. The formulae for the third-body gravitational perturbation have been obtained starting from equations for the third-body potential already available in the literature. However, the final analytical formulae for the variation of the equinoctial orbital elements are a novel derivation. The results are validated, for different orbital regimes, using high-precision numerical orbit propagators.

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