Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study

The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.

Transcatheter methods of treatment of mitral valve pathology: current state of the problem

Во второй части обзора, посвященного транскатетерным методам лечения патологии митрального клапана (МК), рассматриваются вопросы транскатетерного протезирования МК (TMVI), в том числе: имплантация протеза в кальцинированное нативное фиброзное кольцо (valve-in-MAC), в ранее установленные хирургический биопротез (valve-in-valve) и опорное кольцо МК (valve-in-ring). Также кратко обсуждаются сравнительные преимущества и недостатки двух стратегий хирургического лечения - протезирования и пластической реконструкции – в контексте транскатетерной хирургии МК. Issues of transcatheter mitral valve (MV) implantation (TMVI) including implantation of a prosthesis into calcified native fibrous ring (valve-in- MAC), into previously implanted surgical bioprosthesis (valve-in-valve) and MV support ring (valve-in-ring) are considered in the second part of the review devoted to transcatheter methods of treatment of MV pathology. The comparative advantages and disadvantages of two surgical treatment strategies — prosthetics and plastic reconstruction — are also briefly discussed in the context of MV transcatheter surgery.

DIESEL INJECTOR PUMP WITH RING CONTROL VALVE

The studies were carried out with the aim of modernizing the pump injector with a hydraulic actuator of the HEUI system plunger with the development of a control valve model based on a split elastic ring that provides fast fuel injection control. The upgraded device differs from the existing ones in that instead of a control freely floating valve (ball) or a poppet valve with springs, a valve in the form of a split elastic ring is installed in the valve assembly. One end of this ring is fixed rigidly, the other is freely movable to block the drain channel of the liquid. The canal overlaps the free edge of the ring when the electromagnet is turned on (installed with a gap inside the ring), and also (in the absence or malfunction of the electromagnet) from the valve itself running under the pressure of the supplied fluid. When upgrading the pump injector by the proposed method and using an annular control valve with electronic control (with optimal ring parameters), a new technical effect is achieved - reducing the response time of the control valve. This is due to the fact that the free edge of the split elastic ring, like a mechanical multiplier, blocks the drain canal π times faster than the valve stroke when it rises from the pressure of the fluid flow or signal when the electromagnet is on. The ring valve simultaneously acts as a spring to return to its original position, simplifying the design as much as possible. In the course of research, a new mathematical expression was derived for calculating the valve stroke depending on its design parameters. Using this formula, the optimal parameters of the control ring valve of the pump injector were established, which affect the quality of fuel injection in a wide range of diesel operation: diameter - 20 mm, ring width - 12 mm, thickness - 0.46 mm, diameter of the control fluid supply canal - 3 mm.

DIESEL INJECTOR PUMP WITH RING CONTROL VALVE

The studies were carried out with the aim of modernizing the pump injector with a hydraulic actuator of the HEUI system plunger with the development of a control valve model based on a split elastic ring that provides fast fuel injection control. The upgraded device differs from the existing ones in that instead of a control freely floating valve (ball) or a poppet valve with springs, a valve in the form of a split elastic ring is installed in the valve assembly. One end of this ring is fixed rigidly, the other is freely movable to block the drain channel of the liquid. The canal overlaps the free edge of the ring when the electromagnet is turned on (installed with a gap inside the ring), and also (in the absence or malfunction of the electromagnet) from the valve itself running under the pressure of the supplied fluid. When upgrading the pump injector by the proposed method and using an annular control valve with electronic control (with optimal ring parameters), a new technical effect is achieved - reducing the response time of the control valve. This is due to the fact that the free edge of the split elastic ring, like a mechanical multiplier, blocks the drain canal π times faster than the valve stroke when it rises from the pressure of the fluid flow or signal when the electromagnet is on. The ring valve simultaneously acts as a spring to return to its original position, simplifying the design as much as possible. In the course of research, a new mathematical expression was derived for calculating the valve stroke depending on its design parameters. Using this formula, the optimal parameters of the control ring valve of the pump injector were established, which affect the quality of fuel injection in a wide range of diesel operation: diameter - 20 mm, ring width - 12 mm, thickness - 0.46 mm, diameter of the control fluid supply canal - 3 mm.

Clinical and morphological features of malformations of the mitral valve complex

The mitral valve complex is a multicomponent anatomically and functionally coordinated formation, ensuring the activity of the left ventricle and, in general, the heart. Congenital disorders of the structure, quantity, and form of the mitral complex components can be asymptomatic or cause hemodynamic changes that require surgery. Often, clinical signs of mitral complex abnormalities are manifested as mitral stenosis, regurgitation or its combination and contribute to misdiagnosis. To identify the morphological features of abnormalities by echocardiography, it is necessary to know the possible structure aberrations. The article describes the normal anatomy of the mitral valve complex and abnormalities of the fibrous ring, valve leaflets, papillary muscles and chordae tendineae.

Design of Delivery Valve for Hydraulic Pumps

After briefly recalling the main problems that arise in the study of globe valves for alternative pumps, a methodology has been set up in order to refine the design. The obtained method has the advantages of simplicity and independence from empirical diagrams. In summary, from the obtained equation, the suitable values of the parameters can be deduced, based on the assigned data (capacity Q0 and number of rounds n) of all the dimensions of the valve or of the valves. Depending on the parameter values, it is possible to identify the most suitable kind of valve: a single dish-shaped valve, a ring valve, a valve with several rings or a group of valves.