Tilting-disk valves

Tilting disk valve and bileaflet mechanical valve in the mitral position... 

Introduction of the Medtronic Hall tilting-disk valve... 

FIGURE 77.4 (a) Velocity profile 15 mm downstream on the centerline across the major and minor orifices of the Medtronic-Hall tilting disk valve (major orifice to the right), at peak systole (b) velocity profiles 13 mm downstream in the major and minor orifices of the Medtronic-Hall tilting disk valve, at peak systole (c) turbulent shear stress profile 15 mm downstream on the centerline across the major and minor orifices of the Medtronic-Hall tilting disk valve (major orifice to the right), at peak systole (d) turbulent shear stress profiles 13 mm downstream in the major and minor orifices of the Medtronic-Hall tilting disk valve, at peak systole. 

Tilting-Disk Check Valves These valves (Fig. 10-160) may be installed in a horizontal line or in hnes in which the flow is vertically upward. The pivot point is located so that the distribution of pressure in the fluid handled speeds the closing but arrests slamming. Compared with swing checkvalves of the same size, pressure drop is less at low velocities but greater at high velocities. 

Closure at the instant of reversal of flow is most nearly attained in these valves. This timing of closure is not the whole solution to noise and shock at check valves. For example, if cessation of pressure at the inlet of a valve produces flashing of the decelerating stream downstream from the valve or if stoppage of flow is caused By a sudden closure of a valve some distance downstream from the check valve and the stoppage is followed by returning water hammer, slower closure may be necessary. For these applications, tilting-disk check valves are equipped with external dashpots. They are also available with low-cost insert Dodies. 

Assumed the following valve types are NOT used as Isolation valves Air Operated Dlaphram, Solenoid Operated, Pressure Relief Safety, Swing Check, or Tilting Disk Check. 

A CarboMetrics bileaflet valve or Medtronic Hall tilting disk mechanical valve in the aortic position, with normal left atrial size and normal sinus rhythm... 

Closure at the instant of flow reversal is most nearly attained with tilting-disk, dual-plate, and specialty axial-flow check valves. However, quick closure is not the solution to all noise, shock, and water hammer problems. External dashpots are available when a controlled rate of closure is desired. Nonmetallic seats are also available. 

FIG. 10-163 a) Tilting-disk check valve, b) Dual-plate check valve. 

FIGURE 20.1 Orifice and profile views of representative bileailet and tiltingKiisk valves are provided in the upper and lower halves of the figure. Note the larger percentage of open orifice area present in the bileaflet valve. The tilting disk projects farther inKt the downstream ejection zone than the leaflets on the bileaflet valve. 

Currently, about 90,000 valve replacement procedures are conducted in the United States, with about 280,000 such procedures conducted around the world [13]. The world population is expected to increase from 6.1 billion in 2000 to 8.9 billion in 2050, with the percentage of people of the population over 65 years increasing from 6.9% of the world population in 2000 to 15.9% in 2050 [14]. This aging population of patients requiring heart valve replacement is estimated to triple by 2050, from -290,000 in 2003, to over 850,000 by 2050 [15,16]. The most commonly used valve replacements in the developed world are mechanical bileaflet valves and bioprosthetic valves. In developing countries, tilting disk and ball-and-cage valves continue to be used due to lower costs. Across all valves, aortic valves are most widely replaced, followed by the mitral valve, pulmonary valve, and tricuspid valve. 

The most commonly used mechanical valves around the world are tilting disk and bileaflet mechanical heart valves. Both valves have similar durability and the need for anticoagulation therapy, but the bileaflet valves have superior hemodynamic performance. The primary advantage of mechanical valves is their durability, which translates to lesser reoperation rates compared to bioprosthetic valves. The most commonly used bioprosthetic valves in clinical practice are made of bovine or porcine pericardial tissue, mounted on either a stented or stentless assembly. Bioprosthetic valves have significantly lower risk of thrombosis, so the patient does not need lifelong anticoagulant therapy. However, structural... 

Valve Sewing Ring Diameter (mm) Medtronic-Hall Tilting Disk (cm ) St Jude Bileaflet (arf) CarboMedics Bileaflet (cm ) Hancock1 Porcine (cm2) Hancock MO Porcine (cm2) Carpentier-Edwards Pericardial (orf) Starr-Edwards 1260 Ball (cm2)... 

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