Mechanical valves

classification of mechanical valves, types of caged ball valve, single leaflet valve , tilting disc valve, bileaflet valve, ttk chitra valve,ST jude valve, ATS ap valve, On x valve ,carbomedics,

1. Mechanical valves By Dr Vasanthi DNB CTVS Madras medical mission

2. Classification Caged ball – S tarr Edwards, S meloff cutler, Braunwald cutler

3. Hufnagel valve Housing – methacrylate Ball – silicone Unique design – sutureless fixation Miscellaneous – placement in descending aorta

4. Star edwards Housing – stellite ( cobalt,chromium,molybdenum,nickel ) Ball – silastic (silicone) rubbber Unique design – bare metal cage Miscellaneous – first clinical mitral ball valve When blood pressure in the chamber of the heart exceeds that of the pressure on the outside of the chamber the ball is pushed against the cage and allows blood to flow. At the completion of the heart's contraction, the pressure inside the chamber drops and is lower than beyond the valve, so the ball moves back against the base of the valve forming a seal.

5. Tilting disc : Bjork - Shiley valve Lillehei Kaster valve Medronic Hall Omincarbon Monostrut Chitra valve

6. CHITRA VALVE Manufactured by TTK ( Tiruvellore Thattai Krishnamachari ) Materials of construction: Frame(cobalt based alloy of chromium, nickel tungsten) Disc- occluder Ring

7. Opening angle : 60-75 degree The strut attaches disk eccentrically so that the backpressure on a larger segment of the disk will tend to close the valve. Eccentric disc position produces two orifices of different sizes and shapes: A major orifice and a minor orifice .

8. Orientation mitral position- major orifice is directed posteriorly . If chordal preservation - major orifice faced anteriorly Normally during diastole, flow acquires a laminar pattern and enters the left ventricle through the posterior portion of the mitral inflow tract. Anatomic orientation of a tilting-disk prosthesis at the mitral position mimics a “trapdoor ” effect of the natural anterior mitral leaflet and preserves the left ventricular physiologic vortices during diastole Aortic : large orifice oriented towards greater curvature

9. Available models

10. Advantages Complete structural integrity Absence of cavitation related damage Rotatable within the sewing ring to assure Its freedom to rotate if repositioning is required Low profile Low cost

11. Bileaflet valves : Gott-Dagett valve Lillehi Kalke valve SJ Medical valve ON X ATS medical open pivot Carbomedics

12. Parts of bileaflet valve 1) two semicircular occluders /leaflets 2)annular housing 3)hinge region 4) gaps. A) peripheral B) leaflet 5)sewing ring

13. ST JUDE MECHANICAL VALVE First bileaflet valve introduced in 1977 by st jude medical inc. Low profile, bileaflet mechanical valve.

14. DESCRIPTION: Leaflets – Contains 2 semicircular leaflets retained within the ring by hinges leaflets & orifice ring - pyrolytic carbon coated with graphite substrates Leaflets are impregnated with tungsten for radiopacity

15. Sewing cuff – Double velour knitted polyester fiber in the polyester cuff Allows rapid, controlled endothelial ingrowth . Sewing cuff has suture markers – provides reference markings for the placement of the sutures and valve orientation. 3 suture markers in aortic valve prosthesis(120  apart) 4 suture markers in mitral valve prosthesis (90  apart)

16. MASTERS HP(HEMODYNAMIC PLUS) SERIES – Facilitates supra-annular placement, allowing for an increase in orifice size for a given tissue annulus diameter MASTERS SERIES- Intra- annular cuff REGENT FLEXCUFF – The flexcuff is flanged and more pliable than the standard cuff. Supra-annular valve placement

17. ORIFICE- One central rectangular orifice Two lateral orifices Central orifice lateral lateral Supraannular placement will increase EOA for given tissue annulus diameter

18. MECHANISM: Opens by pivot mechanism When the blood passes through the leaflets, it opens at an angle of 80-90  Closing angle 30 Large effective orifice area contributes to normal flow profile with reduced obstruction and turbulence. The central rectangular orifice provides simple laminar flow and better hemodynamic performance. When closed , small amount of blood regurgitates through the recess area

19. VALVE IMPLANTATION: St jude sizers are available to determine the valve prosthesis size Sizer is a double ended tool with A cylindrical end – annulus size replica end, should pass the annulus without resistance. Flanged end – sewing cuff replica end

20. BLOOD FLOWS WITHIN THE PIVOT GUARD BLOOD FLOW PIVOT GUARD LEAFLETS PIVOT GUARD BLOOD FLOW MITRAL AORTIC

21. PROPERTIES : Excellent durability Low thrombo -embolic events Facilitated rotation intra operatively Mr conditional Low turbulence Limitations: Valve clicking sound Recess, where thrombus can form.

22. MEDTRONIC ATS VALVE The ATS(advancing the standards) open pivot bileaflet valve low profile mechanical valve consisting of pyrolytic carbon orifice ring and leaflets.

23. DESCRIPTION: Leaflets – pyrolytic carbon coated over a graphite substrate, impregnated with 20% tungsten for radiopacity . Pivot area – located within the orifice ring , thus decreasing the overall height of the valve Sewing cuff – Made up of double velour polyester fabric mounted on the orifice using titanium stiffening ring and titanium locking wire. Contains 3 markers in aortic and 4 in mitral valve prosthesis.

24. IT IS AVAILABLE IN TWO CONFIGURATIONS Standard Advanced peformance – AP SERIES ATS standard aortic valve – intra-annular valve Valve sizes ranging from 19 mm to 31 mm ATS standard mitral valve – 25 mm to 33 mm

25. ATS AP VALVE – Supra-annular compact cuff configuration for excellent suturability and conformability ATS AP 360 VALVE - Supra-annular flanged cuff configuration for added flexibility, needle penetration, and conformability

26. MECHANISM : The pivot guide in the orifice ring controls the movement of the leaflets. Leaflets works by hinge mechanism and opens at an angle of 85  It allows near laminar flow. The closing angle is 20  to the plane of the orifice ring The hinge mechanism allows rapid closure with very low regurgitant volume and very low noise level I mplantation methods are same as in st jude mechanical valve, whereas to measure the annulus size, one should use the ATS valve sizer .

27. EXCEPTIONAL PROPERTIES Open pivot structure has no recess or cavities , where thrombus can form. Wider orifice area – improved hemodynamic performance Improved durability Exceptional implantability Rotatable orifice Quiet valve function Mr conditional

28. On x valve Leaflet and housing – pure pyrolytic carbon (devoid of silicon) No Other Mechanical Valve Has: 90° leaflets: 1 promotes laminar flow Pure pyrolytic carbon: reduces thrombogenicity Flared inlet: organizes flow; prevents pannus

29. A shorter leaflet closing angle 2point leaflet contact and an actuated pivot(closure is assured when leaflets are open to the full 90°) A length to diameter ratio similar to native valve(is the only mechanical valve with features that mimic natural valve length and inlet flow rate) A low L/D ratio creates more flow resistance because of increased turbulence These features have translated the valve into *Increased strength *Improved valve hemodynamics *Reduced hemolysis * Thrombogenicity

30. Characteristics STATE OF ART ON X VALVE: Elongated orifice with flared inlet Supra annular sewing cuff Flare organizes and increases flow ON X VALVE ANNULUS MAINTENANCE: The on x valve annular flare maintains annulus shape and protects the implanted valve from tissue enroachment

31. ANNULUS MAINTENANCE

32. ON X DESIGN ANNULUS MAINTENANCE

33. ON X- ACTIVATED PIVOT Drag force from change in blood flow direction pushes leaflet tab upwards along closing r amp... ... and 6°toward closedposition...... .... which initiates rapid closure.

34. ON X VALVE DESIGN- TWO POINT LEAFLET CONTACT Soft landing Reduced orifice Contact velocity Reduces blood damage

35. Sizing of aortic on x valve The On-X aortic valve cylindrical sizer is 0.8 mm larger than the stated size. 19 sizer is 19.8 mm outer diameter 21 sizer is 21.8 mm 23 sizer is 23.8 mm 25 sizer is 25.8 mm The On-X aortic replica sizer is the exact sizeof the valve.RIGHT SIZE-all gradients < 10mmHg

36. Valve sizing

37. On x mitral sizing: Sizes 23 and 25 On-X mitral valve sizers are cylindrical in shape. Sizes 27/29 and 31/33 On-X mitral valve sizers are conical in shape These sizers will accommodate the large sized mitrals . ON X VALVE ORIENTATION: aligned anti-anatomically-the same as all bi-leaflet mitral valves.The gap in the leaflet guard will be positioned toward the LVOT or the aortic valve in this orientation.

38. ON X VALVE MITRAL SIZING:

39. CARBOMEDICS VALVE: Housing -a solid pyrolite carbon Leaflets - pyrolite carbon coated graphite that is impregnated with tungsten Stiffening ring composed of titanium which virtually eliminates the risk of leaflet escape. The standard aortic valve prosthesis has the sewing cuff located at the outflow level of the valve cylinder.

40. A high performance valve, the Carbomedics TopHat valve for supraannular implantation, is a standard aortic valve prosthesis where the sewing cuff has been transferred to the inflow level of the valve cylinder . So effective flow orifice over the entire outflow tract . This is particularly advantageous compared to an intraannular position , where part of the effective flow orifice is taken up by the housing and the sewing ring

41. SPECIAL FEATURES: Biolite carbon-covered blood contacting surface on the sewing ring, valve pivot design with absence of pivot guards, Closing angle - 25 degrees Opening angle - 53 degrees from the closed to the open position, or 78 degrees from the plane of the ring.