This presentation is a guide to the historical evolution, modifications and lessons learned in the development of heart valves. It clearly depicts how clinical indications for valve surgery has changed over the years and illustrates the identification of prosthesis and analysis of key features in images, at a time when patients present with malfunctioning valves for reoperations. This is courtesy of Dr. Vinayak Shukla, MS, MCh, FIACS. He presently serves as Professor and Unit Chief of Cardiothoracic and Vascular Surgery at Christian Medical College and Hospital, Vellore - home to one among the first implants in Asia. This presentation is part of a video which belongs to the lecture series of IACTS SCORE 2020 held at the Sri Sathya Sai Institute of Higher Medical Sciences Whitefield, Bengaluru between 7th and 8th March, 2020.

1. Prof. Vinayak Shukla
CMC, Vellore

2. Valve replacement surgery has a long, important and
very inspiring history.

3. Faultless valve function is essential for the graceful
forward movement of blood

4. A valve prosthesis which is ‘safer than the condition it corrects’, remains a
mirage.
Failures fail to frustrate
The spirit refuses to die,
Enthusiasm scents triumph at the very next step
As efforts continue unabated.
We shall not cease from exploration and the end of all our exploring
Will be to arrive where we started and know the place for the first time.
Elliots lines.

5. It must not propagate emboli
It must be chemically inert and not damage blood
It must offer no resistance to physiological flows
It must close promptly, i.e. less than 0.05 second
It must remain closed during the appropriate phase of the
cardiac cycle

6. It must have lasting physical and geometric features
It must be inserted in a physiological site (generally the normal
anatomical site)
It must be capable of permanent fixation
It must not annoy the patient
It must be technically practical to insert

7. Dr. Charles Hufnagel
Implanted an acrylic ball valve prosthesis into the
descending aorta of a 30-year-old woman for aortic
incompetence in 1952 at Georgetown Medical
Center in Washington, DC, who could lead a
normal life after the surgery
It was a methylcrylate chamber containing the
methylcrylaye ball in the middle, which was
"implanted quickly into the descending aorta using
a nonsuture technique."

8. More than 200 implanted Hufnagel valves
functioned for as long as 30 years with no
significant wear.
No anticoagulation was used.
The drawback to this model, besides the mortality
and cumbersome insertion during the brief cross-
clamp period, was that patients could hear the
plastic ball bouncing around inside them.

9. His work proved that biocompatible materials
could be successfully used to create heart valves,
but his problem was placing it where it had to
work.
Not the descending thoracic aorta.

10. 1950- HUFNAGEL developed a ball valve,designed to
be placed in the descending thoracic aorta for aortic
insufficiency
Acrylic ball inserted into the descending aorta

11. As the valve only
prevented the regurgitant
flow from the lower
body,the cardiac work
was not much improved
Embolisation and
thrombosis frequently
occurred
Extremely noisy

12. A biologically compatible material
A hemodynamically tolerant design

13. With the development of the heart-
lung machine and the opportunity
to work within the open heart
Dr Harken working with Mr W. C.
Birtwell at Davol, Inc, developed a
ball valve with a double cage
fabricated of stainless steel
Implanted in 17 patients initially, of
which only two could survive.
Both the patients required
successive valve replacements .

14. Albert Starr, a physician, and Lowell Edwards, an electrical
engineer, simplified the caged-ball valve using a single titanium
cage, a silastic ball, and a sewing ring covered with Teflon.
The Starr-Edwards valve was first implanted in the mitral
position in 1960, and later in the aortic position. The valve
became commercially available in 1965.

15. In the early 1960s, Dr George Magovern, Sr, Chief of
Cardiothoracic Surgery at the University of Pittsburgh Medical
Center, working with an engineer, Mr Harry Cromie,
developed a ball valve that incorporated a unique method of
sutureless fixation
It was inserted by rotating an implantation tool to engage the
multiple vertical pins in the aortic annulus and was particularly
suited for aortic implantation

16. In 1989, Dr Magovern reported on his 25-year experience with
the Magovern-Cromie aortic valve His valve was implanted in
728 patients between 1962 and 1988.

17. This ball valve was the first prosthetic valve
to employ the “full-flow” orifice concept.
This was achieved by a double set of cages
permitting the silicone elastomer ball to rest
on the smaller inflow cage during valve
closure.
In 1989 at the World Congress on Valve
replacement, San Diego, Dr. Smeloff
reported that 50,000 Smeloff valves had
been implanted worldwide, with no
structural failure for 22 years of use.

18. This ball valve was the first prosthetic valve to employ
the ‘full flow’ orifice concept.
The ball rests on the smaller inflow cage during valve
closure.
This has now referred to has the ………….

20. This valve was developed by Dr
Michael DeBakey and Harry Cromie of
Surgitool and was introduced in 1967.
In 1969, the polyethylene poppet was
replaced with a hollow pyrolytic
carbon poppet.
This was the first use of a new carbon
material developed by Dr Jack Bokros
at the General Atomic Company in
LaJolla, California.

21. The fabrication of a hollow ball of pyrolytic carbon (pyrolyte)
for the DeBakey-Surgitool valve in 1969 by the materials
engineer Dr Jack Bokros was a landmark in mechanical valve
development .
Bokros’ pyrolytic carbon, originally developed for the
encapsulation of nuclear fuel rods, would become over the next
decade, the principal biomaterial for virtually all new
mechanical valves

22. Carbon – pyrolytic carbon, oringally used to cover
nuclear fuel rods, and now has become the principal
bio material for virtually all mechanical valves.
Dr Bokros found that highly polished pyrolytic carbon
will not bond with heparin but is the most thrombo
resistant non heparinised material that they have ever
evaluated.

23. Kay-Shiley Disc Valve
Dr Jerome Kay and Mr Donald Shiley
designed the first disc valve that achieved
worldwide use beginning in 1965.
Reliable mitral prosthesis that utilized a stellite
housing and a flat silicone elastomer disc
Unfortunately, there were problems with wear
of the silicone elastomer disc and it was
replaced with a Delrin polymer disc in 1975

24. Bjork-Shiley Flat Disc Valve
(also designated as standard or spherical disc valve) was extremely
successful worldwide, with nearly 300,000 aortic and mitral prostheses
implanted between 1969 and 1986
Bjork-Shiley Convexo-Concave Tilting Disc Valve
. By making a concave pyrolyte disc and modifying the inlet and
outlet struts, the disc could slide forward and down about 2 mm,
thus achieving the desired enlargement of the lesser valve orifice.

25. The inlet and outlet struts were modified such that the
disc could make a slide forward and down movement
for about 2 mm, thereby achieving the desired
enlargement of the valve orifice.
And also a better wash of the entire console with the
forward flow of blood.
This was very stictly followed in the Medtronic Hall
valves.

26. The design of the valve, comprised a unique tilting prolyte disc
with a small central perforation for a thin metal strut that
guides the disc during opening and closing of the valve

27. Dr Victor Hall and Robert Kaster developed this valve,
and hence was known as Hall Kaster valve.
Once the Medtronic company took over manufacturing
this valve was then known as Medtronic Hall and then
later on as Medtronic valve.

28. Just after the era of tilting disc models, the bi-leaflet heart valve
model was introduced.
The valves usually consist of two semicircular leaflets that
rotate about struts attached to the valve housing.
The design of the valve was such that it resulted in a greater
effective orifice area
Gott-Daggett Bileaflet Valve was the very first model of
bileaflet design and was introduced in the late 1960s.

29. Dr Bhagabant Kalke from India went to work with
DR Lillehei.
Common sense : he had observed the passive tidal
floodgates that opened with the outgoing tide and
closed with the incoming tide to protect shore line
crops.
So he came up with a bi leaflet valve with
peripheral hinges and a central opening.

31. Doctor Bhagabant Kalke came from India to work in Dr
Lillehei’s laboratory in 1964.
Doctor Kalke had grown up on the west coast of India and was
familiar with the passive tidal floodgates that opened with the
outgoing tide and closed with the incoming tide to protect
shoreline crops.

32. Doctor Kalke fabricated a polymer valve in Dr Lillehei’s
laboratory based on the configuration of the Indian tidal
floodgates with peripheral hinging leaflets and a central
opening.

33. Why bi leaflet design – to provide a low profile valve
than the bulky caged ball.
So what happened -
The disadvantage was that there was relatively
stagnant blood flow in the area of the struts used to
hold the leaflets.
Thrombus formation took place here.
And so what had to be done.
What did he do ???

34. The pivot sites for the leaflets were placed at the
equator of the annular ring.
And the problem could be overcome.
Then came Robert Kaster who removed the over riding
struts.

35. St Jude Medical Bi leaflet valve came into being.
Mr Manny Villafana
Mr Xinon Posis
Dr Demetre Nicoloff
They too designed a similar valve with pivots near the
periphery and a central opening.

36. Mr Donal Hanson redesigned the valve with the hinge
mechanism located near the central axis of the
housing.
Also, the concept of a leaflet – tab rotating in a
‘butterfly recess’ in the inner wall of the housing.
Mr Villafan - the entire valve made or Mr Bokros’
pyrolytic carbon.

37. Why this name ?
Not even a single name from the ones who contributed
to this valve.
Why not Nicoloff valve.
Mr Villafana’s son was recovering from a serious
illness. St Jude Thaddeus is the patron saint of difficult
times they believed. And that is how the name came.

38. And that is how this SJM valve came into being.
The non rotatable series, had its own difficulties.
The Master series came, which were rotatable.
And then for some time we had silver impregnated
sewing rings, which were withdrawn.
And then the Regent valve came.

39. Improved effective orifice area
By reducing the sewing ring thickness,
shifting the carbon rim to the supra
annular position and
improving the rotation mechanism

40. In 1986, Dr Bokros created the Carbomedics bileaflet valve,
which was similar to the St. Jude valve, but its housing could be
rotated within the sewing ring
Doctor Bokros and Mr Villafana also developed the two other
valves (On-X and ATS respectively)

41. The solid pyrolytic carbon valve has a unique pivot design
pivot areas were entirely within the orifice ring
differs from other valves - that have cavities in
the hinge area.
the open pivot design is intended to decrease blood
stasis and thrombus formation
valve design minimizes overall valve height and generates a larger
orifice area.

42. Approved by FDA in 2002
Pure pyrolytic carbon used in On X valve is stronger than
silicon alloyed pyrolytic carbon used in other mecahnical valves.

43. The inflow has a flared inlet designed to reduce
flow turbulence.
Flared inlet produces higher volume of flow with
increased washing to minimize flow stagnation.
The outflow rim consists of leaflet guards
designed to protect the leaflets while in closed
position.
The leaflets rotate around tabs located within the
inner circumference of the orifice ring.

44. In closed position each leaflet forms an angle of 40
degrees relative to the pane of the orifice.
In open position the plane of each leaflet forms a
nominal angle of 90 degrees relative to the plane of the
orifice.
The leaflets have to travel an arc of 50 degrees to the
closed position.

45. Leaflets open 90 degrees with soft landing leaflets designed to
reduce the blood element stress
Comes in sizes 23 to 33mm

46. Question ??
How this sizing has been done for ON X valve ?

47. Size 25 has an effective orifice area of 2.02 sq cms.
And all the valves have the same area, only the sewing
cuff changes.

48. Developed in Sri Chitra
Institute in Trivandrum and
first implanted in December
1990.
M. S Valiathan was the
surgeon who was the main
force behind the development
of the Chitra valve
The current valve is the
4 th generation valve.

49. The first model had a titanium housing with welded strut
and a Delrin disc.
The housing and struts were then machined from a block
of Haynes -25 coated with titanium nitride and the
occluder was from a single crystal of synthetic sapphire
The final model has Haynes -25 housing and a highly
polished, cryo-machined solid state disc manufactured
from ultra high molecular weight polyethylene. The
sewing ring is made from a knitted polyester fabric.

50. DELRIN® (Acetal Homopolymer) DELRIN® is a
crystalline plastic which offers an excellent balance of
properties that bridge the gap between metals and
plastics.
DELRIN® possesses high tensile strength, creep
resistance and toughness. It also exhibits low moisture
absorption.

51. More than 75000 have been implanted.
It is a tilting disc valve.
The Chitra tilting disc valve has an integrally machined cobalt-
based alloy cage- Haynes metal,
an ultra-high molecular-weight polyethylene disc,
and a polyester suture ring.

53. The label of mechanical and biological heart valves always
consists of the trade name and a number indicating the valve
size (in millimeters)
This valve size represents the outer diameter of the valve
housing/stent tissue annulus diameter(TAD, in millimeters)
The Internal orifice diameter(IOD) of the valve is smaller than
the labeled valve size.

54. Hemodynamically, the most important parameter of both
mechanical valves and bioprostheses is their effective orifice
area (EOA)

55. Geometric orifice area is the whole inner area of the valve
including the area occupied by the opened discs or leaflets,
struts, and other mechanisms of the valve.
By subtracting the area of opening components of the valve
from GOA, the so-called Clear orifice area (COA) is obtained
The EOA is that portion of the valve orifice area through which
the blood really flows. The EOA is usually one quarter or one
third smaller than GOA

56. In a given patient, the most important parameter is the indexed
value ( IEOA), i.e., EOA related to 1 m2 of the patient’s body
surface.
It has to be kept in mind that values declared by the
manufacturer used to look more optimistic (in vitro values) than
post-implantation echocardiography values calculated on the
basis of continuity equation (in vivo values).

57. The aim is to implant a valve large enough to avoid
hemodynamically significant patient–prosthesis mismatch
(PPM).
The original paper that described valve prosthesis–patient
mismatch (VP–PM)stated that “Mismatch can be considered to
be present when the effective prosthetic heart valve area, after
insertion into the patient, is less than that of a normal human
valve”; all prosthetic heart valves (PHVs) are smaller than
normal and thus are inherentlyc stenotic
S.H. RahimtoolaThe problem of valve prosthesis-patient mismatch
Circulation, 58 (1978), pp. 20-24

58. It is important mainly in the aortic position where IEOA of the
implanted valve should be greater than 0.85 cm2/m2.
In the mitral valve the cut-off value for PPM is considered to
be 1.2 cm2/m2.
Severe patient–prosthesis mismatch occurs if IEOA is less than
0.65 cm2/m2 in the aortic position and less than 0.9 cm/m2 in
the mitral position

59. Internal orifice diameter(IOD)
Tissue annulus diameter(TAD)
External sewing ring diameter(ESRD)

60. Stented bioprosthesis have inherent gradients because the
actual valve is supported by a stent and housing material
The EFFECTIVE ORIFICE AREA(EOA) refers to the true
cross sectional area through which the blood must
flow(most important parameter)
EOA=SV/VTI
Cross sectional area of the valve(Gorlin’s formula)
A=Q/(44.3*sq.root of pressure gradient)

74. Thank you for your attention and time.