Prosthetic Heart Valves: A History of Innovation and Improvement

Prosthetic valves the past
present and future
Dr . I.Tammi
Raju
Prosthetic valves Past,Present &
Future

overview
• Evolution of valves
• Present day valves
• Evaluation of functioning of valves
• Complications
• Future of valves

Introduction
• The introduction of valve replacement surgery in the early
1960s has dramatically improved the outcome of patients with
valvular heart disease.
• Despite the improvements in prosthetic valve design and
surgical procedures , valve replacement does not provide a
definitive cure. Instead, native valve disease is traded for
―prosthetic valve disease‖.
Prosthetic valves
Past,Present & Future

• Although the capacity to surgically correct valvular heart
disease through valvuloplasty had been established by the
1920s,
• Initiallly before prosthetic valves-
– Volovotomy –Cuttler & Levine 1923 inserting a
volvotome(knife) in to apex –tearing cusps converting MS
into MR.
– Finger dilation – Henry souttar & bailey (1948)
independently

• The prosthetic heart valve
was built on a foundation
laid down during the first
half of the 20th century with
the
– Introduction of cardiac
catheterization by André
Cournand and Dickinson
Richards,
– The development of
innovative surgical techniques
by Alfred Blalock,
– The invention of the heart–
lung machine by John
Gibbon, and the
– Heparin by Jay McLean and
– Dicumarol by Karl Paul Link.
André Cournand and
Dickinson Richards,
Alfred Blalock,

Evolution of Prosthetic Heart Valves
The development of the original
ball-and-cage valve design can
be attributed to the bottle stopper
in 1858
In the early 1950’s, it led to the idea
of a prosthetic heart valve
consisting of a cage with a
mobile spherical poppet

• 1952- The first ever invented artificial heart valve was
designed by Charles A. Hufnagel which was the caged-ball
design.

Evolution of Prosthetic Heart Valves
This first heart valve was
made of a
Plexiglass(methyl
methacylate)cage
surrounding a silicone-
coated nylon poppet
First implanted in a human in
a closed procedure in
September of 1952
(descending thoracic aorta)

• In 1954, Charles Hufnagel and
his colleagues described 23
patients with aortic insufficiency
who had been treated during the
previous 2 years by rapid
insertion of an acrylic ball valve
into the descending aorta.
• However, since the valve
prevented regurgitant flow only
from the lower body, cardiac
work was only partially relieved
and coronary flow was not
improved.
• In addition, embolization and
thrombosis of the valve occurred
frequently, and the noise
generated by the valve was
disconcerting — reminiscent,
according to some, of a ticking
time bomb.

Evolution of Prosthetic Heart Valve
• Significant advances were made soon after to help the
development of the heart valve:
• In 1953, marked successful use of the heart and lung
machine, paving the way for the 1st open heart
operations
• The idea of using blood from another patient to
oxygenate the blood of the patient was developed
• New methods were came for evacuating air from the
heart
• New materials (Plexiglass, Teflon, and Dacron)

Evolution of the Prosthetic Heart Valve
 On July 22, 1955, at the City General Hospital in
Sheffield, England, Judson Chesterman implanted the first
successful heart valve
 The patient lived 14 hours after the valve was placed, but died
when the poppet twisted out of position
 Valve was made of Perspex, an outer cage, a poppet, and 2
buttons to fasten the valve to the outside of the heart

• Edwards proposed that he and Starr collaborate on the
invention of a mechanical heart that could replace a failing
human heart.
• Starr convinced Edwards to focus on inventing a prosthetic
heart valve.
• Edwards would construct the valve prototypes and Starr would
insert them into the hearts of dogs.
Evolution of Starr-Edwads valve
Edwards, Starr

Starr sutured the first valve using ring of Teflon cloth attached to the
prosthesis. It functioned for several hours before a clot formed and
blocked the Silastic flaps and the animal died. Starr and Edwards
developed a method for fabricating a Teflon tube of cloth material
that provided a superior means of suturing the prosthesis into the
mitral annulus.

INVENTION OF THE SEWING RING
:BALL-IN-CAGE PROSTHESIS
Starr inserted a ball-in-cage valve prosthesis
into the mitral position in the first dog. It was a
spectacular success and the dog survived
vigorously for months, with normal
cardiovascular physiology

• On September
21, 1960, Starr performed
the first successful
orthotopic valve
replacement in the mitral
position, which was
followed by Harken's
implantation of a prosthesis
in the aortic position
Patient Philip Admundson: First successful
mitral valve replacement
Future

• In 1961, after their success with the mitral valve
prosthesis, Edwards and Starr turned their attention to
inventing a ball-in-cage prosthesis to replace the aortic valve
• The four struts were replaced by three struts of reduced
thickness, made of an exceptionally hard alloy, Stellite . The
sewing ring had to be shaped to conform tightly to the high-
pressure flows across the aortic valve.

• Importance of hemodynamics in valve design.
• The energy required to open the ball valve, as reflected by the
pressure gradient, was substantial.
• An aortic valve that resulted in a large pressure drop with
increased resistance to forward flow required greater left
ventricular systolic pressure to drive cardiac output, with a
commensurate increase in myocardial oxygen consumption.
• Moreover, centrally obstructive flow with large recirculation
regions contributed to thrombogenic potential.

Evolution of the Prosthetic Heart
Valve
• Since this time, over 30
mechanical heart designs
have been marketed in the
U.S. and abroad
• These valves have
progressed from the simple
caged ball valves, to strut-
and-leaflet valves and the
modern bileaflet valves, to
human and animal tissue

Types of Prosthetic Heart Valves
• Mechanical
– Bileaflet (St Jude)(A)
– Single tilting disc (Medtronic Hall)(B)
– Caged-ball (Starr-Edwards) (C)
• Biologic
– Stented
• Porcine xenograft (Medtronic
Mosaic) (D)
• Pericardial xenograft (Carpentier-
Edwards Magna) (E)
– Stentless
• Porcine xenograft (Medronic
Freestyle) (F)
• Pericardial xenograft
• Homograft ( allograft)
– Percutaneous
– Expanded over a balloon
(Edwards Sapien) (G)
– Self –expandable (CoreValve)
(H)
Circulation 2009, 119:1034-1048

Mechanical Valves
• Extremely durable with overall survival rates of 94% at 10
years
• Primary structural abnormalities are rare
• Most malfunctions are secondary to perivalvular leak and
thrombosis
• Chronic anticoagulation required in all .

Mechanical Valves:Ball Valves
• This design uses a spherical occluder, or blocking device, held
in place by a welded metal cage
Problem and Why failed:
– Natural heart valves allow blood to flow straight through
the center of the valve (central flow)
– Caged-ball valves completely blocked central flow and
collisions with the occluder ball caused damage to blood
cells
– Finally, these valves stimulated thrombosis, or formation of
blood clots

Starr-Edwards Ball Valve
Model: Starr-Edwards
Type: Aortic Caged Ball
Materials: Silicone Rubber
ball with 2% barium
sulfate, cage-Stellite alloy
No. 21, sewing ring-
knitted Teflon and
polypropelene cloth
Edwards Lifesciences discontinued
production of the Starr-Edwards
valve in 2007.

Magovern-Cromie Ball Valve
Model: Magovern-Cromie
valve
Type:Aortic Caged Ball
Materials: Ball-Silicone
rubber with barium, cage-
titanium, sewing ring-
none, Cage open at top

• Mechanical valves were refashioned in the late
1960s, when a tilting disk was introduced to
– minimize resistance to forward flow,
– decrease turbulence,
– limit regions of stagnation, and
– reduce shear stress.
– Although thromboembolism was not
eliminated, anticoagulation requirements were reduced.

Single Leaflet Disc Valves
• Uses a tilting occluder disk
to better mimic natural
flow patterns through the
heart
• tilting pattern allow more
central flow while still
preventing backflow
• Some damage still occurs
to blood cells
• Reduces thrombosis and
infection, but does not
eliminate either problem

Bjork-Shiley Standard Aortic Valve
Model: Bjork-Shiley Standard
Type: Aortic Tilting Disc
Materials: Disk-Pyrolytic
Carbon, cage-Haynes
25, sewing ring-Teflon

Bjork-Shiley Valve:
Initial Fracture Assessment
• Investigators determined
that the floating disc opens
and slams shut at least 70
times per minute or 40
million times per
year, causing fatigue failure
• Although changes were
made, fractures continued
to occur
• Finally, in 1984, Shiley
discovered the
source, known as ―Bimodal
Closure Phenomenon‖

Bjork-Shiley Valve:Role of the FDA
• In 1979, the Bjork-Shiley valve was approved very
quickly, only six months after Shiley’s first request
• The main criticism of the FDA was its delay in removing the
valve from the market despite knowledge of the outlet struts
susceptibility to fracture
• The Bjork-Shiley heart valve failure prompted the FDA to
make substantial changes in its policies

Medtronic-Hall Valve
Model: Medtronic-Hall
A7700 (aortic), M7700
(mitral)
Type: Aortic and Mitral
Tilting Disk
Materials: Cage-
titanium, Disk-Pyrolytic
carbon, sewing ring-knitted
teflon

Other Single Leaflet Disc Valves
• Another similar valve
is the caged disc valve
• Examples are Starr-
Edward Model 6500
and the Kay-Shiley
Model

• In 1977, the ideal of central unimpeded flow was approached
with the advent of the bileaflet valve.
• Despite improved hemodynamics and the application of
thromboresistant alloys and advanced ceramics, the goal of
substituting the use of antiplatelet agents for lifelong
anticoagulant therapy remains elusive.
BILEAFLET VALVE.

Bileaflet Disc Heart Valves
• Consists of two semicircular
leaflets that pivot on hinges
integrated onto the flange
• Carbon leaflets and flange
exhibit high strength and
excellent biocompatibility
• Largest opening angle-Similar to
central flow
• Allows small amount of
backflow as leaflets cannot close
completely
• Lowest pressure gradients
• Low thrombogenisity and
turbulence.

St. Jude Bileaflet Valve
Model: St. Jude Valve
Standard
Design
:Mitral, Aortic, Tricuspid
Bileaflet Valve
Materials-Cage and disk-
pyrolytic carbon, sewing
ring-double velour knitted
polyester

TTK-CHITRA
ONLY INDIAN-MADE HEART VALVE
• The first implant was December
6, 1990 at Sree
Chitra Institute ,Trivandrum.
• TTK Chitra Heart Valve has been
in Clinical use for over 14 years.
• More than 55,000 TTK Chitra
Heart Valve has been implanted
so far in India, Nepal, Sri
Lanka, Bangladesh and South
Africa(250 CENTERS)
•Complete Structural Integrity
•Absence of cavitation related damage
•Silent operation
•Rotatable within the sewing ring to assure
its freedom to rotate if repositioning needed.
•Low profile,most price-friendly

Bioprosthetic – Why??
Mechanical valve limitations :
 No major change in valve design since first implant.
 Lifelong Anticoagulation therapy
 INR Test every 15 days
 Thrombolysis
 Treatment of Hemorrhage
 Hospitalization
 Congenital Anticoagulation Resistance

Bioprosthetic valve – What??
• Bioprosthetic typically
refers to a xenograft that is
chemically
treated, mounted on some
support structure
(stent), or stentless.
• Term coined by Alan F.
Carpentier.

1960’s
 Tissue valves investigated in an attempt to overcome the
disadvantages of mechanical valves
– 1962: Ross & Boyes performed first successful
allograft replacement from cadaver.
– 1964: Duran & Gunning used the first heterograft,
a porcine aortic valve
- 1965:Jean-Paul Binet and colleagues five patients with
mercurochrome- and-formalin-preserved
heterografts
– 1967: Ross introduced pulmonary autograft for
aortic replacement
– 1968: Carpentier showed that glutaraldehyde
preservation improved stability of heterografts

• In the late 1960s, Carpentier -tissue stability required
the prevention of both immunologic reaction and
collagen denaturation.
• Immunologic reaction-
– washing a porcine aortic valve in Hanks' solution and using
an oxidizing agent.
• Collagen denaturation-
– Further treatment with glutaraldehyde would prevent the
denaturation of collagen by creating stable cross-links
(promotes calcification).

1968: Glutaraldehyde Fixation
Introduced
• Proposed by Carpentier.
• Carpentier in 1968 implanted the first ever
glutaraldehyde treated stent mounted aortic valve.(C-E
valve)
• Glutaraldehyde is chemical used in leather tanning
• All modern xenografts are fixed in glutaraldehyde

1970’s
 Continued development of tissue
valves including stented products
– Early 70’s: Kaiser & Hancock
developed first successful
porcine bioprosthesis - metal
stent - then plastic
– 1976: Carpentier & Edwards
developed porcine valve with
an Elgiloy stent
– 1976: Ionescu & Shiley
introduced bovine pericardial
valve with polyester-covered
flexible stent.
43

1980’s and 90’s
STENTLESS tissue valves
introduced
1988: David implanted the first
stentless porcine bioprosthesis
Mitroflow introduced a bovine
bioprosthesis with Delrin stent
1991: Carpentier-Edwards
received FDA approval for a
bovine pericardial bioprosthesis

Bioprosthetic Valve Types
 Xenografts
Tissue from different species
» Porcine valve
» Bovine pericardium
 Allograft/Homograft
Tissue from same species
» Human valve
 Autograft
Tissue from same individual
» Pulmonary valve to the aortic
position

Types of Stented Tissue Valves
Intact porcine valves
• Reduction of muscle
shelf bar
 Medtronic’s tissue valves
 Edwards’ porcine tissue valves
Composite porcine valves
• Three separate leaflets –
either the left or the non-
coronary cusps
 SJM’s Biocor stented tissue
valves
Pericardial valves
C-Edwards’ valves

Animal Tissue Valves
• Heterograft or
Xenograft Vavles
• Most commonly used
tissues are the porcine
(pig) valve tissue and
Bovine (cow)
pericardial tissue

Porcine (pig) Valves
• Two major brands of
porcine available
today, Hancock and
Carpentier-Edwards
• Has good durability and
and good hemodynamics
Materials: Porcine valve
tissue, stents made of
wire, Elgiloy(cobalt-nickel
alloy), sewing ring-knitted
Teflon

Pericardial (cow) Valves
• Lasts as long as standard
porcine valves at 10 years
• The pericardial valve has
excellent
hemodynamics, even in
smaller sizes(19mm to
21mm)and has gained a
large market share (about
40% of US tissue valves) in
this group of patients

Homografts(Human to Human)
• Homografts are valves transplanted from one human to
another
• After donation, valves are cyropreserved until needed
• Since the valve must be thawed overnight, the patient’s size
must be known beforehand.
• homograft availability is limited by donor availability
• Advantages: resistance to infection, lack of need for
anticoagulation, excellent hemodynamic profile (in smaller
aortic root sizes)
• More difficult surgical procedure limits its use.

Autografts (Ross Procedure)
• Autografts are valves taken from the same patient in which the
valve is implanted.
• Used for patients with diseased aortic valves
• Advantages:
– patient receives a living valve in the aortic position
- Better durability and hemodynamics
Disadvantages:
Difficult procedure for the surgeon and involves considerable skill
Leakage of the valve (aortic regurgitation)

• Stentless Bioprostheses
• The first use of a nonallograft stentless valve was in 1986 by
David, at the Toronto General Hospital.
• Because these prostheses have no rigid metal stent, there is
little inherent gradient across the valve.
• These valves are supported by the aortic root of the patient
when implanted using the subcoronary or inclusion cylinder
technique.
Prosthetic heart valves past
present,future

• less chance for PPM
• Favorable ventricular
remodeling.
• Technically demanding with
longer cross-clamp times;
• long-term durability is also
a question.
• FDA-approved stentless
valves
– Toronto Stentless SPV,
– the Medtronic Freestyle, and
– the Edwards Prima Plus
Stentless Porcine Valve

Stentless Tissue Valves
• Subcoronary
– Medtronic Freestyle
– SJM Toronto SPV
• Full Root
– Medtronic Freestyle
– Edwards Primaplus
– SJM Toronto SPV

Desired valves
• Mechanical valves - preferred in young patients
 who have a life expectancy of more than 10 to 15 years
 who require long-term anticoagulant therapy for other
reasons (e.g., atrial fibrillation).
• Bioprosthetic valves
 Preferred in patients who are elderly
 Have a life expectancy of less than 10 to 15 years
 who cannot take long-term anticoagulant therapy
• A bileaflet-tilting-disk or homograft prosthesis is most suitable
for a patient with a small valvular annulus in whom a
prosthesis with the largest possible effective orifice area is
desired.

Algorithm for choice of prosthetic
heart valve
Prosthetic valves Past,Present & Future

• CLINICAL INFORMATION &CLINICAL EXAMINATION
• IMAGING OF THE VALVES
 CXR
 2D echocardiography
 TEE
 3D echo
 CineFluoro
 CT
 Cardiac
catheterisation
Evaluation of prosthetic valves

CLINICAL INFORMATION
• Clinical data including reason for the study and the patient’s
symptoms
• Type & size of replacement valve,
• Date of surgery
• Patient’s height, weight, and BSA should be recorded to assess
whether prosthesis-patient mismatch (PPM) is present
• BP & HR
– HR particularly important in mitral and tricuspid evaluations because
the mean gradient is dependent on the diastolic filling period
Prosthetic valves

Future

CXR
• Chest x-ray are not performed on a routine basis in the
absence of a specific indication.
• It can be helpful in identification of valve type if information
about valve is not available.
Prosthetic valves

• The location of the cardiac
valves is best determined on
the lateral radiograph.
• A line is drawn on the
lateral radiograph from the
carina to the cardiac apex.
• The pulmonic and aortic
valves generally sit above
this line and the tricuspid
and mitral valves sit below
this line.
Future
CXR

• For further localization
prosthetic valves involves
drawing a second line which
is perpendicular to the
patient's upright position
which bisects the cardiac
silouette.
• The aortic valve projects in
the upper quadrant, the
mitral valve in the lower
quadrant ,the tricuspid valve
in the anterior quadrant and
pulmonary valve in the
superior portion of the
posterior quadrantProsthetic valves Past,Present &
Future
CXR

• On the frontal chest radiograph
( AP or PA ) - longitudinal line
through the mid sternal body.
draw a perpendicular line
dividing the heart horizontally.
• The aortic valve - intersection
of these two lines.
• The mitral valve - lower left
quadrant (patient’s left).
• The tricuspid valve - lower
right corner (the patient's right)
• The pulmonic valve- upper
left corner (the patient's left).
This method is less reproducible

 Some bioprosthetic valves have components that determine
the direction of flow which helps localize the valve
prosthesis.
 If the direction of flow is from
inferior to superior – likely aortic valve.
superior to inferior- likely a mitral valve.

2D ECHO
 Valves should be imaged from multiple views, with attention
to
 determine the specific type of prosthesis,
 confirm the opening and closing motion
 confirm stability of the sewing ring(abnormal rocking motion )
 Presence of leaflet calcification or abnormal echo density -
vegetations and thrombi
 Calculate valve gradient
 Calculate effective orifice area
 Confirm normal blood flow patterns
 Detection of pathologic transvalvular and paravalvular
regurgitation.
Prosthetic valves

TIMING OF ECHO CARDIOGRAPHIC
FOLLOW-UP
• Ideally, a baseline postoperative transthoracic
echocardiography(TTE) study should be performed 3-
12weeks after surgery, when the
 chest wound has healed,
 ventricular function has improved, and
 anaemia with its associated hyperdynamic state has resolved.
• Bioprosthetic valves Annual echocardiography is
recommended after the first 5years,
• Mechanical valves, routine annual echocardiography is not
indicated in the absence of a change in clinical status.
Prosthetic valves
Evaluation of prosthetic valves-2D ECHO

The high reflectance leads to
• shadowing
• Reverberations
• multiple echocardiographic windows must be used
• TEE is necessary to provide a thorough examination.
• For stented valves-ultrasound beam aligned parallel to flow to
avoid the shadowing effects of the stents and sewing ring.
Prosthetic valves

Prosthetic valves

 For bioprostheses, evidence of leaflet degeneration can be
recognized
leaflet thickening (cusps >3 mm in thickness)-earliest sign
calcification (bright echoes of the cusps),
tear (flail cusp).
 Prosthetic valve dehiscence is characterized by a rocking
motion of the entire prosthesis.
 An annular abscess may be recognized as an
echolucent, irregularly shaped area adjacent to the sewing ring
of the prosthetic valve.

PRIMARY GOALS OF DOPPLER INTERROGATION
• Assesment of obstruction of prosthetic valve
• Detection and quantification of prosthetic valve
regurgitation

Doppler Assessment of Obstruction
of Prosthetic Valves
• Quantitative parameters of prosthetic valve function
 Trans prosthetic flow velocity & pressure gradients,
 valve EOA,
 Doppler velocity index(DVI).

Effective orifice area(EOA)
• Continuity equation
 EOA PrAV = (CSA LVO x VTI LVO) / VTI PrAV
However, this method cannot be applied when there is more than
mild concomitant mitral or aortic regurgitation.
Better for bioprosthetic valves and single tilting disc mechanical
valves.
Underestimation of EOA in case bileaflet valves.

 EOA of mitral prostheses:
Pressure half time may be useful if it is significantly delayed or
shows significant lengthening from one follow-up visit to the
other despite similar heart rates.

PPM
 PPM occurs when the EOA of the prosthesis is too small in
relation to the patient’sbody size, resulting in abnormally high
postoperative gradients. (Rahimtoola in 1978)
EOA indexed to the patient’s body surface area
.
PPM AORTIC MITRAL
Insignificant >0.85 cm2/m2. >1.20 cm²/m²
moderate 0.65and0.85cm2/m2. 0.9-1.20 cm²/m²
severe <0.65 cm2/m2. <0.90 cm²/m²

• Clinical implication of PPM
• Impaired exercise capacity,
• less regression of LV hypertrophy,
• less improvement in coronary flow reserve
• adverse cardiac events.
• Moreover, PPM has a significant impact on both short-term
and long-term mortality
• young patients than in older patients

• Prevention of PPM
• Avoid moderate PPM in AVR;
– preexisting LV dysfunction and/or
– severe LV hypertrophy,
– age 65 to 70 years, and
– regular and/or intense physical activity.
• Avoided by systematically
– Calculating the projected indexed EOA of the prosthesis
– Model with better hemodynamic performance
– Aortic root enlargement to accommodate a larger size of
the same prosthesis model.

• The prevention of PPM in the mitral position represents a
much greater challenge than in the aortic position because
valve annulus enlargement or stentless valve implantation is
not an option in this situation.
Magne J, Mathieu P, Dumesnil JG, Tanné D, Dagenais F, Doyle D,
Pibarot P. Impact of prosthesis-patient mismatch on survival after mitral
valve replacement. Circulation. 2007;115:1417–1425.

Transprosthetic jet contour and acceleration time

DOPPLER VELOCITY INDEX
• Dimensionless ratio of the proximal flow velocity in the
LVOT to the flow velocity through the aortic prosthesis
 DVI=VLVOT/VPrAv
• Time velocity time integrals may also be used in Place of
peak velocities
 DVI= TVILVOT /TVIPrAv
• Prosthetic mitral valves, the DVI is calculated by
 DVI=TVIPrMv/TVILVOT

• IMPORTANCE
• DVI can be helpful to screen for valve dysfunction, particularly when the
– Crosssectional area of the LVO tract cannot be obtained
– Valve size is not known.
• DVI is always less than unity, because velocity will always accelerate
through the prosthesis.
• Similar to EOA, DVI is not affected by high flow conditions through the
valve, including AR, whereas blood velocity and gradient across the valve
are.

DVI had a sensitivity, specificity, positive and negative predictive
values, and accuracy of 59%, 100%, 100%, 88%, and 90%, respectively.

Transprosthetic velocity and gradient
• The flow is
 eccentric - monoleaflet valves
 three separate jets - bileaflet valvesmulti-windows examination
Localised high velocity may be recorded by
continuous wave(CW) Doppler
Interrogation through the smaller central
orifice of the bileaflet mechanical prostheses
overestimation of gradient

• Highvelocity or gradient alone is not proof of intrinsic
prosthetic obstruction and may be secondary to
 prosthesis patient mismatch (PPM),
 high flow conditions,
 prosthetic valve regurgitation, or
 localised high central jet velocity in bileaflet
mechanical valves.
 Increased heart rate.

Algorithm for interpreting abnormally high transprosthetic pressure gradients

DETECTION AND QUANTIFICATION OF
PROSTHETIC VALVE REGURGITATION
• Physiologic Regurgitation.
 closure backflow (necessary to close the valve)
 leakage backflow (after valve closure)- washing jets
short in duration
narrow
symmetrical
homogenous
• Pathologic Prosthetic Regurgitation.

Abnormal echoes
• Abnormal echoes that may be found in patients
with prosthetic valves are
spontaneous echo contrast (SEC),
microbubbles or cavitations, strands,
sutures,
vegetations,
 thrombus.

Importance of TEE
• Higher-resolution image than TTE
• Proximity of the esophagus to the heart .
• Size of vegetation defined more precisely
• atrial side of the mitral valve prosthesis and especially the
posterior part of the aortic prosthesis.
• Peri annular complications indicating a locally uncontrolled
infection (abscesses, dehiscence, fistulas) detected earlier.
Evaluation of prosthetic valves-

TEE evaluation immediately after valve replacement
1. Verify that all leaflets or occluders move normally.
2. Verify the absence of paravalvular regurgitation.
3. Verify that there is no left ventricular outflow tract
obstruction by struts or subvalvular apparatus.
TEE diagnosis of prosthetic valve dysfunction
1. Identification of prosthetic valve type.
2. Detection and quantification of transvalvular or paravalvular
regurgitation.
3. Detection of annular dehiscence.
4. Detection of vegetations consistent with endocarditis.
5. Detection of thrombosis or pannus formation on the valve.
6. Detection and quantification of valve stenosis.
7. Detection of tissue degeneration or calcification.
Evaluation of prosthetic valves-

Stress Echocardiography
• Stress echocardiography should be considered in patients
with exertional symptoms for which the diagnosis is not
clear.
• Dobutamine and supine bicycle exercise are most commonly
used.
• Treadmill exercise provides additional information about
exercise capacity but is less frequently used because the
recording of the valve hemodynamics is after completion of
exercise, when the hemodynamics may rapidly return to
baseline.

Stress Echocardiography(cont)
Prosthetic Aortic Valves
• Guide to significant obstruction would be similar to that for
native valves, such as a rise in mean gradient >15 mm Hg with
stress.
Prosthetic Mitral Valves
• Obstruction or PPM is likely if the mean gradient rises > 18 mm
Hg after exercise, even when the resting mean gradient is
normal.

RT-3D TEE
• Excellent spacial imaging
• Ease of use
• Enables enface viewing(surgical view)
• adds to the available information provided by
traditional imaging modalities.

Cinefluoroscopy
• Structural integrity
• Motion of the disc or poppet
• Excessive tilt ("rocking") of the base ring - partial dehiscence
of the valve
• Aortic valve prosthesis - RAO caudal
- LAO cranial
Mitral valve prosthesis - RAO cranial .

Fluoroscopy of a normally functioning CarboMedics bileaflet
prosthesis in mitral position
A=opening angle B=closing angle
Evaluation of prosthetic valves-Cinefluoroscopy

• St. Jude medical
bileaflet valve
– Mildly radiopaque
leaflets are best seen
when viewed on end
– Seen as radiopaque lines
when the leaflets are
fully open
– Base ring is not
visualized on most
models
Evaluation of prosthetic valves-Cinefluoroscopy

Cardiac Catheterization
• measure the transvalvular pressure gradient, from which the
EOA can be calculated
• can visualize and quantify valvular or paravalvular
regurgitation

PREGNANCY AND PROSTHETIC
VALVES

COMPLICATIONS
• Structural deterioration, particularly with bioprosthetic
• Valve obstruction due to thrombosis or pannus
• Systemic embolization
• Bleeding
• Endocarditis and other infections
• Left ventricular systolic dysfunction
• Hemolytic anemia
Future

• FREQUENCY OF COMPLICATIONS —
• The frequency of serious complications depends upon the
valve type and position, and multiple clinical risk factors.
• The overall incidence of complications in appropriately
managed patients is approximately 3 percent per year .
COMPLICATIONS

• Paravalvular Regurgitation
• Paravalvular regurgitation typically is due to
– infection,
– suture dehiscence, or
– fibrosis and calcification of the native annulus, leading to
inadequate contact between the sewing ring and annulus.
COMPLICATIONS

• STRUCTURAL FAILURE —
• Paravalvular leaks early after surgery are common.
• Incidence ranges from 18 to 48 percent of patients with a
mitral or aortic prosthesis; the majority of leaks are trivial or
mild and do not progress over a two to five year follow-up.
• severe regurgitation results from prosthetic valve endocarditis
or structural failure valve implantation.
Rallidis LS, Moyssakis IE, Ikonomidis I, Nihoyannopoulos P. Natural history of early
aortic paraprosthetic regurgitation: a five-year follow-up. Am Heart J 1999;
138:351.
COMPLICATIONS

• Long-term outcomes —
• The incidence of late structural failure varies with the type of
valve and with valve position.
• The risk with current mechanical valves is extremely low.
• Most mechanical valves can be expected to last 20 to 30 years
with the exception of the Bjork-Shiley convexoconcave
(BSCC) valve
Hammermeister KE, Sethi GK, Henderson WG, et al.. Veterans Affairs
Cooperative Study on Valvular Heart Disease. N Engl J Med 1993; 328:1289.
COMPLICATIONS

• In contrast, 10 to 20 percent of human aortic homograft
prostheses, and 30 to 35 percent of porcine heterograft
prostheses fail within 10 to 15 years of implantation.
– O'Brien MF, Stafford EG, Gardner MA, et al. Allograft aortic valve
replacement: long-term follow-up. Ann Thorac Surg 1995; 60:S65.
• Pericardial prostheses may be more durable than porcine
valves .
– Poirer NC, Pelletier LC, Pellerin M, Carrier M. 15-year experience with the
Carpentier-Edwards pericardial bioprosthesis. Ann Thorac Surg 1998; 66:S57.
• The failure rate with porcine valves is higher with valves in the
mitral position (eg, 44 versus 26 percent in the aortic position
at 15 years in the Veterans Administration trial) .
COMPLICATIONS

Future
COMPLICATIONS

• 2.VALVE OBSTRUCTION —
• Unexpected rise in transprosthetic gradient & new
symptomats dyspnea, heart failure, systemic embolization .
• Causes of obstruction include
– thrombus,
– pannus, and
– vegetation.
• study of 112 obstructed mechanical valves,
– thrombus alone -77%
– pannus -11 %,
– pannus with thrombus -12 % .
Deviri E, Sareli P, Wisenbaugh T, Cronje SL. Obstruction of mechanical heart valve
prostheses: clinical aspects and surgical management. J Am Coll Cardiol 1991;
17:646.
COMPLICATIONS

Dürrleman N, Pellerin M, Bouchard D, et al. Prosthetic valve thrombosis: twenty-year
experience at the Montreal Heart Institute. J Thorac Cardiovasc Surg 2004; 127:1388.
COMPLICATIONS
• Valve thrombosis —
• Equal frequency in bioprosthetic valves and mechanical
valves.
• The reported annual incidence of PVT ranges from 0.03 to
5.7%; higher rates with mitral prostheses (in some reports)
and/or subtherapeutic anticoagulation.

Types of prosthetic valves and thrombogenicity
Type of valve Model Thrombogenicity
Mechanical
Caged ball Starr-Edwards ++++
Single tilting disc Bjork-Shiley,Medtronic
Hall
+++
Bileaflet St Jude Medical,Sorin
Bicarbon,Carbomedics
++
Bioprosthetic
Heterografts Carpentier-
Edwards,Tissue Med
(Aspire), Hancock II
+ to ++
Homografts +

• Diagnosis —
• The gold standard for the diagnosis of PVT is transesophageal
echocardiography (TEE) and/or cine-fluoroscopy to assess
both valve motion and clot burden .
• However, transthoracic Doppler echocardiography can
establish the diagnosis in many patients and is also indicated
to assess hemodynamic severity.
COMPLICATIONS

• Treatment —
• Surgery and thrombolytic therapy, but neither is ideal.
• With surgery, there is a high operative mortality that is largely
related to clinical functional class (17.5% in patients in NYHA
class IV compared to 4.7 % with less severe disease in a
review of 106 patients) .
– Deviri E, Sareli P, Wisenbaugh T, Cronje SL. Obstruction of mechanical
heart valve prostheses: clinical aspects and surgical management. J Am
Coll Cardiol 1991; 17:646.
COMPLICATIONS

• As a result, thrombolytic therapy has evolved as an alternative
to surgery.
• The largest study consisted of 127 episodes of obstructive
PVT (almost all left-sided) in 110 patients with mechanical
valves who were treated with various thrombolytic agents:
streptokinase and urokinase initially and recombinant tissue-
type plasminogen activator (alteplase)
COMPLICATIONS
Alpert JS. The thrombosed prosthetic valve: current recommendations based on
evidence from the literature. J Am Coll Cardiol 2003; 41:659.

• The following findings were noted:
• Complete hemodynamic resolution in 71 %, partial resolution in 17%, and
no resolution in 12 %. Surgery was performed in 23 percent.
• There was a trend toward greater efficacy in aortic valve prostheses (80
versus 65 percent in mitral valve prostheses).
• A 2nd dose -in 30 % and a 3rd - 9 percent.
• Complications occurred in 25 % of patients.
– Major bleeding - 4.7 % (including two intracranial hemorrhages),
– systemic embolization in 15 percent, and
– death in 11.8 percent due to complications or primary failure of therapy.
• Recurrent PVT developed in 24 patients (19 %) at a mean interval of 2.1
years.
COMPLICATIONS

• Thrombolytic regimens include
• alteplase (100 mg given as a 10 mg bolus followed by 90 mg
as an infusion over 90 minutes) or
• streptokinase (500,000 IU over 20 minutes followed by 1.5
million IU over 10 hours).
• Intravenous heparin is typically given concurrently to achieve
an activated partial thromboplastin time 1.5 to 2.0 times
control.
COMPLICATIONS

• We agree with the 2006 ACC/AHA guideline -
• For left-sided PVT with
– NYHA class III to IV symptoms OR large clot burden, emergency operation is
suggested.
– NYHA class III to IV symptoms(NYHA class II with large clot). with small or
large clot burden, fibrinolytic therapy may be considered if surgery is high risk
or not available.
– NYHA class II to IV symptoms and a large clot burden, fibrinolytic therapy
may be considered if emergency surgery is high risk or not available.
– NYHA class I to II and small clot burden, fibrinolytic therapy may be
considered as a first-line therapy. Alternatively, intravenous unfractionated
heparin may be considered.
• For right-sided PVT with NYHA functional class III to IV OR large clot
burden, fibrinolytic therapy is suggested.
ACC/AHA 2006 guidelines for the management of patients with valvular heart
disease Circulation 2008; 118:e523.
COMPLICATIONS

• A size threshold for clot burden -
– 2006 ACC/AHA - differing thresholds ranging from 5 to 8 mm.
– 2008 ACCP guidelines a small area -<80 mm2 and a large defined as ≥80
mm2.
• For patients who have had successful resolution of PVT, initiation of IV
UFH and warfarin (or other vitamin K antagonist) therapy is suggested .
• Continuation of IV UFH -until a therapeutic INR is achieved.
• For a mechanical valve in the aortic position, a goal INR of 3.5 (range 3.0
to 4.0) plus aspirin (50 to 100 mg/d) is suggested.
• For a mechanical valve in the mitral position, a goal INR of 4.0 (range 3.5
to 4.5) plus aspirin (50 to 100 mg/d) is suggested.
COMPLICATIONS

• Pannus formation —
• Pannus formation due to fibrous tissue ingrowth is a less
common cause of valve obstruction .
• Since thrombolytic therapy is an alternative to surgery only
for thrombosis, distinction between these two causes is
important; echocardiography and clinical features are helpful
in distinguishing between these
COMPLICATIONS

THROMBUS PANNUS
Shorter time from valve insertion to
valve dysfunction(62 days versus)
Longer(178 days)
Shorter duration of symptoms before
reoperation (9days)
Longer ( 305 days)
Lower rate of adequate
anticoagulation (21%)INR<2.5
Higher(versus 89 %)
Greater total mass length (2.8cm),
primarily due to extension into the left
atrium,mobile
Smaller -1.2 cm
firmly fixed (minimal mobility) to the
valve apparatus
less echo-dense highly echogenic, (fibrous composition)
associated with spontaneous contrast, common in aortic position
Para valve jet suggests pannus

• SYSTEMIC EMBOLIZATION —
• Systemic embolization can result from valve thrombosis (even
when nonobstructed), vegetations, or left atrial thrombus,
particularly in patients with atrial fibrillation.
• Transesophageal echocardiography may be the preferred
method for evaluating these patients
COMPLICATIONS

• The frequency of systemic embolization, predominantly
cerebrovascular events, is approximately 0.7 to 1.0 percent per
patient-year in patients with mechanical valves who are treated
with warfarin .
• In comparison, the risk is 2.2 percent per patient-year with
aspirin and 4.0 percent with no anticoagulation; patients with
mitral valve prostheses are at twice the risk of those with aortic
valve prostheses
COMPLICATIONS

If embolic event occurs while the patient is on adequate
antithrombotic therapy
• If on warfarin with INR of 2.0 to 3.0: increase dose to achieve
INR of 2.5 to 3.5
• If on warfarin with INR of 2.5 to 3.5: add aspirin 50 to 100
mg/d
• If on warfarin with INR of 2.5 to 3.5, plus aspirin 80 to 100
mg/d: aspirin dose may also need to be increased to 325 mg/d
• If on aspirin 325 mg/d: switch to warfarin with goal INR of
2.0 to 3.0

• BLEEDING —
• Bleeding is a not infrequent problem in patients with
prosthetic heart valves .
• The risk is greater with mechanical valves which, because they
are thrombogenic, require chronic anticoagulation.
• In contrast, most patients who receive a bioprosthetic valve
are given only short-term anticoagulation unless there is an
additional risk factor such as atrial fibrillation
Vongpatanasin W, Hillis LD, Lange RA. Prosthetic heart valves. N Engl J Med
1996; 335:407.
COMPLICATIONS

• ENDOCARDITIS —
• Infective endocarditis and other infections such as valve
abscess can occur with prosthetic valves.
• Transesophageal echocardiography is superior to standard
transthoracic echocardiography for the detection of valvular
vegetation, ring abscesses, and other
complications, particularly with mitral prostheses.
COMPLICATIONS

• Early endocarditis < 60 days P.O.D- perioperative bacteremia
from skin/wound infections/contaminated intravascular
devices.
• Staphylococcus epidermidis, S. aureus, gram-negative
bacteria, diphtheroids, and fungi.
• Late prosthetic-valve endocarditis (>60 days POD) is usually
caused by the organisms responsible for native-valve
endocarditis, most often streptococci.
• However,S. epidermidis is a common causative organism up to
12 months after surgery.
Mechanical = Bioprosthetic valves
COMPLICATIONS

• Endocarditis Prophylaxis
• Patients with prosthetic valves are at high risk for endocarditis
because of the foreign valve surface and sewing ring.
• Therefore, a lifelong requirement exists for antibiotic
prophylaxis for dental, endoscopic, and surgical procedures in
patients with a prosthetic valve.

• LEFT VENTRICULAR SYSTOLIC DYSFUNCTION —
• Patients with prosthetic heart valves may develop left
ventricular systolic dysfunction with or without heart failure
– Preoperative left ventricular dysfunction that persists.
– Perioperative myocardial infarction
– Progression of other valve disease
– Complications of the prosthetic valve
– An unrelated disorder such as CAD or hypertension
COMPLICATIONS

• HEMOLYTIC ANEMIA —
• Hemolysis is associated with rapid regurgitant jet and/or high
peak shear rates.
• Mild and subclinical, but is severe in up to 15 percent (ball-
cage and bileaflet valves, or those with paravalvular
regurgitation.)
• It is uncommon with tissue valves (except porcine valve
failure).
• Presenting features may be subtle and include anemia, heart
failure, jaundice, dark urine, increasing serum lactate
dehydrogenase, and a new or changed regurgitant murmur .
• The peripheral smear -schistocytes and smaller red cell
fragments
Maraj R, Jacobs LE, Ioli A, Kotler MN. Evaluation of hemolysis in patients with
prosthetic heart valves. Clin Cardiol 1998; 21:387.
COMPLICATIONS

• Oral iron replacement is effective in the majority of patients,
although transfusion may be required; in occasional patients,
the administration of recombinant human erythropoietin may
eliminate the need for transfusion .
• Reoperation may be required, especially if hemolysis is due to
regurgitation from a paravalvular leak or valve failure.
COMPLICATIONS

• Mortality and morbidity —
• The overall perioperative mortality following nonemergent
replacement of prosthetic heart valves is approximately 10 percent .
• In a review of 2246 consecutive procedures in 1984 patients
between 1963 and 1992, the in-hospital mortality rates in patients
with New York Heart Association class I, II, III, and IV were
2.3, 5.7, 9.1, and 21.0 percent, respectively.
• In-hospital mortality was lowest (1.3 percent) in the healthiest
patients undergoing a first elective reoperation. Similar findings
have been noted in other series.
• Age is another important determinant. It has been estimated that the
perioperative mortality increases about three-fold from age 35 to age
75.
Piehler JM, Blackstone EH, Bailey KR, et al. Reoperation on prosthetic heart values.
Patient-specific estimates of in-hospital events. J Thorac Cardiovasc Surg 1995; 109:30.

• Limitations of the current technology will continue to drive the
field toward new, minimally invasive and endovascular
approaches for valve delivery.
• Valves that have the capacity for growth and self-repair,
especially suited to the treatment of congenital heart disease,
may be within reach through the application of tissue-
engineering strategies.
future

Transcatheter Aortic Valve Implantation
(TAVI)
• 1993: Andersen
– First description of valve sutured in
stent
– Animal model
– Encountered major limitations
• Obstruction of coronary ostia

Cribier- edward valve
 first generation :
Cribier-Edwards valve
 Second generation
Edwards SAPIEN THV
bovine pericardium that
is firmly mounted
within a
tubular, slotted, stainless
steel balloon-
expandable stent

CoreValve Revalving device
first implantation in 2005 - Grube et al
• first-generation : bovine pericardial tissue and was
constrained with 25F delivery catheter.
• second-generation : porcine pericardial tissue within a 21 F
catheter .

FUTURE.
 Stentless pericardial valves.
 Sorin pericarbon Freedom (Aortic and mitral)
3F pericardial equine (aortic)
SJM Quattro (mitral)
- Glutaraldehyde fixed at low concentrations.
- Three commissures created by suturing 3 flaps
of pericardium.

FUTURE..
Autologous pericardial aortic valve.
CardioMed
special instrumentation (sizer, tissue
tester, cutting tool and formers to hold the
tissue in the anatomical position)
to construct the tissue.
tissue treated with 0.6% glutaraldehyde
animal studies.

FUTURE…
Tissue engineered valves (microfabrication techniques.)
 scaffolds either synthetic or natural.
allograft valve decellularised and repopulated in
vitro with the host cells.
endothelial cells from patient harvested, cultured and
incorporated in the scaffold.
living valve then implanted.
Tissue engineered heart valves: better
biocompatibility, less infection, life expectancy of
valve increase,
To make artificial heart valves compatible for
children.

FUTURE….
 Polymers
- durability superior to biological valves.
- haemocompatible.
- polyurethane possess high tensile strength
and resistant to cyclic fatigue.
- surface modification to prevent thrombosis.

FUTURE…..
 Flexible tube as heart valve.
- James L Cox propounded that since the CV
system begins in utero as a simple tube, on
attaining maturity all four heart valve function
as a simple tubes.
- Hence came into existence the concept of heart
valve replacement using flexible tubes.

Heart valve replacement using flexible tubes
US 5480424 A
• Replacement of AV valves (mitral or tricuspid)- the tube inlet
is sutured to a valve annulus from which the native leaflets
have been removed, and the tube outlet is sutured to papillary
muscles in the ventricle.
• To create a semilunar (aortic or pulmonary) valve, the tube
inlet is sutured to an annulus from which the native cusps have
been removed, and the tube is either "tacked" at three points
distally inside the artery; this allows the flaps of tissue
between the three fixation points to function as movable cusps.

• These approaches generate flow patterns that closely duplicate
the flow patterns of native valves.
• Preferred tubular material comprises submucosal tissue from
the small intestine of the same patient.
• By using tissue from the same patient, the risk of immune
rejection and the need to treat the tissue to reduce antigenicity
are eliminated.
FUTURE…..

• The main characteristics of the tri-
leaflet valve
• when completely open
(65degrees) present a large central
area for flow and therefore
present a configuration with small
resistance for blood flow.
• This large opening is the results of
the location of the pivots which
are the closest possible to the ring
and the flow avoid the overgrow
of natural tissue which way
immobilize the leaves.
• permits a flow which is more
similar to the natural valve.

• The main advantage of the present design is not only
– central flow
– velocity gradient in any radial direction is small compared
to the bi-leaflet valve.
• In the case of the tri-leaflet valve, most of the central region
has a high range of velocities between 2.6 -2.0m/s , while in
the bi-leaflet valve the velocity gradient is high.
• In such case the effect of any local disturbance in the flow has
a much larger impact than in the tri-leaflet valve design.

SUMMARY
 For the moment it seems that designing the ideal
prosthetic valve is likely to occupy the visionary for
many years to come. If human efforts is ever able to
achieve absolute perfection in this matter, it would be
the greatest breakthrough in valve replacement
surgery.
 The valve which lasts permanently without
anticoagulation and without structural degeneration is
still a distant reality at present, but surely not an
impossible one.

Prosthetic Heart Valves: A History of Innovation and Improvement

Prosthetic Heart Valves: A History of Innovation and Improvement

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