Prosthetic valve function

OUTLINE
 Approch
 Clinical Examination
 CXR
 2Decho
 Doppler
 TEE
 3D echo
 CineFluoro
 CT
 Cardiac catheterisation
EVALUATION OF PROSTHERIC VALVE
FUNCTION-METHODS AND CLINICAL UTILITY

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”.

Introduction
 After a valve is replaced, the prognosis for the patient
is highly correlated with the function of the prosthetic
valve like-
 hemodynamics,
 durability,
 thrombogenicity.
 Thus, early diagnosis of a prosthetic valve disorder is
crucial for reducing morbidity and mortality.

Introduction
 Symptoms of prosthetic valve dysfunntion may be
nonspecific, making it difficult to differentiate the effects
of prosthetic valve dysfunction from
 ventricular dysfunction,
 pulmonar hypertension,
 the pathology of the remaining native valves,
 noncardiac conditions.
 Although physical examination can alert clinicians to the
presence of significant prosthetic valve dysfunction,
diagnostic methods are often needed to assess the function
of the prosthesis.

Types of prosthetic valves
 Prosthetic Valves are classified as tissue or mechanical
 Tissue:
• Made of biologic tissue from an animal (bioprosthesis or
heterograft) or human (homograft or autograft) source
 Mechanical
 Made of non biologic material (pyrolitic
carbon, polymeric silicone substances, or titanium)
 Blood flow
characteristics, hemodynamics, durability, and
thromboembolic tendency vary depending on the type
and size of the prosthesis and characteristics of the
patient EVALUATION OF PROSTHERIC VALVE

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, 119:1034-1048EVALUATION OF PROSTHERIC VALVE

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
 With adequate anticoagulation, rate of thrombosis is
0.6% to 1.8% per patient-year for bileaflet valves.

Biological Valves
 Stented bioprostheses
 Primary mechanical failure at 10 years is 15-20%
 Preferred in patients over age 70
 Subject to progressive calcific degeneration & failure
after 6-8 years
 Stentless bioprostheses
 Absence of stent & sewing cuff allow implantation of
larger valve for given annular size->greater EOA
 Uses the patient’s own aortic root as the stent, absorbing
the stress induced during the cardiac cycle

Biologic Valves Continued
 Homografts
 Harvested from cadaveric human hearts
 Advantages: resistance to infection, lack of need for
anticoagulation, excellent hemodynamic profile (in
smaller aortic root sizes)
 More difficult surgical procedure limits its use
 Autograft
 Ross Procedure

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

Approach to prosthetic valve
function assesment
 CLINICAL INFORMATION &CLINICAL EXAMINATION
 IMAGING OF THE VALVES
 CXR
 2D echocardiography
 TEE
 3D echo
 CineFluoro
 CT
 Cardiac catheterisation

HISTORY
 Subtle symptoms of cardiac failure or neurologic
events can be clues to serious valve dysfunction.

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

FUNCTION-METHODS AND CLINICAL
UTILITY

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.

 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.
Sometimes the aortic root
can be inferiorly displaced
which will shift the aortic
valve below this line.

 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
quadrant

 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 reproducibleEVALUATION OF PROSTHERIC VALVE

 Patients with cardiac valves often have chamber
enlargement and cardiac rotation which can displace
the positions of the valves as well as create difficulty
when drawing lines through the cardiac silouette.
 These rules are meant as a guideline to better localize
cardiac valves although they do not always work.

 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.

Radiologic Identification
Starr-Edwards caged
ball valve
Radiopaque base ring
Radiopaque cage
Silastic ball impregnated
with barium that is
mildly radiopaque (but
not in all models)

 Appearance of
CarboMedics prosthesis
on plain radiography.

Echo Imaging of 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.

challenges in echocardiography
The high reflectance leads to
 shadowing
 Reverberations
multiple echocardiographic windows must be used to
fully interrogate the areas around prosthetic valves.
 transesophageal echocardiography 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.

The concept of pressure recovery

The primary goals of 2D echo
 Valves should be imaged from multiple views, with
attention to
determine the specific type of prosthesis,
confirm the opening and closing motion of the
occluding mechanism,
confirm stability of the sewing ring(abnormal rocking
motion )
 Presence of leaflet calcification or abnormal echo density
attached to the sewing ring, occluder, leaflets, stents, or
cage such as vegetations and thrombi

Primary goals of 2D echo (cont)
Calculate valve gradient
Calculate effective orifice area
Confirm normal blood flow patterns
Detection of pathologic transvalvular and
paravalvular regurgitation.

Starr-Edwards mitral prosthesis is shown. A: During systole, the poppet is seated
within the sewing ring (arrows). B: During diastole, the poppet moves forward
into the cage (arrows), allowing blood flow around the occluder.EVALUATION OF PROSTHERIC VALVE

St. Jude mitral prosthesis is demonstrated. A: During systole, the hemidisks are
shown in the closed position (arrows). B: During diastole, the two disks are
recorded in the open position (arrows).EVALUATION OF PROSTHERIC VALVE

St. Jude aortic prosthesis is demonstrated. The sewing ring is indicated
by the arrows. The walls of the aortic root (Ao) often obscure the motion
of the disks. EVALUATION OF PROSTHERIC VALVE

M-Mode
 M-Mode echocardiography enables better evaluation
of valve movements and corresponding time intervals
and recognition of quick movements and fibrillations.

 For bioprostheses, evidence of leaflet degeneration can
be recognized as
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.

Assessment of Flow Characteristics
of Prosthetic Valves
 Normal functioning mechanical prosthetic valves
cause:
some obstruction to blood flow
closure backflow (necessary to close the valve)
leakage backflow (after valve closure)
The extent of normal obstruction and leakage of
prosthetic valves depends on prosthetic valve design

Valve type Flow Characteristics
Ball-in-cage prosthetic valve (Starr-
Edwards, Edwards Lifescience)
much obstruction and little leakage.
Tilting disc prosthetic valve (Björk-
Shiley; Omniscience; Medtronic Hall)
less obstruction and more leakage.
Bileaflet prosthetic valves (St. Jude
Medical; Sorin Bicarbon; Carbomedics)
Less obstruction and more leakage.
Bioprostheses. little or no leakage
Homografts, pulmonary autografts, and
unstented bioprosthetic valves
(Medtronic Freestyle,
Toronto, Ontario, Canada)
almost unobstructive to blood flow.
Stented bioprostheses (leaflets
suspended within a frame)
obstructive to flow.

Dopplar interogation

 color flow imaging is
often helpful to define
the location and
direction of the various
flow patterns.
 pulsed and continuous
wave Doppler imaging
can be oriented to
quantify flow velocity.
Whenever velocity is higher than
expected, consider the possibility of
pressure recovery. EVALUATION OF PROSTHERIC VALVE

Challenges in doppler interogation
 variability of flow
through and around the
different prostheses
 Some prosthetic valves
have more than one
orifice
and, consequently, a
complex flow profile

Challenges in doppler interogation
 Because the signal-to-noise ratio for Doppler imaging is
lower compared with two-dimensional
echocardiographic imaging, the shadowing effect is
even more pronounced and the ability to record a
Doppler signal behind a prosthetic valve is very limited
Multiple views must be used to fully interrogate the regurgitant
signal.

Primary goals of dopplar
interogation
 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

 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.
continuity equation using the stroke volume
measured in the LVOT. However, this method cannot
be applied when there is more than mild concomitant
mitral or aortic regurgitation.
o better for bioprosthetic valves and single tilting disc
mechanical valves.
o underestimation of EOA in case bileaflet valves.

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.
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

Transprosthetic jet contour and
acceleration time
AT and AT/ET, angle-independent parameters.
AT/ET > 0.4

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

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

 IMPORTENCE
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.

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
o short in duration
o narrow
o symmetrical
o homogenous
 Pathologic Prosthetic Regurgitation.

Homogeneous in color, with aliasing mostly confined to the base of the
jet EVALUATION OF PROSTHERIC VALVE

Pathologic Prosthetic Regurgitation
 Pathologic regurgitation is either
 central
paravalvular.
 Most pathologic central valvular regurgitation is seen
with biologic valves, whereas paravalvular regurgita-
tion is seen with either valve type and is frequently the
site of regurgitation in mechanical valves.
 Pathologic jets tend to be high
velocity, intense, broad, and highly aliased.

Thrombus and Pannus
 In one surgical study of 112 obstructed mechanical
valves,
 pannus formation was the underlying cause in
11 percent of valves,
 pannus formation in combination with thrombus was
present in 12 percent,
 thrombus alone was the etiology in the remaining
cases.

Distinction between thrombus and
pannus
Thrombus Large,
mobile,
less echo-dense,
associated with spontaneous contrast,
INR<2.5
Pannus Small
firmly fixed (minimal mobility) to the valve apparatus
highly echogenic, (fibrous composition)
common in aortic position
Para valve jet suggests pannus

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.

 Spontaneous echo contrast (SEC)is defined as smoke-
like echoes.
 SEC is caused by increased red cell aggregation that
occurs in slow flow, for example, because of a
low cardiac output,
severe left atrial dilatation,
atrial fibrillation, or
 pathologic obstruction of a mitral prosthesis.
 The prevalence of SEC is 7% to 53%.

 Microbubbles are characterized by a discontinuous
stream of rounded, strongly echogenic, fast moving
transient echoes
 Microbubbles occur at the inflow zone of the valve
when flow velocity and pressure suddenly drop at the
time of prosthetic valve closing, but may also be seen
during valve opening.
 Microbubbles are probably due to carbon dioxide
degassing.

Kaymaz et al
 75% of the normal bileaflet valves compared with 39%
of the tilting-disk valves.
 In prosthetic valves with thrombotic obstruction,
microbubbles were found in only 6% , whereas they
reappeared after successful thrombolytic treatment
with relief of valvular obstruction in 69%
 Microbubbles are not found in bioprosthetic valves.

 Strands are thin, mildly echogenic, filamentous
structures that are several mm long and move
independently from the prosthesis.
 They are often visible intermittently during the car-
diac cycle but recur at the same site.
 They are usually located at the inflow side of the
prosthetic valve
 Strands are found in 6% to 45% of patients.
 Have a fibrinous or a collagenous composition.

 Sutures are defined as linear, thick, bright, multiple,
evenly spaced, usually immobile echoes seen at the
periphery of the sewing ring of a prosthetic valve;
 They may be mobile when loose or unusually long.

TEE
 Careful alignment of the transducer is essential to fully
display leaflet motion as comprehensively as possible.
 Multiplane imaging should be done at a minimum of
every 30˚from 0–180˚.

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.

Importance of TEE
 Higher-resolution image than TTE
 Proximity of the esophagus to the heart .
 Size of vegetation defined more precisely
 Absence of interference with lungs and ribs, a very
detailed image can be obtained of the 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.

 limitation -inability to detect aortic prosthetic-valve
obstruction or regurgitation, especially when a mitral
prosthesis is present.

CONSIDERATIONS IN TAVI
 The echocardiographic evaluation of TAVI is , in
most ways same as that for surgically implanted valves
 But 2 areas of chalenges are
 Caluculation of EOA
 Quantification of post TAVI AR

 LVOT diameter and velocity should be measured
immediately proximal to the apical border of the stent.
 However, if the border of the stent sits low in the
LVOT, which may occur more frequently with self-
expandable prostheses (such as the CoreValve), it may
be preferable to measure the LVOT diameter and
velocity within the proximal portion of the stent at
approximately 5-10 mm below the bioprosthetic valve
leaflets.

 Paravalvular regurgitation is more common following
transcatheter aortic valve implantation versus
standard valve replacement– 30-80% with 5-14%being
moderate or severe.

 Delayed migration and embolisation of the prosthesis
have been reported following transcatheter valve
implantation.
 The distance between the ventricular end of the
prosthesis stent and the hinge point of the mitral valve
measured in the parasternal long axis view can be used
to monitor the position of the prosthesis during
follow-up.

Considerations for Intraoperative
Patients
 TEE and epicardial and epiaortic ultrasound
 TEE remains the most widely used
American Society of Anesthesiologists has recommended
intraoperative TEE as a category II indication in patients
undergoing valve surgery
Current ACC & AHApractice guidelines recommend
TEE as a class 1 indication for patients undergoing valve
replacement with stentless xenograft, homograft, or
autograft valves.

Considerations for Intraoperative
Patients
 Multiple echocardiographic views are obtained to
determine
 Appropriate movement of valve leaflets,
Color flow Doppler should exclude the presence of
paravalvular leaks
• Immediate surgical attention
Any regurgitation that is graded moderate or severe,
‘Stuck’’ mechanical valve leaflets,
Valve dehiscence,
 Dysfunction of adjacent valves

Stress Echocardiography in Evaluating
Prosthetic Valve Function
 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.

Limitations of 3D echo
 poor visualization of anterior cardiac structures,
 poor temporal resolution,
 poor image quality in patients with arrhythmias
 tissue dropout

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 angleEVALUATION OF PROSTHERIC VALVE
FUNCTION-METHODS AND CLINICAL
UTILITY

 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

MULTISLICE CT
 Because of its high temporal and spatial resolution,
MDCT has recently shown good potential in assessing
prosthetic valve disorders.
 to evaluate the prosthetic valve motion in various
planes, with a focus on leaflet motion and on the
residual opening angle between leaflets.

 The residual
openingangle, the angle
between two leaflets when
fully opened, is measured
using the plane
perpendicular to the two
leaflets
• For a single-leaflet
prosthetic valve, the
maximal opening angle is
recorded.
Normal limit (≤ 20°)

 Special attention is also paid
to the relationship between
the suture ring and the
surrounding valve annulus
for detecting
thrombosis,
paravalvular leak (suture
loosening),
 pannus,
pseudoaneurysm formation.

 In IE MDCT clarify the extent of the damage to the
valve and paravalvular region to provide the surgeon
the information required for débridement and a redo
of the valve replacement.

Cardiac Catheterization
 measure the transvalvular pressure gradient, from
which the EOA can be calculated –Gorlin formula.
 can visualize and quantify valvular or paravalvular
regurgitation by Contrast injection.
In clinical practice, it is not commonly performed.
Crossing a prosthetic valve with a catheter should not
be attempted in mechanical valves because of
limitations and possible complications.
Tissue valves can be crossed with a catheter easily, but
a degenerative, calcified bioprosthesis is friable, and
leaflet rupture with acute severe regurgitation is
possible.

Take home
Many of the prosthesis-related complications can be
prevented or their impact minimized through optimal
prosthesis selection in the individual patient and
careful medical management and follow-up after
implantation.

Prosthetic valve function

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