evaluation of prosthetic valve function and clinical utility

DR. DURGAPAVAN,NIMS,HYDERABAD,INDIAEmail:[email protected]

OUTLINEApproachClinical ExaminationCXR2DechoDopplerTEE3D echoCineFluoroCTCardiac catheterization

EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

IntroductionThe 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”.


IntroductionAfter 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.


IntroductionSymptoms of prosthetic valve dysfunction may be

non specific, making it difficult to differentiate the effects of prosthetic valve dysfunction from

ventricular dysfunction, pulmonary hypertension, the pathology of the remaining native valves, no cardiac 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 valvesProsthetic Valves are classified as tissue or

mechanical Tissue:

• Made of biologic tissue from an animal (bioprosthesis or heterograft) or human (homograft or autograft) source

MechanicalMade 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 patientEVALUATION OF PROSTHERIC VALVE

FUNCTION-METHODS AND CLINICAL UTILITY

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 Sapiens) (G) Self –expandable (Core

Valve) (H) Circulation 2009, 119:1034-1048EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

Mechanical ValvesExtremely durable with overall survival rates

of 94% at 10 yearsPrimary structural abnormalities are rareMost malfunctions are secondary to

perivalvular leak and thrombosisChronic anticoagulation required in all With adequate anticoagulation, rate of

thrombosis is 0.6% to 1.8% per patient-year for bileaflet valves.


Biological ValvesStented bioprostheses

Primary mechanical failure at 10 years is 15-20%Preferred in patients over age 70Subject to progressive calcific degeneration &

failure after 6-8 yearsStentless 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 ContinuedHomografts

Harvested from cadaveric human heartsAdvantages: resistance to infection, lack of

need for anticoagulation, excellent hemodynamic profile (in smaller aortic root sizes)

More difficult surgical procedure limits its useAutograft

Ross Procedure


Desired valvesMechanical 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 EXAMINATIONIMAGING OF THE VALVES

CXR 2D echocardiography TEE 3D echo CineFluoro CT Cardiac catheterisation


HISTORYSubtle symptoms of cardiac failure or

neurologic events can be clues to serious valve dysfunction.


CLINICAL INFORMATIONClinical data including reason for the study and

the patient’s symptomsType & size of replacement valve, date of surgeryPatient’s height, weight, and BSA should be

recorded to assess whether prosthesis-patient mismatch (PPM) is present

BP & HRHR particularly important in mitral and tricuspid

evaluations because the mean gradient is dependent on the diastolic filling period


CXRchest 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. EVALUATION OF PROSTHERIC VALVE


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 tricuspid valvevalve in the anterior quadrant and pulmonary valve in the superior portion of the posterior quadrant EVALUATION OF PROSTHERIC VALVE


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 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 FUNCTION-METHODS AND CLINICAL UTILITY

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-UPIdeally, 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 echocardiographyThe high reflectance leads to shadowing Reverberationsmultiple 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.EVALUATION OF PROSTHERIC VALVE


The concept of pressure recovery


The primary goals of 2D echoValves should be imaged from multiple views,

with attention todetermine 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 EVALUATION OF PROSTHERIC VALVE


Primary goals of 2D echo (cont)Calculate valve gradient Calculate effective orifice areaConfirm 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.


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).


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.


M-ModeM-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 Characteristicsof Prosthetic ValvesNormal functioning mechanical prosthetic

valves cause:some obstruction to blood flowclosure 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 designEVALUATION OF PROSTHERIC VALVE


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. JudeMedical; 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.EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

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.


Challenges in doppler interogationvariability 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 interogationBecause 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 interogationASSESMENT OF OBSTRUCTION OF

PROSTHETIC VALVEDETECTION AND QUANTIFICATION OF

PROSTHETIC VALVE REGURGITATION


Doppler Assessment of Obstruction of Prosthetic ValvesQuantitative parameters of prosthetic valve

functionTrans 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.EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

PPM PPM occurs when the EOA of the prosthesis

is too small in relation to the patient's body 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/m²EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

Transprosthetic jet contour and acceleration time


AT and AT/ET, angle-independent parameters.

AT/ET > 0.4

Doppler velocity indexDimensionless 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/TVILVOTEVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY


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) DopplerInterrogation 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.EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

Algorithm for interpreting abnormally high transprosthetic pressure gradients


DETECTION AND QUANTIFICATION OFPROSTHETIC VALVE REGURGITATION• Physiologic Regurgitation. closure backflow (necessary to close the valve)leakage backflow (after valve closure)- washing

jetso short in durationo narrowo symmetricalo homogenous

Pathologic Prosthetic Regurgitation.EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

Homogeneous in color, with aliasing mostly confined to the base of the jet


Pathologic Prosthetic RegurgitationPathologic 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 Smallfirmly fixed (minimal mobility) to the valve apparatushighly echogenic, (fibrous composition)common in aortic position Para valve jet suggests pannus


Abnormal echoesAbnormal 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%.EVALUATION OF PROSTHERIC VALVE


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 al75% 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.EVALUATION OF PROSTHERIC VALVE FUNCTION-METHODS AND CLINICAL UTILITY

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.


TEECareful 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 replacement1. 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 dysfunction1. 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.


TEEHigher-resolution image than TTE Proximity of the oesophagus to the heart .Size of vegetation defined more preciselyAbsence 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 TAVIThe echocardiographic evaluation of TAVI

is , in most ways same as that for surgically implanted valves

But 2 areas of chalenges areCaluculation of EOA Quantification of post TAVI AR


CONSIDERATIONS IN TAVILVOT 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.EVALUATION OF PROSTHERIC VALVE


CONSIDERATIONS IN TAVIParavalvular regurgitation is more common

following transcatheter aortic valve implantation versus standard valve replacement– 30-80% with 5-14%being moderate or severe.


CONSIDERATIONS IN TAVIDelayed 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 PatientsTEE and epicardial and epiaortic ultrasoundTEE remains the most widely used

American Society of Anesthesiologists has recommended intraoperative TEE as a category II indication in patients undergoing valve surgeryCurrent 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 PatientsMultiple echocardiographic views are obtained

to determine Appropriate movement of valve leaflets, Color flow Doppler should exclude the

presence of paravalvular leaks

• Immediate surgical attentionAny regurgitation that is graded moderate or

severe,‘Stuck’’ mechanical valve leaflets, Valve dehiscence, Dysfunction of adjacent valvesEVALUATION OF PROSTHERIC VALVE


Stress Echocardiography in Evaluating Prosthetic Valve FunctionStress 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 ValvesGuide 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 ValvesObstruction or PPM is likely if the mean

gradient rises > 18 mm Hg after exercise, even when the resting mean gradient is normal.


RT-3D TEEExcellent spacial imagingEase of useEnables 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


CinefluoroscopyStructural integrity Motion of the disc or poppetExcessive tilt ("rocking") of the base ring -

partial dehiscence of the valveAortic 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 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 CTBecause 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.


MDCT


Thrombolysis impact


MDCT 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 Catheterizationmeasure 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.


THANK YOU


evaluation of prosthetic valve function and clinical utility

Health & Medicine

clinical utility

prosthetic valve disease

prosthetic valve design

prosthetic valve disorder

serious valve dysfunction

native valve disease

patient functionmethods

implantation of larger