Echoecho Followup After Valve Replacement

8/8/2019 Echoecho Followup After Valve Replacement

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doi: 10.1136/hrt.2008.1520742010 96: 75-85Heart

Tobias Pflederer and Frank A FlachskampfreplacementEchocardiographic follow-up after heart valve

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VALVULAR HEART DISEASE

Echocardiographic follow-up afterheart valve replacementTobias Pflederer, Frank A Flachskampf

Med.Klinik 2, University ofErlangen, Erlangen, Germany

Correspondence to:Professor Frank A Flachskampf,Med.Klinik 2, University ofErlangen, Ulmenweg 18, 91054Erlangen, Germany; [email protected]

The number of patients with prosthetic valves issteadily increasing, in particular because of theepidemic of aortic stenosis in the elderly. InGermany alone, more than 24 000 patientsundergo valve replacement per year. In additionto the patients history and physical examination,echocardiography is the key element in the follow-up of individuals with a prosthetic valve (box 1).

The examination of the patient with a prosthe-tic cardiac valve, however, is one of the most

challenging tasks in echocardiography. For severalreasons echocardiography in these patients is moredifficult than in others:

c Due to the valvular heart disease present beforevalve replacement, these hearts are nevernormal, even with a perfectly functioning valvereplacement.

c The prosthesis itself, especially in the case of amechanical prosthesis, invariably generatesartefacts and often is not well visualised. Forexample, in aortic mechanical prostheses it isoften difficult or impossible to delineateprecisely the extent of occluder motion.

c Even normally functioning valve prosthesespresent a variable degree of obstruction andregurgitation.

This article provides an overview of procedures,the problems that can arise, and recommendationson how to deal with them.

TYPES OF VALVE PROSTHESES

Mechanical valves are the oldest and most durablereplacements for native cardiac valves. Theymainly differ by the mechanism by which theocclusion of the valve is achieved. Currently,mostly bileaflet prostheses are implanted, butsingle disc valves (tilting disc) such as theMedtronic-Hall or the Bjork-Shiley valves exist insubstantial numbers, while the earliest type, theball-in-cage, has become a rarity. Biologicalprostheses span a range from porcine or bovinetrileaflet valves in a rigid ring to stentless bio-prostheses and finally homografts, which areprocessed human cadaveric valves. In addition,the Ross procedure uses an autograft, thepatients own pulmonary valve to replace adiseased aortic valve, while the pulmonary valveis replaced by an ordinary bioprosthesis.Mechanical prostheses are the most difficult to

image, since reverberations and artefacts from thenon-biological material mostly preclude detailedmorphologic assessment (fig 1A). However, in themitral (or tricuspid) position, the occluders (leafletsor tilting discs) can often be seen quite well,particularly by transoesophageal echocardiography(TOE) (fig 24). Mechanical prostheses oftenrelease echocardiographically detectable small gasbubbles, apparently caused by cavitation in blooddue to the fast movement of the occluder. Thisunique phenomenon should be considered normal.Characteristically, Doppler recordings frommechanical valves display the opening and closing

clicks as bright (high intensity), vertical linesenclosing the transprosthetic forward flow profile(fig 1B). Minor changes in the opening amplitudeof occluding discs, which may occur with partialthrombosis or other obstruction, necessitatefluoroscopy to exclude or document with cer-tainty. Stented bioprostheses are easier to image(fig 5), and stentless bioprostheses, homografts,and autografts are often indistinguishable morpho-logically or by transvalvular flow velocities fromnative valves, except for minor echodensities at thevalvular circumference, where the prosthesis hasbeen sewn in. The newly introduced three dimen-

sional TOE probe is able to generate en faceviews of prostheses, resembling visual inspection,

Box 1 The following questions should be systematically answered when

examining a prosthesis by echocardiography

c Does the history or clinical presentation of the patient suggest a prosthesisrelated disorder (for example, new onset of severe dyspnoea, fever, etc)?

c Is the prosthesis firmly implanted as a whole (absence of rocking)?c

In a bioprosthesis, are there morphologic signs of degeneration (thickened,immobile or pathologically mobile leaflets or leaflet segments)? In amechanical prosthesis, do the occluder discs move normally?

c How much regurgitation is there, and is it transprosthetic or paraprosthetic?c What are the mean and maximal transprosthetic gradients, are they in the

normal range, and have they changed substantially from baseline?c Are there fixed or mobile mass lesions attached to the prosthesis (thrombus,

vegetation, pannus)?c Are there other signs of endocarditis, in particular abscess formation at the

prosthetic ring, fistulae, or a pericardial effusion?

The first routine postoperative assessment is particularly important, since it

serves as baseline for later comparison, especially with regard to transprostheticgradients, prosthetic regurgitation, right ventricular peak pressure, left ventricular

function, and other aspects.

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which allow a more intuitive assessment ofprosthetic occluders and rings1 (fig 6).

Recently, interventionally deployable aorticprostheses have been introduced. The CoreValveprosthesis is a porcine pericardial trileaflet bio-prosthesis mounted into a self expanding nitinolframe. The Edwards-Sapien valve is a bovinepericardial trileaflet valve mounted in a balloonexpandable steel stent. Thus, these prosthesesneither have a typical ring nor are they stentless.

After deployment, these prostheses frequentlyhave paraprosthetic leaks and also may leak

centrally (fig 7). Details on peri-interventionalechocardiography can be found elsewhere.2

ECHOCARDIOGRAPHIC CHARACTERISTICS OFSPECIFIC PROSTHETIC IMPLANTATION SITES

Aortic valve prosthesesAortic prostheses should be examined in all crosssections containing the aortic valve, in particular

the parasternal long and short axis. Zoom imagesare helpful. Special attention should be paid to thepara-aortic tissue in order to rule out a para-aorticabscess. While the discs of mechanical prosthesesare often insufficiently viewed, even by TOE,bioprostheses or homografts pose no unusualproblems in imaging and should be examined bytransthoracic echocardiography or TOE, if neces-sary, with regard to opening motion, thickening,calcification, mobile components, masses, andother abnormalities. In the parasternal long andshort axis views and the apical long axis view,paraprosthetic (arising outside the prosthetic ring)

and transprosthetic (arising inside the prostheticring) regurgitation can be detected by colourDoppler. Differentiation of the two types ofregurgitation may be difficult, especially betweena small paraprosthetic leak and the eccentric, buttransprosthetic, normal regurgitation of bileafletprostheses.

Peak and mean gradients across prosthetic aorticvalves should be measured by continuous waveDoppler in long axis views (fig 1B). Care should betaken not to mistake a post-premature beatejection or the ejection after a long filling periodin atrial fibrillation as representative, since in theseinstances the velocities will be atypically high.

Substantial aortic regurgitation or a high outputstate, as in sepsis, also increase gradients. Normalvalues vary drastically depending on type and sizeof prosthesis (table 1).3

In patients who underwent replacement of theaortic valve together with the ascending aorta by avalved graft (Bentall procedure), typically due toannulo-aortic dilatation or to dissection or aneur-

ysm of the ascending aorta, transoesophagealechocardiography is advantageous to assess thewhole thoracic aorta including the graft.Pseudoaneurysm formation at the site of re-implantation of the coronaries has been described,

and the morphology of persistent dissection in thearch and descending aorta may be assessed.4

The interpretation of transprosthetic aorticgradients in mechanical prostheses is complicatedby the occurrence of significant pressure recoveryeffects due to the design, especially of the bileafletprostheses. Pressure recovery also exists in otherprostheses (and, for that matter, in native aorticstenosis), but usually to a minor degree. Thepresence of localised high gradients, in particularbetween the medial orifice of normally functioningbileaflet valves, precludes the usual grading ofstenosis severity. For example, mean (SD) peakvelocities of 2.9 (0.5) m/s and attending peak

gradients up to 35 (11) mm Hg are found routinelyby continuous wave Doppler in St Jude Medical

Figure 1 (A) Mechanical bileaflet prosthesis in the aortic position. Parasternal long axisview. The prosthesis (solid arrow) is obscured by typical artefacts and reverberationsextending into the left atrium (dotted arrow). Asc, ascending aorta; LV, left ventricle.(B) Corresponding continuous wave Doppler recording of aortic transprosthetic gradient.Maximal velocity of 3.4 m/s, corresponding to a peak gradient of 46 mm Hg. Note clicks(vertical lines) at the beginning and end of ejection.

Figure 2 Mechanical bileaflet prosthesis in the mitral position, diastolic apical fourchamber view. The leaflets are in the open, parallel position (arrows). The small image on

the right shows the systolic, closed position (arrow), where the leaflets are notindividually discernible. LA, left atrium; LV, left ventricle.

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bileaflet number 19 prostheses without evidence ofdysfunction, with corresponding effective orificeareas by continuity of only 1.0 (0.2) cm2.3

Moreover, because malfunction of such a valvemay lead to a breakdown of such localisedgradients, a partially stenotic bileaflet valve mayshow only a minor or no increase in velocities andgradients. Calculation of the effective valve orifice

area by the continuity equation does not circum-vent the problem, because it utilises the maximaltransprosthetic velocity which is not representativefor the whole prosthetic orifice(s); the areacalculated will therefore be much lower than theexpected orifice area or the orifice area provided bythe manufacturer, even if there is no malfunction.The use of alternative measures of obstruction is

not routinely recommended.Therefore, interpreting these findings correctly

requires at least one of the following additionalpieces of information:

c A baseline continuous wave Doppler studyproviding values for comparison from a time inwhich the prosthesis was presumably workingwell.

c Fluoroscopy of the valve allowing exact visua-lisation of the maximal opening angle of eachdisc. Finding the optimal projection (often acranially tilted left anterior oblique projection)may be cumbersome.

c Reconstruction of functional datasets of a non-contrast enhanced multi-detector cardiac com-puted tomography, which allows very preciseanalysis of the discs motion.

Assessing the degree of more than mild mechan-ical prosthetic aortic regurgitation is extremelydifficult (even with TOE) and requires utmostcaution. Short of detecting a visibly large para-prosthetic leak, a rocking, dehiscent prosthesis, ortorrential regurgitation filling the entire outflowtract during diastole, secondary signs of severe

Figure 3 Mitral mechanical bileaflet prosthesis in the transoesophageal four chamberview in diastole. The leaflets are in the open, parallel position (arrows). The small imageon the right shows the leaflets during systole in a tent-like, closed configuration. LA, leftatrium; LV, left ventricle.

Figure 4 Mitral tiltingdisc prosthesis (Medtronic-Hall) in thetransoesophageal fourchamber view. (A) Twodimensional (2D) image insystole with disc in closedposition. Arrow points atcentral strut. (B) 2D imagein diastole with disc inopen position. (C) Systoliccolour Doppler image ofnormal central regurgitationaround central strut. LA,left atrium.

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regurgitation should be sought, such as a short(,250 ms) pressure half time of the continuouswave Doppler signal of aortic regurgitation, orholodiastolic backward flow in the descendingaorta by pulsed wave Doppler from the supraster-nal notch. It remains sometimes impossible, how-ever, to be confident about whether an aorticprosthetic regurgitation is moderate or severe.

Another sign of haemodynamic improvementafter aortic valve replacement is regression of left

ventricular mass and improvement in function. Wall thickness decreases and ejection fraction andtissue Doppler parameters of myocardial function

improve after replacement of a stenotic aorticvalve, with functional improvement beginning assoon as 24 h after the procedure. After replacementfor aortic regurgitation, left ventricular diameters,volumes, and mass decrease and ejection fractionusually improves.5 6

EXAMINATION OF MITRAL VALVE PROSTHESES

Compared to aortic prostheses, the larger size ofmitral prostheses and the presence of large bloodfilled heart chambers on both sides of theprosthesis make echocardiographic assessmenteasier. The left atrial side of the prostheses andthe left atrium are obscured by mechanical mitralprostheses when viewed from the apex (comparefig 2). Therefore, examination should includeespecially subcostal views which often visualisethe left atrium well. The most important func-tional parameter is the mean diastolic Dopplergradient by continuous wave Doppler (table 1). Itshould be kept in mind that this gradient is very

sensitive to heart rate and may be substantiallyelevated in spite of a perfectly normal prosthesisduring atrial fibrillation with a rapid ventricularresponse. The pressure half-time (PHT, in ms)depends heavily on prosthesis type and the formula220/PHT for native mitral valve orifice area in cm2

cannot be used for prostheses; however, intra-individual serial comparisons can be performedusing the PHT. Furthermore, when searching forparaprosthetic regurgitation special attentionshould be paid to the presence of proximalconvergence zones on the ventricular side of themitral prosthetic ring; in fact, the presence of areproducible, well formed proximal convergencezone by itself signals substantial paraprostheticregurgitation.7 TOE affords excellent visualisationof mitral prostheses and the left atrium, includingoccluder mobility, but the ventricular side ofmechanical prostheses is obscured (figs 3 and 4).

A secondary sign of haemodynamic improvementafter mitral valve replacement is postoperativereduction in systolic right ventricular pressures,estimated by maximal tricuspid regurgitant velo-city.

TRICUSPID POSITION

Replacement of the tricuspid valve is avoidedwhenever possible in favour of reconstructivesurgery, typically with a ring. Because of therelatively slow right atrial and trans-tricuspid flowvelocities, tricuspid prostheses are at a particularlyhigh risk of thrombosis. Imaging is performed inthe typical cross sections for the tricuspid valve(parasternal right ventricular inflow view, para-sternal short axis view of aortic valve, apical andsubcostal four chamber views). TOE is helpful bysupplying additional transgastric (for example,right ventricular long axis views) and transoeso-phageal images (four chamber, aortic valve shortaxis, and others). Functional performance is

evaluated by continuous wave Doppler measure-ment of mean transtricuspid gradient8 (table 1).

Figure 5 Biological prosthesis in the aortic position.

Parasternal long axis view. The bright reflexes of theprosthetic ring are seen (arrows). LV, left ventricle.

Figure 6 En face view from the left atrium of a bileafletmechanical mitral prosthesis by three dimensional

transoesophageal echocardiography. The two occludersand the sewing ring are clearly discernible.

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PATHOLOGIC FINDINGS IN VALVULAR

PROSTHESES

Obstruction

Flow velocities across a prosthetic valve should beassessed by continuous wave Doppler as in a nativevalve and peak and mean gradients calculated. Theuse of PHT in mitral or tricuspid prostheses ishampered by the fact that the classic formula formitral orifice area A = 220/PHT does not hold.However, serial changes in PHT may be useful todetect obstruction if the pressure half-timeincreases substantially in a given valve.Transprosthetic velocities are always elevated incomparison to the native valve. They are particu-larly high in small bileaflet prostheses in the aorticposition, where localised high pressure gradients

may exist which exceed the net pressure differencebetween the left ventricle and the ascending aorta.These localised pressure gradients are recorded bycontinuous wave Doppler and are indistinguishablefrom gradients generated by true prostheticobstruction.9 10 Therefore, correct motion of theleaflets/occluder should be ascertained. This is bestachieved by fluoroscopy; a systematic comparisonbetween fluoroscopy, transthoracic and transoeso-phageal echocardiography showed that occludingdisc angles of mitral prostheses could be ascertained

Figure 7 Transapicallyimplanted aorticbioprosthesis (Edwards-Sapien).(A) Transoesophagealcolour Doppler image in along axis view. There is aparaprosthetic leak in thearea of the non-coronarycusp. Ao, ascending aorta;LA, left atrium; LV, leftventricle.(B) Transoesophageal twodimensional image in ashort axis view. Notecircumferential stentmaterial.

Table 1 Selection of published ranges of mean transprosthetic Doppler gradients (range of standard deviations) in normally functioning prostheses

Mean transprostheticDoppler gradientsmm Hg

Aortic position (prosthesis sizes 1925):

Mechanical bileaflet prostheses 10219 (226)

Stented bioprostheses 16224 (529)

Mitral position:

Mechanical bileaflet prostheses 425 (122)

Mechanical tilting disc prostheses 326 (122)

Stented bioprostheses 325 (122)

Tricuspid position:

All types 3 (1)For further detail according to type and size of prosthesis, see Rosenhek et al

3

and Connolly et al.8

Figure 8 Small thrombus (full arrow) on the atrial side ofa mitral tilting disc prosthesis. The thrombus resolved

under an improved anticoagulatory regimen. The dottedarrows point at the sewing ring. LA, left atrium.

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transthoracically and by TOE in 85% and 100%,respectively, but that aortic prostheses were notsufficiently assessed.11 It is also helpful to comparewith transvalvular gradients from the postoperativeperiod, when the valve was presumably functioningnormally. Therefore, it is important to record suchgradients or velocities early after surgery in order tohave these baseline values ready for later compar-

ison. This problem does not arise in mitral pros-theses (mainly because of different receivingchamber morphology). Normal values for trans-prosthetic gradients have been published and dependon valve position, type, and size (table 1), but thenormal ranges are wide and, as mentioned above,especially in the aortic position, high gradients canbe both by design and thus normal or due tomalfunction. By exercise or dobutamine stressechocardiography, the range of transprostheticpressure gradients occurring in real life can be furtherestimated, but there is no universally acceptedindication for stress echocardiography to assess

prosthetic function.True obstruction in a mechanical prosthesis is

caused by impaired occluder opening due tothrombosis or pannus (tissue ingrowth), both ofwhich may or may not be directly visible on TOE(fig 8). While thrombus is often associated withdense surrounding spontaneous echo contrast, ahistory of suboptimal anticoagulation, and occursmore often on mitral than aortic prostheses due tohigher flow velocities across the latter,12 pannustends to be more echodense than thrombus, arises

from the prosthetic ring suture line, and only rarelyoccurs early postoperatively.13 Nevertheless, bothpathologies may coexist and often cannot bedifferentiated with confidence.

The management options for prosthetic throm-bosis have been studied in a number of observa-tional studies.12 It seems that small, asymptomaticthrombi not causing embolism or haemodynamic

instability can be treated conservatively by ensur-ing adequate anticoagulation. Laplace et al, usingroutine postoperative transoesophageal echocardio-graphy, have observed an incidence of 9.4% ofthrombi early postoperatively in 680 mechanicalmitral valve replacements.14 Except for twoobstructive thrombi treated surgically, all non-obstructive thrombi were treated medically in anon-standardised fashion by re-initiation ofheparin, re-adjustment of oral anticoagulation, oraddition of aspirin. If patients were stratified bythrombus size, 22% of patients with thrombi>5 mm experienced complications (including neu-

rologic ischaemic events) over the next month, butonly one patient (3.4%) with a thrombus ,5 mm.Elaborate management algorithms have beenrecommended for the choices between anticoagu-lation, thrombolysis, and reoperation, dependingon the presence of obstruction, embolism, orhaemodynamic compromise.1 1 1 2 1 5 1 6

Bioprosthetic ageing leads to degenerativechanges which manifest as leaflet thickening andreduced mobility, with the consequence of func-tional obstruction (fig 9).

Figure 9(A) Degenerative stenosisin a mitral bioprosthesis.Transoesophageal view.Note reduced opening ofthe thickened leaflets. LA,left atrium; LV, leftventricle.(B) Correspondingtransprosthetic continuouswave Doppler recording,showing notably elevatedmean diastolic gradient of15 mm Hg.

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Patientprosthesis mismatch

If the size of a prosthesis is too small for the size ofthe patient (a mosquito valve in the heart of awhale), it will cause functional obstruction

despite mechanically functioning well. This con-cept, originating from Rahimtoola,17 has receivedattention especially in aortic valve prostheses, butis also applicable to mitral prostheses. Crucial formismatch considerations is the effective orifice areaof the prosthesis, which is indexed by body surfacearea to yield the indexed effective orifice area inan individual patient. This effective orifice area isnot to be confused with the manufacturersinternal geometric area, which, like the valvering size, has only a loose relationship to effectiveorifice area. For example, for a bileaflet SorinBicarbon mechanical prosthesis size 21, the effec-tive orifice area is only 1.66 cm2,18 less than half the

number calculated by assuming a circle of 21 mmdiameter (which would come to 3.46 cm2). Foraortic prostheses, an area of 0.85 cm2/m2 bodysurface area is an accepted cut-off value belowwhich patientprosthesis mismatch is assumed,and a cut-off of 0.65 cm2/m2 has been proposed forsevere mismatch. Mild mismatch has been found inone third to one half of aortic valve replacements,19

and severe mismatch (indexed orifice area,0.65 cm2/m2) is present in ,10% of patients.19 20

The presence of patientprosthesis mismatchhas been reported to predict less reversal ofhypertrophy and lower postoperative ejection

fraction (in aortic prostheses19 20

), persistent pul-monary hypertension (in mitral prostheses21), and

in general an adverse prognosis.1921 Differentfindings, however, have been reported by otherresearchers and a vivid debate surrounds thedefinition, grading, and clinical relevance of mis-

match.2225

Moreover, the estimation of effectiveorifice area is difficult, at least in vivo, since it maynot be flow independent and the calculation ofeffective orifice area, especially in bileaflet mechan-ical prostheses, is unreliable due to localisedpressure gradients, as discussed in the section onobstruction. Effective orifice areas calculated by thecontinuity equation therefore are likely to under-estimate true effective orifice area substantially.Importantly, in a mechanical aortic prosthesis it isnot possible to distinguish from Doppler data alone(that is, without additional baseline data and/ordirect imaging of occluding disc motion):

1. High gradients due to localised pressuregradients in a normally functioning and notmismatched prosthesis

2. High gradients due to mechanical obstruction(thrombus, pannus)

3. High gradients due to patientprosthesismismatch, with a normally functioning valve,or

4. Any combination of 13.

Regurgitation

Regurgitation in a prosthetic valve is often difficult

to assess. Mitral prostheses, especially mechanicalones, create acoustic shadowing of the left atrium

Figure 10 Mechanicalprosthesis in the aorticposition withparaprosthetic leak in theregion of the left coronarysinus (arrows).(A) Transoesophagealcolour Doppler long axisview.(B) Transoesophagealcolour Doppler short axisview. Ao, ascending aorta;LA, left atrium.

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when interrogated from the apical window, oftenprecluding colour Doppler assessment of the leftatrium. The parasternal and subcostal views

should be used with particular care to look for aregurgitant jet in this situation. Moreover, morethan mild regurgitation often is detectable by theproximal convergence zone on the ventricular, andthus unobstructed, side of a mitral prosthesis, andsuch convergence zones should be sought in allapical views. TOE is of particular value to assessmitral prosthetic regurgitation.26

All currently implanted mechanical prosthesesare designed to allow a minor amount of trans-valvular leakage, which in the most commonbileaflet valves is supposed to prevent stasis andthrombus formation at the leaflet hinges. This

leakage is detectable throughout the interval inwhich the prosthesis is in the closed position, and

thus is different from the closure leakageoccurring early when the leaflets move to theclosure position. Typically, the inbuilt prosthetic

leakage creates characteristic jet patterns detect-able on colour Doppler, especially by TOE, whicharise at the hinge points in bileaflet valves orcentrallyfor example, in the Medtronic-Halltilting disc valve.27 These jets are strictly transvalv-ularthat is, they occur within the sewing ring.They also are often too small to display a clearlyaliased turbulence zone.

Regurgitant jets arising outside the sewing ring aredue to paraprosthetic leaks, which can occur in anysize and position along the prosthetic circumference(figs 10 and 11). Large paraprosthetic leaks lead toprosthetic dehiscence, which is a term used if the

whole of the prosthesis develops a rocking motiondue to insufficient support. Small paraprosthetic

Figure 11 Mechanical bileaflet prosthesis in the mitral position. Transoesophageal view with the cross section aligned to leaflet axis orientation.(A) Two dimensional (2D) image. LA, left atrium. (B) Colour Doppler visualisation of paraprosthetic leak (arrow); note well developed proximalconvergence zone of paraprosthetic leak; transoesophageal two chamber view. (C) Corresponding 2D zoom of discontinuity between sewing ring andheart wall producing the leakage. (D) Continuous wave Doppler recording of transmitral flow. Peak regurgitant systolic velocity is approximately 4 m/s,implying massively elevated peak systolic left atrial pressure at a systolic blood pressure of 100 mm Hg (100264 = 36 mm Hg). Note also elevateddiastolic transprosthetic velocities (maximal velocity .2 m/s) due to regurgitant volume.

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leaks observed intraoperatively after valve replace-ment may close over the next hours or days.28

Observation of a new paraprosthetic leak in aprosthesis is very suspicious of infective endocarditis.Finally, in rare instances, there may be massive

transprosthetic regurgitation due to loss of struc-tural integrity of the prosthesisnotoriously thisoccurred in a series of tilting disc valves that sufferedfrom strut fractures, with subsequent disc embolisa-tion and catastrophic regurgitation. Massive regur-gitation can also occur if mechanical obstructionby thrombus or pannus freezes the occluder in a

semi-open position. In bioprostheses, minor regur-gitation is frequent and may increase in severity ifdegenerative changes (restricted leaflet motion orleaflet tears) ensue. Endocarditis is always a concernin a newly detected prosthetic regurgitation.

Grading of severity of regurgitation follows thegeneral principles for native valves.29

Infective endocarditisCardiac valve prostheses carry a high risk ofinfective endocarditis. During the first year afterimplantation, the rate has been estimated to be3%, and approximately 0.5%/year thereafter.30 31

Especially in mechanical prostheses, identifyingsmall vegetations is very difficult. In bioprostheses,on the other hand, the presence of degenerativeleaflet changes with thickening and increasedechogenicity often makes it difficult or impossibleto exclude incipient endocarditis with confidence.Moreover, an unsatisfactory sensitivity for thedetection of paraprosthetic abscesses has beennoted, which has not decreased substantially inspite of todays higher image quality. Therefore,the clinical suspicion of endocarditis in a patientwith a prosthetic valve should regularly lead to atransoesophageal examination, as recommendedby the European guidelines.32 Much higher diag-nostic accuracy for vegetations and in particular forabscess detection (fig 12) has been well documen-ted for TOE.33

FOLLOW-UP: WHEN AND HOW?

It is crucial that each patient who has received avalve replacement should receive a baseline echo

Figure 12 Severestaphylococcalendocarditis ofbioprosthetic aortic valvereplacement.(A) Transoesophageal longaxis view. Upper arrowindicates thickening ofposterior aortic wallindicating abscessformation. Lower arrowpoints at vegetations in theleft ventricular outflowtract. (B) Transoesophagealshort axis view. Solidarrow indicates fistula toright atrium. Dotted arrowpoints at echolucentabscess centre in the aorticwall; the abscess is verylarge and encompassesalmost half thecircumference of theprosthesis (fromapproximately 11 to 4oclock). Ao, ascendingaorta; LA, left atrium,LV, left ventricle; RA, rightatrium; RV, right ventricle.

Echocardiography follow-up after valve replacement: key points

c Echocardiography is the crucial and usually sufficient imaging technique in thefollow-up of patients with valvular prostheses. Whenever prosthetic

dysfunction or endocarditis is suspected, transoesophageal echocardiography(TOE) due to its higher diagnostic yield should be harnessed. Especially inaortic mechanical prostheses, occluder motion is often not well seen even byTOE and may necessitate fluoroscopy for precise assessment.

c Even normally functioning prostheses, except homografts and autografts,create some degree of obstruction to flow, and most exhibit some degree ofregurgitation. Therefore, baseline echocardiographic assessment earlypostoperatively, when normal prosthetic function can be assumed, isextremely valuable for later comparison. This is of particular importance in theassessment of aortic transprosthetic gradients, which have a wide range ofnormalcy.

c Echocardiography, if necessary including TOE, should be promptly performedin newly symptomatic patients with valvular prostheses. Routine yearlyechocardiographic examination is recommended after the fifth year in patients

with a bioprosthesis.

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after the operation to be able to compare withsubsequent findings. The examination should beperformed at a time when the patient is haemo-dynamically stable, off ventilator or circulatorysupport and mobilised, with special attention totransprosthetic gradients and the presence ofregurgitation; within 12 weeks after operation isthe current recommendation,16 although it seemsreasonable to perform this earlierfor example,before discharge from hospital. TOE is notroutinely required if the prosthesis appears tofunction normally. Recently, the routine post-

operative performance of TOE in patients withmitral mechanical prostheses has been advocatedbased on findings of clinically silent, postoperativethrombi in 10%,14 which predicted a higher adverseevent rate during follow-up. However, it remainsto be proven whether such a strategy would entailsignificant and beneficial changes in patientmanagement.

Further regular follow-up should be planned.The intervals are largely arbitrary; currentEuropean guidelines stipulate yearly clinical exam-inations and Transthoracic echocardiographyshould be performed if any new symptoms occur

after valve replacement or if complications aresuspected. Yearly echocardiographic examination isrecommended after the fifth year in patients withbioprosthesis.16

Competing interests: In compliance with EBAC/EACCME guide-lines, all authors participating in Education in Heart have disclosedpotential conflicts of interest that might cause a bias in the article.The authors have no competing interests.

Provenance and peer review: Commissioned; internally peerreviewed.

REFERENCES1. Sugeng L, Shernan SK, Weinert L, et al. Real-time three-

dimensional transesophageal echocardiography in valve disease:

comparison with surgical findings and evaluation of prostheticvalves. J Am Soc Echocardiogr 2008;21:134754.

2. Chin D. Echocardiography for transcatheter aortic valveimplantation. Eur J Echocardiogr 2009;10:i219.

c Good, detailed introduction into the details of interventionalaortic valve replacement from an echocardiographersview.

3. Rosenhek R, Binder T, Maurer G, et al. Normal values for Dopplerechocardiographic assessment of heart valve prostheses. J AmSoc Echocardiogr 2003;16:111627.

c Authoritative and largest published reference on this topiccompiled from the literature on transvalvular gradients,categorised by prosthesis position, type, and ring size (over7000 aortic prostheses and over 1600 mitral prostheses).

4. Morocutti G, Gelsomino S, Spedicato L, et al. Transesophagealechocardiography follow-up of patients undergoing replacement ofthe ascending aorta and aortic valve with a Cabrol procedure forchronic aneurysm and dissection. J Am Soc Echocardiogr2003;16:3606.

5. Krayenbuehl HP, Hess OM, Monrad ES, et al. Left ventricularmyocardial structure in aortic valve disease before, intermediate, andlate after aortic valve replacement. Circulation 1989;79:74455.

c Landmark paper on left ventricular remodelling after aorticvalve replacement.

6. Bauer F, Eltchaninoff H, Tron C, et al. Acute improvement in globaland regional left ventricular systolic function after percutaneousheart valve implantation in patients with symptomatic aorticstenosis. Circulation 2004;110:14736.

7. Yoshida K, Yoshikawa J, Akasaka T, et al. Value of accelerationflow signals proximal to the leaking orifice in assessing the severity

of prosthetic mitral valve regurgitation. J Am Coll Cardiol1992;19:3338.

c This paper shows the value of searching carefully for aproximal acceleration zone on the ventricular side of amitral prosthesis during transthoracic echocardiography,where direct evaluation of the left atrium for regurgitantjets is severely compromised by artefacts from theprosthesis.

8. Connolly HM, Miller FA Jr, Taylor CL, et al. Doppler hemodynamicprofiles of 82 clinically and echocardiographically normal tricuspidvalve prostheses. Circulation 1993;88:27227.

c Useful reference for normal transprosthetic gradients in thetricuspid position.

9. Baumgartner H, Khan S, DeRobertis M, et al. Discrepanciesbetween Doppler and catheter gradients in aortic prosthetic valvesin vitro. A manifestation of localized gradients and pressurerecovery. Circulation 1990;82:146775.

c Landmark paper analysing in vitro the phenomenon ofpressure recovery in aortic prostheses.

10. Baumgartner H, Schima H, Kuhn P. Effect of prosthetic valvemalfunction on the Doppler-catheter gradient relation for bileafletaortic valve prostheses. Circulation 1993;87:13207.

c Extension of the previous work, with important clinicalconsequences: a high transprosthetic gradient in an aorticbileaflet prosthesis may be normal or due to obstruction; theabsolute value alone does not distinguish between the two.

11. Muratori M, Montorsi P, Teruzzi G, et al. Feasibility and diagnosticaccuracy of quantitative assessment of mechanical prosthesesleaflet motion by transthoracic and transesophagealechocardiography in suspected prosthetic valve dysfunction.

Am J Cardiol 2006;97:94100.

c This study analysed how often mechanical occluder motionin aortic or mitral prostheses can be precisely evaluated bytransthoracic or transoesophageal echocardiography,

against a standard of fluoroscopy.12. Roudaut R, Serri K, Lafitte S. Thrombosis of prosthetic heartvalves: diagnosis and therapeutic considerations. Heart2007;93:13742.

c Important overview of detection and management ofprosthetic thrombosis.

13. Kondruweit M, Flachskampf FA, Weyand M, et al. Early failure ofa mechanical bileaflet aortic valve prosthesis due to pannus: a rarecomplication. J Thorac Cardiovasc Surg 2008;136:2134.

14. Laplace G, Lafitte S, Labeque JN, et al. Clinical significance ofearly thrombosis after prosthetic mitral valve replacement: apostoperative monocentric study of 680 patients. J Am Coll Cardiol2004;43:128390.

c Important, large study with systematic postoperative TOE,finding a surprisingly high rate (almost 10%) ofpostoperative thrombus formation in mitral prostheses.

15. Lengyel M, Fuster V, Keltai M, et al. Guidelines for managementof left-sided prosthetic valve thrombosis: a role for thrombolytic

therapy. Consensus Conference on Prosthetic Valve Thrombosis.J Am Coll Cardiol 1997;30:15216.

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16. Vahanian A, Baumgartner H, Bax J, et al, the Task Force onthe Management of Valvular Heart Disease. ESC guidelines onthe management of valvular heart disease. Eur Heart J2007;28:23068.

c The current, detailed, and authoritative recommendationsfor the management of valvular heart disease andprosthetic valves, from the European Society of Cardiology.

17. Rahimtoola SH. The problem of valve prosthesis-patientmismatch. Circulation 1978;58:204.

18. Pibarot P, Dumesnil JG. Hemodynamic and clinical impact ofprosthesis-patient mismatch in the aortic valve position and its

prevention. J Am Coll Cardiol 2000;36:113141.19. Blais C, Dumesnil JG, Baillot R, et al. Impact of prosthesispatient

mismatch on short-term mortality after aortic valve replacement.Circulation 2003;108:9838.

c Analysis of 1266 aortic valve replacements with regard tothe implications of prosthesis size relative to patient size onshort term prognosis.

20. Tasca G, Brunelli F, Cirillo M, et al. Impact of valve prosthesis-patient mismatch on left ventricular mass regression followingaortic valve replacement. Ann Thorac Surg 2005;79:50510.

c With a longer follow-up than the previous study, this paperdescribes functional and clinical implications of patientprosthesis mismatch in the aortic position.

21. Magne J, Mathieu P, Dumesnil JG, et al. Impact of prosthesis-patient mismatch on survival after mitral valve replacement.Circulation 2007;115:141725.

c Although mitral patientprosthesis mismatch is a less

common problem, in this study it was found to influence thepostoperative course and prognosis.22. Koch CG, Khandwala F, Estafanous FG, et al. Impact of

prosthesispatient size on functional recovery after aortic valvereplacement. Circulation 2005;111:32219.

c In over 1100 patients with aortic valve replacement, theseauthors did not see clear prognostic effects of patientprosthesis mismatch.

23. Mohty D, Malouf JF, Girard SE, et al. Impact of prosthesis-patientmismatch on long-term survival in patients with small St JudeMedical mechanical prostheses in the aortic position. Circulation2006;113:4206.

24. Mascherbauer J, Rosenhek R, Fuchs C, et al. Moderate patient-prosthesis mismatch after valve replacement for severe aorticstenosis has no impact on short-term and long-term mortality.

Heart 2008;94:163945.c Another paper calling into question the clinical relevance of

patientprosthesis mismatch.

25. David T. Is prosthesis-patient mismatch a clinically relevantentity? Circulation 2005;111:31867.

c Good editorial sketching the positions in the debate on theclinical relevance of patientprosthesis mismatch.

26. Flachskampf FA, Hoffmann R, Franke A, et al. Does multiplanetransesophageal echocardiography improve the assessment ofprosthetic valve regurgitation? J Am Soc Echocardiogr1995;8:708.

27. Flachskampf FA, Guerrero JL, OShea JP, et al. Patterns ofnormal transvalvular regurgitation in mechanical valve prostheses.

J Am Coll Cardiol 1991;18:14938.

c This study evaluated in vitro the colour Doppler patterns ofregurgitant jets in normally functioning mechanicalprostheses, establishing typical configurations of normalregurgitation in these prostheses.

28. Morehead AJ, Firstenberg MS, Shiota T, et al. Intraoperativeechocardiographic detection of regurgitant jets after valvereplacement. [Erratum in: Ann Thorac Surg 2001;72:984] AnnThorac Surg 2000;69:1359.

29. Zoghbi WA, Enriquez-Sarano M, Foster E, et al.Recommendations for evaluation of the severity of native valvularregurgitation with two-dimensional and Doppler echocardiography.

J Am Soc Echocardiogr 2003;16:777802.

c Excellent overview and recommendation paper on how toassess valvular regurgitation by echocardiography. Thebasis for looking at the more difficult evaluation ofprosthetic regurgitation.

30. Calderwood SB, Swinski LA, Waternaux CM, et al. Risk factorsfor the development of prosthetic valve endocarditis. Circulation1985;72:317.

31. Piper C, Korfer R, Horstkotte D. Prosthetic valve endocarditis.Heart 2001;85:5903.

32. Horstkotte D, Follath F, Gutschik E, et al, the Task Force Memberson Infective Endocarditis of the European Society of Cardiology.Guidelines on prevention, diagnosis and treatment of infectiveendocarditis executive summary; the task force on infectiveendocarditis of the European Society of Cardiology. Eur Heart J2004;25:26776.

c Current recommendations on clinical management ofendocarditis by the European Society of Cardiology; lookout for the update.

33. Daniel WG, Mugge A, Martin RP, et al. Improvement in thediagnosis of abscesses associated with endocarditis bytransesophageal echocardiography. N Engl J Med1991;324:795800.

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Echoecho Followup After Valve Replacement