prothetic heart valves

8/12/2019 Prothetic Heart Valves

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Prosthetic Heart

Valves


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AIM , Target , what do you

want exactly to know

Selection of the Optimal Prosthesis.

Long Term Management of the prostheticvalve and its possible complications


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we should realize that no perfect valvesubstitute, The matter is it to choose the

optimal prosthesis for the individual patientand careful medical management and follow-up after implantation.


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types of prosthetic

valves

A) Mechanical valves bileaflet.Monoleaflet

Cage and Ball


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types of prosthetic

valves

A) Bioprosthetic valve s Stented bioprothesis.Stentless bioprothesis.

Percutaneous bioprothesis.


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Homographt:

It provides no durability advantages over thepericardial bioprothesis in metanalysis andso, for a technical concerns, limitedavailability, and increased complexity ofreoperation it is of restrict the use

the main indication for homograft's is acute

infective endocardities with perivalvularlesions.


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pulmonary autograft in the

aortic position (Ross procedure)

its main advantage is in children, asthe valve and new aortic annulus

appear to grow with the child .


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Bioprosthetic Versus Mechanical Valve


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Selection of the Prosthesis Model and Size


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step I: After the prosthesis type, i.e.,mechanical versus biological, isselected, one should contemplate theprosthesis models that have a well-established track record with regard to

long-term durability (bioprothesis) andlow thrombogenicity (mechanicalprostheses)


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step II: is to prevent prosthesis patient

mismatch (PPM) , choosing the modelproviding the largest valve effective orifice

area (EOA) in relation to the patients annulus size, that determine thehemodynamic performance of the

prosthetic)


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prosthesis patient mismatch ,PPM:It occurs when EOA of a normallyfunctioning prosthesis is too small in relationto the patients body size (and thereforecardiac output requirements), resulting in

abnormally high postoperative gradients .


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Threshold Values of Indexed Prosthetic ValveEOA for the Identification and Quantificationof PPM


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proper Implantation of the prosthesis


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for mitral valve replacement (MVR) :

it is recommended that:

- the chordae be preserved to prevent

postoperative deterioration in LV geometry andfunction.

- implant the bileaflet valves in the

antianatomic position and monoleaflet valveswith their larger orifice oriented posteriorly toensure more physiological flow patterns


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for Aortic valve replacement :

in the case of anticipated PPM, using,aortic root enlargement to accommodatea larger size of the prosthetic model.


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Long-Term Management

I. Base line assessment andfollow up.


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A complete baseline assessmentideally, be performed 6-12 weeks aftersurgery.

This includes clinical assessment, chestX-ray, ECG, TTE, and blood testing.


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A postoperative visit is, to improvepatient education on endocardities

prophylaxis and, if needed, onanticoagulant therapy and toemphasize that new symptoms shouldbe reported as soon as they occur.


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patient with prosthetic valve requirelifelong follow-up , in order to detect

early deterioration in prostheticfunction or ventricular function, orprogressive disease of another heartvalve


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Echocardiography is the method ofchoice to evaluate prosthetic valvefunction, Cine fluoroscopy and MSCTprovide useful additional information ifvalve thrombus or pannus are suspected


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Echocardiographic follow-up

Echocardiographic examination should beperformed at discharge and then 6 to 12

months after operation and/or when a clinicalsuspicion of prosthetic valve dysfunction ispresent.

yearly, regular follow-up is recommendedafter 5 years in patients with a bioprosthesis.


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Parameters of Prosthesis

FunctionLeaflet Morphology and MobilityTransesophageal echocardiography (TOE)

Improve the image quality and detection of cuspcalcification, thickening, valvular vegetationscaused by endocardities, thrombus or pannus, and

reduced leaflet mobility.


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Quantitative Parameters

Transprosthetic Velocity and Gradient.Effective Orifice Area

The Doppler velocity index (DVI):

a dimensionless ratio of the proximal velocityin the LVOT to that of flow velocity throughthe prosthesis: DVI= VLVOT/VPV.

> 0.35 in aortic valve / and >0.45 for mitralvalve


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Interpretation of High Gradients:

Distinguishing Between High-FlowStates, PPM, and Pathological ValveObstruction


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Prosthetic Valve Regurgitation

Mechanical prostheses have a normalregurgitant volume known as leakageBackflow , short in duration, narrow, andsymmetrical.

In the case of pathological regurgitation,it is important to localize the origin of theregurgitant jet(s) to distinguishparavalvular from transvalvularregurgitation.


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In patient with mechanical mitral

prosthesis regurgitation is suspected whenflow convergence downstream of the prosthesis

during systole.

increased mitral peak E-wave velocity (_2 m/s)and/or mean gradient (_5 to 7 mm Hg).

DVI _0.45. unexplained or new worsening of pulmonary

arterial hypertension


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TOE may provide important causalinformation such as flail bioprosthetic cusp,presence of pannus or thrombus interactingwith leaflet closure, prosthesis dehiscence,and location and size of paravalvular jets.


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Identifying TTE Indirect

Signs of Dysfunction The size and function of the LV and atrialchambers.

level of systolic pulmonary arterial pressure.

these measurements can be comparedwith previous measurements and often arethe first sign to alert attention when theregurgitation is difficult to visualize


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II. Antithromboticmanagement:


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Target INR for mechanicalprosthesis


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Self-management of anticoagulationhas been shown to reduce INR

variability and clinical events,although appropriate training is

required.

A i l i d i


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Anticoagulation duringnon-cardiac surgeryIt is recommended not to interruptoral anticoagulation for most minor

surgical procedures (including dentalextraction, cataract removal) andthose procedures where bleeding is

easily controlled(recommendation class I, level ofevidence C).


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Major surgical procedures require an INR


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UFH remains the only approved heparintreatment in patients with mechanicalprostheses; intravenous administrationshould be favoured over the

subcutaneous route.(recommendation class IIa, levelof evidence C).


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Despite The widespread use ofsubcutaneous LMWH as an alternative to

UFH for bridging and the positive resultsof observational studies , their use arenot approved in patients with mechanical

prostheses, due to the lack of controlledcomparative studies with UFH.

If LMWH used


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If LMWH used ,

twice a day using therapeutic doses, adapted tobody weight,monitoring of anti-Xa activity with a target

of 0.51.0 U/ml. LMWHs are contraindicated in cases of severe

renal failure.

The last dose of LMWH should be administered12 hours before the procedure, whereas UFHshould be discontinued 4 hours before surgery .


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Aspirin therapy should be discontinued 1 week

before a non-cardiac procedure.


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Subcutaneous UFH , 17,500 to 20,000 U /12H

with target aPTT 1.5-2 times the control6hours after the injection till the 12 TH week.

Then resume warfarin till 36week then backto heparin use.

Anticoagulation during

pregnancy


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The patient with prosthetic valve is consideredhigh risk patient that is indicated forendocardities prophylaxis on major surgicalintervention.


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Thromboembolic andBleeding Complications


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VALVE THROMBOSIS

Annual incidence 0.2- 1.8%.

tricuspid> mitral> aortic.

Presentation; a cute onset of dyspnea , embolicevent especially after a period of inadequateanticoagulation or a cause for increasedcoagulability (e.g. dehydration, infection, etc).

The diagnosis should be confirmed by TTE and/orTOE or cinefluoroscopy

Management of left sided


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Management of left-sidedobstructive prosthetic

thrombosis.


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Management of left-sided

non-obstructive prostheticthrombosis

Management of thromboembolism


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Management of thromboembolism

Prevention of further Thromboembolicevents involves :

Treatment or reversal of riskfactors such as AF, hypertension,hypercholesterolemia, diabetes, smoking,

infection, and prothrombotic blood testabnormalities.


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Optimization of anticoagulation control, ifpossible with patient self-management, onthe basis that better control is more effectivethan simply increasing the target INR.

Low-dose aspirin (100 mg daily) shouldbe added, if it was not previously prescribed,after careful analysis of the risk-benefitratio, avoiding excessive anticoagulation


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Embolic stroke :

there is increased risk of stroke over first2weeks 1% per day , so

if no evidence of hemorrhage is detectedon CT 24-48 hours IV heparin with smallto moderate stroke.

In large infarcts withhold anticoagulantfor 5 to 7 days and for 1-2 weeks in case ofhemorrhagic transformation .


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Bleeding complications :

In patients on long-termanticoagulation, the annual risk of a

hemorrhagic event is ~1% per patient-year.

In patients with mechanical valves, thebleeding events are most often due toexcessive anticoagulation,


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In the absence of bleeding, (or minorbleeding), its reasonable to stop oral

anticoagulation and allow the INR to fallgradually and/or to give oral vitamin K inincrements of 1 or 2 mg and If the INR is .10,

higher doses of oral vitamin K (5 mg) .

.


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Immediate reversal of anticoagulation isrequired only for severe bleeding,Intravenous prothrombin complexconcentrate When available, is preferredover fresh frozen plasma, and if used,should be combined with oral vitamin K


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Hemolysis & PVL

A large proportion of patients withmechanical valves have some

degree of intravascular hemolysis.

clinical hemolysis is associatedwith ; multiple prosthetic valves ,periprothetic leakage and PVE.


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Blood tests for hemolysis (lactatedehydrogenase) should be part of routinefollow-up.

Echocardiographic findings consistent withmechanical hemolysis include : abnormalrocking and paravalvular leakage ( so TOEmay be needed).


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Reoperation is recommended if PVL is

related to endocardities, or if PVL causeshemolysis requiring repeated bloodtransfusions or leading to severe symptoms

(recommendation class I, level of evidenceC).


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Medical therapy iron supplementation,beta-blockers and erythropoietin, isindicated in patients with severe hemolyticanemia and PVL not related toendocardities, where contraindications tosurgery are present, or in those patients

unwilling to undergo reoperation.


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Transcatheter closure of PVL is feasible butexperienceis limited and there is presentlyno conclusive evidence to show a

consistent efficiency. It may be consideredin selected patients in whomreintervention is deemed high-risk or is

contraindicated.


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Infective endocardities

Early (


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Patient with mechanical prostheticendocardities should continue on oralanticoagulant


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Management of bioprosthetic

failure


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Predictors of SVD

Risk factors previously found to be associatedwith bioprosthetic SVD include;

younger age at time of implantation, mitralvalve position, renal insufficiency, andhyperparathyroidism.

Hypothetical model for the


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ypstructural deterioration of

bioprosthetic valves.


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.Early signs of SVD includeleaflet stiffening, calcification, reducedeffective orifice area, and/or regurgitation.


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Reoperation is recommended insymptomatic patients with a significantincrease in trans-prosthetic gradient orsevere regurgitation

(recommendation class I, level of

evidence C)


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Reoperation should be considered inasymptomatic patients with any significantprosthetic dysfunction, provided they areat low risk for reoperation.

(recommendation class I, level of

evidence C)


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Prophylactic replacement of abioprosthesis implanted .10 years ago,without structural deterioration, may be

considered during an intervention onanother valve or on the coronary arteries

(recommendation class IIb, level of

evidence C).


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Future Perspective

Percutaneous implantation of a newbioprosthesis within the failed bioprosthesisimplantation (valve in valve) may provide agood alternative to surgical replacement ofthe prosthesis, particularly in high-riskpatients.


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Echocardiography assessment

of prosthetic valves

http://www.youtube.com/watch?v=3ftvT-lCdw8


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prothetic heart valves

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