Presentation on theme: "Echocardiography of Prosthetic Valves"— Presentation transcript:
1Echocardiography of Prosthetic Valves Dr. Tehrani
2Different Types of Valves Homografts (allograft)Cadaveric human aortic and pulmonary valvesHeterograft (Xenograft)Prosthetic ValvesBioprosthetic valvesPig aortic valveBovine pericardial (other)MechanicalUrethane ball in a cageSingle or multiple discs
4Homografts Homograft Valves Harvested soon after death w/ the endothelium still viablePreparation for implantationStorage in ABXCryopreservation (more recently)No anticoagulationLow incidence of endocarditisFailure due to gradual aortic incompetence
5Homografts Position Mitral Fitted w/ stent, not proved successful (high failure rate at 5 years)Stentless grafts not an option for MVRAorticStentlessSubcoronaryRoot ReplacementWhat should I say about Tricuspid and pulmonic positions???
6Echocardiography of Stentless Aortic Homografts Fig weyman, and 10-ADoppler flow characteristics similar to native valve.Only 2-D evidence: Increased Echo intensity, and Thickness of aortic annulus.
8Stentless Heterografts (Xenograft) Same utility as allografts for AVR:Subcoronary implantation, andRoot replacementAdvantage over allografts is wider availabilityDurability is at least as good as allograftsInsert Pic from Doty’s Lecture
10Bio-Prosthetic and Mechanical Prosthetic Prosthetic ValvesBio-Prosthetic and Mechanical ProstheticAll Prosthetic valves have a sewing ringanchored to the native tissue with suturesThe occluding portion of the valve:Tissue leaflets Bio-ProstheticSingle or multiple discs/ Urethane ball in a cage Mechanical Prosthetic
12Carpentier-Edwards bioprosthesis Bioprosthetic ValvesTwo types, of occluding mechanismPorcine aortic valve (the valve size of the biggest pig is limiting)Hancock, andCarpentier-Edwards bioprosthesisCarpentier-Edwards bioprosthesis
13Bioprosthetic valves Bovine Pericadium leaflets are shaped to size. More choicesEchocardiographiaclly these two valves types are indistinguishable.Fig. 38-2, and 3, Actual picturesIonescu-Shiley(1976)
14Bioprosthetic valves Mitral Position 38-25A, 38-32, two diff views of mitral bioprosthetic2-D ECHOCARDIOGRAPHIC APPEARANCE
15Bioprosthetic valves Aortic Position 38-34, 38-27, aortic bioprosthetic2-D ECHOCARDIOGRAPHIC APPEARANCE
16Bioprosthesis Used extensively in a variety of sites: Aortic Mitral TricuspidAdvantage:Low thrombogenicity => No anticoagulation
17Bioprosthesis Disadvantages: Less durable than mechanical prosthesis Mitral position worseDue to greater backpressure gradientDysfunction:Leaflet thickening, and Ca++Fracture, tears, or progressive stenosisIn vivo, roughly 10% of normal bioprosthetic valves have some leakage.
18Overview of Various Devices Bio-Prosthetic ValvesMechanical Prosthetic Valves
19Mechanical Vlaves Ball-and-Cage Valves Tilting disc Prosthesis Single diskBileaflet
20Mechanical Prosthesis The occluding mechanism dictates both:The echocardiographic appearance of the valve, andThe flow pattern through the valveTo assess performance, the type of valve implanted must be known
21Ball-and-Cage Valves First implanted by starr and Harken in 1960. Figure 38-4
22Opening and closure of the ball-valve Ball-and-Cage ValvesFigOpening and closure of the ball-valve
23Ball-and-Cage Valves Axisymmetric flow around the valve. Stagnant flow in the shadow of the ball.Figures 38-5,
24Ball-and-Cage Valves Doppler assessment at the margins of the ball Fig. 38-6Doppler assessment at the margins of the ball
25M-Mode assessment of Ball-Cage Valve Ball-and-Cage Valves38-29, m-modeM-Mode assessment of Ball-Cage Valve
26Ball-and-Cage Valves Durable Mitral position Satisfactory profile with the largest size (34 or 32 mm diameter devices)Can affect the interventricular septumAortic positionSmall prosthesis required, which can be associated with significant gradientRegurgitation limited to closure backflow.
27Tilting Disc Prosthesis All essentially similar consisting ofCircular prosthetic material, andOne or two hinged and mobile disc(s)Disc attachment to the ring is eccentricClosure occurs by backpressure on the largest portion of the disk
28Single Disc Prosthesis Single Disc devices:Hall-Medtronics monostrutBjork-ShileyOpening arch is degreesFlow orifice:Major and minor flow orificesStreamlines of flow passing through the sewing ring and then laterally out and around the prosthetic disc38-7-c, 38-8-a, comment that it is identical of BS-standard
29Single Disc Prosthesis Bjork-ShileyStandardConvex-concaveMany other variations in the marketAll of these devices have a zone of stagnation behind the disc thrombus formation38-7-a, and 38-8-b
30Single Disc Prosthesis Bjork-Shiley in the Mitral position38-25-b, echo of BS tilting disc
31Single Disc Prosthesis Leak around:Central strutDominant jetBetween the occluding disc and sewing ring.Two smaller peripheral jetsNormal hemodynamicsReg.Frac. approx. 12%Tachycardia, and low outputReg.Frac. upto 37%Figure a and b
34Single Disc Prosthesis DysfunctionGradual ingrowth of fibrous tissue (panus)Flow obstructionIntermittent sticking of the valve with associated flash pulmonary edema
35Bileaflet Mechanical Prosthesis St. Jude prosthesisThe most commonly used.Two equal sized semi-circular leaflets attached by a midline hinge.Discs can tilt in excess of 80 degrees, resulting in larger:Orifice areaFigure 38-11
36Bileaflet Mechanical Prosthesis St. Jude prosthesisThe most commonly used.Two equal sized semi-circular leaflets attached by a midline hinge.Discs can tilt in excess of 80 degrees, resulting in larger:Orifice area38-11Regurgitant back flow
37Bileaflet Mechanical Prosthesis Fig (a&b)Regurgitation occurs at the disc marginsThe regurgitant jets converge toward the center of the valve
38Bileaflet Mechanical Prosthesis 38-25-c, 38-33, echo of st.judesSt. Jude valve in the mitral position.
40Special Problems of 2-D Imaging Artificial Valves Echocardiographs are calibrated to measure distance based on the speed of sound in tissue.Prosthetic valves have different acoustic properties than tissue. Hence, distortion of:SizeLocation, andAppearance, of the prosthesis.Insert this and the following slides in the section for bioprosthetic valves, right before x? the dopplar features
41Special problems of artificial valves Intense reverberation, andShadowingLess gain leads to less:Reverberation, andShadowing, as well asBetter visualization of non-biologic components of the valveHOWEVER Decreased definition of cardiac structures
42Special problems of artificial valves First image at normal settings, thenReduce the gain to interrogate the leaflets of Bio-prosthetic valves.Utilize multiple views.
44G E N E R A L L Y Prosthetic Stenosis (and Regurgitation) is: A question of degree,Not a question of whether.
45Prosthetic Valve Stenosis Determinants of gradients across normal prosthetic valves include:Valve type, i.e., ManufacturerValve sizeFlow through the valveWide range of “Normals”
46Aortic Prosthesis Gradients as a Function of Valve TYPE and SIZE Dependence on:Valve type, andSizeNo.21FigNo.27
47Gradient as a Function of Valve Type Pg 508, Table 1Normal Dopplar data in patients with various types of prosthetic valves in the Aortic Position
48Gradient as a Function of Valve Size Pg 508, Table 2Valve specifications and doppler echocardiographic data in 67 St. Jude medical valves in the Aortic positionChafizadeh ER, Circ. 83:213, 1991
49Gradient as a Function of Flow Valve type, i.e.,ManufacturerValve sizeNo.21Flow through the valve
50Indicies of Valve Stenosis which are Less Flow Depenent Contour of jet velocityDoppler velocity indexEffective orifice areaValve resistance
51A-Contour of the jet velocity With prosthetic obstruction there is:Late peaking of the velocity,More rounded contour,Prolonged ejection.Pg 508, fig. 1
52B-Doppler Velocity Index DVI= Pk VelLVOT/Pk VeljetFlow independent0.2 – 0.27 cutoff for critical stenosisCaveat: Pressure recoveryTo be discussed …
53C-Effective Orifice Area Continuity Eqn.Caveat: Pressure recoveryTo be discussed …
54D-Valve resistanceAt cutoff of 280 dynes.sec.cm5, best at differentiating AS, from NL (Zoghbi et al.)
55Special Caveats Re: Overestimation of Gradients Two scenarios:The velocity upstream from the valve is not negligible in application of the Bernoulli Eqn.Usually in AV when proximal velocity on the LVOT is > 1.5 m/s
56…Overestimation of Gradients Central acceleration with the St. Jude valve:Increase of velocities (and gradients) is created at the level of the valve through the smaller central orifice.Most significant with:High flow statesSmall valvesThe only other valve where this is holds true is the Ball-Cage valve
57…Overestimation of Gradients Central acceleration with the St. Jude valve:CW Doppler records these high velocities.Catheter-derived gradients show pressure recovery at 30mm downstream from the valve.
58Indicies which are Less Flow Dependent, BUT… Contour of jet velocityDoppler velocity indexEffective orifice areaValve resistanceClearly, both ofThese ParametersWill be Affected byThe PressureRecoveryPhenomenon.
60MismatchRahimtoola 1978:“Mismatch is present when the effective prosthetic valve area, after insertion into the patient, is less than that of a normal human valve.”By definition:Some such “mismatch” will almost always be present.
61MismatchLiterature identifies the above as a cut-off for mismatch
62Mismatch This is the EOA that The patient physiologically Needs. Next locate the publishedin-vivo EOA of the valveused.
63MismatchNot the company reported dataJACC Review Article, 10/2000
65Mitral Prosthesis Stenosis Parameters used for assessment of function:PHT/Area by PHTEffective Orifice Area by continuityMean gradient
66Mitral Prosthesis Stenosis A-PHT/Area by PHTNot expected to yield accurate valve areaThe empiric constant of 220 validated for the geometry of rheumatic MSUseful in longitudinal follow-up of valve FxShould not be used when diastolic filling period is short (fusion of E and A)TachycardiaLong first degree block
67Mitral Prosthesis Stenosis B-Effective Orifice Area by continuity Eqn.One underlying assumption is absence of significant AI or MRPhysiologic prosthetic MR 10-30% (Medtronic-Hall, significant central MR, specific design feature less thrombogenic)
68Mitral Prosthesis Stenosis C-Mean gradient, function of:SizeType of prostheticFlowPg.512, Table 3 Croocked, sraighten it outHeart rate(should also bereported whenevaluating MVA)
70Prosthetic Valve Regurgitatoin Two issues:Physiologic v.s. Pathologic regurgitationTTE v.s. TEE for assessment of regurgitation
71Prosthetic Valve Regurgitation Physiologic RegurgitationEarly onset and brief durationReflects backflow from closing movement of occluding deviceTilting disc and bileaflet valves have additional late backflow leakageIntended to reduce risk of thrombosis
72Aortic Prosthesis Regurgitation Criteria similar to grading native valve AI:Jet widthPHT < 350Holodiastolic flow reversalRegurgitant fraction>40%
73Mitral Prosthesis Regurgitation TTE of limited value in assess MR due to acoustic shadowing of the LADoppler findings suggestive of severe MRE wave > 1.9 m.sPISAShort isovolumetic relaxation timeTVILVOT/TVIPr-MV < 0.4