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Non-Invasive Assessment of Prosthetic Valves

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Presentation on theme: "Non-Invasive Assessment of Prosthetic Valves"— Presentation transcript:

1 Non-Invasive Assessment of Prosthetic Valves
November 21, 2007 Alex Morss

2 Terms and definitions Prosthetic valves: manmade replacements of heart valves, either mechanical (nonorganic) or bioprosthetic (organic materials used in construction, i.e. animal or human parts) Assessment: visual evaluation Non-invasive: taking pictures of hidden things without using sharp objects (i.e., essentially nonviolent means of seeing them undressed)

3 Main Characters (Protagonists)
Mechanical Valves Ball-cage Tilting disc Bileaflet Bioprosthetic Valves Stented Unstented (aortic root) Homograft, allograft

4 The Antagonists Endocarditis +/- vegetations
Paravalvular leak (+/- dehiscence) Thrombosis Pannus formation Degeneration, +/- calcific stenosis or leaflet tear Strut fracture, disc embolization Unseating of valve

5 The Arsenal Roentgenography (X-Ray) Fluoroscopy Cardiac MRI (?)
Echocardiography TTE will often best allow optimal Doppler angles TEE will often best allow optimal direct visualization Intangibles

6 The Main Characters Mechanical Valves
Ball-cage (Starr-Edwards) Tilted-disc (Bjork-Shiley, Medtronic-Hall) * Note: the convexoconcave version of the Bjork-Shiley valve earned a bad name due to cases of strut fracture and disc embolization Bileaflet (St. Jude, Carbomedics) All valves are sized by diameter, mm O’Neill NEJM 1995

7 Main Characters, Part Deux
Bioprosthetic Valves Stented: Carpentier-Edwards, Hancock, Ionescu-Shiley, St. Jude Mosaic Stentless: Biocor. Homografts/autografts: may not be able to detect noninvasively Also sized by diameter, mm Hancock Mosaic Stentless porcine

8 Unveiling the arsenal Old School: Roentgenography
Mechanical and many stented bioprosthetic valves are radiopaque, allowing determination of valve type and position on chest X-ray. May be used to assess for device fracture in some cases Starr-Edwards valve seen in aortic position in From Nery, Heart 2004

9 Up a Notch: Fluoroscopy
Best methodology to assess mechanical leaflet motion due to outstanding spatial and temporal resolution. May be used to assess stability of valve ring with the cardiac cycle May optimally position angle to best assess subtle fracture O’Neill NEJM 1995

10 Disc embolization disc O’Neill NEJM 1995

11 Cardiac MRI Cardiac MRI may visualize mechanical valves, but lacks the temporal resolution and Doppler capablities of echocardiography May show gross valve position, function, and regurgitation

12 More cardiac MRI


14 Echocardiography Transthoracic Transesophageal
Allows assessment of valve area and regurgitation via Doppler, which is generally adequate to exclude significant obstructive or regurgitant change. Flow velocity is the crucial measurement. Inadequate to assess infection or small structural changes (e.g. strut fracture, small vegetation, paravalvular leak) Transesophageal Ideal for visual inspection of valve apparatus and seating; may not accurately quantify valve flow velocities. May directly measure aortic valve area via planimetry

15 Echo by valve position Aortic Mitral Tricuspid Pulmonic
Accurate TTE assessment relies on accurate Doppler assessments in multiple views Often many TTE views partially obscured by shadowing. Often TEE required to view leaflets Mitral Among the best positions for TTE visualization, usually able to see leaflets via apical views Tricuspid Also usually adequately visualized by TTE directly and via Doppler Pulmonic Rarest position for valve replacement. Difficult to visualize for both TTE and TEE, no clear advantage

16 Aortic Prostheses Focus on Doppler imaging of aortic outflows to determine mean and peak gradients Can identify prosthesis type by direct visualization As with all prostheses, need to know their SIZE to allow assessment of normal vs. pathologically increased transvalvular gradient. Size varies from mm in diameter Normal gradients for each valve type and size may be found on reference tables

17 Normal aortic bileaflet valve




21 Peak gradient 20mmHg, mean 12 mmHg
Normal bileaflet gradients are dependent on valve size

22 Normal mechanical aortic valve peak gradients
Bileaflet 19mm: 33 +/- 11 29mm: 13 +/- 5 Tilting disc 19mm: 46 29mm: 12+/- 8 Ball-cage 23mm: 33+/-13 29mm: 29+/-9 Approximate flow velocities: 19mm m/sec 29 mm m/sec (+/- 0.5 m/sec) Feigenbaum 2005 Full tables are available in echo texts or on fellowship echo website

23 Normal aortic bioprosthetic valve



26 Peak gradient 17mm- need valve size and ideally baseline gradient at time of valve implantation to assess for normal value May also use continuity equation with measurement of LVOT to calculate effective aortic valve area

27 Tilting disc AVR





32 Ball-cage AVR




36 Name the AVR type



39 Aortic bioprosthetic valve with paravalvular leak, valvular regurgitation

40 What’s wrong?






46 Tilting disc valve with thrombosis causing partial obstruction
Talley, Can J Card 1986

47 Mitral prosthetic valves
Better visualization on TTE Much lower normal gradients than aortic valves due to lower flow velocities and larger size overall Sizes generally vary from 25-33mm in diameter

48 Normal bioprosthetic MVR



51 Peak mitral velocity of 1
Peak mitral velocity of 1.30 m/sec, peak gradient 8 mmHg, mean 5mmHg (normal ~ 5 depending on valve size)

52 Bileaflet MVR



55 Appropriate regurgitation shown- 2 jets in bileaflet valve
By design in mechanical valves to minimize thrombosis risk


57 Ball-cage MVR



60 Cage-ball valves have the highest nomal valve gradients due to design



63 Mean gradient 9 mmHg Standard mean gradient for ball-cage MVR is 5-7 +/- 3, depending on size

64 Mitral endocarditis Kort, JASE 2006 (from Gelfand)

65 Mitral unpleasantries, part II





70 A league of its own





75 Summary Valve type and position often easily determined on CXR
Fluoroscopy optimal for assessing mechanical valve leaflet motion, unable to see bioprosthetic leaflets TTE may identify flow velocities and gross structure, best suited for MVR and exclusion of obstruction due to good Doppler views. Doppler velocities and valve gradients are likely better than calculation of valve area due fewer variables TEE allows better visualization of smaller structural changes, vegetations, and paravalvular leaks. It is the study of choice for concerns of endocarditis in any prosthetic valve. CMR limited role and not generally used to assess prosthetic valves.

76 Thank you!

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