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

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)

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

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

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

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, 19-33 mm O’Neill NEJM 1995

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, 19-33 mm Hancock Mosaic Stentless porcine

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 1965. From Nery, Heart 2004

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

Disc embolization disc O’Neill NEJM 1995

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

More cardiac MRI

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

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

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 19-29 mm in diameter Normal gradients for each valve type and size may be found on reference tables

Normal aortic bileaflet valve

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

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 2.9 m/sec 29 mm 1.9 m/sec (+/- 0.5 m/sec) Feigenbaum 2005 Full tables are available in echo texts or on fellowship echo website

Normal aortic bioprosthetic valve

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

Tilting disc AVR

Ball-cage AVR

Name the AVR type

Aortic bioprosthetic valve with paravalvular leak, valvular regurgitation

What’s wrong?

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

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

Normal bioprosthetic MVR

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)

Bileaflet MVR

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

Ball-cage MVR

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

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

Mitral endocarditis Kort, JASE 2006 (from Gelfand)

Mitral unpleasantries, part II

A league of its own

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.

Thank you!