Prosthetic Valves Flashcards
What is most well known caged ball mechanical valve?
Starr-Edwards high profile ( tall cage), it has a turbulent high velocity peripheral circumferential jet. No flow thru the center of the prosthesis due to location of the ball
Mechanical Caged disc?
low profile (short cage), flow had to change direction around the occluder, increased pressure gradient, cell damage,
Mechanical tilting disc?
Bjork-Shiley, pivoting disc (toilet seat), creates a major and a minor orifice
Mechanical Bi-Leaflet
St. Jude, 2 tilting discs, creates 3 orifices and least stenotic of all the mechanical prosthetic valves.
Bioprosthetic Valves
All made to resemble AOV, used in AOV or MV position. All have 3 cusps
Heterograft (xenograft)
Animal to human valve, pig = porcine AOV = Carpentier-Edwards or the cow = Bovine pericardium to fashion the valve
Homograft (allograft)
person to person, preserved human tissue from a cadaver, usually AOV. stented or stenless, used for AOV or PV replacements, rarely used for MV or TV replacements
What is TAVI or TAVR
Transcatheter Aortic Valve Implant/Replacement, cath delivered biologic tissue valve mounted in stent
What are 2 approaches for TAVI?
Transfemoral or trans-apical
Echo in TAVI
evaluate AS preprocedure - AI = careful eval of LVOT and annulus msmts. Device migration or significant paravalvular leak from under-sizing device. And problems crossing AOV from oversizing device
Valved conduits
Used for congenital repairs, homograft or goretex or dacron material, may have mechanical or bioprosthetic valve
Carpentier Ring
Used for TV/MV repair, serves as annulus to support valve leaflets
Selection of a Tissue valve for?
Elderly where long-term durability is less important, patients where chronic anticoagulation is not advised or those at an increased risk for thromboembolism
Selection of a Mechanical Valve for?
Children and young adults except women in their child bearing years, patients with renal failure, small valve annulus, high reoperative risk, A-FIB, and patients requiring AOR replacement - such as AO dissection with severe AI
What might be an advantage of a bioprosthetic over a mechanical valve?
Can be stentless, central flow dynamics and may avoid anticoagulation
Normal prosthetic valves have higher flow velocities than native valves
True
All prosthetic valves are inherently stenotic compared to a normal native valve
True
P 1/2 time is going to overestimate or underestimate the MVA of a mechanical valve
Overestimate the MVA of a mechanical valve
Is P 1/2 time ok for bioprosthetic valve area calcs?
Yes
What to check for when doing an echo
Type of valve, dehiscence, gradients, areas and regurg lesions, normal versus peravalvular leaks, LV fx, leaflet motion, occluder/poppet motion, vegs, thrombus, pannus ingrowth of tissue, calcific changes and abscesses
What are some pitfalls & tech difficulties of mech valves?
Reverberations, acoustic shadowing, flow masking, flow characteristics vary with type of valve = be aware of overestimation potential. Struts will cause pressure recovery interruption and throw off calcs. cause tapered shape.
Mechanical Valve dysfunction?
With the valve itself, ball variance, thrombus formation, pannus ingrowth or endocarditis, tissue around the valve
Tissue valve dysfunction?
Tissue degeneration, problem with prosthetic valve,
problem with tissue around the valve, can be caused by endocarditis or abscess, loose/torn sutures or calcific changes in the native annulus
What is Ball Variance?
Changes in the disc or ball due to abrasion and deposits of blood lipids. Results in changes in size or contour of the ball or disc.
