Caged Disk (low profile) – used in the 1970’s. Similar to caged ball valves but disk enclosed in cage and attached to fabric covered sewing ring. Blood flow would go around disk so it produced high velocities and therefore high pressures. Blood turbulence and cell damage were problems. Not currently used.
Example: Beal-Surgitool, Kay-Suzuki
Tilting Disk or the “toilet seat” valve – a single disk that creates a large opening and a small opening. Also low profile. High pressure gradients, high thromboembolic complications. Used in 1970’s and 80’s.
Examples:
–Medtronic Hall Omnicarbon, Monostrut, and Bjork-Shiley (discontinued)
Bileaflet Tilting Disk – Two tilting disks create three orifices and promote central flow through valve. That is the key in recognizing it by echo. Least stenotic. Low profile.
Examples:
–St. Jude – most common in US
–CarboMedics
–ATS Open Pivot
–Conform-X
8 Complications of Mechanical Prosthetic Valves
1. They are more stenotic than tissue valves.
2. Risk of “pannus” or fibrous ingrowth of tissue that may lead to stenosis or regurgitation.
3.Perivalvular leaks – all mechanical valves leak a little.
4. Dehiscence can cause perivalvular leaks
5. Ring abscess
6. Infective endocarditis
7. Mechanical failure
8. Hemolysis – damage red blood cells as they pass through valve.
Advantage: They last a long time!
Mechanical valves in the mitral position have an M-mode that resembles what other valve's m-mode?
Mechanical valves in the mitral position have an M-mode that resembles a box, just like the native aortic valve.
True or False
Bioprosthetic MV spectral Doppler tracings are similar to native valve. Flow is fairly laminar with a small amount of regurgitation.
True
What valve is possible to confuse with calcification?
the Carpentier ring
A flexible ring that is sewn into the annulus to decrease the amount of opening and thus regurgitation. It is considered a repair instead of replacement.
The Carpentier ring
equation used to estimate the area of a mechanical prosthesis
MVA continuity equation
MVA=.785 (LVOT diameter squared)(LVOT VTI) MV VTI
bioprosthetic MVA using what equation
P 1/2T
MVA= 220 P1/2T
What gradient is important to look at on mitral valve?
the mean gradient
Mitral valve should be replaced when vlalve area is ___ cm squared or less and/or MR of such severity it leads to ____ failure or the patient is _____.
1.0 cm
LV failure
Symptomatic
Aortic valve should be replaced if it is:
*___ cm squared or less
*has a mean gradient of ___ mmHg
*progressive LVH
*LVESd of ___mm or 5.5 cm
*.5cm squared or less
*50 mmHg
*LVESd of 55mm or 5.5cm
All prosthetic valves are to some degree ____.
stenotic
have higher then normal velocities
2 types of valves that can be implanted:
Synthetic or mechanical valves
Bioprosthetic or tissue valves
which valve does the patient have to be on a blood thinner for the rest of their life?
Synthetic or mechanical valves
Which valve would last the longest?
mechanical or tissue
Mechanical
Which of these two types would be more stenotic?
Mechanical
How does the physician decide which valve to use?
*Patient age
*Medical history
The older the patient, the more likely they will be to have a ______ valve.
bioprosthetic or synthetic?
bioprosthetic/tissue valve
M-mode for a MV prosthetic valve:
Types of Bioprosthetic valves
1. Autograft
2. Homograft
3. Allograft
4. Heterograft or Xenograft
graft of tissue from one site to another-same individual. Self to self. No problems with rejection.
Examples:
–Ross procedure, CABG, skin grafts, fascia lata (thigh muscle covering is prepared and used as a heart valve)
Autograft
graft from one individual to another of same species. Genetic makeup must be the same.
Example:
–Identical twins – harvested from deceased, kidneys are harvested from family members.
–Dura mater (from brain covering) can be prepared and used as heart valve.
Homograft
The transplant of an organ or tissue from one individual to another of the same species with a different genotype. A transplant from one person to another, as in heart transplant.
Allograft
graft from one individual to another of different species.
Examples:
–Porcine (pig) valve to aortic
–Bovine (cow) pericardium mounted on stents and sewing ring
–Common brands include: Carpentier-Edwards, Medtronic, Hancock, Ionescu-Shily (discontinued), Edwards Prima Plus, Toronto SPV
Advantages: laminar flow, resembling native valve, lower incidence of thromboembolism.
Disadvantages: last 10-12 years
Heterograft or Xenograft
complications of bioprosthetic valves
Calcification and degeneration with age.
Thrombus
Infective endocarditis
Perivalvular leaks – regurgitation around the sewing ring.
Dehiscence – sutures becoming loose or break causing rocking and perivalvular leaks
