RHD is prevalent in India, many patients requires valve replacement. understanding of prosthetic valve anatomy, morphology and early detection of valve related complication is very important for saving life. TTE and TEE are important tool for identifying these complications.
2. Introduction
The introduction of valve replacement surgery in the early 1960s has
dramatically improved the outcome of patients with valvular heart disease.
Despite the improvements in prosthetic valve design and surgical
procedures , valve replacement does not provide a definitive cure. Instead,
native valve disease is traded for “prosthetic valve disease”.
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3. Types of prosthetic valves
Prosthetic Valves are classified as tissue or mechanical
Tissue:
Made of biologic tissue from an animal (bioprosthesis or heterograft) or human
(homograft or autograft) source
Mechanical
Made of non biologic material (pyrolitic carbon, polymeric silicone substances,
or titanium)
Blood flow characteristics, hemodynamics, durability, and thromboembolic
tendency vary depending on the type and size of the prosthesis and
characteristics of the patient
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9. Mechanical Valves
Extremely durable with overall survival rates of 94% at 10 years
Primary structural abnormalities are rare
Most malfunctions are secondary to perivalvular leak and thrombosis
Chronic anticoagulation required in all
With adequate anticoagulation, rate of thrombosis is 0.6% to 1.8% per
patient-year for bileaflet valves.
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10. Biological Valves
Stented bioprostheses
Primary mechanical failure at 10 years is 15-20%
Preferred in patients over age 70
Subject to progressive calcific degeneration & failure after 6-8 years
Stentless bioprostheses
Absence of stent & sewing cuff allow implantation of larger valve for given
annular size->greater EOA
Uses the patient’s own aortic root as the stent, absorbing the stress induced
during the cardiac cycle
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11. Biologic Valves Continued
Homografts
Harvested from cadaveric human hearts
Advantages: resistance to infection, lack of need for anticoagulation, excellent
hemodynamic profile (in smaller aortic root sizes)
More difficult surgical procedure limits its use
Autograft
Ross Procedure
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13. Approach to prosthetic valve function
assessment
CLINICAL INFORMATION &CLINICAL EXAMINATION
IMAGING OF THE VALVES
CXR
2D echocardiography
TEE
3D echo
CineFluoro
CT
Cardiac catheterisation
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17. CXR
chest x-ray are not performed on a routine basis in the absence of a specific
indication.
It can be helpful in identification of valve type if information about valve is not
available.
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19. Echo evaluation
primary goals of 2D echo-
Valves should be imaged from multiple views, with attention to
determine the specific type of prosthesis
confirm the opening and closing motion of the occluding mechanism,
confirm stability of the sewing ring(abnormal rocking motion
Presence of leaflet calcification or abnormal echo density attached to the sewing ring,
occluder, leaflets, stents, or cage such as vegetations and thrombi.
Calculate valve gradient
Calculate effective orifice area
Confirm normal blood flow patterns
Detection of pathologic transvalvular and paravalvular regurgitation
Estimate PASP and chamber function
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20. St. Jude mitral prosthesis is demonstrated. A: During
systole, the hemidisks are shown in the closed position
(arrows). B: During diastole, the two disks are recorded
in the open position (arrows).
Starr-Edwards mitral prosthesis is shown. A: During
systole, the poppet is seated within the sewing ring
(arrows). B: During diastole, the poppet moves forward
into the cage (arrows), allowing blood flow around the
occluder.
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22. Assessment of Flow Characteristics
of Prosthetic Valves
Valve type Flow Characteristics
Ball-in-cage prosthetic valve (Starr-Edwards,
Edwards Lifescience)
much obstruction and little leakage.
Tilting disc prosthetic valve (Björk-Shiley;
Omniscience; Medtronic Hall)
less obstruction and more leakage.
Bileaflet prosthetic valves (St. Jude
Medical; Sorin Bicarbon; Carbomedics)
Less obstruction and more leakage.
Bioprostheses. little or no leakage
Homografts, pulmonary autografts, and
unstented bioprosthetic valves (Medtronic
Freestyle,
Toronto, Ontario, Canada)
almost unobstructive to blood flow.
Stented bioprostheses (leaflets suspended
within a frame)
obstructive to flow.
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40. Distinction between thrombus and
pannus
Thrombus Large,
mobile,
less echo-dense,
associated with spontaneous contrast,
INR<2.5
Pannus Small
firmly fixed (minimal mobility) to the valve apparatus
highly echogenic, (fibrous composition)
common in aortic position
Para valve jet suggests pannus
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43. Prosthetic valve regurgitation
Most mechanical valves and many biologic valves are associated with trivial
or mild transprosthetic regurgitation (physiologic regurgitation)
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44. Pathologic Prosthetic Regurgitation
Pathologic regurgitation is either
central
paravalvular.
Most pathologic central valvular regurgitation is seen with biologic valves,
whereas paravalvular regurgita-tion is seen with either valve type and is
frequently the site of regurgitation in mechanical valves.
Pathologic jets tend to be high velocity,
intense, broad, and highly aliased.
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50. TEE in prosthetic valve
TEE evaluation immediately after valve replacement
1. Verify that all leaflets or occluders move normally.
2. Verify the absence of paravalvular regurgitation.
3. Verify that there is no left ventricular outflow tract obstruction by
struts or subvalvular apparatus.
TEE diagnosis of prosthetic valve dysfunction
1. Identification of prosthetic valve type.
2. Detection and quantification of transvalvular or paravalvular
regurgitation.
3. Detection of annular dehiscence.
4. Detection of vegetations consistent with endocarditis.
5. Detection of thrombosis or pannus formation on the valve.
6. Detection and quantification of valve stenosis.
7. Detection of tissue degeneration or calcification.
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51. Cinefluoroscopy
Structural integrity
Motion of the disc or poppet
Excessive tilt ("rocking") of the base ring - partial dehiscence of the valve
Aortic valve prosthesis - RAO caudal
- LAO cranial
Mitral valve prosthesis - RAO cranial .
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52. Fluoroscopy of a normally functioning CarboMedics
bileaflet prosthesis in mitral position
A=opening angle B=closing angle
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53. St. Jude medical bileaflet valve
Mildly radiopaque leaflets are best
seen when viewed on end
Seen as radiopaque lines when
the leaflets are fully open
Base ring is not visualized on most
models
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Starr-Edwards mitral prosthesis is shown. A: During systole, the poppet is seated within the sewing ring (arrows). B: During diastole, the poppet moves forward into the cage (arrows), allowing blood flow around the occluder.