1. Echocardiography of Prosthetic Valves
Dr. Tehrani

2. Different Types of Valves
Homografts (allograft)
Cadaveric human aortic and pulmonary valves
Heterograft (Xenograft)
Prosthetic Valves
Bioprosthetic valves
Pig aortic valve
Bovine pericardial (other)
Mechanical
Urethane ball in a cage
Single or multiple discs

3. Homografts (allograft)

4. Homografts Homograft Valves
Harvested soon after death w/ the endothelium still viable
Preparation for implantation
Storage in ABX
Cryopreservation (more recently)
No anticoagulation
Low incidence of endocarditis
Failure due to gradual aortic incompetence

5. Homografts Position Mitral
Fitted w/ stent, not proved successful (high failure rate at 5 years)
Stentless grafts not an option for MVR
Aortic
Stentless
Subcoronary
Root Replacement
What should I say about Tricuspid and pulmonic positions???

6. Echocardiography of Stentless Aortic Homografts
Fig weyman, and 10-A
Doppler flow characteristics similar to native valve.
Only 2-D evidence: Increased Echo intensity, and Thickness of aortic annulus.

7. Stentless Heterografts (Xenograft)

8. Stentless Heterografts (Xenograft)
Same utility as allografts for AVR:
Subcoronary implantation, and
Root replacement
Advantage over allografts is wider availability
Durability is at least as good as allografts
Insert Pic from Doty’s Lecture

9. Prosthetic Valves

10. Bio-Prosthetic and Mechanical Prosthetic
Prosthetic Valves
Bio-Prosthetic and Mechanical Prosthetic
All Prosthetic valves have a sewing ring
anchored to the native tissue with sutures
The occluding portion of the valve:
Tissue leaflets  Bio-Prosthetic
Single or multiple discs/ Urethane ball in a cage  Mechanical Prosthetic

11. Bio-prosthetic Valves

12. Carpentier-Edwards bioprosthesis
Bioprosthetic Valves
Two types, of occluding mechanism
Porcine aortic valve (the valve size of the biggest pig is limiting)
Hancock, and
Carpentier-Edwards bioprosthesis
Carpentier-Edwards bioprosthesis

13. Bioprosthetic valves Bovine Pericadium leaflets are shaped to size.
More choices
Echocardiographiaclly these two valves types are indistinguishable.
Fig. 38-2, and 3, Actual pictures
Ionescu-Shiley
(1976)

14. Bioprosthetic valves Mitral Position
38-25A, 38-32, two diff views of mitral bioprosthetic
2-D ECHOCARDIOGRAPHIC APPEARANCE

15. Bioprosthetic valves Aortic Position
38-34, 38-27, aortic bioprosthetic
2-D ECHOCARDIOGRAPHIC APPEARANCE

16. Bioprosthesis Used extensively in a variety of sites: Aortic Mitral
Tricuspid
Advantage:
Low thrombogenicity => No anticoagulation

17. Bioprosthesis Disadvantages: Less durable than mechanical prosthesis
Mitral position worse
Due to greater backpressure gradient
Dysfunction:
Leaflet thickening, and Ca++
Fracture, tears, or progressive stenosis
In vivo, roughly 10% of normal bioprosthetic valves have some leakage.

18. Overview of Various Devices
Bio-Prosthetic Valves
Mechanical Prosthetic Valves

19. Mechanical Vlaves Ball-and-Cage Valves Tilting disc Prosthesis
Single disk
Bileaflet

20. Mechanical Prosthesis
The occluding mechanism dictates both:
The echocardiographic appearance of the valve, and
The flow pattern through the valve
To assess performance, the type of valve implanted must be known

21. Ball-and-Cage Valves First implanted by starr and Harken in 1960.
Figure 38-4

22. Opening and closure of the ball-valve
Ball-and-Cage Valves
Fig
Opening and closure of the ball-valve

23. Ball-and-Cage Valves Axisymmetric flow around the valve.
Stagnant flow in the shadow of the ball.
Figures 38-5,

24. Ball-and-Cage Valves Doppler assessment at the margins of the ball
Fig. 38-6
Doppler assessment at the margins of the ball

25. M-Mode assessment of Ball-Cage Valve
Ball-and-Cage Valves
38-29, m-mode
M-Mode assessment of Ball-Cage Valve

26. Ball-and-Cage Valves Durable Mitral position
Satisfactory profile with the largest size (34 or 32 mm diameter devices)
Can affect the interventricular septum
Aortic position
Small prosthesis required, which can be associated with significant gradient
Regurgitation limited to closure backflow.

27. Tilting Disc Prosthesis
All essentially similar consisting of
Circular prosthetic material, and
One or two hinged and mobile disc(s)
Disc attachment to the ring is eccentric
Closure occurs by backpressure on the largest portion of the disk

28. Single Disc Prosthesis
Single Disc devices:
Hall-Medtronics monostrut
Bjork-Shiley
Opening arch is degrees
Flow orifice:
Major and minor flow orifices
Streamlines of flow passing through the sewing ring and then laterally out and around the prosthetic disc
38-7-c, 38-8-a, comment that it is identical of BS-standard

29. Single Disc Prosthesis
Bjork-Shiley
Standard
Convex-concave
Many other variations in the market
All of these devices have a zone of stagnation behind the disc  thrombus formation
38-7-a, and 38-8-b

30. Single Disc Prosthesis
Bjork-Shiley in the Mitral position
38-25-b, echo of BS tilting disc

31. Single Disc Prosthesis
Leak around:
Central strut
Dominant jet
Between the occluding disc and sewing ring.
Two smaller peripheral jets
Normal hemodynamics
Reg.Frac. approx. 12%
Tachycardia, and low output
Reg.Frac. upto 37%
Figure a and b

32. Single Disc Prosthesis

34. Single Disc Prosthesis
Dysfunction
Gradual ingrowth of fibrous tissue (panus)
Flow obstruction
Intermittent sticking of the valve with associated flash pulmonary edema

35. Bileaflet Mechanical Prosthesis
St. Jude prosthesis
The most commonly used.
Two equal sized semi-circular leaflets attached by a midline hinge.
Discs can tilt in excess of 80 degrees, resulting in larger:
Orifice area
Figure 38-11

36. Bileaflet Mechanical Prosthesis
St. Jude prosthesis
The most commonly used.
Two equal sized semi-circular leaflets attached by a midline hinge.
Discs can tilt in excess of 80 degrees, resulting in larger:
Orifice area
38-11
Regurgitant back flow

37. Bileaflet Mechanical Prosthesis
Fig (a&b)
Regurgitation occurs at the disc margins
The regurgitant jets converge toward the center of the valve

38. Bileaflet Mechanical Prosthesis
38-25-c, 38-33, echo of st.judes
St. Jude valve in the mitral position.

39. Imaging of Prosthetic Valves

40. Special Problems of 2-D Imaging Artificial Valves
Echocardiographs are calibrated to measure distance based on the speed of sound in tissue.
Prosthetic valves have different acoustic properties than tissue. Hence, distortion of:
Size
Location, and
Appearance, of the prosthesis.
Insert this and the following slides in the section for bioprosthetic valves, right before x? the dopplar features

41. Special problems of artificial valves
Intense reverberation, and
Shadowing
Less gain leads to less:
Reverberation, and
Shadowing, as well as
Better visualization of non-biologic components of the valve
HOWEVER 
Decreased definition of cardiac structures

42. Special problems of artificial valves
First image at normal settings, then
Reduce the gain to interrogate the leaflets of Bio-prosthetic valves.
Utilize multiple views.

43. Prosthetic Valve Pathology
Prosthetic Valve Stenosis
Aortic
Mitral
Prosthetic Valve Regurgitation

44. G E N E R A L L Y Prosthetic Stenosis (and Regurgitation) is:
A question of degree,
Not a question of whether.

45. Prosthetic Valve Stenosis
Determinants of gradients across normal prosthetic valves include:
Valve type, i.e., Manufacturer
Valve size
Flow through the valve
Wide range of “Normals”

46. Aortic Prosthesis Gradients as a Function of Valve TYPE and SIZE
Dependence on:
Valve type, and
Size
No.21
Fig
No.27

47. Gradient as a Function of Valve Type
Pg 508, Table 1
Normal Dopplar data in patients with various types of prosthetic valves in the Aortic Position

48. Gradient as a Function of Valve Size
Pg 508, Table 2
Valve specifications and doppler echocardiographic data in 67 St. Jude medical valves in the Aortic position
Chafizadeh ER, Circ. 83:213, 1991

49. Gradient as a Function of Flow
Valve type, i.e.,
Manufacturer
Valve size
No.21
Flow through the valve

50. Indicies of Valve Stenosis which are Less Flow Depenent
Contour of jet velocity
Doppler velocity index
Effective orifice area
Valve resistance

51. A-Contour of the jet velocity
With prosthetic obstruction there is:
Late peaking of the velocity,
More rounded contour,
Prolonged ejection.
Pg 508, fig. 1

52. B-Doppler Velocity Index
DVI= Pk VelLVOT/Pk Veljet
Flow independent
0.2 – 0.27 cutoff for critical stenosis
Caveat: Pressure recovery
To be discussed …

53. C-Effective Orifice Area
Continuity Eqn.
Caveat: Pressure recovery
To be discussed …

54. D-Valve resistance
At cutoff of 280 dynes.sec.cm5, best at differentiating AS, from NL (Zoghbi et al.)

55. Special Caveats Re: Overestimation of Gradients
Two scenarios:
The velocity upstream from the valve is not negligible in application of the Bernoulli Eqn.
Usually in AV when proximal velocity on the LVOT is > 1.5 m/s

56. …Overestimation of Gradients
Central acceleration with the St. Jude valve:
Increase of velocities (and gradients) is created at the level of the valve through the smaller central orifice.
Most significant with:
High flow states
Small valves
The only other valve where this is holds true is the Ball-Cage valve

57. …Overestimation of Gradients
Central acceleration with the St. Jude valve:
CW Doppler records these high velocities.
Catheter-derived gradients show pressure recovery at 30mm downstream from the valve.

58. Indicies which are Less Flow Dependent, BUT…
Contour of jet velocity
Doppler velocity index
Effective orifice area
Valve resistance
Clearly, both of
These Parameters
Will be Affected by
The Pressure
Recovery
Phenomenon.

59. Prosthesis-Patient Mismatch

60. Mismatch
Rahimtoola 1978:
“Mismatch is present when the effective prosthetic valve area, after insertion into the patient, is less than that of a normal human valve.”
By definition:
Some such “mismatch” will almost always be present.

61. Mismatch
Literature identifies the above as a cut-off for mismatch

62. Mismatch This is the EOA that The patient physiologically Needs.
Next locate the published
in-vivo EOA of the valve
used.

63. Mismatch
Not the company reported data
JACC Review Article, 10/2000

64. Prosthetic Valve Pathology
Prosthetic Valve Stenosis
Aortic
Mitral

65. Mitral Prosthesis Stenosis
Parameters used for assessment of function:
PHT/Area by PHT
Effective Orifice Area by continuity
Mean gradient

66. Mitral Prosthesis Stenosis
A-PHT/Area by PHT
Not expected to yield accurate valve area
The empiric constant of 220 validated for the geometry of rheumatic MS
Useful in longitudinal follow-up of valve Fx
Should not be used when diastolic filling period is short (fusion of E and A)
Tachycardia
Long first degree block

67. Mitral Prosthesis Stenosis
B-Effective Orifice Area by continuity Eqn.
One underlying assumption is absence of significant AI or MR
Physiologic prosthetic MR 10-30% (Medtronic-Hall, significant central MR, specific design feature  less thrombogenic)

68. Mitral Prosthesis Stenosis
C-Mean gradient, function of:
Size
Type of prosthetic
Flow
Pg.512, Table 3 Croocked, sraighten it out
Heart rate
(should also be
reported when
evaluating MVA)

69. Prosthetic Valve Pathology
Prosthetic Valve Stenosis
Aortic
Mitral
Prosthetic Valve Regurgitation

70. Prosthetic Valve Regurgitatoin
Two issues:
Physiologic v.s. Pathologic regurgitation
TTE v.s. TEE for assessment of regurgitation

71. Prosthetic Valve Regurgitation
Physiologic Regurgitation
Early onset and brief duration
Reflects backflow from closing movement of occluding device
Tilting disc and bileaflet valves have additional late backflow leakage
Intended to reduce risk of thrombosis

72. Aortic Prosthesis Regurgitation
Criteria similar to grading native valve AI:
Jet width
PHT < 350
Holodiastolic flow reversal
Regurgitant fraction>40%

73. Mitral Prosthesis Regurgitation
TTE of limited value in assess MR due to acoustic shadowing of the LA
Doppler findings suggestive of severe MR
E wave > 1.9 m.s
PISA
Short isovolumetic relaxation time
TVILVOT/TVIPr-MV < 0.4