1. Original slides courtesy of Dr. Alex Morss
Prosthetic Valves
Original slides courtesy of Dr. Alex Morss
2008
Zoll Firm Lecture Series

2. Zoll Firm Lecture Series
Mechanical Vlaves
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, mm
O’Neill NEJM 1995
2008
Zoll Firm Lecture Series

3. Zoll Firm Lecture Series
Bioprosthetic valves
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, mm
Hancock
Mosaic
Stentless porcine
2008
Zoll Firm Lecture Series

4. Hemodynamic effect of prosthetic valves
Native valve repair should always be considered instead of valve replacement
Good experience with mitral valve repair- leads to preservation of left venticular
All prosthetic valves have effective orifices that are smaller than that of the native valve; this results in mild stenosis of the valve that is replaced. The “normal” gradient depends on the type of valve that is used, the size of the valve, as well as the aortic or mitral position
For example, normal gradients for a 19mm normal bifleaflet mechanical aortic valve is 33+/- 11mmHg.
2008
Zoll Firm Lecture Series

5. Zoll Firm Lecture Series
Bioprosthetic valves
Higher rate of structural failure
15% for aortic and 36% for mitral valves at approx 10 year follow up.
Thought to have a lifespan of years.
Lower rate of structural failulre in older patients
No need for anticoagulation.
Valve of choice in patients with a contraindication to chronic anticoagulation.
Preferred for older patients (>70 years).
2008
Zoll Firm Lecture Series

6. Zoll Firm Lecture Series
Mechanical valves
Low rate of structural failure
Expected to last years
Disadvantage of requiring long-term anticoagulation.
Generally preferred in patients younger than 60 years or patients already on permanent anticoagulation.
2008
Zoll Firm Lecture Series

7. Zoll Firm Lecture Series
Complications
Structural deterioration
Valve obstruction (due to thrombosis or pannus formation)
Newly symptommatic patient with an unexpected rise in transprosthetic gradient
Pannus formation: can’t be treated with thrombolytics
Valve thrombosis:
More frequent in patients who are not therapeutically anticoagulated.
For small thrombus with no hemodynamic effect, can consider continuing anticoagulation with heparin/coumadin
Thrombolysis (80% success, 10 % CVA)
Surgery (high risk)
2008
Zoll Firm Lecture Series

8. Zoll Firm Lecture Series
Complications
Systemic embolization
Approximatey 0.7-1% per year in those who are therapeutically anticoag.
Endocarditis or other infections (can cause dehiscence)
Medical cure for prosthetic valve endocarditis is a lot more difficult
Indications for surgery are similar to those with native valves with the addition of prosthesis dehiscence .
Bleeding from anticoagulation
Hemolysis
Subclinical hemolysis is present in many patients with mechanical valves but rarely result in significant anemia. Can be managed conservatively with iron supplementation…etc.
Clinical hemolysis are associated with small prothesis, perivalvular leaks…etc. Later case may require surgical treatment.
2008
Zoll Firm Lecture Series

9. Zoll Firm Lecture Series
Echocardiography
Transthoracic
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.
2008
Zoll Firm Lecture Series

10. Zoll Firm Lecture Series
What’s wrong?
2008
Zoll Firm Lecture Series

11. Zoll Firm Lecture Series
2008
Zoll Firm Lecture Series

12. Zoll Firm Lecture Series
Anticoagulation
Warfarin to an INR of in all mechanical valves in the mitral position
Wafarin to achieve an INR of 2-3 in the aortic valve position except
If risk factors are present
Starr-Edwards or tilting disc valve
Risk factors includes atrial fibrillation, LV dysfunction, and hypercoagulable state
Patients generally needs to be bridged with heparin if they need surgery
The exception is a bileaflet valve in the aortic position with no risk factors.
Aspirin for ALL PATIENTS WITH PROSTHETIC VALVES
2008
Zoll Firm Lecture Series