Prosthetic Valves

Question 1

Heart valve replacement surgery can be indicated by what type of scar?
What does this also indicate?

Answer 1

Midline Sternotomy scar

• Mitral valve replacement
• Aortic valve replacement
• Coronary artery bypass graft.

Question 2

What does lateral thoracotomy scar indicate?

Answer 2

• Mitral valve replacement

- Lobectomy

Question 3

What are the different types of prosthetic valves?

Compare their features?

Answer 3

1) Bioprosthetic valves (Porcine valve).

> Limited life-span (around 10 years)

> Does not require lifelong anti-coagulation. Therefore this type of valve is very ideal for elderly patients.

2) Metallic mechanical valves
> Longer life-span (>20 years)

> Requires lifelong anticoagulation with warfarin.

> INR target is 2.5- 3.5

Question 4

What are the different types of mechanical valves?

Answer 4

1) Starr-Edwards Valve
> Ball in cage valve
> Very successful but its not longer being used
> This is because it had a very high risk of thrombus formation.

2) Tilting disc valve
> A single tilting disc

3) St Jude’s valves
> Two tilting metal discs
> The two discs mean they are also called bileaflet valves
> Have the least risk of thrombus formation.

Question 5

What major complications are associated with mechanical valves?

Answer 5

1) Thrombus Formation (due to blood stagnation).
2) Infective endocarditis (this is due to infection of the prosthesis).
3) Haemolysis, deu to the valve churning up the red blood cells.

Question 6

Mechanical valves produce a click.

What type of valve replacement does a S1 click represent?

What type of valve replacement does a S2 click represent?

Answer 6

S1 click –> metallic mitral valve

S2 click –> metallic aortic valve

Question 7

What is transcatheter aortic valve implantation (TAVI)?

How do you carry it out?

What are its indication?

When is it not used first line?

Answer 7

Procedure to insert a bioprosthetic valve to replace a very stenosed aortic valve, in patients who are described as being very high risk.

Under Xray guidance, feed a catheter into the femoral artery, and pass into the left ventricle. Then replace the stenosed aortic valve with the porcine valve.

Indications
- In elderly patients who are at high risk for an open valve replacement operation.

In younger patients, its used second line as we dont know the long term outcomes of the TAVI procedure. So you patients are given an open valve replacement surgery.

Question 8

Whats infective endocarditis caused by?

Risk of mortality if there is infection of the prosthetic valve?

Answer 8

Three gram positive cocci organisms

• Staphylcoccus
• Streptococcus
• Enterococcus

Risk of mortality
- Very high (15%)