Mechanical heart valve replacement vs Biological valve?

Dear Sir or Madam,

There are four heart valves
1)The tricuspid valve.
2)The pulmonary valve.
3)The mitral valve.
4)The aortic valve.

There are two types of heart valve replacement.
1)The mechanical heart valve ....(which lasts for all pracitcal
purposes forever)
2)The biological valve.....(which lasts about fifteen years ...on
average)

The questions I am asking are.
1)Which type of existing heart valve is replaced by which choice of
heart valve(mechanical vs biological)?
2)What are the mortality rates from the initial operation in the
short term(1 year) and the long term...for each type of heart valve
operation and the chosen replacement?
3)How often do the mechanical and biological valves require
replacement?
4)Who makes the biological and mechanical heart valves used at your
hospital.

For the time period I would like two statistical snap shots from
a)A time period of such length as to be useful for a long term
study .
b)The heart valves used over the last year.

Yours faithfully,

Paul GaffneyLLB BA

Dear Merrell Kate,

Thanks for the reply.
I'll look at it later .
I am however otherwise engaged.

Yours sincerely,

Paul GaffneyLLB BA