Mitral valves

  I am going to have surgery performed for a my mitral valve and I am leaning
  toward a pig mitral valve if my natural valve cannot be repaired. I know
  that the pig valves last only 8 to 10 years. During those 8 to 10 years,
  do they work as well as the mechanical valve, or do they begin to leak
  very soon, say, in year 3 or 4?
  Also, is a better, more durable tissue mitral valve that doesn't
  require lifelong coumidin on the horizon (much like the aortic valve that
  was approved by the FDA in 1996?), and if so, can there be any specuation
  about when it will become available?
  Finally, is there really a minimally invasive method of valve replace-
  ment, and how is such a major operation performed without full invasive
  procedure?

[CCF Cardio MD - MTR]

_
Dear Tom, thank you for your question.  The choice of how to treat mitral valve disease
is complex and depends a lot on the architecture of the valve and what caused the problem
to begin with.  Pig valves these days are fashioned from the pericardium (lining of the
heart) and are reinforced by metal struts.  No anticoagulation is needed with pig valves
because the tissue doesn't cause clots to form.  The lifespan of a pig valve is typically
10-12 years but is highly variable from patient to patient.  The valves degenerate by
accumulating calcium which causes the leaflets to become thickened resulting in
a narrowed valve opening or valvular insufficiency (leaking).  Aortic valves can now
be replaced by homograft valves obtained from cadavers who have died of natural causes
without heart disease.  Mitral valve homografts are experimental and the success rate is
not impressive mainly because of the differences between the aortic and mitral valves.
The mitral valve leaflets are attached to muscles called papillary muscles which control
the valve opening and closing.  Aortic valves don't have muscles attached to the leaflets
so are easier to replace with homografts.  When a homograft is attached to the papillary
muscles, the muscles often don't function normally and vavular insufficiency results.  
However, mitral valve repair has become a refined procedure and is very successful for
treating mitral vavle insufficiency due to degenerated mitral valve leaflets.  A surgeon at
our institution, Dr. Delos Cosgrove, has pioneered mitral valve repair and his usual
approach is to resect part of the degenerated leaflets and reinforce the valve with an
annuloplasty ring around the base of the valve.  Dr. Cosgrove has also pioneered the
minimally invasive approach to mitral valve repair where a small 3-4 inch incision
replaces the traditional sternotomy incision down the entire sternum.  Results so far are
good and patients have a shorter convalescence and less pain post-operatively.  A
minimally invasive approach works because the whole heart doesn't need to be exposed
to do this surgery.  As far as technical aspects of the surgery, it's similar to a regular
sternotomy approach but those details are probably better left to a surgeon.  I hope you
find this information useful.
Information provided in the heart forum is for general purposes only.  Specific diagnoses
and therapies can only be provided by your physician.