I once saw a programme on Discovery Channel (probably) about the
developments in mechanical hearts, and although this is revolutionary
technology, it's still no easy fix like you find in "Star Trek", or
something 'elegant' like being a "Robocop" cyborg.

The heart must get its power through chords to a battery belt, or
a stationary power device, and it must be monitored all the time.
(I guess there's limited time before the body reacts to it, too...)

In the programme they told about the problem of preventing the blood
from clotting when pumped with a mechanical pump.  The movement in
ordinary pumps caused turbulence in the blood stream, and this was
enough to produce clots.  (Also heart atrium flutter makes turbulence
in the blood stream, thus increasing the risk of clotting, and
therefore this condition is very important to prevent with medicines,
although the heart will pump well enough as long as the main chambers
do not flutter.)

The revolutionary solution was to make a heart/pump that "softly" and
gently squeezed the blood through with no abrupt or turbulent movements
in opposition to a metal valve or turbine pump.  I cannot remember the
construction of the pump, but I believe it was a French patent.

The patient must take medicines to prevent the blood from clotting,
and even worse, he or she must bring heavy equipment everywhere.  One
great concern was the electric battery, which was fitted in a belt that
the patient could wear for easy movement around in the house, or a
cable to a power supply/charger for nighttime use, that also had
monitoring equipment so the operation of the mechanical heart could be
checked.  There was also a battery alarm which sounded when there was
short battery time left!  :-o

Fortunately the heart could be operated manually by pumping on some
device by a helper -- I guess that's one of the reasons that Jonathan
will have to have someone with him 24 hours a day.  (I think it was a
little "emergency lever" you could squeeze in your hand, to keep the
patient alive.)  If this was pneumatic, or generated electric power for
the heart, I do not know.

The patient in that programme had some, but not much, flexibility,
although the battery belt made it possible to walk around a lot.
Imagine what could happen if the patient stumbled and fell and a cord
broke by accident.

Jonathan Holmes, I can understand that you just now feel how vulnerable
life is, and you might not want to speak more detailed about the
subject, but since you brought it up in this technical forum, some of
us might be curious about more technical details, in addition to
hearing how you're doing at this difficult time in your life.

A couple of questions that I wonder about for example:

1.  How much effect is needed to pump the blood with this heart, 10W?
50W? 100W?

2.  Can you regulate the pump rate depending on what you're doing,
or is this regulated automatically with some sort of pacemaker?  How
does your body react to the mechanical device?

3.  How is it really working?  (Do you have Internet links to more
information about the heart?)

Maybe the pump patent in a larger scale could be good for player
pianos.  Less turbulence and less abrupt movements also means less
noise...  :-)

Best regards
Thomas Henden, Norway.

 [ Thomas discovered MMD as a medical student in Oslo several years ago.
 [ Now, for relaxation, he enjoys working on his Duo-Art piano with its
 [ mechanical "heart" pumping air.  :)  -- Robbie