The Halving, by Robin Robertson

General anaesthesia; a median sternotomy
achieved by sternal saw; the ribs
held aghast by retractor; the tubes
and cannulae drawing the blood
to the reservoir, and its bubbler;
the struggling aorta
cross clamped, the heart chilled
and stopped and left to dry.
The incompetent bicuspid valve excised,
the new one - a carbon-coated disc, housed
expensively in a cage of tantalum -
is broken from its sterile pouch
then heavily implanted into the native heart,
bolstered, seated with sutures.
The aorta freed, the heart re-started.
The blood allowed back
after its time abroad
circulating in the machine.
The rib-spreader relaxed,
the plumbing removed, the breast-bone
lashed with sternal wires, the incision closed.

Four hours I'd been away: out of my body.
Made to die then jerked back to the world.
The distractions of delerium
came and went and then,
as the morphine drained, I was left with a split
chest that ground and grated on itself.
Over the pain, a blackness rose and swelled;
'pump-head' is what some call it
- debris from the bypass machine
migrating to the brain - but it felt
more interesting than that.
Halved and unhelmed,
I had been away, I said to the ceiling,
and now I am not myself.