12.01.2013 Views

ischaemic preconditioning of the human heart. - Leicester Research ...

ischaemic preconditioning of the human heart. - Leicester Research ...

ischaemic preconditioning of the human heart. - Leicester Research ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

ABSTRACT<br />

Ischaemic <strong>preconditioning</strong> (PC) describes <strong>the</strong> increased resistance to myocardial<br />

infarction that follows short sublethal periods <strong>of</strong> ischaernia. It has been shown to exist<br />

in all mammalian species<br />

investigated to date. In <strong>the</strong> early 90's, some evidence started<br />

to evolve which reported that this powerful card ioprotect 1 ve phenomenon exists in<br />

man. After ischaernia that triggers <strong>preconditioning</strong>, <strong>the</strong>re are 2 phases <strong>of</strong> protection:<br />

an early phase (short-lived) termed early <strong>of</strong> classic <strong>preconditioning</strong> and a late (more<br />

prolonged) phase termed a second window <strong>of</strong> protection. The evidence for this has<br />

primarily come from work on <strong>the</strong> rabbit and rat isolated <strong>heart</strong>s. There is no<br />

information related to <strong>the</strong> characteristics <strong>of</strong> this <strong>preconditioning</strong> phenomenon in<br />

<strong>human</strong>s.<br />

The study commenced with <strong>the</strong> development <strong>of</strong> an itt Wiro model <strong>of</strong> <strong>human</strong><br />

myocardium to study <strong>the</strong> effects <strong>of</strong> ischaernia and reperfusion injury. The data<br />

provided evidence that <strong>the</strong> in t4fro incubation <strong>of</strong> <strong>human</strong> atrial tissue is stable and<br />

slices are viable for at least 24 hr and that this permits <strong>the</strong> study <strong>of</strong> early and delayed<br />

consequences <strong>of</strong> ischaemia and reperfusion in <strong>the</strong> <strong>human</strong> myocardium. This model<br />

was also used to study <strong>the</strong> <strong>preconditioning</strong> phenomenon fully. There were some<br />

unanswered questions pertaining to <strong>the</strong> characteristics <strong>of</strong> <strong>the</strong> PC phenomenon. The<br />

results showed that maximal protection can be achieved with 4-6 min <strong>of</strong> ischaernic<br />

stimulus/5min reperfusion and beyond that, protection was abolished. It also reported<br />

that this early phase was protective for only 2 hours after <strong>the</strong> tfigger and that in <strong>the</strong><br />

atnum, a second window <strong>of</strong> protection existed although much less potent.<br />

iii

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!