772-776In order to know the beneficial effect of
preconditioning electrocardiography recording were used as tool to assess myocardial
malfunction and for this perfusion apparatus was setup. Electrophysiological
changes for each heart were recorded during perfusion at 1,2,3,5, 10, 20, 30
and 60 min of global ischaemia and also during the equal period of reperfusion.
Recordings demonstrate that the normal rate was about 240 beats/min with an
"R" amplitude of 4mV. During the first ischaemic episode of 1 min the
rate was 180 ± 15 beats/min (counted as per 'R' wave deflection), at 2 mins it
was 60 ± 6 beats/min, at 3 min the rate was 40 ± 2 beats/min, at 5 mins of
ischaemia it was 90 ± 6 beats/min, at 10 min 20 ± 2 beats/min, at 20 min the
rate was 60 ± 4 beats/min, and at 30 mins there were nil beats/min. The
recovery during all the periods of reperfusion was restored to between 120 and 180
beats/min in all episodes. Further after a 60 min of ischaemia the heart
stopped to elicit any mechanical response. It is concluded that short term
ischaemia can induce a resilient effect on the beating of the heart after a few
episodes as seen subsequent to 1 and 2 min of ischaemia. Further,
preconditioning was beneficial up to 30 min, beyond which the heart showed
signs of fatigue and irreversible injury