The Annals of Thoracic Surgery, Vol 45, 482-488, Copyright © 1988 by The Society of Thoracic Surgeons
Prolonged asystole during intraoperative myocardial reperfusion: an experimental study
AM Addetia, BF O'Reilly, GW Walsh and P Reid
Health Sciences Complex, Memorial University of Newfoundland, St. John's, Canada.
It has been observed in a proportion of patients, that clinically cardiac
asystole persists for a prolonged period during intraoperative reperfusion.
To evaluate this phenomenon, isovolumic functional indices (left
ventricular [LV] balloon) and myocardial oxygen consumption (MV02) were
compared in 22 canine preparations before and after two different
interventions. After 45 minutes of normothermic global ischemia, (1) the
control group (N = 11) was maintained on cardiopulmonary bypass with the
hearts beating empty and (2) the experimental group (N = 11) was subjected
to cardioplegia reperfusion at normothermia for one hour. In
contradistinction to the initial hypothesis, functional recovery was better
in the experimental group compared with the controls. Significant
differences were observed in recovery of LV peak developed pressure (LVPDP)
(controls, 66.8 +/- 7.3% [mean +/- standard error of the mean], and
experimental group, 99.5 +/- 8.9%; p less than 0.05), maximum rate of rise
of LV pressure (controls, 116.6 +/- 16.2%, and experimental group, 147.7
+/- 10.1; p less than 0.05), and maximum fall of LV pressure (controls,
100.3 +/- 15.8%, and experimental group, 143.1 +/- 11.5%; p less than
0.05). Correlation between LVPDP and MVO2 was also better preserved in the
experimental group (controls: r = 0.15, N = 74, p = 0.18; experimental
group: r = 0.47, N = 75, p less than 0.001). Values for myocardial water
content and total creatine kinase in the two groups were similar. It was
concluded that prolonged asystole during intraoperative reperfusion is not
detrimental; on the contrary, there is enhanced functional recovery of the
myocardium similar to that seen after secondary cardioplegia.
