Objective: To investigate the interrelationship of free
radicals (FRs), ischemic preconditioning (IP), and hemodynamic function
in coronary artery bypass graft (CABG) patients.
Design: Prospective, randomized, and controlled clinical
Patients: Forty CABG patients were
randomized into an IP group (n = 20) and a control group
(n = 20).
Intervention: The IP group was
preconditioned with two cycles of two-min ischemia followed by 3-min
reperfusion before cross-clamping.
results: FR content in coronary sinus blood was measured directly
using α-phenyl-N-tert-butylnitrone-electron spin-trapped
spectroscopy. A small amount of FRs was generated after the IP protocol
(5.6% above the baseline) but not in control subjects. A larger amount
was generated 10 min after declamping in both groups (8.4% in IP
protocol and 7.7% in control subjects). Hemodynamic function recovered
better in the IP group at 1 h and 6 h after declamping. There
was a significant negative correlation between FR generation after
declamping and left ventricular stroke work index (LVSWI) at 1 h
and 6 h after declamping (r = −0.71 and−
0.59, respectively) in the control subjects but not in the IP
group. There was a significant positive correlation between FR
generation after the IP protocol and cardiac index at 1 h and
6 h (r = 0.50 and 0.61, respectively) and LVSWI
at 1 h and 6 h (r = 0.56 and 0.54,
respectively) after declamping in the IP group but not in the control
Conclusion: FR generation after the
operation correlates with ventricular functional depression in CABG
patients. IP protects the stunning heart but does not alter FR
generation. The association of better hemodynamic recovery after CABG
with FR generation during the IP period suggests that FRs might act as
one of the triggers for IP.