The Annals of Thoracic Surgery, Vol 26, 499-506, Copyright © 1978 by The Society of Thoracic Surgeons
Effects of cardioplegic solution on human contractile element velocity
DM Behrendt, MM Kirsh, KE Jochim and H Sloan
A technique for measuring the maximum contractile element velocity (Vpm) of
the myocardium was developed, verified, and employed in patients to allow
accurate intraoperative assessment of the adequacy of myocardial
protection. Four groups of patients were studied. Ten patients had coronary
artery bypass grafts (CABG) with cardioplegia; 13 had CABG with coronary
perfusion, ventricular fibrillation at 28 degrees C, and aortic clamping
for distal anastamoses; 6 had aortic valve replacement (AVR) with
cardioplegia; and 7 had AVR with coronary perfusion to the beating heart.
For cardioplegia, a solution of 5% dextrose in 0.2% saline at 4 degrees C
with 25 mEq of potassium chloride and 12.5 gm of mannitol was infused
initially, followed by 500 ml every 30 minutes. Clinically all patients did
well, and there were no deaths. Patients having CABG with intermittent
coronary perfusion during ventricular fibrillation had significant (p less
than 0.01) depression of Vpm from 38.3 to 30.8 sec-1 while Vpm in patients
having CABG with cardioplegia was unchanged. Patients having AVR with
continuous coronary perfusion or with cardioplegia (average anoxia time,
70.4 minutes) had no significant change in Vpm. We conclude that this
cardioplegic solution provided adequate protection of myocardial function
for up to 105 minutes of continuous aortic clamping in humans. The
depression in Vpm observed following CABG with intermittent coronary
perfusion is consistent with previous suggestions that this combination is
detrimental because of maldistribution of coronary blood flow during
ventricular fibrillation.
