The Journal of Thoracic and Cardiovascular Surgery, Vol 76, 158-172, Copyright © 1978 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Myocardial protection by intermittent perfusion with cardioplegic solution versus intermittent coronary perfusion with cold blood
H Laks, HB Barner, JW Standeven, JW Hahn, M Jellinek and LJ Menz
The myocardial protection provided by cardioplegic solution using buffered,
isosmotic potassium (30 mEq. per liter) was compared with intermittent cold
coronary perfusion for 2 hours of aortic cross- clamping in dogs. The
cardioplegic solution (Group CS) or cold blood (Group CB) was infused every
15 minutes through a cooling coil to reduce the perfusate temperature to 5
degrees C. Myocardial function after 30 minutes of reperfusion and
rewarming was reduced in Group CB with a significant reduction in peak
systolic pressure at a left ventricular (LV) balloon volume of 20 ml. and a
significant reduction of dp/dt. In contrast, in Group CS, LV function was
unchanged from the base-line period. LV compliance also was significantly
reduced in Group CB while being unchanged in Group CS. Myocardial
extravascular water content, obtained by dessication, was significantly
higher in Group CB than in Group CS, which may explain the reduction in
compliance. Electron microscopy showed normal ultrastructure in Group CS
but extracellular edema in Group CB. Total coronary blood flow showed a
sustained increase during reperfusion in both groups. Oxygen consumption
rose with rewarming to base-line levels in both groups, whereas lactate and
pyruvate consumption was reduced in both groups, particularly Group CB.
Cardioplegic solution thus appears to be superior to the intermittent
perfusion of cold blood for myocardial protection. The addition of
potassium arrest, by markedly reducing myocardial metabolism, improves the
protection afforded by cold blood perfusion alone.
