The Journal of Thoracic and Cardiovascular Surgery, Vol 76, 577-589, Copyright © 1978 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Cold cardioplegia versus hypothermia for myocardial protection. Randomized clinical study
VR Conti, EG Bertranou, EH Blackstone, JW Kirklin and SB Digerness
Seventeen of 34 consecutive patients undergoing coronary artery bypass
grafting were randomly assigned to one of two methods of myocardial
preservation. With the cold cardioplegic method (Group A), a 4 degrees C.
asanguineous solution with 30 mEq. of potassium per liter was infused into
the aortic root for about 2 minutes immediately after aortic cross-clamping
and again after about 45 minutes or when myocardial temperature rose above
19 degrees C. External cardiac cooling was provided by constant infusion of
4 degrees C. Ringer's solution into the pericardium. Seventeen patients
were assigned to simple cardiac cooling by hypothermic systemic perfusion
before aortic cross-clamping plus external cardiac cooling (Group B).
Electromechanical activity ceased within 1 to 2 minutes in Group A but
continued throughout the ischemic period in 14 patients in Group B.
Myocardial temperature (mean for all observations) during aortic cross-
clamping was 17.2 +/- 0.44 degrees C. In Group A and 24.0 +/- 0.70 degrees
C. in Group B. Operating conditions were better in Group A. Card-ac
function early postoperatively was good in both groups clinically and
according to measurements, but only in the cold cardioplegic group (A) was
cardiac index not adversely affected by longer cross-clamp time. Myocardial
necrosis occurred in both groups but was probably less in the cold
cardioplegic group. Thirteen patients (76 percent) in Group A had no
electrocardiographic evidence of myocardial injury, compared with eight (47
percent) in Group B (p = 0.08). Eleven (65 percent of Group A had no or
short-lived appearance of ceatine phosphokinase isoenzyme (CK-MB), compared
with six (35 percent) of Group B (p = 0.08). Time-related CK-MB and SGOT
mean levels were consistently lower in Group A.