Advantages of intermittent blood cardioplegia over intermittent ischemia during prolonged hypothermic aortic clamping.
Ten dogs underwent 2 hours of hypothermic (22 degrees C) aortic clamping. Arrest was produced by ischemia in five dogs, with 150 ml of 22 degrees C unmodified blood reperfused every 20 minutes. Five others underwent cardioplegic arrest (500 cc pH 7.8 blood containing 30 mEq/L KCl, 0.6 mEq/L Ca++) with 150 ml of blood cardioplegia solution replenished each 20 minutes. Seven additional dogs underwent 4 hours of continuous coronary perfusion without ischemia. Continuous coronary perfusion did not change myocardial ATP or water content, but reduced left ventricular contractility (maximum positive dP/dt, peak systolic pressure) 16% (P < 0.05) and decreased left ventricular compliance moderately (50%). Hypothermic ischemic arrest reduced myocardial ATP 39% (P < 0.05), raised myocardial water 3.2% (P < 0.05), reduced compliance 83% (P < 0.05), and depressed left ventricular performance 64% (P < 0.05), despite intermittent reinfusion of unmodified blood each 20 minutes. In contrast, blood cardioplegia reduced postischemic left ventricular compliance only slightly 17%, P < 0.05) and resulted in normal postischemic ATP, water, and contractility.
Follette
D M
DM
Division of Thoracic Surgery, UCLA Medical Center, Los Angeles, California 90024, USA.
Steed
D L
DL
Foglia
R
R
Fey
K
K
Buckberg
G D
GD
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology; D004285:Dogs; D006324:Heart Arrest, Induced / Q000379:methods*; D007036:Hypothermia, Induced; D007423:Intra-Aortic Balloon Pumping / Q000379:methods*; D023421:Models, Animal; D017202:Myocardial Ischemia / Q000503:physiopathology*; D010101:Oxygen Consumption; D012449:Safety; D016277:Ventricular Function, Left / Q000502:physiology