Preconditioning improves myocardial preservation in patients undergoing open heart operations.
BACKGROUND
Our previous work has shown that preconditioning can promote the recovery of cardiac function in patients having an open heart procedure. Because preconditioning is regarded as the most powerful form of endogenous myocardial protection, we tested the hypothesis that preconditioning protects against myocardial ischemia-reperfusion injury in patients undergoing prolonged cold crystalloid cardioplegic arrest.


METHODS
Thirty patients who had rheumatic heart disease and required both aortic and mitral valve replacement were studied. Patients were randomly divided into two equal groups. Preconditioning was accomplished using two cycles of 2-minute occlusion of the vena cava and aorta followed by 3 minutes of reperfusion under cardiopulmonary bypass. All hearts were arrested with 4 degrees C St. Thomas' Hospital cardioplegic solution. Myocardial protective effects were assessed by changes in myocardial levels of adenosine triphosphate, electrocardiographic activity, leakage of myocardial enzymes, and myocardial contractility.


RESULTS
The adenosine triphosphate content in ischemic myocardium was higher in the preconditioning group than in the control group (p < 0.05 90 minutes after ischemia), and there was a significant reduction in release of the myocardial-specific isoenzyme of creatine kinase in the preconditioning group. Preconditioning improved the recovery of myocardial contractility (first derivative of left ventricular developed pressure, 1,490 +/- 102 mm Hg/s versus 1,250 +/- 97 mm Hg/s 30 minutes after reperfusion; p < 0.05), and there was also a protective effect on electrocardiographic activity.


CONCLUSIONS
Our results suggest that ischemic preconditioning protects the myocardium in humans from the severe ischemia-reperfusion injury produced after prolonged arrest with cold crystalloid cardioplegia.
Lu
E X
EX
Department of Cardiac Surgery, Xiangya Hospital, Hunan Medical University, Changsha, People's Republic of China. erxiong@public.cs.hn.cn
Chen
S X
SX
Yuan
M D
MD
Hu
T H
TH
Zhou
H C
HC
Luo
W J
WJ
Li
G H
GH
Xu
L M
LM
D000255:Adenosine Triphosphate / Q000032:analysis; D000328:Adult; D006348:Cardiac Surgical Procedures; D003402:Creatine Kinase / Q000378:metabolism; D004562:Electrocardiography; D005260:Female; D006324:Heart Arrest, Induced; D019918:Heart Valve Prosthesis Implantation; D006351:Heart Valves / Q000601:surgery*; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial; D007527:Isoenzymes; D008297:Male; D009200:Myocardial Contraction; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism; D017725:Ventricular Pressure
D007527:Isoenzymes; D000255:Adenosine Triphosphate; D003402:Creatine Kinase