Estimation of myocardial ischemic injury during ventricular fibrillation with total circulatory arrest using high-energy phosphates and lactate as metabolic markers.
OBJECTIVE
To define the time course of myocardial ischemic injury using high-energy phosphate (HEP) depletion and the cessation of lactate production as metabolic markers.


METHODS
Data were collected in a laboratory animal model.


METHODS
Ten immature mixed breed swine weighing 23.2 +/- 3.5 kg.


METHODS
After thoracotomy, transmural myocardial biopsies were taken in vivo during normal sinus rhythm and at designated times during ventricular fibrillation with total circulatory arrest (VF-TCA).


RESULTS
Frozen tissue samples were analyzed for adenine nucleotides, by high-performance liquid chromatography, and lactate by enzymatic assay. At five minutes of VF-TCA, myocardial adenosine triphosphate averaged 50% of control. At 15 minutes of VF-TCA, 89% of animals had myocardial adenosine triphosphate levels above 20% of control and adenylate charge ratio above 0.60. With more than 30 minutes of VF-TCA, all animals had adenosine triphosphate levels below 10% of control and adenylate charge ratio below 0.30. In addition, myocardial lactate levels plateaued after 30 minutes of VF-TCA, indicating the cessation of lactate production.


CONCLUSIONS
These results suggest that the myocardium can tolerate VF-TCA for as long as 15 minutes without irreversible injury; however, post-ischemic myocardial dysfunction may occur after as little as five minutes of VF-TCA. With more than 30 minutes of VF-TCA, myocardial injury is likely to be irreversible.
Neumar
R W
RW
Department of Emergency Medicine, Ohio State University, Columbus 43210.
Brown
C G
CG
Van Ligten
P
P
Hoekstra
J
J
Altschuld
R A
RA
Baker
P
P
D000244:Adenosine Diphosphate / Q000032:analysis* / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000032:analysis* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000737:chemistry; D001706:Biopsy; D006323:Heart Arrest / Q000150:complications*; D006335:Heart Injuries / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D007511:Ischemia / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D007773:Lactates / Q000032:analysis* / Q000096:biosynthesis; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism / Q000473:pathology; D013552:Swine; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000150:complications*
D015415:Biomarkers; D007773:Lactates; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate