Cardiac dysfunction and inefficiency after substrate-enriched warm blood cardioplegia.
OBJECTIVE
The study assessed the outcome after prolonged warm continuous antegrade blood cardioplegia (WCBC) with substrate enrichment, in terms of mechanical performance and mechanoenergetic efficiency.


METHODS
WCBC was given for 3 h to three groups of pigs on cardiopulmonary bypass; WCBC alone (n=7), WCBC+glucose and insulin (+GIK, n=7) and WCBC+L-glutamine (+GLN, n=7). Cardiac systolic and diastolic function, pressure-volume area (PVA) and myocardial oxygen consumption (MVO(2)) were assessed before, and twice after WCBC using pressure-conductance catheter, coronary flow-probes and O(2)-content difference.


RESULTS
In the WCBC, +GIK and +GLN groups respectively, the following parameters decreased after WCBC compared to baseline: left ventricular developed pressure by 26, 19 and 25% (P<0.001); dP/dt(max) by 36, 37 and 34% (P<0.001); preload recruitable stroke work by 35, 41 and 28% (P<0.001); mechanoenergetic efficiency (PVA/MVO(2)) by 44, 41 and 22% (P<0.001). End-diastolic stiffness increased early after WCBC in the WCBC and +GLN groups, while it was unchanged in the +GIK group (P=0.032).


CONCLUSIONS
Despite continuous aerobic conditions and additional substrates, post-WCBC cardiac contractile function and mechanoenergetic efficiency was severely depressed. The results demonstrate the hazards of sustained normothermic hyperkalemic perfusion.
Korvald
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Department of Thoracic and Cardiovascular Surgery, University Hospital in Tromsø, Tromsø, Norway. christian.korvald@rito.no
Elvenes
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OP
Myrmel
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Sørlie
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DG
D000818:Animals; D001769:Blood; D002314:Cardioplegic Solutions; D002315:Cardiopulmonary Bypass; D004734:Energy Metabolism; D005947:Glucose / Q000008:administration & dosage; D005973:Glutamine / Q000008:administration & dosage; D006324:Heart Arrest, Induced / Q000009:adverse effects / Q000379:methods; D006439:Hemodynamics; D007328:Insulin / Q000008:administration & dosage; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption; D011188:Potassium / Q000008:administration & dosage; D013552:Swine; D013696:Temperature; D016277:Ventricular Function, Left
D002314:Cardioplegic Solutions; D007328:Insulin; D005973:Glutamine; D005947:Glucose; D011188:Potassium