title: Adenosine instead of supranormal potassium in cardioplegic solution improves cardioprotection.
abstract: OBJECTIVE
  To determine whether adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest and improved cardioprotection. Cold crystalloid cardioplegia with adenosine, procaine and magnesium (A) was compared with standard cold crystalloid hyperkalemic cardioplegia (K).
  
  
  METHODS
  Sixteen pigs were randomized to receive either cold K (n=8) or A (n=8), where hyperkalemia was substituted with 1.2 mM adenosine. The cold (6 degrees C) cardioplegia was given intermittently and antegradely, with an aortic cross-clamp time of 1 h. Hemodynamic data was continuously measured and pressure-volume conductance catheters were used to determine global left ventricular systolic and diastolic function. Coronary flow and O2 content differences allowed determination of left ventricular energetics. Blood samples, and left ventricular microdialysis were used to measure parameters of ischemia. Measurements were done at 1 and 2 h after cross-clamp release.
  
  
  RESULTS
  Mean arterial pressure was reduced with 55 mmHg (standard deviation, SD: 19) in the K group versus 30 mmHg (SD: 14) in the A group 2 h after cross-clamp release (p=0.030). Left ventricular contractility expressed as slope of the preload recruitable stroke work index (Mw) was reduced to 53% (SD: 14) in the K group versus 78% (SD: 23) in the A group 2h after cross-clamp release (p=0.046). Reduction of maximum of first derivate of pressure with respect to time (dP/dtmax) was 804 mmHg/s (SD: 189) in the K group versus 538 mmHg/s (SD: 184) in the A group (p=0.033). The slope of the myocardial oxygen consumption-pressure volume area was at 2 h reperfusion increased from 1.37 (SD: 0.64) to 2.86 (SD: 1.27) in the K group, whereas no shift was detected in the A group (p=0.019). Cardiac troponin T measured in the coronary sinus 1 h after cross-clamp release was 1.25 microg/l (SD: 0.64) in the K group versus 0.73 microg/l (SD: 0.31) in the A group (p=0.046).
  
  
  CONCLUSIONS
  Adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest, improves post cardioplegic left ventricular systolic function and efficiency, and attenuates myocardial cell damage.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University Hospital of North Norway and Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway. oyvind.jakobsen@fagmed.uit.no
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Jakobsen
authors.forename: Stig
authors.initials: S
authors.lastname: Muller
authors.forename: Erling
authors.initials: E
authors.lastname: Aarsaether
authors.forename: Tor
authors.initials: T
authors.lastname: Steensrud
authors.forename: Dag G
authors.initials: DG
authors.lastname: Sørlie
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D002314:Cardioplegic Solutions / Q000737:chemistry* / Q000627:therapeutic use; D006324:Heart Arrest, Induced / Q000379:methods*; D009200:Myocardial Contraction / Q000187:drug effects*; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D011188:Potassium / Q000494:pharmacology*; D011897:Random Allocation; D013552:Swine
chemical_list: D002314:Cardioplegic Solutions; D000241:Adenosine; D011188:Potassium