Adenosine instead of supranormal potassium in cardioplegic solution improves cardioprotection

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 8C) 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. Bloodsamples,andleft ventricularmicrodialysis were usedto measureparameters of ischemia. Measurements were doneat1 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) inthe A group2 h aftercross-clamprelease (p = 0.030).Left ventricular contractility expressedas slope ofthe preloadrecruitablestroke work index (Mw) was reduced to 53% (SD: 14) in the K group versus 78% (SD: 23) in the A group 2 h 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)to2.86(SD:1.27)intheKgroup,whereasnoshiftwasdetectedintheAgroup(p = 0.019).CardiactroponinTmeasuredinthecoronarysinus 1 h after cross-clamprelease was 1.25 mg/l (SD: 0.64) inthe K group versus 0.73 mg/l(SD: 0.31) in the A group (p = 0.046).Conclusion: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. # 2007 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.