Objective: Cardioplegia is an important step to facilitate cardiac surgery while limiting intraoperative myocardial injury. Although recent advances in cardioplegic arrest methods have significantly contributed to better postoperative outcomes, there is still controversy regarding the optimal composition and temperature of the cardioplegic solution. Accordingly, we aimed to assess whether cold or lukewarm Sabax cardioplegia offer improved myocardial protection compared with the classical Krebs-Henseleit solution.
Methods: The hearts of 40 male Wistar rats were isolated and submitted to constant-flow retrograde perfusion using a Langendorff perfusion apparatus. The hearts were randomly assigned to cold Krebs-Henseleit (K-H), cold Sabax, or lukewarm Sabax cardioplegia. The ECG, heart rates, and left ventricular systolic pressures (LVSP) were recorded pre- and post-cardioplegia. The time needed for cardioplegia induction and post-cardioplegia recovery were also noted.
Results: Both cold and lukewarm Sabax cardioplegia insured faster induction and faster recovery following isothermic reperfusion compared to the standard K-H solution (both p< 0.01). With K-H cardioplegia, the hearts presented a 21.7% force loss after reperfusion (p< 0.001), whilst Sabax cardioplegia was associated with a slight increase in ventricular mechanical activity (3% LVSP increase with lukewarm Sabax cardioplegia, p< 0.001 and 2% LVSP increase with cold Sabax cardioplegia, p = 0.02). With Sabax cardioplegia the hearts displayed considerably less major arrhythmic events and presented less significant bradycardia.
Conclusions: The present data suggest that Sabax cardioplegia may be superior to the classical cold crystalloid K-H solution in preserving mechanical activity of the heart and may provide superior protection against major arrhythmias.