Development of cardioplegic solution without potassium: experimental study in rat.

INTRODUCTION: Myocardial preservation during open heart surgeries and harvesting for transplant are of great importance. The heart at the end of procedure has to resume its functions as soon as possible. All cardioplegic solutions are based on potassium for induction of cardioplegic arrest.
OBJECTIVE: To assess a cardioplegic solution with no potassium addition to the formula with two other commercially available cardioplegic solutions. The comparative assessment was based on cytotoxicity, adenosine triphosphate myocardial preservation, and caspase 3 activity. The tested solution (LIRM) uses low doses of sodium channel blocker (lidocaine), potassium channel opener (cromakalin), and actin/myosin cross bridge inhibitor (2,3-butanedione monoxime).
METHODS: Wistar rats underwent thoracotomy under mechanical ventilation and three different solutions were used for "in situ" perfusion for cardioplegic arrest induction: Custodiol (HTK), Braile (G/A), and LIRM solutions. After cardiac arrest, the hearts were excised and kept in cold storage for 4 hours. After this period, the hearts were assessed with optical light microscopy, myocardial ATP content and caspase 3 activity. All three solutions were evaluated for direct cytotoxicity with L929 and WEHI-164 cells.
RESULTS: The ATP content was higher in the Custodiol group compared to two other solutions (P<0.05). The caspase activity was lower in the HTK group compared to LIRM and G/A solutions (P<0.01). The LIRM solution showed lower caspase activity compared to Braile solution (P<0.01). All solutions showed no cytotoxicity effect after 24 hours of cells exposure to cardioplegic solutions.
CONCLUSION: Cardioplegia solutions without potassium are promised and aminoacid addition might be an interesting strategy. More evaluation is necessary for an optimal cardioplegic solution development.