Intraoperative myocardial protection in pediatrics is always still challenging. The morphologic but mainly metabolic differences to adult hearts demand for a sophisticated approach to this topic.
Besides aspects of anaesthesia and cardiopulmonary bypass application cardioplegia plays the most significant role. Concerning cardioplegia two parameters exist: Formulation of the solution applied and application mode.
Numerous experimental studies in ‘immature’ hearts have demonstrated that single dosing is superior to multidosing being mostly used worldwide. This discrepancy is related to one biochemical fact: Rate of intra-ischemic lactate production is much higher in ‘immature’ hearts than in adults. To minimize myocardial acidification either pediatric hearts must be cardioplegically reperfused at certain intervals (10 – 30 mins) or a highly buffered cardioplegic solution is applied. However, adding of a highly concentrated buffer to a cardioplegic solution is only possible if an intracellular type of solution (low Na) is used.

The only cardioplegic solution world wide, that is highly buffered, is the histidine buffered Bretschneider HTK solution (CUSTODIOL®), which allows safe x-clamping periods upto 3 hours in pediatrics including neonates after only single, initial application. The prerequisite for this longterm protection bases on an optimal initial equilibration of the extracellular space with HTK solution. Such an equilibration requires an initial perfusion time of about 4 – 6 mins.
Furthermore experimental data have proven that slightly increased magnesium and low calcium concentration in any solution improve protective power in pediatric hearts
Physiological aspects and specific intraoperative clinical data in pediatrics using HTK solution are presented and discussed.