Thorac Cardiovasc Surg 2009; 56 - MP14
DOI: 10.1055/s-0029-1191537

Platelet reactivity in paediatric cardiac surgery: Should pharmacological platelet protection be performed during cardiopulmonary bypass and hypothermia in young infants?

A Straub 1, J Smolich 2, D Schiebold 3, HP Wendel 3, G Ziemer 3, Y d'Udekem 4, C Brizard 4, K Peter 5, S Horton 4
  • 1University of Tübingen, Dept. of Thoracic, Cardiac and Vascular Surgery, Tübingen, Germany and Baker IDI Heart and Diabetes Institute, Centre for Atherothrombosis and Vascular Biology, Melbourne, Australia
  • 2Murdoch Children's Research Institute, Australia and New Zealand Children's Heart Research Centre, Melbourne, Australia
  • 3University of Tübingen, Dept. of Thoracic, Cardiac and Vascular Surgery, Tübingen, Germany
  • 4Royal Children's Hospital, Cardiac Surgical Unit, Melbourne, Australia
  • 5Baker IDI Heart and Diabetes Institute, Centre for Atherothrombosis and Vascular Biology, Melbourne, Australia

Objectives: Cardiopulmonary bypass (CPB) and hypothermia cause platelet activation and dysfunction, which can contribute to thrombotic events as well as bleeding during cardiac surgery. Short-acting platelet inhibitor administration can protect platelets against CPB- and hypothermia-induced damage. In young infants, however, platelets are immature and may therefore be hyporeactive during cardiac surgery. Hence, it is unclear from what age pharmacological platelet protection may be beneficial. This study aimed to measure effects of CPB and hypothermia on platelet activation in young infants.

Methods: Congenital cardiac defects were repaired in young infants using hypothermic CPB [group 1 (n=8); median age: 9 (range: 2–111) days; lowest temperature: 26°C] and using deep hypothermic circulatory arrest (DHCA) [group 2 (n=5); median age: 84 (range: 20–99) days; lowest temperature: 15°C].

Using flow cytometry, the following platelet activation parameters were assessed before (baseline), during, and after CPB: percentages of platelet P-selectin expression and aggregate-bound platelets (all patients) as well as platelet GPIbα internalisation (group 1).

Results: In group 1 the following significant (p<0.01) changes occurred: Baseline platelet P-selectin expression and aggregation increased from mean±SEM 4.1±0.8% and 7.8±0.9% respectively to 21.7±3.3% and 17.1±1.5% respectively directly after CPB. GPIbα-expression decreased from baseline 81.3±10 to 44.8±11 fluorescence units directly after CPB.

During DHCA in group 2, P-selectin expression increased by mean 3.3 (range: 0.25–11.5)% (p=0.031).

There was no correlation of CPB- and hypothermia-induced P-selectin expression with age (r=0.18, p=0.53).

Conclusion: In young infants distinct platelet activation occurs during CPB and hypothermia. These patients may therefore benefit from pharmacological platelet protection.