European Journal of Cardio-Thoracic Surgery, Vol 2, 364-371, Copyright © 1988 by European Association for Cardio-thoracic Surgery
Reperfusion with nifedipine: improved functional recovery after cold cardioplegic arrest
S Dzumhur and AH Brown
Cardio-thoracic Department, Freeman Hospital, Newcastle upon Tyne, UK.
Nifedipine, an antagonist of myocardial calcium uptake, given after a
period of a cold, cardioplegic arrest (150 min, 18 degrees C, St Thomas'
cardioplegic solution) improved contractile recovery of the isolated
working rat heart model of cardiopulmonary bypass. The hearts were
reperfused with various concentrations of nifedipine in Krebs- Henseleit
buffer (37 degrees C, 100 cm H2O) and their functional recoveries were
compared with the control series reperfused without nifedipine. A
bell-shaped dose/response curve was produced by the drug, and optimal
protection observed with 0.1 mumol/l of nifedipine which improved the
post-ischaemic recovery of the aortic flow from 56.8% +/- 3.7% to 80.1% +/-
3.2% (P less than 0.001). The importance of careful dose adjustment is
stressed since it was noted that higher concentrations inhibit both
functional and metabolic performance. This study supports the hypothesis
that at the end of a cold cardioplegic arrest there are still reversibly
injured cells which could restore their function if the cellular ingress of
Ca++ during reperfusion is reduced by nifedipine.