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The delivery of cardioplegia has traditionally been constrained by the physical limitations of the mechanical devices in use, yet myocardial protective strategies may vary both according to patient condition and operative requirements. The need for a cardioplegia administration device that allows flexibility and safety is evident. The purpose of this study was to evaluate the performance of the Quest Myocardial Protection System (MPS) during clinically simulated conditions. The MPS was evaluated in an in vitro setting under the following conditions: blood to crystalloid ratios (1:1, 4:1, 8:1, all blood), potassium concentrations ([K+]) of 10 and 25 mmol/L, calcium concentrations ([Ca++]) of 1.4 and 2.8 mmol/L, and at flow rates of 100 and 300 ml/min. Predicted values from the MPS were compared with measured values, with statistically significance accepted at p.05 level. Significant differences were seen between measured and MPS cardioplegia delivery volumes at the 4:1, 8:1 and all blood ratios with a flow rate of 300 ml/min. There were no significant differences seen between measured and expected [K+] and [Ca++] delivery values across all combination of flow rates and ratios. Differences between delivery pressures of the MPS and measured values for flow rates of 100, 250 and 500 ml/min were 0.4, 1.2 and 7.6 mmHg respectively. The mean cardioplegia cooling time from 37 degrees C to 9 degrees C was 37 +/- 4.5 seconds, while rewarming from 7 degrees C to 37 degrees C, took 53 +/- 10.4 seconds. In conclusion, the Myocardial Protection System performance characteristics were precise in ratio delivery, concentrations of potassium agents, additive agent concentration, temperature, and pressure across all experimental conditions, with the exception of delivery volume. |
