An on-line system for delivery of blood cardioplegia.

: A simplified system for delivery of cold blood potassium cardioplegia was tested in 12 experimental animals subjected to 180 minutes of aortic cross-clamping. This on-line system utilized blood drawn from the pump oxygenator which was volumetrically combined with a pre-mixed electrolyte solution (9 parts blood: 1 part drug). A separate heat exchanger was employed to deliver the cardioplegic infusate at 10-15 degrees C. Use of this system permits accurate regulation of infusate potassium concentration, pH, injection pressure and flow rate. Less than one minute is required to obtain an unlimited quantity of arrest solution at steady state values for these parameters. The efficacy of this method of delivery of blood cardioplegia was verified by biochemical and functional studies which revealed no significant changes in myocardial ATP, ultrastructure, compliance, or ventricular function after 3 hours of crossclamping. It is concluded that this system offers a safe and more simplified method of delivering blood cardioplegia than heretofore available.