Comparison of roller pump versus pressurized bag administration of potassium cardioplegic solution

We sought to determine the relative efficacy of administering cardioplegia by the pressurized bag versus roller pump technique. Fourteen dogs were placed on cardiopulmonary bypass at 30 degrees C and subjected to 2 hours of cardioplegic arrest. Group 1 (7 dogs) was administered cardioplegic solution from a plastic bag under pressure into the ascending aorta every 20 minutes for the 2-hour period, and Group 2 (7 dogs) was given cardioplegia by means of a roller pump. Myocardial temperature decreased in Group 1 to 13.4 degrees C following administration of the cardioplegic solution, and to 13.1 degrees C in Group 2 (not significant). These temperatures were reached in 3.0 minutes in Group 1 and 1.9 minutes in Group 2 (p less than 0.03). Aortic root pressures during cardioplegic infusion were 31 +/- 2 mm Hg in Group 1 versus 46 +/- 2 mm Hg in Group 2 (p less than 0.01). No significant differences between groups were noted in myocardial distribution of cardioplegia, myocardial blood flow or metabolism, or left ventricular hemodynamics. We conclude that both methods of administering cardioplegia lowered myocardial temperature adequately and protected the myocardium for a period of 2 hours in these normal hearts. The roller pump method facilitated faster cooling and produced significantly higher aortic perfusion pressures, however, which may be important in hearts with coronary stenosis.