Single-dose versus multidose cardioplegia in neonatal hearts

Single-dose versus multidose cardioplegia in neonatal heartsWe designed an experiment to compare single-dose versus multidose cardioplegia (calcium 0.3 mmolj L) in neonatal rabbit hearts 1, 4 and 6 weeks of age at 25°C and 32°C.Isolated hearts had a stabilization period of retrograde perfusion, a working period, a period of ischemia with single or multidose cardioplegia, reperfusion, and a final working period.We measured hemodynamic recovery, creatine kinase during reperfusion, and coronary vascular resistance during administration of the cardioplegic solution.One-week and 4-week-old hearts exhibited better recovery with single-dose than with multidose cardioplegia.Six-week-old hearts, on the other hand, showed better recovery with multidose cardioplegia.Four-week-old hearts at 25°C showed increased creatine kinase release with multidose cardioplegia.The 6-week-old hearts tended toward lower creatine kinase release with multidose cardioplegia.Coronary vascular resistance rose with subsequent administrations in J-week and 4-week-old hearts at 25°C but did not rise in 1-and 4-week-old hearts at 32°C or in 6-week-old hearts at either temperature.On the basis of hemodynamic recovery, single-dose cardioplegia appears to provide better protection than multidose cardioplegia to 1-and 4-week-old isolated rabbit hearts.Once the rabbit has reached 6 weeks of age, multidose cardioplegia has some advantage over single-dose cardioplegia, similar to the findings in adult hearts.Creatine kinase release and coronary vascular resistance data corroborate the hemodynamic findings.(