Rapid cooling contracture of the myocardium

Myocardial Contractility and Relaxation After Deep Hypothermic Circulatory Arrest in a Neonatal Piglet Model

“…Anyway, DHCA for surgery of congenital heart defects requires a period of cooling on CPB. Rebeyka et al (1) reported the clinical observation of neonatal heart rigidity during the period of rapid cooling before circulatory arrest followed by either significant postoperative low cardiac output or intraoperative mortality.Therefore, they performed animal experiments with iso-lated rabbit hearts and they found that there was a significant myocardial injury especially when they combined rapid cooling and hypothermic perfusion in the pre-arrest state with a subsequent period of cardioplegic ischemic arrest (1). However, their findings have had a significant limitation; the hearts were of adult rabbits.…”

“…The previous mentioned studies (1,2) were performed using the model of isolated heart. We decided to apply a neonatal in vivo model because the reperfusion may be different in such a model and this period of reperfusion is extremely essential.…”

“…Nevertheless, deep hypothermia may influence the outcome of cardiac surgery due to alterations in myocardial performance. Although previous experimental studies on isolated hearts demonstrated significant alterations in myocardial contractility related to pre‐arrest cooling (1,2), there are many limitations: (i) the data are conflicting, (ii) most studies were performed in vitro, and (iii) most experiments were performed on hearts of adult animals.…”

Delivery of a nonpotassium modified maintenance solution to enhance myocardial protection in stressed neonatal hearts: A new approach

“…Unmodified blood can potentially cause a reperfusion injury because the heart is ischemic between cardioplegic doses and as Rebeyka showed unmodified blood can be detrimental in infants. 1,2,13,14 A modified cardioplegia-like solution might help limit this injury. To test this new approach, the integrated strategy was modified in 10 piglets by infusing a cold modified nonpotassium blood maintenance solution (Table 3) in place of unmodified blood.…”

“…To parallel this experimentally, we used stressed (hypoxic and ischemic) neonatal hearts to evaluate the conventional techniques of intermittent cardioplegia and standard integrated protection. The standard integrated strategy has the potential problem of producing a reperfusion injury, however, because it exposes the ischemic heart to multiple infusions of cold unmodified blood, which Rebeyka and associates 13 have shown is dangerous in infants. We therefore also evaluated a new approach, which replaces the cold unmodified blood with a cold modified (nonpotassium, magnesium-enriched, citrate-phosphate-dextrose, tromethamine) blood solution.…”