Effect of calcium and preischemic hypothermia on recovery of myocardial function after cardioplegic ischemia in neonatal lambs

Protecting the aged heart during cardiac surgery: Use of del Nido cardioplegia provides superior functional recovery in isolated hearts

“…The del Nido cardioplegia strategy results in lower postoperative troponin release in pediatric patients compared with our standard cardioplegia. 9 Because elderly myocardium is similar to immature myocardium in that both are particularly susceptible to reperfusion injury related to Ca 2þ overload, [3][4][5][6][7][8][12][13][14] we hypothesized that a del Nido cardioplegia strategy also may be beneficial in the elderly. We previously showed, in cardiomyocytes from aged rats (z24 mo), that arrest with del Nido cardioplegia results in less activity during the ischemic period, lower diastolic Ca 2þ during ischemia and reperfusion, and avoidance of Ca 2þ -induced hypercontraction during early reperfusion.…”

Postischemic functional recovery in immature hearts is influenced by performance index and assessment technique

“…preload-dependent performance; preload-independent performance; performance indexes; ventricular function; ischemia-reperfusion CONTROVERSY PERSISTS regarding the immature heart's potential for postischemic recovery of contractile performance.Althoughmanystudiesreportmoderatepostischemic functional recovery, some studies have identified recovery above 85% (1,11,28,30) or below 30% (23,30,36). The use of different contractile performance indexes and assessment techniques could contribute to these conflicting findings.…”

“…The use of different contractile performance indexes and assessment techniques could contribute to these conflicting findings. For instance, various studies report contractile performance indexes, including peak systolic pressure (9,10,12,15,20,23,35,36), developed pressure (1,13,15,17,23,28,30,32,36), systolic pressure-rate product (10,20), and maximum rate of systolic pressure increase per unit time (ϩdP/dt max ) (1,8,10,12,13,17,23,36), but rarely examine more than one or two of these indexes simultaneously. Interestingly, studies (23,36) that examined two indexes found that peak systolic pressure had two-to threefold greater postischemic functional recovery than either developed pressure or ϩdP/dt max .…”

“…For example, in the isolated immature heart, common fixed-preload assessment techniques include the working Langendorff model with fixed left atrial pressure (11,12,20,23,36) or isovolumetric intraventricular balloon (1,2,8,13,15,17,29,30,32). These techniques are also commonly used to examine the functional response of the immature heart to stresses such as ischemia (1,2,8,13,15,17,29,30,32). In contrast, variable-volume performance assessment techniques, generated by incrementally increasing the end-diastolic volume and determining the intraventricular pressure-volume relationship, are more frequently reported in adult hearts and rarely reported in the immature heart (9,10).…”

Myocardial stunning in the neonate

“…Thus although hypothermia is believed to improve tolerance to ischaemia, intracellular Ca ;; accumulation induced by hypothermia may lead to exacerbation of ischaemia-reperfusion injury. Experimental studies have indicated that hypothermic perfusion before ischaemia may attenuate functional recovery after reperfusion, but that this detrimental effect can be ameliorated by hypocalcaemic perfusion before 5 or during cardioplegic arrest. 13 One clinical study suggested that rapid myocardial cooling could result in significant damage and recommended "slow" cooling before induction of cardioplegic arrest.…”