Benefits of normothermic induction of blood cardioplegia in energy-depleted hearts, with maintenance of arrest by multidose cold blood cardioplegic infusions

Integrated Myocardial Management: Background and Initial Application

“…The original studies of cold blood cardioplegia showed that complete recovery of function follows up to 4 hours of aortic clamping when cold multidose blood cardioplegia (at 20-to 30-min intervals) is delivered to normal hearts,2.14 underscoring its capacity to "prevent ischemic damage.'' Unfortunately, normal myocardium is becoming a surgical rarity, and subsequent studie~6~*?l9, 20 show that retention of the capacity to prevent further damage in the energy-and substrate-depleted heart is an insufficient endpoint, and that impaired function may persist despite avoidance of further injury with primary reliance on hypothermic blood cardioplegic techniques (Fig. 1).…”

“…Most surgeons stop the heart with high-dose potassium blood cardioplegia (20 mEq/L) and use multidose low-dose potassium (8 to 10 mEq/L) for the remainder of the operation, since hypothermia potentiates electromechanical quiescence, and more marked hyperkalemia is superfluous. The use of cold normal blood antegrade coronary perfusion was described previously and documented by Bromfim in studies of patients undergoing aortic valve replacement.…”

<![CDATA[Myocardial metabolism after hypothermic retrograde continuous blood cardioplegia with anterograde warm cardioplegic induction]]>

“…This inadequate cellular metabolism during reperfusion might be due to mitochondrial alterations with transitory incapacity to maintain a normal aerobic metabolism. Also it is possible that depletion of adenine nucleotides with consequent loss of ATP precursors had delayed the regeneration of myocardial ATP [14,19,[22][23][24][25].…”

“…The objective of this study is to determine alterations suffered by the myocardium, utilizing continuous retrograde hypothermic sanguineous cardioplegia in addition to normothermic anterograde cardioplegia induction. The aim of this technique is to better preserve myocardium ATP reserves during the asystole induction phase or even to re-establish these reserves if there is a preexistent depletion [14,15].…”

Protean Causes of Myocardial Stunning in Infants and Adults

“…14 Warm induction replenishes creatinine phosphate (CP), but does not restore myocardial ATP levels, although mito chondria harvested from these hearts retain a normal capacity for oxidative phosphorylation and ATP production. 12 Evidence of cardiac stun ning in this model was evident from: (1) marked functional depression in hearts reperfused with normal blood by simply unclamping the aorta after 45 minutes; (2) failure of cold blood car dioplegic solution to restore function of energy and substrate depleted hearts; and (3) the capacity to use the interval of warm induction and warm reperfusion interspersed with intermit tent cold blood cardioplegia to restore greater than 80% of contractile capacity, despite 2 added hours of aortic clamping. 1214 These data suggest that cardiac stunning may be limited in severity in energy and substrate depleted hearts by initiating the process of reperfusion (i.e., during cardioplegia and/or induction before aor tic unclamping) with a warm blood cardioplegic solution that averts several of the consequences of reperfusion damage.…”