retrograde cardioplegic delivery as the strongestindependent predictor of in-hospital mortality [46].. Warm cardioplegia may resuscitate ischemic myocardium if it can be delivered unifor
Trang 1retrograde cardioplegic delivery as the strongest
independent predictor of in-hospital mortality
[46]
Warm cardioplegia may resuscitate ischemic
myocardium if it can be delivered uniformly but
intermittent discontinuation to permit
visualiza-tion of distal anastomoses can result in ischemic
anaerobic metabolism [47] The Toronto Group
has reported that blood cardioplegia at 29C
(so-called ‘‘tepid cardioplegia’’) can reduce lactate
acid production compared with warm (37C)
cardioplegia This treatment resulted in better
contractile function compared with cold (10C)
blood cardioplegia [48] Others have suggested
that patients who have unstable angina or
prolonged preoperative ischemia may deplete
metabolic reserves and benefit from
substrate-enhanced cardioplegia with Krebs Cycle
interme-diates, such as glutamate, malate, succinate, or
fumarate [49] Patients who have diabetes have diffuse atherosclerotic disease, which may limit cardioplegic distribution and prevent complete revascularization Some authors therefore recom-mend both antegrade and retrograde infusions
[50] The rationale is that the different approaches perfuse different myocardial territories and that the combination may provide more homogeneous cardioplegia delivery
The management of patients at risk for low cardiac output syndrome
Three categories of patients are at substantial risk First are those who present urgently for surgery, already in cardiogenic shock, often with
a complication of myocardial infarction or in-fective endocarditis Second is the group Fig 2 (continued)
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MAXIMIZING SURVIVAL POTENTIAL IN CARDIAC SURGERY