RT Book, Section
A1 Athanasuleas, Constantine L.
A1 Buckberg, Gerald D.
A2 Yuh, David D.
A2 Vricella, Luca A.
A2 Yang, Stephen C.
A2 Doty, John R.
SR Print(0)
ID 1104588484
T1 Myocardial Protection
T2 Johns Hopkins Textbook of Cardiothoracic Surgery
YR 2014
FD 2014
PB McGraw-Hill Education
PP New York, NY
SN 978-0-07-166350-2
LK accesssurgery.mhmedical.com/content.aspx?aid=1104588484
RD 2024/04/20
AB Cardioplegia  markedly  reduces  oxygen  demand  in  the  arrested  heart  and  must  be  delivered  uniformly  in  sufficient  quantity  to  match  this  low  demand.“Integrated  myocardial  protection”  is  a  myocardial  protection  strategy  that  includes  antegrade  and  retrograde  delivery  of  cold-blood  cardioplegia  and  warm  cardioplegia  perfusion  for  induction  and  resuscitation.Hypothermia  reduces  myocardial  oxygen  demand  and  ischemic  injury  when  coronary  flow  is  interrupted;  however,  it  does  not  completely  prevent  injury  in  chronically  ischemic  hearts.Blood  cardioplegia,  which  typically  comprises  four  parts  blood  to  one  part  crystalloid  solution,  is  a  natural  buffering  agent,  maintains  oncotic  pressure,  possesses  advantageous  rheologic  properties,  and  is  a  free-radical  scavenger.High  potassium  in  cardioplegia  maintains  cardiac  arrest  and  prevents  sudden  intracellular  calcium  accumulation  and  sarcolemma  disruption.Complete  myocardial  recovery  occurs  after  4  h  of  ischemia  in  normal  hearts  when  protected  with  cold-blood  cardioplegia.Antegrade  or  retrograde  delivery  of  cardioplegia  alone  does  not  provide  homogeneous  distribution  even  with  normal  coronary  arteries.Paradoxical  septal  motion,  seen  in  up  to  40  percent  of  cardiac  surgical  patients,  can  lead  to  acute  right  ventricular  failure  and  may  be  caused  by  inadequate  distribution  of  cardioplegia.Warm-blood  cardioplegia  induction  limits  reperfusion  injury  in  ischemic  hearts.During  antegrade  infusion  of  cardioplegia,  aortic  pressure  should  be  maintained  between  60  and  80  mm  Hg  at  a  flow  rate  of  200  cm3/min  or,  in  hypertrophied  hearts,  at  250  cm3/min.