title: Blood cardioplegia serves as a bicarbonate donor to the myocardium during ischemia: effects of anoxia and hypercapnia on acid-base characteristics of blood cardioplegic solution.
abstract: OBJECTIVE
  We investigated the alterations of acid-base characteristics of the blood cardioplegia (BCP) solution during aortic cross-clamping in hearts arrested with BCP and during in vitro-simulated ischemia.
  
  
  METHODS
  Following aortic cross-clamping, the hearts of 40 patients undergoing cardiac surgery were intermittently infused with an 18°C BCP solution and finally with a 34°C BCP solution prior to aortic cross-clamp release. We measured the pH, partial CO(2) pressure (pCO(2)), [HCO(3)(-)], and [Cl(-)] of the coronary sinus effluent in the final BCP solution. The BCP solution was assessed under in vitro gassing at 34°C with 95% N(2) + 5% CO(2) (n = 6), 50% N(2) + 50% CO(2) (n = 3), or 100% CO(2) (n = 6).
  
  
  RESULTS
  The coronary sinus effluent, compared with the preinfusion BCP solution, exhibited a significantly lower pH and a greater pCO(2) with no change in the [HCO(3)(-)] level. In vitro, the 95% N(2) + 5% CO(2) gassing (simulated hypoxia) group exhibited a slight increase in [HCO(3)(-)] with no change in pCO(2) or pH whereas the 50% N(2) + 50% CO(2) gassing and the 100% CO(2) gassing (simulated hypoxia and hypercapnia) groups exhibited a significant increase in [HCO(3)(-)] under high pCO(2)-induced acidification.
  
  
  CONCLUSIONS
  Under anoxia and CO(2) retention during aortic cross-clamping, the BCP solution can be a bicarbonate donor to the myocardium.
authors.affiliation: Department of Cardiovascular Surgery, Akita University, School of Medicine, Akita, Japan. h-yama@cvs.med.akita-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Goh
authors.forename: K
authors.initials: K
authors.lastname: Magishi
authors.forename: T
authors.initials: T
authors.lastname: Sasajima
authors.forename: F
authors.initials: F
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D001639:Bicarbonates / Q000737:chemistry / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry / Q000378:metabolism*; D002314:Cardioplegic Solutions / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D006324:Heart Arrest, Induced; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D002314:Cardioplegic Solutions; D002245:Carbon Dioxide