Interstitial pH during myocardial preservation: assessment of five methods of myocardial preservation.
We investigated changes in myocardial pH during cardioplegic arrest with five methods of preservation at 15 degrees +/- 1 degree C. Twenty-five dogs were subjected to cardiopulmonary bypass for 150 minutes. Group I (control) had hypothermia only. Group II received THAM-buffered blood cardioplegia, group III a bicarbonate-buffered blood cardioplegic solution, group IV infusions of hyperkalemic blood, and group V oxygenated St. Thomas 2 solution. After 120 minutes of ischemia, interstitial pH in group I was markedly depressed (6.4 +/- 0.07; p < 0.01). The pH in groups II and IV was well maintained (7.23 +/- 0.05 and 7.27 +/- 0.07) and differed significantly (p < 0.05) from that of the remaining groups. The pH in groups III and V was less well maintained (7.14 +/- 0.02 and 7.01 +/- 0.05), with no significant difference (p > 0.05) between these two groups. Postreperfusion functional recovery after 45 minutes was 24% +/- 6% in group I, 92% +/- 3% in group II, 82% +/- 5% in group III, 84% +/- 4% in group IV, and 66% +/- 6% in group V. Creatine kinase levels were significantly (p < 0.01) increased and ultrastructural damage was more prominent in group I compared with the remaining groups. Myocardial water content significantly increased in all groups. We conclude that a strongly buffered blood-based cardioplegic solution is more effective in preventing interstitial acidosis during moderate hypothermia and that maintenance of an optimal tissue pH plays an important role in postischemic functional recovery.
Neethling
W M
WM
Department of Cardiothoracic Surgery, Medical School, University of the Orange Free State, Bloemfontein, Republic of South Africa.
van den Heever
J J
JJ
Cooper
S
S
Meyer
J M
JM
D000818:Animals; D001639:Bicarbonates / Q000008:administration & dosage; D001769:Blood; D001834:Body Water / Q000378:metabolism; D002122:Calcium Chloride / Q000008:administration & dosage; D002314:Cardioplegic Solutions; D002315:Cardiopulmonary Bypass; D003402:Creatine Kinase / Q000378:metabolism; D004285:Dogs; D006324:Heart Arrest, Induced / Q000379:methods*; D006439:Hemodynamics; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000008:administration & dosage; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D011188:Potassium; D011189:Potassium Chloride / Q000008:administration & dosage; D012965:Sodium Chloride / Q000008:administration & dosage; D014325:Tromethamine / Q000008:administration & dosage; D016277:Ventricular Function, Left
D001639:Bicarbonates; D002314:Cardioplegic Solutions; C041711:St. Thomas' Hospital cardioplegic solution; D014325:Tromethamine; D012965:Sodium Chloride; D011189:Potassium Chloride; D003402:Creatine Kinase; D008274:Magnesium; D002122:Calcium Chloride; D011188:Potassium