Continuous warm versus intermittent cold cardioplegic infusion: a comparison of energy metabolism, sodium-potassium adenosine triphosphatase activity, and postischemic functional recovery in the blood-perfused rat heart.
We used metabolic, enzymatic, and functional end points to compare the protective properties of continuous warm and intermittent cold cardioplegic infusion in isolated, blood-perfused rat hearts. After excision, hearts (n = 12 per group) were preserved for 3 hours by one of the following cardioplegic procedures: (1) continuous infusion of warm (37 degrees C) blood cardioplegic solution prepared by mixing Fremes' solution with rat arterial blood in a ratio of 1:4, (2) continuous infusion of warm (37 degrees C) crystalloid cardioplegic solution prepared by mixing Fremes' solution with bicarbonate buffer solution in a ratio of 1:4, or (3) intermittent infusion of cold (20 degrees C) St. Thomas' Hospital cardioplegic solution number 2 infused for 3 minutes every 30 minutes during a 3-hour period of ischemia. In the continuous-infusion cardioplegic groups, the solution was infused through the aorta at a flow rate of 0.8 ml.min-1.gm-1 heart. At the end of the 3-hour preservation period, myocardial sodium-potassium adenosine triphosphatase activity (an index of ion-exchange activity) was assessed in six hearts in each group. The remaining hearts in each group were then aerobically perfused at 37 degrees C with arterial blood (from a support rat) for a further 50 minutes, during which time they were atrially paced at 320 beats/min. At the end of this period, left ventricular developed and end-diastolic pressures were assessed with an intraventricular balloon; the hearts were then freeze-clamped and taken for the measurement of tissue adenosine triphosphate and creatine phosphate content. Hearts (n = 6) aerobically perfused with blood for 50 minutes (no cardioplegic infusion) served as control preparations. At a balloon volume of 180 microliters, the mean final values for left ventricular developed pressure in the continuous warm blood, continuous warm crystalloid, and intermittent cold cardioplegic groups were 98 +/- 5 mm Hg (p < 0.05), 70 +/- 5 mm Hg, and 78 +/- 5 mm Hg, respectively. This was compared with 122 +/- 5 mm Hg in control hearts (p < 0.05 vs the rest). For left ventricular end-diastolic pressure, the corresponding values were 33 +/- 3 mm Hg, 32 +/- 6 mm Hg, and 14 +/- 4 mm Hg (p < 0.05), respectively. The control value was 16 +/- 3 mm Hg (p < 0.05 vs continuous warm blood and continuous warm crystalloid groups). Tissue content of adenosine triphosphate was similarly reduced to approximately 50% of control values in all groups, and creatine phosphate content fully recovered in all groups. Sodium-potassium adenosine triphosphatase activity was poorly preserved in continuous warm crystalloid-treated hearts (0.012 +/- 0.003 vs 0.030 +/- 0.008 mumol inorganic phosphate-mg-1.min-1.
Qiu
Y
Y
Department of Cardiovascular Research, Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
Galiñanes
M
M
Haddock
P S
PS
Hcarse
D J
DJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001011:Aorta; D001639:Bicarbonates / Q000008:administration & dosage; D001769:Blood; D002122:Calcium Chloride / Q000008:administration & dosage; D002304:Cardiac Pacing, Artificial; D002314:Cardioplegic Solutions / Q000008:administration & dosage*; D003080:Cold Temperature; D000077324:Crystalloid Solutions; D004734:Energy Metabolism; D006321:Heart / Q000502:physiology*; D006324:Heart Arrest, Induced / Q000379:methods*; D006358:Hot Temperature; D007261:Infusions, Intra-Arterial; D007474:Ion Exchange; D007552:Isotonic Solutions; D008274:Magnesium / Q000008:administration & dosage; D008297:Male; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010952:Plasma Substitutes / Q000008:administration & dosage; D011189:Potassium Chloride / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000008:administration & dosage; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
D001639:Bicarbonates; D002314:Cardioplegic Solutions; D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010710:Phosphates; D010952:Plasma Substitutes; C041711:St. Thomas' Hospital cardioplegic solution; D010725:Phosphocreatine; D012965:Sodium Chloride; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D002122:Calcium Chloride