Objectives: To study the changes in myocardial tissue pH and PO2 during cold- and warm-blood cardioplegic arrests.
Design: An experimental study in dogs.
Methods: Nine dogs underwent the following procedures: 30 minutes with an empty heart beating under cardiopulmonary bypass (control period); 30 minutes of warm (33 degrees C) cardioplegic arrest with a 1:4 mix of crystalloid in blood solution administered continuously at 150 mL/min; 30 minutes of cold (15 degrees C) cardioplegic arrest; and 30 minutes of myocardial reperfusion. The cardioplegic blood solution was administered antegradely through the ascending aorta.
Main outcome measures: Tissue pH and PO2. Arterial and coronary sinus oxygen content and myocardial consumption calculated.
Results: There was a modest but significant increase in the left anterior descending (LAD) and circumflex (Cx) tissue pH throughout the experiment. PmO2 in the LAD territory averaged 44 (7) mm Hg (mean and standard error of the mean) during the bypass period, 123 (23) mm Hg at the termination of warm cardioplegic arrest, 146 (28) mm Hg at the end of cold arrest and 66 (17) mm Hg after reperfusion. Oxygen consumption averaged 0.65 (0.15) mL/min during the bypass period, 0.3 (0.18) mL/min at the end of warm arrest, 0.25 (0.16) mL/min at the end of cold arrest and 0.45 (0.08) mL/min after reperfusion (p < 0.05). Oxygen delivery to the LAD territory was greater than myocardial oxygen consumption by an average of 2.02 (0.4) mL/min during bypass, 2.02 (0.62) mL/min after warm arrest, 2.12 (0.5) mL/min after cold arrest and 1.55 (0.25) mL/min after reperfusion (p > 0.05).
Conclusions: During cardioplegic arrest, tissue PO2 increased and oxygen consumption decreased significantly, whereas tissue pH remained normal, suggesting that continuous warm- and cold-blood cardioplegia maintained aerobic glycolysis during myocardial arrest. Thus, the increase in myocardial tissue PmO2 during cardioplegic arrest reflects the decrease in myocardial oxygen consumption while maintaining oxygen supply.
Objectifs:
Étudier les changements du pH et de la P
Conception: Étude expérimentale sur des chiens.
Méthodes: Neuf chiens ont subi les interventions suivantes: 30 minutes avec cœur vide battant en circulation extracorporelle (période témoin); 30 minutes d’arrêt cardioplégique à chaud (33 °C) avec un mélange 1:4 de cristalloïde en solution sanguine administré sans interruption à raison de 150 mL/min; 30 minutes d’arrêt cardioplégique à froid (15 °C); et 30 minutes de reperfusion du myocarde. La solution de sang cardioplégique a été administrée de façon antérograde par l’aorte ascendante.
Principales mesures de résultats:
pH et P
Résultats:
On a constaté une augmentation modeste mais significative du pH du tissu de l’artère inter-ventriculaire antérieure (AIA) et de l’artère circonflexe (Cx) pendant toute l’expérience. La Pm
Conclusions:
Au cours de l’arrêt cardioplégique, la P