Interventricular Differences Research Articles

Regional differences in myocardial acid production have not been characterized during administration of either asanguineous or sanguineous cardioplegia. To investigate this, miniature glass pH electrodes were placed in the right ventricular (RV) myocardium, the left ventricular subendocardial (LV endo) region, and the subepicardial (LV epi) region in a canine model. Multiple doses of either blood cardioplegia (Group 1; N = 11) or crystalloid cardioplegia (Group 2; N = 11) were administered during 4 hours of aortic cross-clamping. The accumulation of hydrogen ions during the cross-clamp period was greater in Group 2 than Group 1 in the LV endo region (629 ± 79 nm/L versus 66 ± 31 nm/L; p < 0.001), the LV epi region (623 ± 66 nm/L versus 72 ± 32 nm/L; p < 0.001), and the RV myocardium (814 ± 296 nm/L versus 150 ± 54 nm/L; p < 0.05). Within each group, the time course of myocardial pH and the accumulation of hydrogen ions did not differ among the LV endo region, LV epi region, and the RV myocardium ( p = not significant). These data indicate that transmural and interventricular differences in myocardial pH and hydrogen ion accumulation are not produced in the vented, arrested canine heart. In addition, when compared with asanguineous cardioplegia, blood cardioplegia globally and transmurally reduces acid accumulation during ischemic arrest.

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