Buckberg's blood cardioplegia for protection of adult and senile myocardium in a rat in vitro model of acute myocardial infarction.

BACKGROUND

In patients undergoing surgical myocardial revascularization for acute myocardial infarction, excellent myocardial protection can be achieved by blood cardioplegia. We investigated the influence of age on cardiac function, metabolism, and infarct size using Buckberg's blood cardioplegia (BCP).

METHODS

The hearts of male Wistar rats ("adult", age 3 months, n = 8; "senile", age 24 months, n = 8) were excised and mounted on a blood-perfused isolated heart apparatus. An acute myocardial infarction was induced by coronary artery ligation for 30 min before aortic clamping and infusion of Buckberg's BCP. Throughout the experiment, functional parameters were recorded: coronary blood flow (normalized by heart weight), left ventricular peak developed pressure (LVpdP), and positive and negative derived left ventricular pressure over time (dLVPdtmax and dLVPdtmin). Oxygen consumption (MVO2) and lactate production of the hearts were calculated. The infarct size after 90 min of reperfusion (in % of the area at risk) was measured with triphenyl tetrazolium chloride staining of the myocardium.

RESULTS

The baseline coronary flow normalized by heart weight was significantly lower in the senile hearts (1.6 ± 0.4 ml/(min ∗ g)) compared with the adult hearts (2.0 ± 0.3 ml/(min ∗ g); p = 0.04). After 90 min of aortic clamping, hemodynamic function of senile hearts recovered better than that of adult hearts: LVpdP (adult 57% of baseline [BL]; senile 88% BL; p = 0.044) and dLVPdtmax (adult 74% BL, senile 102% BL; p = 0.12). In contrast, myocardial infarct size was similar between the adult (26%) and senile (21%; p = 0.45) hearts, and coronary flow recovered to a similar extent (55% BL and 58% BL, respectively). During reperfusion, MVO2 (80% BL and 81% BL) and lactate production (1.2 and 1.3 μmol/min) were similar in the two groups.

CONCLUSION

After acute myocardial infarction in a rat model, hearts recovered function after reperfusion with Buckberg's BCP solution. Hearts from aged animals recovered better than those from younger animals.