Experimental Evaluation of Esmolol-Crystalloid Cardioplegia Compared to Blood Cardioplegia with Calafiore in Rat Hearts

Background: Numerous cardioplegia solutions have been developed for myocardial protection during cardiac surgery. We compared hemodynamic performance, myocardial metabolism and ultrastructural preservation in rat hearts after the application of a crystalloid-based, beta blocker-based formula called esmolol crystalloid cardioplegia (ECCP) and Calafiore blood cardioplegia (Cala).

Methods: The hearts of 18 Wistar rats were excised and inserted into a blood perfused isolated heart apparatus (Langendorf perfusion). During 120 min. of ischemia, hearts received ECCP or Calafiore every 20 min. During 90 minutes of reperfusion, cardiac functional parameters were recorded, including coronary blood flow, left ventricular developed pressure (LVDP) and velocity of myocardial contraction or relaxation (±dp/dt). Oxygenconsumption and lactate production of the hearts were calculated, and Troponin I levels were measured. After perfusion fixation, the hearts were investigated for cellular oedema and mitochondrial damage by morphometry using transmission electron microscopy

Results: Baseline (BL) values of left ventricular developed pressure (LVDP), coronary flow(CF) and velocity of myocardial contraction of relaxation (±dp/dt) were similar in both groups. After 90 min. of reperfusion, hemodynamic parameters were significantly higher in the Esmolol group, respectively CF in ECCP 85 ± 43% vs. in Cala group 42 ± 24% (p = 0.002).At the end of reperfusion, hearts exposed to ECCP revealed higher LVDP (91 ± 40% values indicating improved cardiac recovery under ECCP compared to Cala (43 ± 10%)(p = 0.003). Myocardial contraction and relaxation were notably better in the ECCP group(dLVP/dt max 111 ± 40% in ECCP vs. 59 ± 13% in Cala, dLVP/dt min 88 ± 34% in ECCP group and 40 ± 7% in Cala group, respectively p = 0.002 and p = 0.001. In addition, at the end of reperfusion, lactate production with 1.9 ± 1.0 μmol/min in ECCP group and 1.1 ± 0.7 μmol/min in Cala group was similar (p = 0.084) in both groups, but myocardial oxygen consumption in the Cala group was lower 15.9 ± 1.7% than in the ECCP group32,4 ± 0,742%, (p = 0.010). Troponin I levels measured in Cala hearts at the end of reperfusion were significantly higher than in ECCP hearts (Cala 1102 ± 788 ng/mL vs. ECCP 442 ± 361 ng/mL, p = 0.036). Moreover, ultrastructural integrity indicated more pronounced cellular oedema in the Cala group.

Conclusion: In rat hearts, ECCP offers better hemodynamic recovery and better protection from ischemia/reperfusion-related damages than Cala.

Publication History

Article published online:
13 February 2024