Abstract
Objectives
After cardiac surgery, long aortic clamping times and extracorporeal circulation times
are associated with worse outcomes. This study compares hemodynamic performance, myocardial
metabolism, and ultrastructural preservation in rat hearts after applying esmolol
crystalloid cardioplegia (ECCP) or Calafiore blood cardioplegia (Cala).
Materials and Methods
Hearts from 18 Wistar rats were perfused in a Langendorff system. Following 120 minutes
of ischemia at 36 °C, hearts received either ECCP at 32 °C for 3 minutes or Cala at
36 °C for 2 minutes every 20 minutes. During 90 minutes of reperfusion, coronary blood
flow (CF), left ventricular developed pressure (LVDP), and contraction/relaxation
velocities (±dp/dt) were recorded. Myocardial oxygen consumption, lactate production,
and troponin I levels were measured. Electron microscopy was used for ultrastructural
assessment.
Results
Baseline (BL) values of LVDP, CF, and ±dp/dt were similar between the two groups.
After 90 minutes of reperfusion, CF was significantly higher in the ECCP group: 85 ± 43%
of BL in the ECCP group versus 42 ± 24% of BL in the Cala group (p = 0.002). At the end of reperfusion, hearts exposed to ECCP had higher LVDP (91 ± 40%)
values than Cala (43 ± 10%), indicating improved cardiac recovery with ECCP. Myocardial
contraction and relaxation were notably better in the ECCP group: dLVP/dtmax was 111 ± 40% versus 59 ± 13% in the Cala group (p = 0.002), and dLVP/dtmin was 88 ± 34% versus 40 ± 7% (p = 0.001). Troponin I levels measured in Cala hearts at the end of reperfusion were
higher than in ECCP hearts (Cala 1,102.6 ± 361.3 ng/mL vs. ECCP 442.3 ± 788.4 ng/mL,
p = 0.036).
Conclusion
In rat hearts, ECCP offers better hemodynamic recovery and protects the myocardium
from ischemia/reperfusion-related damage, better than Cala blood cardioplegia, even
with aortic clamping times of 120 minutes.
Keywords
esmolol cardioplegia - blood cardioplegia - myocardial protection - ischemia–reperfusion
injury
