Is Cooler Safer and More Advantageous? A Feasibility Study in Rabbits.

Area of Science:

• Cardiovascular Surgery
• Experimental Medicine
• Surgical Innovation

Background:

• Aortic arch reconstructions require prolonged aortic cross-clamp (ACC) times, posing risks of metabolic burden and end-organ injury.
• Extending ACC duration safely is crucial for complex aortic procedures.

Purpose of the Study:

• To investigate if induced hypothermia (IH) can safely extend ACC time.
• To evaluate the impact of IH on metabolic burden and end-organ injury during aortic arch clamping.
• To determine the potential of IH in facilitating comprehensive aortic arch reconstructions.

Main Methods:

• 62 New Zealand white rabbits were randomized into normothermia (39°C) and mild hypothermia (35°C) groups.
• Animals underwent proximal aortic arch (PAA) clamping for 20, 30, or 40 minutes.
• Biochemistry, oxidative stress biomarkers, blood gases, lactate, and histopathology were analyzed.

Main Results:

• Normothermia led to increased oxidative stress, acidosis, and end-organ injury with prolonged clamping.
• IH significantly attenuated these adverse effects, preserving acid-base balance and reducing histological injury.
• 40 minutes of hypothermic ischemia showed comparable injury to 20 minutes of normothermic ischemia.

Conclusions:

• IH protects against ischemia-reperfusion injury by minimizing oxidative damage and maintaining metabolic balance.
• IH allows for safely extended ACC times, with a safety margin of approximately 30 minutes.
• IH facilitates complex aortic arch reconstructions and warrants clinical trials.