Functional recovery after ischemia: warm versus cold cardioplegia

Area of Science:

• Cardiology
• Cardiac Surgery
• Cardiovascular Physiology

Background:

• Warm continuous retrograde cardioplegia is proposed for myocardial protection during cardiac surgery, aiming to prevent ischemia during arrest.
• Its efficacy compared to standard cold intermittent antegrade cardioplegia, especially after acute global ischemia, requires investigation.

Purpose of the Study:

• To compare the myocardial protective effects of warm continuous retrograde cardioplegia versus cold intermittent antegrade cardioplegia following acute global ischemia in a canine model.

Main Methods:

• 12 dogs underwent 15 minutes of normothermic global ischemia followed by 75 minutes of cardioplegic arrest.
• Animals received either warm continuous retrograde cardioplegia (37°C) or cold intermittent antegrade cardioplegia (10°C).
• Left ventricular function, high-energy nucleotides, and myocardial edema were assessed pre- and post-ischemia.

Main Results:

• Warm retrograde cardioplegia resulted in significantly inferior myocardial preservation compared to cold antegrade cardioplegia.
• This was evidenced by reduced preload recruitable stroke work slope and decreased nucleotide levels.
• Increased end-diastolic stress-strain relationship (alpha constant) and myocardial edema were observed with warm retrograde cardioplegia.

Conclusions:

• Under the studied conditions, warm continuous retrograde cardioplegia at clinically relevant flow rates and volumes provided inadequate myocardial protection.
• Cold intermittent antegrade cardioplegia demonstrated superior myocardial preservation in this canine model of acute global ischemia.