Effect of increasing volume of cardioplegic solution on postischemic myocardial recovery

Area of Science:

• Cardiology
• Cardiac Surgery
• Biochemistry

Background:

• Multidose cardioplegia is considered superior to single-dose for myocardial protection during ischemia.
• Concerns exist that large volumes of cardioplegic solution may lead to detrimental washout of adenine nucleotide degradation products, limiting adenosine triphosphate recovery.

Purpose of the Study:

• To investigate the effects of increasing cardioplegic solution volume on postischemic myocardial recovery.
• To determine if higher volumes of cardioplegic solution exacerbate the washout of adenine nucleotides.

Main Methods:

• Four groups of subjects received different cardioplegia regimens: single dose, or multidose infusions every 30 or 20 minutes for 1 or 2 minutes.
• All groups underwent 2 hours of ischemia at 20°C.
• Myocardial function, adenine nucleotide levels, and total tissue purines were assessed after reperfusion.

Main Results:

• While washout of nucleotide degradation products during ischemia increased with higher cardioplegic volumes, total washout after reperfusion was similar across all groups.
• Multidose cardioplegia groups demonstrated better functional recovery and significantly higher total tissue purines after 30 minutes of reperfusion.
• No significant differences in adenosine triphosphate levels were observed among the groups post-reperfusion.

Conclusions:

• Increasing the volume of cardioplegic solution within a clinically relevant range does not increase adenine nucleotide loss from cardiac cells.
• Higher volumes of cardioplegic solution, when administered multidose, are not associated with impaired postischemic myocardial functional recovery.