Describe cold cardioplegia and its purpose during on-pump CABG.

• A. Warm saline to arrest the heart.
• B. Cold saline to hydrate the heart.
• C. Cold cardioplegia is a cold, crystalloid or blood-based solution delivered to arrest the heart and provide myocardial protection by reducing metabolic demand.
• D. No cardioplegia is used.

Answer: (C)

During on-pump CABG, protecting the heart while it’s deprived of normal blood flow is essential. Cold cardioplegia accomplishes this by delivering a cold, potassium-rich solution to arrest the heart and offer myocardial protection. The cold temperature lowers the heart’s metabolic rate and oxygen consumption, helping preserve energy stores during the ischemic period. The solution can be crystalloid or blood-based and is given through the coronary circulation (antegrade via the aorta or retrograde via the coronary sinus), often in repeated doses to maintain protection until the heart is reperfused. This approach creates a still surgical field and reduces the risk of ischemia-reperfusion injury. The other options don’t fit because warm saline would not reliably arrest or protect the heart, cold saline to hydrate ignores the protective effect, and omitting cardioplegia leaves the myocardium vulnerable during bypass.