CVP CVP Myocardial Protection and Cardioplegia 2 — Questions and Answers
Question 1: Warm blood cardioplegia is delivered at approximately what temperature?
- 4°C
- 10°C
- 28°C
- 37°C (Correct answer)
Correct answer: 37°C
Warm blood cardioplegia is delivered at normothermia (approximately 37°C) to maintain aerobic metabolism while the heart is arrested.
Question 2: What is the primary advantage of Del Nido cardioplegia over traditional formulations?
- It requires more frequent re-dosing
- It allows a single dose to provide 60–90 minutes of cardiac arrest (Correct answer)
- It contains no potassium
- It must be delivered retrograde only
Correct answer: It allows a single dose to provide 60–90 minutes of cardiac arrest
Del Nido cardioplegia is a single-dose, crystalloid-based formulation designed to maintain arrest for 60–90 minutes, reducing re-dosing interruptions.
Question 3: What is the purpose of adding magnesium to cardioplegia solution?
- To increase cardiac contractility on reperfusion
- To provide membrane stabilization and reduce calcium-mediated injury (Correct answer)
- To lower viscosity of the solution
- To decrease the potassium concentration needed
Correct answer: To provide membrane stabilization and reduce calcium-mediated injury
Magnesium acts as a physiologic calcium antagonist, stabilizing cell membranes and reducing calcium overload during ischemia.
Question 4: How often is cardioplegia typically re-dosed during prolonged cardiac arrest with intermittent technique?
- Every 5–10 minutes
- Every 20–30 minutes (Correct answer)
- Every 60 minutes
- Only once at the beginning
Correct answer: Every 20–30 minutes
Intermittent cardioplegia is re-dosed every 20–30 minutes to replenish protective concentrations washed out by non-coronary collateral flow.
Question 5: Retrograde cardioplegia is preferred over antegrade delivery in which clinical situation?
- Mild mitral regurgitation
- Severe aortic regurgitation (Correct answer)
- Tricuspid stenosis
- Pulmonic valve disease
Correct answer: Severe aortic regurgitation
In severe aortic regurgitation, antegrade cardioplegia leaks back into the left ventricle rather than perfusing the coronaries, making retrograde delivery more reliable.
Question 6: What does the term 'hot shot' refer to in cardioplegia delivery?
- High-temperature retrograde cardioplegia at the start
- A warm blood reperfusate delivered just before aortic cross-clamp removal (Correct answer)
- A bolus of cold crystalloid for rapid arrest
- Rapid high-pressure antegrade cardioplegia
Correct answer: A warm blood reperfusate delivered just before aortic cross-clamp removal
A 'hot shot' is a terminal warm blood cardioplegia dose delivered before removing the cross-clamp to restore aerobic metabolism and wash out ischemic metabolites.
CVP CVP Myocardial Protection and Cardioplegia 2
Warm blood cardioplegia is delivered at approximately what temperature?