CVP CVP Myocardial Protection and Cardioplegia 1 — Questions and Answers
Question 1: What is the primary purpose of cardioplegia solution in cardiac surgery?
- To dilute blood during CPB
- To arrest the heart and protect the myocardium from ischemic injury (Correct answer)
- To improve systemic circulation during bypass
- To provide systemic anticoagulation
Correct answer: To arrest the heart and protect the myocardium from ischemic injury
Cardioplegia solution is used to induce electromechanical cardiac arrest and provide metabolic protection to the myocardium during ischemia.
Question 2: Which electrolyte is primarily responsible for inducing cardiac arrest in cardioplegia solution?
- Sodium
- Calcium
- Potassium (Correct answer)
- Magnesium
Correct answer: Potassium
High concentrations of potassium (15–30 mEq/L) depolarize the myocardial cell membrane and arrest the heart in diastole.
Question 3: What temperature range is typically used for cold blood cardioplegia delivery?
- 37°C
- 28°C
- 4–10°C (Correct answer)
- 20°C
Correct answer: 4–10°C
Cold cardioplegia (4–10°C) reduces myocardial metabolic demand by lowering temperature, slowing enzymatic reactions.
Question 4: Antegrade cardioplegia is delivered via which route?
- Coronary sinus
- Aortic root or coronary ostia (Correct answer)
- Pulmonary artery
- Left ventricle directly
Correct answer: Aortic root or coronary ostia
Antegrade cardioplegia follows normal coronary blood flow, delivered into the aortic root proximal to the cross-clamp or directly into the coronary ostia.
Question 5: Retrograde cardioplegia is delivered via which structure?
- Aortic root
- Right atrium
- Coronary sinus (Correct answer)
- Left atrium
Correct answer: Coronary sinus
Retrograde cardioplegia is infused through the coronary sinus, flowing backwards through the venous coronary system to perfuse the myocardium.
Question 6: What is the typical potassium concentration in a standard cardioplegia solution compared to normal plasma?
- Similar to plasma (3.5–5 mEq/L)
- Slightly elevated (6–10 mEq/L)
- Markedly elevated (15–30 mEq/L) (Correct answer)
- Extremely elevated (50–70 mEq/L)
Correct answer: Markedly elevated (15–30 mEq/L)
Standard cardioplegia contains 15–30 mEq/L of potassium, roughly 4–6 times the normal plasma level, sufficient to arrest the heart.
CVP CVP Myocardial Protection and Cardioplegia 1
What is the primary purpose of cardioplegia solution in cardiac surgery?