Cardiac Surgery Certification Exam Coronary Artery Bypass Grafting (CABG) 1 — Questions and Answers
Question 1: The internal mammary artery (IMA) is preferred for coronary bypass grafting because:
- It has superior long-term patency compared to saphenous vein grafts (Correct answer)
- It is easier to harvest
- It has greater diameter matching all coronary targets
- It requires less anticoagulation
Correct answer: It has superior long-term patency compared to saphenous vein grafts
The left internal mammary artery has a 10-year patency rate exceeding 90%, far superior to saphenous vein grafts (50–60%), making it the gold-standard conduit.
Question 2: The most common coronary artery target for the left internal mammary artery (LIMA) graft in CABG is:
- Left anterior descending (LAD) artery (Correct answer)
- Right coronary artery (RCA)
- Obtuse marginal (OM) artery
- Posterior descending artery (PDA)
Correct answer: Left anterior descending (LAD) artery
LIMA-to-LAD grafting is the cornerstone of CABG because the LAD supplies the largest territory and the LIMA-LAD anastomosis has the best long-term outcomes.
Question 3: Off-pump CABG (OPCAB) differs from conventional CABG primarily in that:
- The procedure is performed on a beating heart without cardiopulmonary bypass (Correct answer)
- The aorta is not cross-clamped
- Only venous conduits are used
- TEE monitoring is not required
Correct answer: The procedure is performed on a beating heart without cardiopulmonary bypass
OPCAB avoids CPB by using mechanical stabilizers and heart positioners to expose coronary targets while the heart continues beating.
Question 4: The saphenous vein graft failure rate at 10 years is approximately:
- 40–50% (Correct answer)
- 5–10%
- 80–90%
- Less than 5%
Correct answer: 40–50%
Saphenous vein graft attrition is significant, with approximately 40–50% of vein grafts occluded by 10 years due to intimal hyperplasia and atherosclerosis.
Question 5: Competitive flow in a coronary bypass graft occurs when:
- A native coronary with moderate stenosis provides sufficient native flow to outcompete the graft (Correct answer)
- The bypass graft flow is greater than native coronary flow
- Two grafts are placed to the same coronary territory
- The graft is kinked near the anastomosis
Correct answer: A native coronary with moderate stenosis provides sufficient native flow to outcompete the graft
Competitive flow occurs when the native coronary is not critically stenosed, allowing antegrade native flow to compete with graft flow and potentially causing graft failure.
Question 6: Which intraoperative finding most commonly prompts conversion from off-pump to on-pump CABG?
- Hemodynamic instability during cardiac displacement (Correct answer)
- Inadequate conduit length
- Anesthesia failure
- Absence of epicardial fat
Correct answer: Hemodynamic instability during cardiac displacement
Hemodynamic instability when the heart is displaced to expose posterior targets is the most common reason for urgent conversion to CPB during OPCAB.
Cardiac Surgery Certification Exam Coronary Artery Bypass Grafting (CABG) 1
The internal mammary artery (IMA) is preferred for coronary bypass grafting because: