What Can We Learn From Cases of Internal Mammary Artery Damage in Coronary Artery Bypass Graft?

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What Can We Learn From Cases of Internal Mammary Artery Damage in Coronary Artery Bypass Graft?

Coronary artery bypass grafting (CABG) is a life-saving procedure for millions with severe coronary artery disease, and the left internal mammary artery (LIMA) is the gold-standard graft for restoring heart blood flow—thanks to its long-term durability and patency. But when this critical artery is damaged during surgery, outcomes can be compromised. A 20-year study from Beijing’s Anzhen Hospital offers vital lessons for surgeons and hope for patients navigating complications.

The Study: 20 Years of IMA Damage Data

From July 1997 to April 2017, researchers led by Mi Chen, Fang-Jiong Huang, and colleagues from the Department of Cardiac Surgery at Anzhen Hospital, Capital Medical University, analyzed 10,360 CABG surgeries where the IMA was harvested. They found 286 cases of IMA damage—an incidence of 2.7%, which the team notes is relatively high.

Why the higher rate? Inexperience: While one surgeon (Fang-Jiong Huang) led all procedures, over 200 young, less-experienced surgical assistants handled IMA harvesting across multiple hospitals. This learning curve was the primary driver of injury.

6 Critical Tips for Young Surgeons to Prevent IMA Damage

The team’s biggest takeaway? Preventing IMA damage starts with training. Here’s their evidence-based advice for early-career surgeons:

  1. Master LIMA Anatomy: The LIMA is easily injured if it’s tightly stuck to the sternum or kinks significantly near its origin. Always inspect for these red flags before harvesting.
  2. Use Low-Power Coagulation: Stick to 20 W coagulation output—higher power increases thermal damage risk.
  3. Keep Electrocautery at a Distance: Maintain at least 0.5 cm between the electrocautery tool and the IMA, and minimize use time. For a gentler approach, choose radiosurgery over electrosurgery (a 2014 study found radiosurgery causes less thermal harm to the IMA).
  4. Avoid Clips + Electrocautery: If you’ve placed a clip on an IMA branch, use scissors instead of electrocautery—clips conduct heat and can damage the artery.
  5. Skip Intraluminal Tools When Possible: Metal probes or retrograde papaverine injections (used to treat spastic IMA) often cause dissection. Only use these as a last resort, and with extreme caution.
  6. Wait for Heparinization Before Clamping: Never use a Bulldog clamp on the IMA until full heparinization is complete—this prevents dangerous blood clots.

How to Fix IMA Damage: A Targeted Protocol

When injury did occur, the team tailored treatment to the cause and location of damage—key to preserving graft function:

  • Proximal Damage (Near the Origin): For endothelial disruption or stenosis, use free IMA grafts to bypass the injured segment.
  • Distal Damage (Far from the Origin): Opt for a skeletonized IMA (stripped of surrounding tissue) or extend the IMA with the great saphenous vein (GSV).
  • Middle Damage or Dissection: For patients over 60, replace the IMA with GSV (a more flexible option for older adults). For younger patients, use the radial artery (RA) or right IMA (RIMA) depending on where the left anterior descending artery (LAD) is narrowed.
  • Bleeding IMA: Suture directly or use a GSV patch. If the IMA is too short, switch to free IMA grafts.
  • Hidden Damage: Use transit-time flow measurement (Medistim VeriQ) to check for silent issues. If the LIMA-LAD pulsatility index (PI) is above 5 or flow is below 15 mL/min near the anastomosis, add a GSV graft from the aorta to the LAD.

Postoperative Outcomes: What We Learned

Of the 286 cases, 8 (2.8%) had adverse events—including:

  • 1 death from extensive thrombosis in the LIMA and GSV grafts
  • 2 cerebral infarctions
  • 2 cases requiring an intra-aortic balloon pump
  • 1 conversion from minimally invasive to full sternotomy
  • 1 switch from off-pump (OPCAB) to on-pump CABG due to ventricular fibrillation
  • 1 acute heart attack 4 hours post-surgery

Seven of these were major adverse cardiovascular and cerebrovascular events (MACCEs)—a stark reminder of how critical careful IMA handling is.

Minimally Invasive Surgery: Balancing Innovation and Risk

Minimally invasive CABG (MIDCAB) and robotic CABG (RobECAB) have revolutionized surgery—but IMA damage can force surgeons to abandon minimal access and switch to full sternotomy, eroding the benefits of less-invasive techniques. The team noted that when LIMA injury occurred in these cases, they had to convert to open surgery. However, a 2016 study by Athanasiou et al. offered alternatives: axillary bypass for proximal injury, shunts for mid-LIMA damage, and extensions for distal injury—all to avoid sternotomy.

Long-Term Insights: Patency and Pitfalls

While long-term follow-up data is limited, the team shared two key case studies:

  • Success: An 8-year postoperative angiogram showed excellent flow in a LIMA-GSV conduit—suggesting this method is viable for short IMAs. Placing the anastomosis closer to the GSV’s origin helped preserve LIMA function.
  • Caution: Directly suturing an IMA injury (with an 8-0 propylene suture) led to stenosis at the site 6 months later. For injuries larger than half the IMA’s diameter, the team now uses free IMA grafts instead of direct suturing to avoid recurrence.

The Bottom Line: A Protocol That Works

The team’s tailored approach to IMA damage proved effective—balancing patient age, injury location, and graft availability. For surgeons, the takeaway is clear: prevention through training and adherence to best practices is non-negotiable. For patients, it’s reassurance that even when complications arise, evidence-based strategies exist to adapt.

References

  1. Bulat C, Pesutic-Pisac V, Capkun V, Marovic Z, Pogorelic Z, Druzijanic N. Comparison of thermal damage of the internal thoracic artery using ultra high radiofrequency and monopolar diathermy. Surgeon: J R Coll Surgeon Edinb Irel 2014;12:249–255. doi: 10.1016/j.surge.2013.09.005.
  2. Athanasiou T, Ashrafian H, Harling L, Casula R. Bailouts to LIMA damage for avoiding conversion in minimal access coronary procedures. Ann Thorac Surg 2016;102:e173–e176. doi: 10.1016/j.athoracsur.2016.02.059.

How to cite this article: Chen M, Huang FJ, Wu Q, Zou YX, Zhu EJ, Zhang JW, Zhou Y, Yu JB, Cai KQ, Han B. What can we learn from cases of internal mammary artery damage in coronary artery bypass graft? Chin Med J 2019;132:377–378. doi: 10.1097/CM9.0000000000000023

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