What causes early bypass graft failure or pseudoaneurysm formation within 30 days post-operatively?

From the Guidelines

Early bypass failure or pseudoaneurysm formation within 30 days of surgery is primarily caused by technical errors during the operation, infection, hypercoagulable states, hemodynamic factors, and graft material issues. The most common causes include inadequate suture technique leading to anastomotic leakage, improper graft handling causing intimal injury, and poor vessel selection with diseased target vessels 1. Infection is another significant factor, particularly with Staphylococcus aureus being the most common pathogen. Hypercoagulable states can lead to early thrombosis, especially in patients with inherited thrombophilias or those who have inadequate antiplatelet or anticoagulation therapy postoperatively. Hemodynamic factors such as poor inflow, competitive flow, or low cardiac output states can compromise graft patency. Graft material issues, including kinking, twisting, or compression of the conduit, may also lead to early failure.

Some key factors to consider in preventing these complications include:

• Meticulous surgical technique
• Appropriate antiplatelet therapy, typically aspirin 81-325mg daily, sometimes with additional clopidogrel 75mg daily for high-risk cases, started immediately postoperatively 1
• Careful monitoring for infection with prompt antibiotic treatment
• Attention to proper graft positioning during closure

It is essential to note that the use of clopidogrel prior to coronary artery bypass grafting can increase the risk of bleeding complications, and it is recommended to withhold clopidogrel for at least 5 to 7 days in patients scheduled for elective CABG surgery 1. Understanding these mechanisms is crucial as early intervention for failing grafts or developing pseudoaneurysms can salvage the bypass and prevent catastrophic complications like rupture or limb loss.

From the Research

Causes of Bypass Failure or Pseudoaneurysm

• Bypass failure or pseudoaneurysm can occur due to various factors, including patient characteristics, clinician characteristics, and postoperative factors 2
• Risk factors for perioperative mortality and morbidity after CABG surgery can be divided into three categories: patient characteristics, clinician characteristics, and postoperative factors 2
• Postoperative complications of CABG surgery can result in significant morbidity and mortality, and physicians must rapidly diagnose these conditions while evaluating for other diseases 2

Pseudoaneurysm Formation

• Left ventricular pseudoaneurysm is a rare but serious complication of acute myocardial infarction, and prompt diagnosis and early surgical intervention is essential for patients with large or expanding left ventricular pseudoaneurysms due to the high propensity of fatal rupture 3
• Anastomotic false aneurysms are a late complication of aortic grafting, and treatment usually consists of débridement of the degenerated tissue and placement of a short interposition graft 4

Factors Influencing Bypass Failure

• Diabetes mellitus significantly increases the incidence of graft sepsis and cardiovascular morbidity in patients undergoing above-the-knee femoro-popliteal bypass 5
• The incidence of superficial wound infection, deep infection, and cardiovascular complications were significantly higher in diabetic patients undergoing above-the-knee femoro-popliteal bypass 5

Treatment Options

• Elective surgical repair of anastomotic pseudoaneurysms is preferred since emergent repair has significantly higher morbidity and mortality 4
• Peripheral angioplasty (PTA) is an effective method for revascularizing secondary obstructions in patients with graft failure, and also effective in at least one subgenicular artery in patients with diabetes with inadequate run-off after femoropopliteal bypass grafting 6