What is the management for a postoperative air embolism stroke following a Maze procedure and mitral valve repair?

Management of Post-Operative Air Embolism Stroke Following Maze Procedure and Mitral Valve Repair

Obtain urgent brain MRI with diffusion-weighted imaging (DWI) immediately, as standard CT scans miss 58-100% of new brain lesions following cardiac valve procedures and have poor sensitivity for acute ischemic stroke within the first 6-24 hours when post-cardiac surgery neurological complications most commonly occur. 1, 2

Immediate Diagnostic Workup

Neuroimaging Protocol

• Brain MRI with DWI sequences is the gold standard for detecting acute ischemic stroke from air embolism and is far more sensitive than CT 1, 2
• Obtain CT angiography immediately to identify large vessel occlusion (ELVO), which occurs in approximately 10.9% of post-cardiac surgery strokes 2, 3
• Add CT perfusion imaging to determine salvageable brain tissue and guide intervention decisions in the extended window 3
• Do not attribute neurological deficits to "post-operative delirium" without excluding stroke with MRI 1

Timing Considerations

• 40% of strokes occur intraoperatively, with 60% occurring postoperatively, peaking at 40 hours after surgery 3
• Air embolization during valve repair is a well-documented cause of stroke, particularly if de-airing techniques were inadequate 4, 2

Acute Stroke Treatment

Mechanical Thrombectomy Decision

If ELVO is identified on CT angiography, strongly consider mechanical thrombectomy despite the recent cardiac surgery, as post-cardiac surgery patients with ELVO show a trend toward improved functional outcomes with this intervention. 2, 3

• Use individualized perfusion imaging data to guide the decision for expanded window thrombectomy 2, 3
• Communicate with the cardiothoracic surgical team before administering anticoagulation or thrombolytics, as patients with open thoracic approaches are generally not candidates for intravenous thrombolysis 3

Vascular Access Strategy

• Check for existing arterial access from the cardiac surgery, which may expedite revascularization 3
• If bilateral femoral cutdowns were performed, use transradial approach 3
• If radial artery was harvested during surgery, use transfemoral approach 3

Hyperbaric Oxygen Therapy

• Hyperbaric treatment is the definitive therapy for cerebral air embolism 5
• Although most effective when administered early, excellent outcomes can occur even with late treatment (initiated 30 hours post-embolism in documented cases) 5

Anticoagulation Management

Immediate Post-Operative Period (First 3 Months)

Initiate warfarin with target INR 2.5-3.5 for at least 3 months post-mitral valve repair, as the Maze procedure does not eliminate the need for anticoagulation in the immediate post-operative period. 1, 2

This recommendation is based on multiple high-risk factors:

• The Maze procedure involves extensive atrial manipulation and creates multiple surgical lesions that serve as thrombogenic surfaces 1
• Blood stasis from loss of atrial contraction post-Maze, combined with surgical trauma, creates a prothrombotic state 1
• Even with the Maze procedure, persistence of atrial fibrillation occurs in 80% of patients who had pre-operative atrial fibrillation ≥3 months 1
• The immediate post-operative period carries the highest thromboembolism risk due to inadequate anticoagulation, inflammatory state, and potential atrial stunning 1

Long-Term Anticoagulation Strategy

• Anticoagulation strategy must be individualized based on rhythm status and valve type after the initial 3-month period 1, 2
• For bioprosthetic mitral valves, the risk of thromboembolism is approximately 2.4% per patient-year 1, 2
• Success rates for sinus rhythm conversion range from 75-95% with maze versus 10-40% without ablation 1, 2

Monitoring for Additional Complications

Thrombogenic Sources

• Incomplete left atrial appendage closure or residual peridevice leak occurs in 26-57% of cases and is associated with increased thromboembolism risk 1, 2
• Device-related thrombus formation can occur in 2-5% of cases, typically within 180 days post-procedure 1, 2
• Atrial manipulation during maze procedure and left atrial appendage removal increases thromboembolic risk 3

Rhythm Management

• Routine placement of temporary epicardial pacing wires during surgery is recommended (Class I) 2
• Permanent pacing before discharge is indicated in patients who have new postoperative sinus node dysfunction or atrioventricular block with persistent symptoms or hemodynamic instability that does not resolve after surgery (Class I) 2

Critical Pitfalls to Avoid

• Never rely on CT head alone to exclude stroke - it misses the majority of acute ischemic events in this timeframe 1, 2
• Do not discontinue anticoagulation early based on successful rhythm conversion, as ablation with radiofrequency/cryoenergy or atrial suture lines provides an endocardial thrombogenic milieu 4
• Recognize that surgical LA appendage occlusion can be incomplete, maintaining stroke risk despite the procedure 4
• Most post-cardiac surgery brain lesions visible on MRI disappear by 3 months, but clinical significance of subclinical lesions remains unclear 1