Introduction

Nonbacterial thrombotic endocarditis (NBTE) is a rare condition typically associated with malignancy or autoimmune disorders. It presents unique diagnostic and perioperative challenges. The case presents the anesthetic management of a 37-year-old female with NBTE requiring surgical excision of mitral valve vegetation.

 

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Case Summary

• The patient is a 37F with a complex hypercoagulable history, including multiple spontaneous abortions, recurrent VTE (including PEs on anticoagulation), and uterine fibroids.

• She was referred for mitral valve surgery due to enlarging vegetations on TEE (1 cm anterior leaflet, 2 mm posterior kissing lesion).

• Extensive infectious and autoimmune workup was negative.

• Diagnosis: Nonbacterial thrombotic endocarditis (NBTE).

• The plan was for vegetation excision with possible valve replacement.

 

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Preoperative Planning

• Multidisciplinary collaboration was conducted with cardiology, infectious disease, cardiothoracic surgery, and hematology.

• Heparin resistance was anticipated based on clinical history.

• A pre-induction arterial line was placed.

• Induction was performed with IV midazolam, fentanyl, lidocaine, propofol, and rocuronium.

• Post-induction, a central line and PA catheter were placed.

 

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Intraoperative Course

• An initial heparin bolus of $300~u/kg$ did not achieve an ACT >400.

• A repeat bolus was ineffective; the ACT remained <400.

• The Pre-op AT III level was 74% (normal: 80-120%).

• Intraoperative AT III administration was given to achieve an ACT >400, and CPB was initiated.

• Successful mitral valve vegetation excision was performed, and the valve was preserved.

 

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Postoperative Management

• Heparin infusion was bridged to warfarin (goal INR 2.5).

• Daptomycin was initiated due to MRSE growth from intraoperative cultures.

• Weekly monitoring labs included CBC, CMP, ESR, CRP, and CPK.

• Pain control utilized non-narcotic analgesia and lidoderm.

• Post Op pericarditis was managed with colchicine and ibuprofen.

 

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Discussion

• NBTE vs. Infective Endocarditis (IE) Differences:

• NBTE vegetations are typically small, noninvasive, and non-destructive

• Unlike infective endocarditis, NBTE vegetations rarely cause overt hemodynamic compromise

• Despite being non-destructive, NBTE vegetations still pose a substantial risk of systemic embolization

• Anticoagulation Challenges (Heparin Resistance):

• NBTE presents unique anesthetic challenges driven by its prothrombotic state and embolic potential

• In this case, heparin resistance was recognized only after the failure of two 300 u/kg boluses to achieve the target ACT

• Borderline AT III levels likely contributed to this resistance

• Functional AT III deficiency is a known but often underrecognized contributor to heparin resistance, especially in hypercoagulable states

• Management and Anesthesiologist's Role:

• The necessity for swift intraoperative troubleshooting is underscored by the failed heparin boluses

• Timely administration of AT III concentrate was essential, as it restored adequate anticoagulation, allowing for safe progression to cardiopulmonary bypass (CPB)

• Anesthesiologists must anticipate unpredictable ACT kinetics in NBTE

• It's necessary to ensure immediate access to adjunctive anticoagulants (e.g., AT III, Fresh Frozen Plasma (FFP), Direct thrombin inhibitors)

• Multidisciplinary coordination is vital for surgical and anesthetic planning.