Residency · Residency · Cardiothoracic Surgery
Infective Endocarditis: Surgical Indications and Technique
Overview
Infective endocarditis (IE) is a life-threatening infection of the cardiac valves and endocardium that frequently requires surgical intervention. Nearly 50% of IE patients undergo surgery during their index hospitalization. The CT surgeon must understand the indications for surgery, timing of intervention, principles of radical debridement, and reconstruction strategies for both native and prosthetic valve endocarditis.
Microbiology and Pathophysiology
Common Organisms
Staphylococcus aureus is the most common cause of infective endocarditis overall and tends to be aggressive, destructive, and associated with high mortality. Viridans group streptococci present more subacutely and carry a more favorable prognosis. Enterococcus is increasingly common, particularly in healthcare-associated settings. Coagulase-negative staphylococci are especially relevant in prosthetic valve endocarditis. The HACEK organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) are slow-growing and generally carry a better prognosis. Fungi, including Candida and Aspergillus, are rare but highly lethal and almost always require surgical intervention. Culture-negative IE accounts for 5-10% of cases and is often attributable to prior antibiotic administration; in these situations, organisms such as Coxiella, Bartonella, Brucella, and Tropheryma whipplei should be considered.
Pathology
The pathologic hallmark of IE is the vegetation — an infected fibrin-platelet mass on the valve surface. Progressive valve destruction manifests as leaflet perforation, chordal rupture, and annular abscess formation. Embolic events are a major source of morbidity, including stroke, mycotic aneurysms, splenic and renal infarcts, and (in right-sided IE) septic pulmonary emboli. Paravalvular extension of infection can produce abscess, fistula, and pseudoaneurysm formation.
Diagnosis
Modified Duke Criteria
The Modified Duke Criteria remain the standard diagnostic framework for IE. Major criteria include positive blood cultures (two separate cultures with a typical organism, or persistently positive cultures) and endocardial involvement on imaging (vegetation, abscess, new prosthetic valve dehiscence, or new valvular regurgitation). Minor criteria include a predisposing condition or intravenous drug use, fever of 38 degrees Celsius or greater, vascular phenomena (emboli, mycotic aneurysm, Janeway lesions, conjunctival hemorrhage), immunologic phenomena (Osler nodes, Roth spots, glomerulonephritis, positive rheumatoid factor), and positive blood cultures not meeting major criteria. Definite IE is diagnosed with 2 major criteria, 1 major plus 3 minor, or 5 minor criteria. Possible IE requires 1 major plus 1 minor, or 3 minor criteria.
Modified Duke Criteria Summary
| Category | Criteria |
|---|---|
| Major: Blood cultures | 2 separate cultures with typical organism, or persistently positive cultures |
| Major: Endocardial involvement | Vegetation, abscess, new prosthetic valve dehiscence, or new valvular regurgitation on imaging |
| Minor | Predisposing condition or IV drug use |
| Minor | Fever ≥ 38°C |
| Minor | Vascular phenomena (emboli, mycotic aneurysm, Janeway lesions) |
| Minor | Immunologic phenomena (Osler nodes, Roth spots, glomerulonephritis) |
| Minor | Positive blood cultures not meeting major criteria |
| Definite IE | 2 major, or 1 major + 3 minor, or 5 minor criteria |
| Possible IE | 1 major + 1 minor, or 3 minor criteria |
Imaging
Transthoracic echocardiography (TTE) is the initial screening modality, with sensitivity of 50-60% for native valve IE and lower for prosthetic valves. Transesophageal echocardiography (TEE) achieves sensitivity greater than 90% and is essential for prosthetic valve IE, abscess detection, and surgical planning. PET-CT with 18F-FDG is increasingly used for prosthetic valve IE diagnosis and can identify paravalvular infection. Cardiac CT delineates abscess extent, pseudoaneurysm, and coronary anatomy before surgery. Brain MRI detects silent cerebral emboli, which are present in 60-80% of left-sided IE, and its findings influence the timing of surgery.
Surgical Indications
ACC/AHA and ESC Guideline Indications
Class I (Surgery Recommended)
Surgery is recommended for heart failure caused by valve dysfunction refractory to medical therapy, uncontrolled infection defined as persistent bacteremia beyond 5-7 days despite appropriate antibiotics or abscess, fistula, or enlarging vegetation despite therapy, and prevention of embolism when a vegetation exceeds 10 mm with a previous embolic event or with other surgical indications present. Fungal endocarditis requires surgical treatment in virtually all cases. Prosthetic valve endocarditis with dehiscence, abscess, or heart failure is also a Class I indication.
Class IIa (Surgery Reasonable)
Surgery is reasonable for a large vegetation (greater than 10 mm) on the anterior mitral leaflet with severe MR and high embolic risk, for recurrent embolic events despite appropriate antibiotics, and for highly resistant organisms such as Pseudomonas, Brucella, or multidrug-resistant organisms.
Surgical Indications for IE
| Class | Indication |
|---|---|
| I | Heart failure from valve dysfunction refractory to medical therapy |
| I | Uncontrolled infection (persistent bacteremia > 5-7 days, abscess, fistula) |
| I | Prevention of embolism: vegetation > 10 mm with prior embolic event |
| I | Fungal endocarditis |
| I | Prosthetic valve IE with dehiscence, abscess, or heart failure |
| IIa | Large vegetation (> 10 mm) on anterior mitral leaflet with severe MR |
| IIa | Recurrent embolic events despite appropriate antibiotics |
| IIa | Highly resistant organisms (Pseudomonas, Brucella, MDR) |
Timing of Surgery
Emergency surgery (within 24 hours) is indicated for refractory pulmonary edema or cardiogenic shock from acute valve dysfunction. Urgent surgery (within days) is warranted for uncontrolled infection, abscess, or large mobile vegetation with high embolic risk. Elective surgery (1-2 weeks) is appropriate after adequate antibiotic therapy in stable patients. Regarding the relationship to stroke, surgery within 72 hours of a non-hemorrhagic stroke is generally safe, while a delay of 3-4 weeks is recommended after hemorrhagic stroke if clinically feasible.
Surgical Principles
Radical Debridement
The most critical step in the surgical treatment of IE is the removal of all infected and necrotic tissue. Infected valve leaflets, vegetations, and any paravalvular infected tissue must be excised. Abscess cavities are debrided down to healthy tissue. All specimens should be sent for culture and pathology, and irrigation with antiseptic solutions (some centers use betadine or antibiotic irrigation) completes the debridement.
Reconstruction Strategies
Native Valve Endocarditis
For mitral valve IE, repair is preferred when possible — particularly when destruction is limited to the posterior leaflet. Repair techniques include leaflet resection, pericardial patch repair of perforations, and neochordae placement. Replacement is performed when extensive destruction precludes a durable repair. For aortic valve IE, replacement is usually necessary because repair is rarely feasible with extensive infection. Pericardial patch repair of cusp perforations is possible in selected cases, and autologous pericardium can be used for limited reconstruction.
Prosthetic Valve Endocarditis
The infected prosthesis must be removed entirely, followed by radical debridement of all infected and necrotic paravalvular tissue. When the annulus has been destroyed, reconstruction options include autologous pericardial patch reconstruction, homograft root replacement (preferred for aortic root abscess), and prosthetic material such as Dacron patch to reconstruct the LVOT or annulus. A new prosthesis is then implanted on the reconstructed tissue.
Aortic Root Abscess
Aortic root abscess represents one of the most technically challenging scenarios in cardiac surgery. Complete debridement of the abscess cavity is essential. Homograft aortic root replacement is considered the gold standard because it is resistant to reinfection and conforms well to irregular cavities. Prosthetic root replacement (Bentall) is acceptable when tissue quality permits secure suturing. The autograft (Ross procedure) is occasionally used in young patients with root abscess. Patch reconstruction of the abscess cavity with bovine pericardium combined with valve replacement is another option. Aorto-ventricular discontinuity may require Dacron interposition.
Right-Sided Endocarditis (Tricuspid Valve)
Right-sided endocarditis is most common in patients with intravenous drug use. Vegetectomy alone may suffice for limited disease. Valve repair with debridement and annuloplasty is preferred over replacement. When replacement is necessary, a bioprosthetic valve is strongly preferred because the low-pressure tricuspid environment carries high mechanical valve thrombosis risk. In rare cases of recurrent endocarditis with poor compliance, valve excision without replacement has been performed; this is hemodynamically tolerated in the short term but long-term outcomes are poor.
<image>Intraoperative surgical views of aortic valve endocarditis with paravalvular abscess. Panel A shows the surgeon's view of the aortic root after excision of the infected aortic valve, with a large abscess cavity visible in the noncoronary sinus extending into the aortic-mitral intervalvular fibrosa. The abscess cavity is debrided to healthy tissue with its boundaries marked. Panel B shows reconstruction of the abscess cavity with a bovine pericardial patch sutured to the rim of healthy tissue. Panel C shows a cryopreserved aortic homograft being seated into the reconstructed aortic root with the left and right coronary buttons prepared for reimplantation. Panel D shows the completed homograft root replacement with reimplanted coronary buttons and distal aortic anastomosis.</image>
Antibiotic Therapy
Duration
Native valve IE requires a minimum of 4-6 weeks of intravenous antibiotics, counted from the date of the first negative blood culture or from the date of surgery if operated. Prosthetic valve IE requires a minimum of 6 weeks of intravenous antibiotics. The specific regimen is determined by the causative organism, and infectious disease consultation is essential.
Timing Relative to Surgery
The full antibiotic course is completed postoperatively, with the "clock" restarted from the operative date based on intraoperative culture results. Negative intraoperative valve cultures are a good prognostic sign, and the preoperative course is completed. Positive intraoperative cultures necessitate a full course from the operative date.
Special Situations
IVDU-Associated Endocarditis
Endocarditis associated with intravenous drug use is predominantly right-sided, affecting the tricuspid valve. The recidivism rate is high, with reinfection after surgery occurring in 30-40% of cases. The question of whether surgery should be withheld from patients with substance use disorder is an important ethical consideration; current consensus holds that surgery should not be denied based on substance use disorder and that multidisciplinary addiction treatment should be integrated into the surgical plan. Valve repair is preferred over replacement to minimize prosthetic material.
Device-Related Endocarditis
Pacemaker or ICD lead endocarditis requires complete device and lead extraction. Transvenous extraction is performed in specialized centers, with surgical extraction indicated when leads are heavily encapsulated. Vegetations on leads exceeding 20 mm may require surgical extraction to avoid pulmonary embolism during transvenous removal.
<image>Comparison of right-sided versus left-sided infective endocarditis. A split-panel illustration shows: Left panel -- tricuspid valve endocarditis with large vegetation on the anterior leaflet, septic pulmonary emboli shown in the lung fields (wedge-shaped opacities), and the typical clinical scenario (IV drug use, fever, respiratory symptoms). Right panel -- mitral valve endocarditis with vegetation on the anterior leaflet, systemic embolic complications shown (stroke, splenic infarct, mycotic aneurysm, Janeway lesions on the hand), and the typical clinical features (heart failure, embolic events, immunologic phenomena). A central table compares microbiology, complications, and surgical approach for each.</image>
Clinical Pearls
The cornerstone of surgical treatment for IE is radical debridement — leaving behind infected tissue is the primary cause of recurrent infection and operative failure. Timing of surgery should not be delayed by arbitrary antibiotic duration requirements; if a surgical indication exists, operate promptly. After a non-hemorrhagic stroke, surgery within 72 hours is safe and should not be delayed, while after hemorrhagic stroke a delay of 3-4 weeks is warranted if the patient is stable enough to wait. Aortic root abscess is among the most technically demanding operations in cardiac surgery, and homograft root replacement is the gold standard for this indication due to its resistance to reinfection. Brain MRI should be performed in all patients with left-sided IE before surgery, even without neurologic symptoms, as silent emboli are present in 60-80%. PET-CT is increasingly valuable for diagnosing prosthetic valve endocarditis when echocardiographic findings are equivocal. In IVDU-associated tricuspid endocarditis, every effort should be made to repair the valve rather than replace it, and addiction medicine consultation should be part of the surgical plan. Fungal endocarditis is almost universally fatal without surgery, and lifelong suppressive antifungal therapy is typically required after surgical debridement.
References
- Pettersson GB, Coselli JS, et al. 2016 AATS Guidelines for the surgical treatment of infective endocarditis. J Thorac Cardiovasc Surg. 2017;153(6):1241-1258.
- Habib G, Lancellotti P, Antunes MJ, et al. 2015 ESC Guidelines for the management of infective endocarditis. Eur Heart J. 2015;36(44):3075-3128.
- Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for Valvular Heart Disease. Circulation. 2021;143(5):e72-e227.
- Nishimura RA, Otto CM, Bonow RO, et al. AHA/ACC focused update on infective endocarditis. Circulation. 2017;135(25):e1159-e1195.
- Mayer K, Aicher D, Feldner S, et al. Repair versus replacement of the aortic valve in active infective endocarditis. Eur J Cardiothorac Surg. 2012;42(1):8-15.
