Tricuspid Valve Endocarditis

Etiology

Important risk factors for tricuspid valve infective endocarditis (TVIE) include:

Intravenous drug users (IVDU): Infections resulting from IVDU involve 30% to 40% of all TVIE cases. 

Cardiac implantable electronic device (CIED) Infection: TVIE is considered device related if there is evidence of valvular vegetation and tricuspid regurgitation in the presence of positive blood cultures. 

Indwelling catheter: hemodialysis, parenteral nutrition, and chemotherapy requiring long term central venous access. 

Epidemiology

It is certain that cases of right-sided infective endocarditis (RSIE) and TVIE are increasing. In one study, hospitalizations for IVDU related infective endocarditis increased 12-percent. [4] IVDU accounts for 86% of TVIE. TVIE is more common among males, although the ratio is normalizing.  Over time, the population with TVIE has become younger, and more commonly white. [4]

History and Physical

History and physical exam are essential towards making an adequate diagnosis in cases of TVIE. Establishing diagnosis can be more difficult in these cases because presentation can often be subacute or present with absence of typical IE features. Peripheral phenomenon such as splinter hemorrhages is less common, as is a cardiac murmur. However, clinicians must always be aware of potential complications of this disease process that are manifested by the various embolic phenomenon. Characteristics, which should lead clinicians to consider TVIE, include:

• Fever
• Chills
• Anorexia
• Weight loss
• Fatigue
• Malaise
• Arthralgia
• Dyspnea on exertion
• A cough
• Pleuritic pain
• Abdominal Pain

Physical Exam Findings

• Tachypnea
• Hypotension
• Cardiac murmur
• Splenomegaly
• Splinter hemorrhages
• Petechiae
• Janeway lesions
• Osler nodes
• Roth spots
• Focal neurologic deficits
• Joint effusion
• Clubbing

Evaluation

Diagnosis of TVIE is based upon the modified Duke Criteria. This criterion is widely used to diagnose TVIE like all other forms of IE. This criterion allows one to stratify infective endocarditis into a category of definite, possible, or rejected. Based on clinical criteria definite endocarditis is defined as two primary criteria, one major with three minor criteria, or five minor criteria. Possible endocarditis is measured by the presence of one major with two minor criteria, or with three minor criteria alone.  [5] The criteria classes are as follows:

Major Criteria

Positive blood culture(any of the followings):

• Two separate blood cultures with organisms known to cause infective endocarditis or
• Organism consistent with endocarditis from blood cultures obtained 12 hours apart or
• Positive culture for organisms that are common skin contaminant in 3 or the majority of ≥4 separate blood cultures (first and last sample drawn at least 1 hour apart) or
• Single positive blood culture of Coxiella burnetti

Evidence of endocardial involvement (vegetation, abscess, new valvular regurgitation, dehiscence of a prosthetic valve)

Minor Criteria

• Fever > 38 degrees C (100.4 degrees F)
• Immunologic occurrence: Roth spots, Osler nodes, glomerulonephritis. 
• Predisposing heart defect or IVDU
• Vascular phenomena: septic emboli, arterial emboli, conjunctival hemorrhages, splinter hemorrhages, Janeway lesions, mycotic aneurysm
• A positive blood culture that does not meet essential criteria.

Routine laboratory values in IE are generally nonspecific. Basic workup should be done. Some abnormalities which may be found include leukocytosis, elevated ESR, elevated CRP, normocytic anemia, or urinalysis revealing hematuria, proteinuria, or pyuria. EKG may reveal conduction anomalies such as heart block. [6]

• Chest radiographs should be obtained to evaluate for septic emboli or infiltrate.
• CT scan of the abdomen is helpful to evaluate for metastatic emboli. Such emboli include splenic or renal infarcts. Clinicians should have a low threshold to locate these potential foci.
• Blood cultures should be obtained in all individuals with suspected TVIE. A minimum of three sets should be collected from different sites. [26341945]
• Echocardiography should be performed in all individuals with suspected TVIE. Transthoracic echocardiogram (TTE) is the first test that is done. TTE is very specific. Transesophageal echocardiography should be pursued if TTE is negative, but a high clinical suspicion for IE exists. TEE may also be used if significant valve regurgitation exists and needs to be further evaluated prior to surgery. [7]

Treatment / Management

Some individuals with TVIE may be candidates for shorter duration antibiotic regimens(no evidence of renal failure, the absence of extrapulmonary metastatic infections or simultaneous left sided infection). The 2-week regimens are not used in patients with IE of the aortic or mitral valve, in patients with MRSA, or patients with complicated IE. [8] Patients with TVIE should be started on an empiric antibiotic regimen once it is suspected.

Initial empiric antibiotics should include coverage against the most common pathogens. Thus staphylococcus and streptococcus coverage are recommended. Vancomycin is used as an initial choice of antibiotic. These medicines should be tailored based upon blood cultures results. Once an organism has been specified, antibiotics regimen should typically be continued for six weeks from the date of first negative blood culture. Very limited patients can be trialed with a short duration course. These candidates include those with isolated TVIE, those without any complications secondary to IE, and those with IE from HACEK organisms. [9] For patients with methicillin-sensitive Staph aureus (MSSA) IE, it is vital to change vancomycin to an antibiotic more specific against MSSA. Such antibiotics include nafcillin, oxacillin, or cefazolin. Patient with MRSA IE should be treated with vancomycin for six weeks.(B3)

Surgical treatment of IE is reserved for individuals with the following: [10](A1)

• TV vegetation > 2cm with septic pulmonary emboli.
• Persistent bacteremia for one week despite adequate treatment.
• Severe tricuspid regurgitation with right-sided heart failure.

Differential Diagnosis

Infective endocarditis of any form can be difficult to identify. IE can have many nonspecific complaints which can overlap in various autoimmune, infectious, or neoplastic processes. It is important to think of IE as a syndrome. The Duke Modified Criteria serves as the principal diagnostic tool that takes into account all the potential manifestations of this disease process. Some of the differential diagnoses which may also be considered include:

• Systemic lupus erythematosus
• Polymyalgia rheumatic
• Lyme Disease
• Antiphospholipid syndrome
• Libman sacks endocarditis
• Atrial myxoma
• Rheumatic fever
• Marantic endocarditis

Prognosis

Patients with TVIE have good prognosis compared to those with other forms of IE. The fatality rate is lower in these patients. [11] In one study evaluating native valve endocarditis, overall mortality was 6%. [12] Vegetation size is an important prognostic factor. Those with vegetation greater than 1cm have significantly increased mortality. Individuals who have concurrent left-sided infective endocarditis have a worse prognosis. This diagnosis is due to the higher risk of abscess development in these cases. [1]

Complications

Complications of TVIE include [13]

• Peri-annular abscesses
• Septic pulmonary emboli
• Splenic abscess
• A mycotic aneurysm
• Heart failure