Reasoning in Radiology

Infective endocarditis: Beyond TEE By Cathy R. Kessenich, DSN, ARNP, and Megan Flanagan, BSN

Mr. O is a 66-year-old White male with a history of hypertension, hyperlipidemia, and infective endocarditis diagnosed and treated with antibiotic therapy 8 years ago. He has a regular follow-up appointment with a cardiology nurse practitioner (NP) every 6 months. However, he called for an appointment 2 months early because of a low-grade fever, fatigue, malaise, and an inability to complete his daily 3-mile walk. He recalls feeling this way 8 years ago and is concerned that his infective endocarditis may have reoccurred. During the history interview, Mr. O reports that he has been having some right lower jaw pain and that he is scheduled to see his dentist next week. Upon exam, Mr. O appears pale and tired and moves listlessly around the exam room. His temperature is 99.0° F (37.2° C), pulse 78, respirations 32, BP 105/55, and oxygen saturation 97% on room air. His right lower mandibular area is tender to palpation, and his oral exam reveals redness on the lower right gum line. The remainder of his physical exam reveals no abnormalities. The NP suspects that Mr. O has an infected tooth and makes a call to the dental office to arrange for an earlier appointment. Additionally, the NP scheduled Mr. O for a transesophageal echocardiogram given his history of infective endocarditis. ■ Infective endocarditis background Approximately 10,000 to 15,000 cases of infective endocarditis are diagnosed in the United States every year.1 In 2009, as

many as 28,000 hospital discharges were related to infective endocarditis.2 Infective endocarditis can cause serious intra- and extracardiac complications.3 Early detection and treatment are key in preventing complications and reducing mortality of infective endocarditis.3,4 The rates of infective endocarditis continue to rise particularly because of an increasing number of implantable cardiac devices: pacemakers, defibrillators, prosthetic valves, and indwelling catheters being used in cardiac care management.2 Without early detection, infective endocarditis is associated with high mortality.2-5 In 1994, researchers at Duke University improved upon existing criteria for diagnosis of infective endocarditis.6 The Duke criteria have continued to be modified to best assist practitioners’ diagnosis of infective endocarditis.6 Duke criteria assist to breakdown the diagnosis of infective endocarditis into definite, possible, and rejected; this is helpful to an NP when debating differential diagnoses and determining diagnostic testing.6

■ Signs and symptoms Signs and symptoms of infective endocarditis depend on the extent of cardiac disease and causative organism. The presentation of infective endocarditis can be subacute or acute. Subacute typically presents with prolonged low-grade fever, complaints of fatigue, myalgia, diaphoresis, weight loss, and exercise intolerance.7 The above case patient has many of these textbook symptoms. Acute presentation is typically associated with Staphylococcus aureus and can cause progressive and fulminant cardiac failure.7 Patients with acute infective endocarditis look severely ill and typically have high fevers.7 Petechiae may be noted on the skin during the physical exam, specifically on the extremities, and splinter hemorrhages may be seen in nail beds.8 Careful attention should be paid to signs of new or worsening systolic murmurs as well as heart failure upon performing a cardiac exam.8

■ Pathology Organisms commonly implicated in the infective endocarditis disease process include: Staphylococcus aureus, viridans streptococci, enterococci, and coagulase-negative staphylococci.1 Studies suggest that infective endocarditis occurs because endothelial damage leads to platelet and fibrin deposition with the formation of thrombotic endocardial lesions. In addition organisms may stick to those lesions and multiply if bacteremia is present, resulting in infective vegetation, and therefore, endocarditis.5

■ Diagnosis Diagnosis of infective endocarditis can usually be aided by taking a careful history of all dental and medical procedures that put patients at risk for a potential bacteremia.1,8 Identifying high-risk groups, such as patients (especially males) over 60, those with poor dentition, those who have a history of injection drug use, or who have had a previous endocarditis, also assist a provider in diagnosis.1 At least two sets of blood cultures should be obtained as well as a urinalysis, echocardiogram,

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Reasoning in Radiology electrocardiography, and chest X-ray.8 An erythrocyte sedimentation rate and a C-reactive protein may also be drawn but are relatively nonspecific.8 Diagnosis is straightforward with the help of the Duke criteria, especially when the blood cultures reveal a pathogen likely to cause infective endocarditis.6 Those diagnosed with endocarditis in the past have a greater chance of reoccurrence.5,9 The American Heart Association (AHA) guidelines recommend antimicrobial prophylaxis for the high-risk patient population before specific dental, gastrointestinal, and genitourinary procedures in which the mucosa is penetrated.5 High-risk population is defined by the AHA as patients with underlying cardiac conditions associated with the highest risk of adverse outcome from infective endocarditis–not necessarily those with an increased risk of acquisition of infective endocarditis.5 Prophylaxis recommendations changed with the 2007 AHA guidelines because studies showed that a large number of patients would need prophylaxis to prevent a very small number of infective endocarditis cases; the study concluded that benefit did not outweigh the risk.9 ■ Echocardiogram Echocardiogram is the primary and noninvasive imaging modality for cardiac visualization with use of ultrasound waves.10 An echocardiogram is part of the criteria for a diagnosis of infective endocarditis and helpful in determination of surgical approach if surgical intervention is required.11,12 A vegetation looks like a mobile mass attached to the surface of the valve on echocardiogram; it shows an independent motion from the underlying valve.11 The diagnostic test can be done by either of two methods: transesophageal echocardiogram or transthoracic echocardiogram.

■ Transesophageal echocardiogram (TEE) The TEE is known as the gold standard test for the diagnosis of endocarditis.12 To perform a TEE, a cardiologist inserts a thin tube with an ultrasound transducer on the end into the patient’s esophagus and presses on the esophagus wall to image cardiac structures– particularly the difficult to see posterior anatomy.13 A TEE allows for identification of vegetation on the valves, evaluates for dysfunction, assesses hemodynamic function, and abnormalities. A TEE should be performed if the practitioner determines the patient’s likelihood of infective endocarditis is high.11 Because the TEE is more expensive than the TTE, it should not be included as first-line diagnostic testing in patients with low suspicion of infective endocarditis.11 TEE has a reported sensitivity of 100% for detection of infective endocarditis; this is significantly greater than TTEs.11 Better resolution and multiple study planes helped the TEE achieve this level of sensitivity.12 A patient does not require antimicrobial prophylaxis to undergo a TEE, as it should not penetrate the mucosa.5 The TEE is better for detecting small vegetations and abnormal valvular morphology.12 TEE is available in two- and threedimensional views. TEE should always be used over TTE if the patient has prosthetic valves, previous endocarditis, or a limited transthoracic window.14 The practitioner should inform the patient what can be expected in preparation for a TEE. A TEE requires patients to be NPO for 8 hours prior to testing.13 The patient will have an I.V. placed for moderate sedation medication used during the procedure.13 Patients may be groggy after the sedation and need to make plans for a ride home from the procedure. The patient can also expect to receive lidocaine throat spray to numb the throat before transducer insertion.13

TEE is contraindicated in the following patients: those with esophageal stricture or malignancy, a history of dysphasia, cervical spine arthritis with decrease range of motion, severe thrombocytopenia, Zenker diverticulum, and anyone that has an active or recent esophageal perforation.15 Complications from TEE include sore throat, esophageal perforation, grogginess from sedation, and potential endotracheal intubation for airway protection during procedure.15 ■ Transthoracic echocardiogram (TTE) Although TTE remains a cornerstone of diagnostic cardiac ultrasound, it is not the best diagnostic test for patients who are highly suspicious for infective endocarditis.10 TTE uses a handheld transducer manipulated over the cardiac area to allow for visualization of cardiac structures through the chest wall.15 Historically, TTE was considered the less effective form of echocardiography because from 1984 to 1994, image quality, lesion location, and vegetation size gave this diagnostic test 50% sensitivity.12 With advances in technology and improved harmonic imaging, the TTE now has a high concordance with TEE imaging regarding sensitivity.15 In addition, there are no complications or risks associated with TTE.15 Proximity and imaging of TEE allow for optimal viewing for investigation of infective endocarditis.8,11,12 The TTE is a less expensive, less sensitive test, and although it continues to be used in the diagnosis of endocarditis, the TEE remains the gold standard diagnostic test for infectious endocarditis.8,11,12 ■ Achieving an early diagnosis The results of Mr. O’s TEE were positive, confirming his diagnosis of subacute infective endocarditis. He was The Nurse Practitioner • September 2014 19

Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

Reasoning in Radiology immediately referred to the infectious disease physician who treated him previously for antibiotic therapy. Infective endocarditis can be diagnosed with traditional echocardiogram, TEE, or TTE. TEE is a first-line diagnostic choice for patients with a previous history of the diagnosis, and every effort should be made to achieve an early diagnosis and avoid valvular destruction.

5. Nishimura RA, Carabello BA, Faxon DP, et al. American Heart Association. 2008. ACC/AHA 2008 guideline update on valvular heart disease: focused update on infective endocarditis: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines: endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation. 2008;118(8):887-896.

12. Casella F, Rana B, Casazza G, et al. The potential impact of contemporary transthoracic echocardiography on the management of patients with native valve endocarditis: a comparison with transesophageal echocardiography. Echocardiography. 2009;26(8):900-906.

6. Sexton D. Infective endocarditis: historical and Duke criteria. 2013. infective-endocarditis-historical-and-duke-criteria.


7. O’Brien S. Infective endocarditis in children. 2014.

14. Cecchi E, Chirillo F, Faggiano P, et al. The diagnostic utility of transthoracic echocardiography for the diagnosis of infective endocarditis in the real world of the Italian registry on infective endocarditis. Echocardiography. 2013;30(8):871-879.

1. Sexton D. Epidemiology, risk factors and microbiology of infective endocarditis. 2013. www.upto 2. American Heart Association. What is infective endocarditis? 2012. Cardiovascular conditions.

Echocardiography in the assessment of valvular vegetations. Echocardiography. 2009;26(10): 1264-1273.

8. Sexton D, Fowler V. Clinical manifestations and diagnosis of infective endocarditis. 2013. www. 9. Sexton D. Antimicrobial prophylaxis for bacterial endocarditis. 2012. antimicrobial-prophylaxis-for-bacterial-endocarditis.

3. Roychoudhury D, Chaithiraphan V, Stathopoulos I, et al. Culture-negative suppurative endocarditis causing severe mitral valve obstruction: complementary use of transesophageal and transthoracic echocardiography. Echocardiology. 2003;20(5):429-434.

10. Manning W. Echocardiography Essentials: physics and instrumentation. 2012. contents/echocardiography-essentials-physicsand-instrumentation.

4. Hansalia S, Biswas M, Dutta R, et al. The value of live/real time three-dimensional Transesophageal

11. Harris KM, Li DY, L’Ecuyer P, et al. The prospective role of transesophageal echocardiography in

the diagnosis and management of patients with suspected infective endocarditis. Echocardiography. 2003;20(1):57-62.

13. National Heart, Lung, and Blood Institute. Echocardiography. National Institute of Health. tee/printall-index.html.

15. Manning W, Kannam J. Transesophageal echocardiography: indications, complications, and normal views. 2013. contents/transesophageal-echocardiographyindications-complications-and-normal-views. Cathy Kessenich is a professor of nursing and MSN program director, and Megan Flanagan is a graduate assistant at University of Tampa, Tampa, Fla. The authors have disclosed that they have no financial relationships related to this article. DOI-10.1097/01.NPR.0000452982.66503.b5

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Infective endocarditis: Beyond TEE.

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