Welcome to another ultrasound-based case, part of the “Ultrasound For The Win!” (#US4TW) Case Series. In this case series, we focus on a real clinical case where point-of-care ultrasound changed the management of a patient’s care or aided in the diagnosis. In this case, a 40-year-old woman presents with a fever, chest pain, shortness of breath, cough, and generalized weakness.
A 40-year-old woman presents to the Emergency Department (ED) for evaluation of multiple complaints including fever, chest pain, shortness of breath, cough, and generalized weakness. She denies any known sick contacts or recent travels, and denies any significant past medical history. Her review of systems is otherwise unremarkable. On social history, she endorses intravenous (IV) drug abuse.
- BP 93/56 mmHg
- P 109 bpm
- RR 24 breaths/min
- O2 93% room air
- T 38.0 C
- Acute Coronary Syndrome (ACS)
- Influenza-Like Illness (ILI)
- Pulmonary Embolism (PE)
She is placed in an isolation room. On physical examination, you find a woman who appears older than stated age. She is in moderate respiratory distress and diaphoretic. On auscultation, her heart is tachycardic and regular without murmurs or rubs. She has coarse breath sounds throughout. Examination of the skin reveals track marks on bilateral ventral forearms, with no other sores, petechiae, or lesions noted.
Fluid resuscitation is started via two large-bore IVs, and initial laboratory studies including blood cultures are drawn. While awaiting a portable chest x-ray, the emergency physician performs a point-of-care echocardiogram.
Given the concern for infective endocarditis, broad-spectrum antibiotics are started. At this point, the chest x-ray is performed:
Laboratory studies return and are unremarkable:
- WBC 7.9 x10³/µL
- Lactate 1.1 mg/dL
- Hemoglobin 9.2 g/dL
- Three (3) sets of blood cultures are sent and pending
Ultrasound Image Quality Assurance (QA)
Infective endocarditis (IE) has been historically diagnosed clinically with the aid of the Duke Criteria; however, the requirements for diagnosis are not typically met in the ED as they require a prolonged hospitalization. Thus, the Duke Criteria is largely irrelevant in the ED, making IE a particularly challenging diagnosis for emergency physicians. Fortunately, point-of-care trans-thoracic echocardiogram (TTE) is readily available in most EDs, and can be considered the initial imaging study of choice to look for vegetations.
Vegetations on echocardiogram are visualized as mobile masses on the cardiac valves that move independently from the valves themselves. Vegetations as small as 6 mm can be seen with TTE.1 The identification of right-sided vegetations in particular can be difficult to visualize with a parasternal view. A subxiphoid or apical-4-chamber view may be needed to better visualize these vegetations which highlights the importance of obtaining multiple views when performing a point-of-care echocardiogram.
Valvular incompetence can be evaluated when vegetations are identified or suspected, and has been found to be both diagnostic and prognostic.1 Assessing for tricuspid or mitral regurgitation involves the use of Color Doppler in the apical-4-chamber view. A regurgitant jet is identified with color flow moving away from the probe when the valves close. Additionally, atrial enlargement may be associated with regurgitation.
Abscesses can also be associated and identified with IE (albeit difficult with TTE) as a thickened region with an associated heterogenous echogenic area.
Is TEE sensitive enough to rule out endocarditis in the Emergency Department?
Studies comparing the test characteristics of TTE vs. TEE in the identification of vegetations reveal sensitivities of 30-65% for TTE compared with sensitivities of 87-100% for TEE.2,3 However for right-sided endocarditis, there is an improved sensitivity with TTE, and TEE may not be necessary if clear vegetations are visualized with TTE.3 Of course, the size of a vegetation is a large determinant in its ability to be visualized with TTE. One study revealed that 25% of vegetations <5 mm in size were identified by TTE, 70% of those between 6-10 mm were identified, and 84% of vegetations >10 mm were identified with TTE (Figure 6).1
The data from Figure 6 above can prove particularly useful for emergency physicians as larger vegetations (i.e. >10 mm) or vegetations with severe mobility are independent prognostic factors that are associated with a higher risk of complications (including septic emboli) and mortality.1,4 If these higher-risk patients can be identified by emergency physicians by TTE, more aggressive management and consultation can be initiated earlier, potentially decreasing patient morbidity and mortality.
Thus the utility for the use of TTE in patients with suspicion for infective endocarditis in the ED may be in the ability to risk-stratify patients who are at higher risk for complications such as embolic events and death.
Disposition and Case Conclusion
The visualization of vegetations on the tricuspid valves on point-of-care trans-thoracic echocardiogram helped confirm the diagnosis of right-sided infective endocarditis. The patient was admitted to the ICU for continued IV antibiotics and medical management, in consultation with cardiothoracic surgery during her hospitalization.
A transesophageal echocardiogram was performed during her admission the following day, which revealed:
Multiple large tricuspid valve vegetations (20 mm and 10 mm) attached to both the anterior and posterior leaflets of the tricuspid valve. Mild tricuspid regurgitation. No abscess cavity. Mitral, aortic, pulmonic valves appear normal. Normal biventricular systolic function. No pericardial effusion.
Blood cultures grew gram positive cocci, confirmed to be methicillin-resistant staphylococcus aureus (MRSA), sensitive to vancomycin.
After a prolonged hospitalization, the patient was discharged to home in stable condition with no complications.
Infective endocarditis (IE) is an uncommon and life-threatening disease with significant morbidity and mortality.1 There are an estimated 10,000 to 15,000 new cases of IE in the United States annually.5 The most common presenting symptoms of IE are non-specific and include fever, anorexia, weight loss, and night sweats.6 The classic physical exam findings including cardiac murmurs, petechiae, Janeway lesions, and Osler’s nodes are relatively rare and may not be evident in cases of IE.6 In fact, a study by Pathak et. al. revealed that tricuspid regurgitation could only be identified 12-33% of the time via cardiac auscultation by Internal Medicine residents and Cardiology fellows.5
Risk factors for IE include patients with prosthetic heart valves, structural heart disease, and intravenous drug use.5 As compared to left-sided endocarditis, right-sided endocarditis tends to affect patients who are younger, have a history of IV drug abuse, and tend to have larger vegetations.3
Complications from IE include septic shock and embolic events. The mortality rate of IE is high (up to 40%) with the most common causes of death being septic shock and multi-organ failure.4,6,7 Thus, a high index of suspicion with early recognition and diagnosis with aggressive early management is needed.
Treatment of IE includes aggressive resuscitation, broad spectrum IV antibiotics that cover the most common organisms (staphylococci and streptococci), which may include vancomycin + gentamicin.8 Cardiothoracic surgery consultation can be considered for potential valvulectomy.6 The indications for valvulectomy include persistent fever, large vegetations, severe right-sided heart failure, or recurrent pulmonary emboli.8
Trans-Esophageal Echocardiography (TEE) in the ED
While not yet widespread, TEE is becoming increasingly used in EDs by emergency physicians, primarily in patients with cardiac arrest. A great online resource for learning more about TEE is the Virtual Transesophageal Echocardiography Simulator by the Toronto General Hospital, Department of Anesthesia.
Take Home Points
- Infective endocarditis (IE) is a life-threatening disease with a high morbidity and mortality that often presents with non-specific symptoms. This challenging diagnosis requires a high-index of suspicion by the emergency physician.
- Trans-thoracic echocardiogram, while not as sensitive as trans-esophageal echocardiogram, can be used to risk stratify patients at high risk for complications of IE including septic emboli.
- Vegetations appear as mobile masses on the valves that move independently from the valves themselves. Vegetations as small as 6 mm can be visualized with TTE.
- Management of IE includes aggressive medical management including broad spectrum antibiotics, hospital admission, and consideration for cardiothoracic surgery consultation.