Early Diagnosis of Tricuspid Valve Infective Endocarditis by Point of Care Ultrasonography
Published on: July 12, 2023
A 40-year-old female with unknown past medical history was brought in from a shelter, after she was found altered with right sided weakness. On arrival she was tachycardic, tachypneic, febrile, and saturating 92% on room air. Neurologic exam was notable for lethargy, expressive aphasia, right facial weakness, and right hemiplegia. General physical exam revealed track marks on her arms and petechiae on the soles of her feet. Toxicology screen was positive for opiates and cocaine. Non-contrast CT head demonstrated a left frontal lobe hemorrhage measuring 4 cm x 2.7 cm x 2 cm, with surrounding vasogenic edema.
Bedside point of care ultrasonography (POCUS) revealed diffuse B lines, reduced left ventricle contractility, and a vegetation on the tricuspid valve. Figure 1 is a parasternal long view which shows a mobile echogenicity within the right ventricle. Maintaining the same view but tilting the ultrasound probe towards the right hip gives us a better view of the tricuspid valve which reveals the vegetation (Figure 2). The apical four chamber view (Figure 3) also demonstrates the vegetation on the tricuspid valve.
Given her clinical presentation as well as POCUS findings, heart failure due to infective endocarditis was suspected. The intracranial pathology was thought to be due to hemorrhagic conversion of an embolic stroke secondary to endocarditis. Blood cultures were obtained and she was started on broad spectrum antibiotics. CT chest and abdomen showed numerous bilateral pulmonary cavitating nodules consistent with septic emboli. Formal transthoracic echocardiogram (TTE) obtained on hospital day two showed a mobile 1.7 cm by 1.4 cm vegetation on the ventricular side of the tricuspid valve, severe right ventricle dilation, moderate hypokinesis of the left ventricular walls, decreased ejection fraction (approximately 30%), and right to left shunting at the atrial level. Blood cultures grew methicillin sensitive staphylococcus aureus (MSSA) and antibiotics were subsequently narrowed. On hospital day five, she underwent digital subtraction angiography (DSA) which was negative for mycotic aneurysms.
Throughout the following days, she was persistently tachypneic with increasing oxygen requirements. Repeat CT chest showed worsening burden of pulmonary embolism and cavitary lesions as well as fluid overload. Repeat TTE on hospital day seven showed two vegetations on the tricuspid valve, now up to 2.8 cm in size. Five days later, she was found acutely unresponsive with a fixed and dilated left pupil. Stat CT head showed a new 2.5 cm left parieto-occipital hemorrhage resulting in 0.7 cm of midline shift. CT angiogram of the head revealed a 3mm saccular aneurysm arising from the left posterior middle cerebral artery (MCA) thought to be a mycotic aneurysm. She underwent an emergent left sided hemicraniectomy with hematoma evacuation and resection of the mycotic aneurysm. Hospital course was further complicated by new onset seizures requiring levetiracetam, phenytoin, and clobazam. She ultimately underwent Angiovac procedure 28 days into her hospitalization. TTE performed approximately three months after initial presentation showed a normal left ventricular ejection fraction (approximately 55%), no left ventricular dilation, severe right atrial dilation, right ventricle dilation, and no vegetations. She was ultimately discharged to acute inpatient rehabilitation.
Infective endocarditis (IE) is an infection of the endocardial surface of the heart, typically involving the heart valves.1 Risk factors for IE include pre-existing valvular or congenital heart disease, immunosuppression, intravenous drug use, poor dentition or recent dental procedure, the presence of indwelling catheters, or intracardiac devices such as ventricular assist devices or balloon pumps.1,2 Our patient’s bacteremia and subsequent IE was due to MSSA, a common skin flora, which likely occurred due to unsanitary intravenous drug use.
Diagnosis of IE should be suspected in patients with bacteremia and relevant risk factors. The modified Duke criteria are used to establish definite, possible, or rejected IE.3 These criteria rely on positive cultures and visualization of pathologic lesions such as vegetations or intracardiac abscesses. This can lead to delays in diagnosis while clinicians await culture data or formal imaging studies. The increased availability of POCUS can aid in quicker suspicion and diagnosis of IE. Our patient was noted to have a tricuspid valve vegetation as well as reduced left ventricle contractility and signs of heart failure on POCUS performed at admission. Along with a clinical picture concerning for IE, POCUS allowed for prompt initiation of antibiotics, management of acute heart failure, and involvement of appropriate consultants.
Neurologic complications of infective endocarditis include ischemic strokes, intracranial hemorrhage, and brain abscesses. Ischemic stroke in IE is caused by septic emboli. Septic emboli occur when there is an obstruction of a blood vessel caused by an infected thrombus that has been dislodged and traveled through the bloodstream.4 Typically, right-sided infective endocarditis embolizes to the lungs causing pulmonary infarcts, abscesses, pleural effusions, and empyemas.2 Our case was unique in that the presence of a patent foramen ovale (PFO) allowed for paradoxical emboli to enter the systemic circulation and cause ischemic strokes. Figure 4 is an apical four chamber view with positive agitated saline test suggesting the presence of a right-to-left shunt which was later confirmed on formal TTE. Intracranial hemorrhage in IE can occur from hemorrhagic conversion of an ischemic stroke or rupture of a mycotic aneurysm. Our patient was initially suspected to have hemorrhagic conversion of an ischemic stroke, but was later found to also have a left MCA mycotic aneurysm. Mycotic aneurysms form as the arterial walls dilate in response to the infection seeding the intima and causing local inflammation.5
Fortunately, the prognosis for patients with right-sided IE is relatively favorable.2 Treatment of IE includes long-term antibiotics specified to target the organism growing in the blood cultures and source control.1,6 However, the cornerstone of management is prompt diagnosis and early initiation of therapies. This significantly reduces the risk of complications, need for surgical management, and gives patients their best chance for a favorable outcome.7
Figure 1: Movie file showing parasternal long view with a mobile echogenicity in the right ventricle
Figure 2: Movie file of parasternal long view with the probe tilted towards the right hip to better view right ventricle vegetation
Figure 3: Movie file showing parasternal long view with a mobile echogenicity in the right ventricle
Figure 4: Movie file of parasternal long view with the probe tilted towards the right hip to better view right ventricle vegetation
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