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Point-of-Care Ultrasound Facilitated Detection of Femoral Occlusive Septic Emboli During Mitral Valve Surgery

A Case Report

Bellomy, Melissa L., MD*; Eagle, Susan, MD*; Pretorius, Mias, MBChB, MSCI*; Barton, Ben R., MD; Liang, Yafen, MD*

doi: 10.1213/XAA.0000000000000619
Case Reports: Case Report
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Acute lower extremity ischemia from septic emboli is a surgical emergency. Timely diagnosis and management are critical to improve patient outcome. However, traditional diagnostic modalities such as intraoperative angiogram are time-consuming, require special equipment and personnel, and introduce contrast exposure for critically ill patients. There are limited reports of utilization of point-of-care ultrasound to detect peripheral septic emboli. We present a case where femoral occlusive septic emboli were identified by point-of-care ultrasound after mitral valve replacement. This facilitated early surgical embolectomy and limb salvage. We suggest that perioperative point-of-care ultrasonography should be used as a first-line screening test in patients with acute lower extremity ischemia.

From the *Department of Anesthesiology and Department of Cardiac Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.

Accepted for publication June 28, 2017.

Funding: None.

The authors declare no conflicts of interest.

Address correspondence to Yafen Liang, MD, Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232. Address e-mail to yafen.liang@vanderbilt.edu.

Embolic event remains one of the most common and feared complications of infective endocarditis (IE), causing significant mortality and morbidity. Early diagnosis and intervention can improve patient outcome. However, the current diagnostic modalities are time-consuming, require special technology and equipment, and also expose patient to intravenous contrast media. We present a case where femoral occlusive emboli were diagnosed with point-of-care (POC) ultrasound after intraoperative transesophageal echocardiography (TEE) raised suspicion for embolization. This case highlights the importance and advantage of POC ultrasound in the detection of septic emboli in the perioperative setting. The patient provided written permission for publication of this report. This case report is waivered for institutional review board review and approval.

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CASE DESCRIPTION

A previously healthy 30-year-old man presented with 1 month of fever, malaise, night sweats, and arthralgias. On examination, the patient appeared acutely ill. His heart rate was in the 100 beats per minute range and arterial blood pressure in the 80/50 mm Hg range. There was a grade 3/6 holosystolic murmur on cardiac auscultation. Transthoracic echocardiogram showed a 2.5 × 2.0 cm highly mobile heterogeneous mass (Figure 1A) attached to the anterior mitral leaflet intermittently prolapsing into the mitral valve orifice with resulting mild mitral stenosis and severe mitral regurgitation. Computed tomography scan revealed disseminated septic infarcts of the kidneys, spleen, lungs, and brain. Despite appropriate medical therapy, the patient remained febrile to 40°C with significant leukocytosis and was displaying symptoms of progressive heart failure. Therefore, surgical intervention was chosen 4 days after initial identification of the vegetation.

Figure 1

Figure 1

Following induction of anesthesia, TEE demonstrated a smaller mass compared to the preoperative transthoracic echocardiogram, measuring only 1.7 × 0.7 cm (Figure 1B) with an uneven surface raising concern for interval breakdown and embolization of the vegetation. A conventional median sternotomy with aortic cross clamping was performed and manipulation of the heart was minimized to reduce the risk of further embolization of the vegetation. On surgical inspection of the valve, a large macerated fungating vegetation was identified, involving the majority of the atrial surface of the anterior leaflet with central ulceration, rendering it unrepairable. Therefore, the mitral valve, along with the attached vegetation, was removed in its entirety and replaced with a 29 mm St Jude mechanical mitral valve. The patient was separated from cardiopulmonary bypass successfully.

Figure 2

Figure 2

When the drapes were removed at the end of surgery, both lower extremities appeared extremely mottled (Figure 1C). Doppler ultrasound examination revealed diminished dorsalis pedis and posterior tibial pulses in both lower extremities. As the patient also had significant bleeding from the central line insertion site without obvious surgical problem, disseminated intravascular coagulopathy was suspected. Blood samples were sent for tests (including fibrinogen and D-dimer concentrations, platelet count) to rule out disseminated intravascular coagulopathy. All findings were within normal limits. The patient was hemodynamically stable on minimal vasopressors, making vasoconstriction-induced ischemia unlikely. A POC ultrasound was performed by the anesthesiologist, which revealed a large occlusive thrombus at the left femoral artery. Proximal to the thrombus, the artery was patent with normal blood flow when color Doppler was applied (Figure 2A). At the occlusion site, there was a hyperechogenic mass causing a complete filling defect (Figure 2B). Distal to the occlusion, the artery was patent; however, there was no blood flow (Figure 2C). Given this finding, an intraoperative vascular consult was sought immediately and emergent bilateral embolectomies were performed before we could examine the right femoral artery. Multiple emboli (Figure 2D) were retrieved from both femoral arteries with immediate reperfusion to both lower extremities (Figure 1D). Pathology examination of the emboli demonstrated fibrin thrombus with bacterial overgrowth, consistent with septic emboli. The endotracheal tube was removed 3 hours after surgery. Lower extremity perfusion was monitored by Doppler examination every 4 hours for 48 hours. On postoperative day 1, the patient was started on heparin infusion and then transitioned to oral Coumadin because of his mechanical valve. He was discharged home on postoperative day 11.

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DISCUSSION

Patients with IE have up to 49% incidence of embolic events.1 The current recommendation for surgical intervention to avoid systemic embolization in IE remains individualized, with benefit being greatest in the early phase of IE when embolic rates are highest and when other predictors of a complicated course (ie, recurrent embolization; congestive heart failure; aggressive, antibiotic-resistant organisms; or prosthetic-valve IE) are present.2 Because of his history of septic emboli, length of vegetation >10 mm with significant mobility, and location on the mitral valve, this patient was at high risk for additional emboli.1,3 This, in combination with change in size of the lesion on intraoperative TEE, led to increased suspicion of arterial emboli on discovery of cold, mottled extremities. Among all the potential locations of embolization, approximately two-thirds of noncerebral emboli obstruct the lower extremities, and approximately two-thirds of these involve the aorto-ilio-femoral arteries. The femoral artery is the most common site of embolization.4 Because POC ultrasonography has been used to accurately evaluate aneurysm of the aorta and iliac bifurcation5 and identify femoral vasculature for line placement,6 it could be also potentially used to detect septic emboli in those locations.

There is very limited literature on the use of POC ultrasound for the detection of acute limb ischemia, even though duplex ultrasonography is used frequently in the diagnosis and operative planning in chronic limb ischemia. This is the first case report where POC ultrasound was rapidly utilized to demonstrate a visible septic embolus in a patient with acute limb ischemia in the perioperative setting. Compared to traditional time-consuming diagnostic modalities such as intraoperative angiography or computed tomography angiogram (CTA), POC ultrasound allowed for timely diagnosis, vascular surgery consultation, and restoration of perfusion.7 One systematic review showed that in patients with arterial occlusion, duplex ultrasonography was less sensitive, but as specific (median sensitivity 90%, specificity 99%) as CTA (median sensitivity 97%, specificity 99.6%) and magnetic resonance angiogram (median sensitivity 94%, specificity 99.2%).8 Additionally, our patient had baseline renal impairment caused by septic renal infarcts and was spared a contrast load. Because of its relatively low sensitivity, if an arterial occlusion is not identified by ultrasound, further imaging such as CTA and magnetic resonance angiogram should be considered in clinically suspicious patients.

With anesthesiologists leading the perioperative surgical home, POC ultrasound becomes an emerging attractive tool for perioperative physicians. The scope of POC ultrasound is no longer limited to intraoperative TEE, vascular access, and regional anesthesia. It has been also used to diagnose various lung pathologies such as pneumothorax, evaluate gastric content in fasted patients, and assess respiratory variation of inferior vena cava to evaluate volume status in the intensive care units.9 Our case presentation adds to this literature. Anesthesiologist-performed POC ultrasound facilitated diagnosis and management of acute limb ischemia in the perioperative setting.

In conclusion, septic emboli from endocarditis can occur perioperatively. A perioperative physician-performed POC ultrasound focusing on the aorta, iliac vessels, and femoral artery bifurcation may serve as a feasible and superior screening test to quickly identify the location of an acute arterial occlusion, facilitate surgical consultation and intervention, and potentially allow limb salvage.

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DISCLOSURES

Name: Melissa L. Bellomy, MD.

Contribution: This author helped design the overall study and prepare the manuscript.

Name: Susan Eagle, MD.

Contribution: This author helped prepare the manuscript.

Name: Mias Pretorius, MBChB, MSCI.

Contribution: This author helped prepare the manuscript.

Name: Ben R. Barton, MD.

Contribution: This author helped design the study and prepare the manuscript.

Name: Yafen Liang, MD.

Contribution: This author helped design the overall study and prepare the manuscript.

This manuscript was handled by: Hans-Joachim Priebe, MD, FRCA, FCAI.

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REFERENCES

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