Large septic pulmonary embolus complicating streptococcus mutans pulmonary valve endocarditis

2017-09-08 16:08:45

Category: Chest & Cardiac Imaging, Region: Thorax-Vessels, Plane: Axial

A 41-year-old female with a past medical history of cervical squamous cell carcinoma and pulmonary valve stenosis was admitted following a 2-week history of fever and shortness of breath. Family and social history were unremarkable. Vital signs were notable for low-grade fever and tachypnea, and physical exam was notable for a systolic ejection murmur and poor dentition. Initial laboratory workup revealed leukocytosis and acute kidney injury. She was started on intravenous fluids and antibiotics. Overnight, the patient suddenly developed worsening tachypnea and hypoxemia but remained hemodynamically stable. Chest radiograph demonstrated findings suggestive of interstitial pulmonary edema (Fig. 1). Modified Well’s score suggested a high likelihood of pulmonary embolism. Computed tomographic pulmonary angiography (CTPA) revealed a large pulmonary embolus at the main pulmonary artery bifurcation without radiological evidence of right heart strain (Fig. 2). Additionally, multiple lower lobe-predominant peripheral nodules, some which were cavitary, were seen in random distribution throughout both lungs, concerning for septic emboli (Fig. 3). The patient was started on an intravenous heparin drip, supplemental oxygen, and continued on intravenous antibiotics. Blood cultures returned positive for Streptococcus mutans. Subsequent transthoracic echocardiogram did not show vegetations on the tricuspid or pulmonary valves, but demonstrated a peak pressure gradient of 80 mmHg at the level pulmonary valve (Fig. 4), consistent with severe stenosis. Lower extremity duplex for deep venous thrombosis was unrevealing (Fig. 5) and troponins and serum brain natriuretic peptide where undetectable. Transesophageal echocardiogram was not attempted as the patient was thrombocytopenic and considered unstable for the procedure. The patient progressed unfavorably with further episodes of worsening tachycardia, fever and tachypnea. Repeat CTPA 10 days following the initial scan showed interval increase in the number of lower lobe-predominant subpleural nodules (Fig. 6) and new pleural-based consolidations (Fig. 7), thought to reflect increasing septic emboli burden. Furthermore, a new pulmonary embolus was seen in a right upper lobe segmental pulmonary artery (Fig. 8). Despite intravenous antibiotic treatment according to culture susceptibilities, the patient continued to progress unfavorably with severe sepsis and worsening renal insufficiency. She subsequently underwent pulmonary artery exploration and embolectomy. An organized pulmonary artery thrombus measuring up to 2.5 cm in maximal diameter attached to the anterior wall of the main pulmonary artery and a 0.5 cm vegetation in the posterior pulmonary valve annulus were found. Both were excised and the pulmonary valve was reconstructed. Pathology report from the embolus revealed a thrombus with numerous bacterial microorganisms. The patient’s clinical course improved with resolution of her severe sepsis and acute kidney injury. Subsequent blood and surgical specimen cultures were negative. The patient was discharged on post-procedural day 14 with a 6-week course of intravenous antibiotics.