**5. Septic embolization to spleen**

during the 1 month delay, as well as reducing further embolic events that can cause permanent disability [39]. As a result, evidence is emerging that early operative treatment for patients with nonhemorrhagic cerebral embolic events does not lead to worse outcomes. In a recent report, 198 patients undergoing valve replacement following cerebral infarction were analyzed with 58 undergoing early surgery (1–7 days) and 140 undergoing late surgery (>7 days). There was no survival benefit in delaying otherwise indicated surgery for IE among patients with cerebral SE [68]. Another retrospective study reviewed operative results of 308 patients with IE, finding no difference in key outcomes (postoperative stroke, 30-day mortality, long-term survival) when comparing patients with cerebral SE undergoing early surgery (<14 days) to patients undergoing surgery for IE without cerebral complications [40]. However, some authors report that early cardiac surgery is associated with neurological complications [43]. Both the American Heart Association and The Society of Thoracic Surgeons workforce on evidence-based surgery report that it is probably safe to proceed with an early operation in patients with small ischemic infarction, while delaying a surgery for 2–4 weeks might be preferred for those with a large ischemic infarction or a hemorrhagic event, respectively. In those with worsening cardiac function, recurrent stroke, uncontrolled infection or recurrent

Despite numerous case reports, available clinical data on SE to the kidneys continue to be limited [2, 69–71]. Embolic events associated with IE involve kidneys in 6–14% cases (**Fig‐ ure 1**) and exhibit highly variable pattern of presentation [2, 69]. Most patients complain of an acute onset of abdominal, flank, or back pain. The pain is typically constant. Approximately half of reported cases present with fever and vomiting. Acute secondary hypertension from renin release due to decreased arterial perfusion may be seen. Laboratory findings may include leukocytosis, proteinuria, hematuria, elevated levels of lactate dehydrogenase, serum glutamic-oxaloacetic transaminase, serum glutamic-pyruvic transaminase, and alkaline phosphatase [70]. Potential complications of septic emboli include hematuria, glomerulonephritis, or infarction leading to loss of renal function. Three types of severe renal manifestations may be seen: renal infarcts, focal "embolic" glomerulonephritis, and acute diffuse glomerulonephritis [72]. Renal loss due to embolic occlusion of the renal artery has been reported [71]. Of interest, localized renal infarcts were found in over 30% of necropsy samples, with more than half attributable to SE in patients infected with *Staphylococcus aureus* [69]. Renal SE and infarction may be associated with concurrent embolic events to other organs (**Figure 4**) [73]. In one reported case, renal infarction was found in conjunction with SE to the coronary arteries and the spleen [74]. In another case, multiple acute SE infarcts due to Gram-positive aortic valve IE were found in the brain, spleen, kidneys, and the intestine [75]. Treatment is usually supportive, consisting of systemic antibiotics, renal replacement therapy (if indicated) [69], and only rarely involves percutaneous or open procedural interventions [14, 76]. Preservation

emboli, a delay of less than 4 weeks may be reasonable [50, 58].

**4. Septic embolism to the kidneys**

150 Contemporary Challenges in Endocarditis

of renal function is the primary goal.

Splenic involvement is often seen in the setting of left-sided valvular vegetations from IE [12]. The two primary manifestations are splenic infarction (most common) and splenic abscess. Although often asymptomatic, splenic infarct may be associated with acute abdominal (usually left upper quadrant) pain and can be complicated by abscess formation (the primary source of subsequent morbidity and mortality) [12, 77]. Splenic abscess formation is due to hematogeneous spread from a distant source of infection, with IE being associated with up to two-thirds of such instances, either via bacteremic seeding or direct embolization of infected valvular debris [78, 79].

In one study, splenic infarcts were found in 19% of cases of IE, including asymptomatic cases identified on CT examination [12]. Streptococci and staphylococci are among the most common offending microorganisms, accounting for >80% of cases [4, 12]. While *Streptococcus viridans* and *Staphylococcus aureus* are frequently encountered, other bacterial species including *K. pneumoniae, S. epidermidis,* and *P. mirabilis* have been described in this setting [79].

Because mortality associated with splenic abscess is high, prompt and appropriate therapy is critical. Management includes antibiotics based on microbial sensitivity, image-guided aspiration or drainage, and surgical intervention by splenectomy (open or laparoscopic) in selected cases [80–83]. Early detection may help reduce the need for surgical intervention. Although the identification of SE to the spleen does not constitute a surgical indication, the presence of an abscess refractory to nonoperative approaches (e.g., antibiotics with or without percutaneous drainage), uncontained abscess rupture, or the presence of vascular complications (e.g., pseudoaneurysm or a large infarction) should prompt the consideration of splenectomy [84–87]. Likewise, refractory pain may also constitute a surgical indication (or be a clinical warning sign of one of the above complications) [80, 87, 88]. The decision to operate in the setting of therapeutic uncertainty should be considered in the context of the simultaneous presence of any other relative indications, risks, and benefits. The diagnosis of splenic infarct is not a contraindication for a cardiac operation when such intervention is indicated. The situation is not as clear in the presence of a splenic abscess. In most cases, it is preferable to perform splenectomy prior to valve surgery in order to prevent re-infection of the valve prosthesis or annuloplasty ring [58, 89]. Combined cardiac procedure and splenectomy has been reported with good outcomes [90].
