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Preoperative care of the critically ill endocarditis patient
Introduction
In-hospital mortality for patients with infective endocarditis (managed medically and/or surgically) remains high, ranging from 10% to 20% [ ]. At 6 months, nearly 30% of patients will have died, and at roughly 7 years, mortality will be over 50% [ , ]. Various factors increase mortality, including older age, the occurrence of neurologic or pulmonary complications, embolic events, and renal injury at the time of admission [ , , ]. Hasbun et al. created a four-tiered scoring system for 6-month mortality in patients with left-sided native-valve endocarditis, which includes the patient's mental status, Charlson comorbidity scale score, degree of congestive heart failure, causative microbiology, and treatment (medical or surgical) [ ].
The proportion of endocarditis patients requiring admission to an intensive care unit (ICU) prior to medical or surgical cure has not been specifically studied, but intensive care is typically necessary when end-organ injury or heart failure is present [ ]. An estimated 60% of patients with endocarditis experience at least one major complication, and surgical intervention is required in up to 50% [ , ]. Not surprisingly, a 50% in-hospital mortality is experienced by those patients who require ICU care [ , ]. Generally speaking, the complications from endocarditis result from direct damage to the heart, from vegetation embolization, or from systemic hypoperfusion due to septic or cardiogenic shock. Systemic embolization occurs in approximately 30% of cases [ , ]. Antimicrobial therapy is, of course, paramount to treatment and is covered in Chapter 7 .
This chapter will review the care of the critically ill endocarditis patient prior to definitive surgical repair. We will first discuss the management of heart-related complications of endocarditis including valvular dysfunction and conduction abnormalities. We will then discuss the treatment of neurologic, renal, respiratory, and visceral complications ( Table 8.1 ). The subsequent chapter will address the postoperative care and management of complications in this critically ill population.
Table 8.1
Summary of preoperative complications of infective endocarditis.
| Organ | Complication | Incidence | Diagnosis | Therapy |
|---|---|---|---|---|
| Heart | Valvular insufficiency | 40% | Echocardiogram | Surgical intervention |
| Conduction abnormalities | 25% | EKG, echocardiogram | Surgical intervention | |
| Acute coronary syndrome | Rare | CT, coronary catheterization | Surgical intervention | |
| Brain | Embolic stroke | 20%–40% | CT brain, MRI | Consider anticoagulation |
| Cerebral hemorrhage | 20%–40% | CT brain, MRI | Supportive care; ensure no concomitant mycotic aneurysm requiring intervention | |
| Mycotic aneurysm | Uncommon | MRA | Neurosurgery, interventional neuroradiology for clipping versus coiling | |
| Meningitis | 1%–5% | Lumbar puncture | IV antimicrobial therapy | |
| Cerebral abscess | 1%–5% | MRA | Needle aspiration, drainage | |
| Encephalopathy | 25% | Clinical diagnosis, MRI | Supportive care, correct nutritional or metabolic deficiencies (B12, folate, thiamine) | |
| Kidney | Acute kidney injury | 30%–35% | Urinalysis, urine electrolytes, metabolic panel | IV antibiotics, maintaining kidney perfusion, fluid management |
| Septic emboli | Up to 30% | Urinalysis, CT abdomen/pelvis | IV antibiotics, maintaining kidney perfusion, fluid management | |
| Glomerulonephritis | 25% | Urinalysis (red cell casts), metabolic panel | IV antibiotics, maintaining kidney perfusion, fluid management | |
| Acute interstitial nephritis | 10% | Urinalysis (white cell casts), metabolic panel | IV antibiotics, maintaining kidney perfusion, fluid management | |
| Lung | Septic emboli | 5%–10% | Chest XR, CT chest | IV antimicrobial therapy Surgical resection for treatment failure |
| Spleen | Septic emboli | 30%–35% | CT abdomen, labs | Splenectomy |
| Bone | Osteomyelitis | 5% | Radiography, CT, MRI, nuclear bone scan | Prolonged IV antibiotics |
CT , computed tomography; EKG , electrocardiogram; IV , intravenous; MRA , magnetic resonance angiography; MRI , magnetic resonance imaging; XR , X-ray.
Preoperative management of cardiac complications
Cardiac complications affect over half of all patients with infective endocarditis. The most common cardiac abnormalities associated with infective endocarditis are valvular insufficiency with subsequent heart failure, conduction abnormalities, and acute coronary syndrome (ACS).
Valvular insufficiency
Acute valvular insufficiency in the setting of infective endocarditis is generally the result of perivalvular abscesses, which occur in up to 40% of all patients. Perivalvular abscesses most commonly complicate prosthetic-valve endocarditis, followed by endocarditis involving the native aortic and then the mitral valve. Valvular insufficiency occurs as perivalvular abscesses disrupt normal coaptation during diastole, or when the inflammatory process leads to primary valve leaflet disruption such as perforations or tears. Multiple valvular involvement, which is present in roughly 15% of all endocarditis cases, is thought to be due to secondary infection of the additional valve from direct extension or from satellite infections that arise from regurgitant jets of infected blood. Regardless of the mechanism, acute valvular insufficiency is a medical emergency as failure to quickly treat the valvular disruption may result in acute heart failure, cardiopulmonary collapse, and death.
Acute valvular insufficiency of left-sided heart structures commonly presents with sudden onset shortness of breath and fatigue. The physical examination is often notable for tachycardia with a high-grade diastolic decrescendo or holodiastolic murmur, evidence of pulmonary congestion, including increased work of breathing and bilateral rales, and other exam findings suggestive of decreased cardiac output, e.g., hypotension, cool extremities, and pallor. Urgent workup should include cardiac enzymes and an echocardiogram, which will usually be diagnostic and may show valvular insufficiency in the presence of flail leaflets or calcified echodensities on the involved valves. In the setting of acute aortic valvular insufficiency resulting in acute pulmonary edema, the patient should undergo emergent surgery, as medical treatment of the pulmonary edema in this setting is of limited benefit. In patients who do not present with acute pulmonary edema or in extremis, initial care should include medical management, broad spectrum antibiotics, and optimization for surgery, with a focus on managing the heart failure with diuresis and decreasing afterload with the use of vasodilators. Definitive treatment remains surgical and will be discussed in subsequent chapters.
Conduction abnormalities
Conduction disorders are found in roughly 25% of patients with endocarditis and are independently associated with increased mortality and worse prognosis [ , ]. Typically atrioventricular or bundle branch blocks are usually the result of perivalvular abscesses that extend into the conduction system [ ]. Conduction disorders are most commonly seen with aortic root involvement and occur due to the anatomic proximity of the aortic valve to the interventricular septum and bundle of His. The resulting abnormalities vary but all fall under the category of heart block, i.e., a bundle branch, or first, second, or complete heart block.
Conduction abnormalities are commonly detected by EKG. Suspicion for conduction system involvement as a result of endocarditis should be followed by an echocardiogram [ ]. Echocardiographic findings of an annular or valvular mass with perivalvular extension in the setting of new onset atrioventricular block should prompt immediate surgical intervention, likely entailing both valve replacement and, at times, repair of the involved annulus or septum [ ].
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