Strange and Schafermeyer's Pediatric Emergency Medicine, Fourth Edition (Strange, Pediatric Emergency Medicine), 4th Ed.

CHAPTER 41. Inflammatory and Infectious Heart Disease

William T. Tsai

HIGH-YIELD FACTS

• Pericarditis presents with chest pain in the older child. Pleuritic or positional chest pain, fever, tachycardia, friction rub, and electrocardiographic changes may be noted.

• Tachycardia and fatigue may be signs of myocarditis. These patients should be admitted to a pediatric intensive care unit for careful monitoring and aggressive supportive management.

• Obtain echocardiography in patients with suspected myocarditis.

• The at-risk patient with endocarditis presents with unexplained fever, myalgia, new murmur, and elevated acute-phase reactants.

INTRODUCTION

Inflammatory diseases of the heart may affect the pericardium, myocardium, or endocardium. Pancarditis describes inflammation involving all layers of the heart. Such inflammatory cardiac disorders may be infectious, noninfectious, or rheumatologic and enter into the differential diagnosis in children presenting with complaints that range from chest pain, to acute gastrointestinal symptoms, to symptoms of cardiovascular collapse.

This chapter will discuss the presentation, diagnosis, and management of pericarditis, myocarditis, and endocarditis in children presenting to the emergency department.

PERICARDITIS

Pericarditis usually follows a benign clinical course. Presenting symptoms include pleuritic or positional chest pain, fever, dyspnea, or abdominal pain. Causes overlap with those of myocarditis (Table 41-1).

TABLE 41-1

Etiology of Pericarditis

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Signs include a pericardial friction rub and tachycardia. If there is a large enough pericardial effusion, one may not hear a friction rub because the visceral and parietal pleura are not apposed. As effusions increase in volume, dyspnea, or shock may develop. In the presence of pericardial tamponade, distended jugular veins and hepatomegaly may become noticeable. As cardiac output decreases because of decreased cardiac stroke volume, delayed capillary refill, decreased urine output, and hypotension develop. Pulsus paradoxus, an exaggerated decrease in systolic blood pressure during inspiration, may be appreciated.1

In patients with little or no effusion, the chest radiograph may be normal. Cardiomegaly is noted on chest radiography when moderate or large pleural effusions are present (Fig. 41-1). The electrocardiogram may be diagnostic with diffuse ST-T wave changes, and PR depression may occur. A decreased QRS amplitude or electrical alternans may be seen with large effusions. Echocardiography will rapidly demonstrate the presence, size, and location of a pericardial effusion and can rapidly identify cardiac tamponade using 2D and Doppler techniques.

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FIGURE 41-1. Chest radiograph of an infant with cardiomegaly secondary to a large pericardial effusion (left). Same infant after placement of a pericardiocentesis catheter (right).

Management depends on the presence and extent of pericardial effusion. Treatment is generally supportive and includes treatment with anti-inflammatory medication and cardiology consultation. Consider hospitalization in children with effusion. Obtain urgent cardiology and critical care consultation in children with large effusions and hemodynamic instability.

Children with pericarditis and pericardial effusion, who exhibit signs of hemodynamic instability secondary to cardiac tamponade, should have emergent pericardiocentesis. Although pericardiocentesis can be lifesaving in cases of tamponade, the possibility of severe complications and the high overall rate of complications mandate that this procedure be performed by clinicians with considerable experience and expertise and with echocardiographic guidance (Fig. 41-2).2

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FIGURE 41-2. Subcostal view echocardiogram of a patient. A large pericardial effusion is seen surrounding the right and left ventricle.

MYOCARDITIS

Acute myocarditis is a serious but relatively uncommon diagnosis in the emergency department. Symptoms can progress from those of a nonspecific respiratory illness to those of cardiovascular collapse and death in a short period of time. Some patients present with fulminant disease, whereas others have an indolent course that progresses over time to dilated cardiomyopathy with chronic congestive heart failure. Signs and symptoms may point to an obvious cardiac etiology, but subtler and misleading presentations require the clinician to have a high index of suspicion.

The incidence of myocarditis in the United States is not known because of patients with subclinical infection and difficulties in precise diagnosis. Myocarditis was found at autopsy in between 3% and 40% of infants and children with sudden death.37 Frequently, a diagnosis of myocarditis is suspected but never confirmed. More recently, in a survey of the incidence of pediatric cardiomyopathy in two regions of the United States, the incidence of myocarditis as a cause of dilated cardiomyopathy was approximately 0.2 per 100,000 children.6

image ETIOLOGY

In cases of suspected myocarditis, an etiologic agent is identified in less than one-third of the time.8 Laboratory techniques include observing acute and convalescent titer for specific viruses, viral cultures from fluid or tissue, and PCR amplification of viral genome. Viral etiologies predominate, however bacteria, rickettsia, fungi, and parasites are known agents (Table 41-1).

image CLINICAL PRESENTATION

Myocarditis may be difficult to diagnose because signs and symptoms may mimic other very common disorders. Frequently, it is not until later in the clinical course that these symptoms are noted to be of cardiac origin. The clinical presentation can be divided into specific symptom complexes based on presentation (Table 41-2). In general, the pathophysiology of the symptom complexes follows the gradual onset of congestive heart failure to frank cardiogenic shock. The patient may present with tachycardia and rhythm disturbances.

TABLE 41-2

Myocarditis Presenting Symptom Complexes

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Complaints include cough, wheeze, congestion, fever, or tachypnea. Tachypnea may be compensation for metabolic acidosis. Bronchospasm responding poorly to conventional therapy may suggest early myocarditis. Red flags include the child who is tachypneic, but lack symptoms of wheezing or supporting evidence for the diagnosis of pneumonia. Other signs and symptoms include those associated with congestive heart failure, poor feeding, cyanosis, and grunting. Murmur, gallop rhythm, rales, or organomegaly may confirm the diagnosis (Table 41-3). Myocarditis should be considered in any child who deteriorates despite aggressive treatment for bronchospasm or reactive airway disease.9

TABLE 41-3

Physical Findings

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The onset of metabolic acidosis secondary to severe hypoperfusion (cardiogenic shock) accounts for some of the symptoms seen. Metabolic acidosis can cause tachypnea, retractions, and grunting.10,11Gastrointestinal symptoms arise because of viral processes but also because of gastrointestinal hypoperfusion. Severe acidosis may also affect mental status causing lethargy and coma.

image DIAGNOSIS

Diagnosis requires a high index of suspicion. Unfortunately, standard laboratory, radiographic, and electrocardiographic testing is nonspecific. Chest radiograph is positive in only 42% to 75% of cases (Fig. 41-3).911 All patients should receive ECG testing. Electrocardiographic changes include nonspecific ST-T wave and axis changes. Rarely, heart block or infarct patterns may emerge.

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FIGURE 41-3. Chest radiograph in an infant with myocarditis. Note cardiomegaly and increased vascular congestion consistent with pulmonary edema.

Elevations in creatine phosphokinase, lactate dehydrogenase, troponin,12 and brain natriuretic peptide lack specificity.8 Indicators of inflammation such as erythrocyte sedimentation rate and c-reative protein are nonspecific. Patients who may have myocarditis should receive echocardiography. Findings include increased end-diastolic chamber dimensions, reduced shortening fraction, atrioventricular valve regurgitation, and regional wall abnormalities (Fig. 41-4).

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FIGURE 41-4. Apical four-chamber echocardiogram from infant in Figure 41-3, showing left ventricular dilation. Ejection fraction 28%.

image TREATMENT

Children with acute myocarditis should be admitted to a pediatric intensive care unit (PICU) for continuous monitoring because of the risks of ventricular ectopy and cardiogenic shock. Preferably, the PICU should have the ability to provide aggressive mechanical cardiac support if needed. Initial management includes the treatment of cardiogenic shock or congestive heart failure. Consider use of invasive monitoring. Ionotropic support with dopamine, dobutamine, epinephrine, or milrinone may be necessary. An aggressive approach to dysrhythmias may prevent sudden death. Heart block is an indication for transvenous pacing. Meticulous supportive care of acid–base derangements, metabolic abnormalities, and fluid status is mandatory. The use of corticosteroids and other immunosuppressants is not well supported by current studies.13 The use of intravenous immunoglobulin remains unproven but is frequently used.14 Patients with fulminant myocarditis should receive aggressive mechanical support of the circulation with extracorporeal membrane oxygenation (ECMO) because of the excellent long-term prognosis if these patients can survive the initial period of cardiogenic shock.15,16 Ultimately, transplantation may be required for end-stage cardiomyopathy secondary to myocarditis.

ENDOCARDITIS

Bacterial endocarditis occurs in children with congenital heart disease or central venous catheters or in adolescents who use intravenous drugs. Seeding can occur via dental caries, skin infections, and manipulation of the airway, gastrointestinal tract, or genitourinary tract. Staphylococcal and streptococcal species predominate, with HACEK organisms (Hemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella) and Candida as occasional offenders. Diagnosis is suspected in the at-risk patient in the presence of unexplained fever, weakness, myalgia, and arthralgia. A new murmur is present in fewer than 50% of cases. Other findings may include congestive heart failure secondary to valvular insufficiency, petechiae, or new neurologic findings. Adult cutaneous hallmarks such as Janeway lesions or Osler nodes are rare. Blood culture will identify the organism in 90% of cases. Other supportive data include elevated acute-phase reactants such as white blood cell count or erythrocyte sedimentation rate, anemia, hematuria, or embolic infiltrates. The echocardiogram has a 70% to 80% detection rate, with failure occurring in children who have complex congenital heart disease.

Identification of the causative organism allows more specific antibiotic therapy. However, in the sickest of patients, start appropriate broad-spectrum coverage in consultation with a consultant. Bacteremia will persist in some patients despite antibiotics. Removal of vegetation or valve replacement may be indicated. Other sequelae, such as threatened or recurrent embolization, severe valve failure, recalcitrant arrhythmia secondary to vegetation, or myocardial abscess may occur. Pulmonary or neurologic emboli are dependent on the location of the vegetations and presence of intracardiac shunting. Overall, endocarditis carries a mortality rate of 6% to 14%.

Because of the high mortality rate, prevention of endocarditis is important. The emergency physician plays an important role in endocarditis prophylaxis. Indications are dynamic. The American Heart Association updated its endocarditis prophylaxis in cardiac conditions guidelines. The most recent guidelines suggest endocarditis prophylaxis for high risk and moderate risk conditions. The high risk conditions include: prosthetic valves, previous bacterial endocarditis, cyanotic cardiac malformations, surgical system demo pulmonary shunts, congenital defects repaired with prosthetic material or device. The moderate risk conditions include: Rheumatic or acquired valvular dysfunction, hypertrophic cardiomyopathy, MVP with regurgitation or thickened leaflets, most other complex cardiac malformations. It also includes cardiac transplant patients. Endocarditis prophylaxis is not recommended for isolated secundum ASD, or for repaired secundum ASD, VSD, PDA without residual after six months. It is also not recommended for innocent murmurs, previous Kawasaki syndrome without valvular dysfunction, previous rheumatic fever without valvular dysfunction, cardiac pacemakers and implanted defibrillators. For patients with high risk cardiac conditions antibiotic prophylaxis is recommended for all dental procedures that involve manipulation of the gingival tissues or periapical region of teeth or perforation of the oral mucosa. Prophylaxis is not needed for routine dental procedures. It is also recommended for invasive respiratory tract procedures involving incision or biopsy. Prophylaxis is also indicated in patients undergoing surgical procedure that involves infected skin structure or musculoskeletal tissue any agent should be active against staphylococci and beta-hemolytic streptococci.

ACUTE RHEUMATIC FEVER

Valvar involvement characterizes the carditis of acute rheumatic fever. The acute phase begins 2 to 3 weeks after a group A streptococcal illness. Jones criteria are outlined in Table 110-1. Typically, carditis follows arthritis and can involve all three layers of the heart. A benign acute phase can be followed years later with valvular insufficiency. Mitral insufficiency is most common and is characterized by a holosystolic, high-pitched, blowing apical murmur radiating to the axilla. Regurgitant aortic murmurs are middiastolic, high-pitched, and blowing, located at the base, radiating into the neck. Other cardiac findings include tachycardia, gallop rhythm, pericardial rub, or congestive heart failure. The ECG may demonstrate PR prolongation, conduction delays, left ventricular hypertrophy, or dysrhythmia. Echocardiography is helpful in the follow-up of patients with rheumatic heart disease and may have a role in the evaluation of patients without murmur or with subclinical heart involvement.18

Treatment during the acute phase includes hospitalization and bed rest and cardiac rehabilitation follows. High-dose aspirin is started upon confirmation of the diagnosis. Penicillin or erythromycin is given to eradicate residual streptococci. Corticosteroids are controversial and may have a role in the treatment of carditis or chorea. Long-term follow-up of patients with acute rheumatic fever includes surveillance for recurrence, endocarditis prophylaxis, and treatment of chronic failure. Patients without early cardiac involvement are unlikely to develop delayed valvular disease.

REFERENCES

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13. Mason JW, O’Connell JB, Herskowitz A, et al. A clinical trial of immunosuppressive therapy for myocarditis. The myocarditis treatment trial investigators. N Engl J Med. 1995;333:269.

14. Drucker NA, Colan SD, Lewis AB, et al. Gamma-globulin treatment of acute myocarditis in the pediatric population. Circulation. 1994;89:252.

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17. Dajani AS, Taubert KA, Gerber MA, et al. Prevention of bacterial endocarditis: recommendations by the American Heart Association. JAMA. 1997;277:1794.

18. Committee on Rheumatic Fever, Endocarditis, and Kawasaki disease; and American Heart Association. Guidelines for the diagnosis of rheumatic fever. JAMA. 1992;268:2069.