Purulent pericarditis generally refers to bacterial infection of the pericardium. Inflammation of the pericardium may result from numerous nonbacterial microorganisms, however, or may occur with a variety of noninfectious illnesses ( Box 27.1 ). Regardless of the cause of pericarditis, the responses of the pericardium are limited to acute inflammation, effusion with or without tamponade, and fibrosis with or without constriction. Because untreated purulent pericarditis is rapidly fatal, suspecting the disease early and approaching the diagnosis aggressively are important.
Idiopathic
Benign
Recurrent
Infectious
Purulent
Bacterial: Staphylococcus aureus, Haemophilus influenzae, streptococci, Neisseria meningitidis, Streptococcus pneumoniae, anaerobes, Francisella tularensis, Salmonella, enteric bacilli, Pseudomonas, Listeria, Neisseria gonorrhoeae, Actinomyces, Nocardia
Tuberculosis
Fungal: Histoplasma, Coccidioides, Aspergillus, Candida, Blastomyces, Cryptococcus
Viral
Coxsackieviruses B
Other: influenza A and B, mumps, echoviruses, adenoviruses, Epstein-Barr virus, hepatitis, measles, influenza, human immunodeficiency virus, parvovirus B19, cytomegalovirus
Other
Rickettsial: typhus, Q fever
Mycoplasmal: Mycoplasma pneumoniae
Parasitic: Entamoeba histolytica, Echinococcus
Spirochetal: syphilis, leptospirosis
Chlamydial: psittacosis
Protozoal: toxoplasmosis
Noninfectious
Postpericardiotomy syndrome
Kawasaki disease
Rheumatic fever
Connective tissue disorders: juvenile rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, periarteritis nodosa
Trauma: blunt or penetrating
Metabolic: uremia, myxedema
Hypersensitivity: serum sickness, pulmonary infiltrates with eosinophilia, Stevens-Johnson syndrome, drugs (hydralazine, procainamide, chemotherapy)
Neoplasm: leukemia, metastatic
After irradiation
Anatomy and Function
The pericardium is composed of two loosely approximated layers: visceral and parietal. The visceral pericardium is composed of mesothelial tissue, which closely follows the contour of the heart and extends for a short distance beyond the atria and ventricles to the great vessels. The outer parietal pericardium is a more fibrous structure, composed of layers of collagen interlaced with elastic fibers. The pericardial sac is attached to the diaphragm below; to the sternum in front; and to the thoracic vertebrae, esophagus, and aorta posteriorly. It is surrounded by the lungs on either side and is related closely to the main bronchi and the mediastinal lymph nodes. The phrenic and vagus nerves supply a network of pain fibers to the parietal pericardium.
The dynamics of the pericardial fluid are poorly understood. The pericardial membrane is active in the transfer of water, electrolytes, and small molecules. Molecules of large molecular weight are absorbed poorly from the pericardial space because lymphatic channels are sparse, and drainage must occur primarily through the epicardial capillaries.
Ainger summarized the function of the pericardium as follows: prevention of overdistention of the heart, protection of the heart from infection and adhesions, maintenance of the heart within a fixed geometric position within the chest, and regulation of the interaction between the stroke volumes of the two ventricles.
Bacterial Pericarditis
Population and Incidence
Although purulent pericarditis is not a common infection in pediatric patients, it is an important one to recognize because of its life-threatening nature. In an extensive early review of the literature on purulent pericarditis, half of 425 cases occurred in children younger than 13 years of age. In a review of 162 reported children with pericarditis from 1950 to 1977, 67% of the children were 48 months old or younger. From 1962 to 1974, 67 cases were recognized at St. Louis Children’s Hospital ( Table 27.1 ). During this 12-year period, pericardial disease of all causes occurred in approximately 1 of every 850 hospital admissions. Twelve (18%) of these children had purulent pericarditis.
| Etiology | No. Patients |
|---|---|
| Unknown | 28 |
| Purulent | 12 |
| Juvenile rheumatoid arthritis | 9 |
| Acute rheumatic fever | 8 |
| Uremia | 5 |
| Viral | 2 |
| Blunt chest trauma | 2 |
| Dermatomyositis | 1 |
a Patients with postpericardiotomy pericarditis and patients with small exclusions at autopsy were excluded from consideration.
Most cases in younger children are infectious. Acute pericarditis was found in 20 children between 1987 and 1997 in a hospital in Iran. The causes of pericarditis were bacterial in eight (40%), collagen vascular disease in six (30%), viral in four (20%), and secondary to mediastinal mass invasion in two (10%). In another series from Turkey, 18 children with purulent pericarditis were encountered from 1990 to 2000. At the Boston Children’s Hospital, fewer than 10 patients seen among more than 1700 patients in consultation by the pediatric cardiologists had pericarditis during the period July 1, 2001, to June 30, 2002. Over a 21-year period, 31 children with an inflammatory large pericardial effusion requiring drainage were admitted to one tertiary care children’s hospital; 12 of the effusions were caused by bacterial infections. Although rare, purulent pericarditis also can occur in neonates. In most series, a marked male predominance has been noted.
Etiology
Primary purulent pericarditis is a rare disease; it accounted for only seven of 50 cases of pericarditis reported by Gersony and McCracken. The disease is associated most often with infection from another site, with hematogenous or direct spread to the pericardium. Feldman reviewed all cases of bacterial pericarditis reported in the English language literature from 1950 to 1977. Bacteria were isolated in 146 (90%) of 162 cases. No other infection was found in 10 patients. The most common concomitant site involved was the lung, especially for Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae. When septic arthritis, osteomyelitis, or skin infections were found, S. aureus usually was the cause of pericarditis. Neisseria meningitidis and H. influenzae most often were responsible for concomitant meningitis and pericarditis.
Before the introduction of antibiotics, pneumococcal and streptococcal organisms were the most frequent causes of purulent pericarditis in children. Most cases were associated with pulmonary infections. Nearly half of patients with streptococcal pericarditis had associated postinfluenzal pneumonia. Hemolytic streptococci were isolated most often; 10% were nonhemolytic streptococci, and 5% were viridans streptococci. Kauffman and colleagues reviewed 113 cases of pneumococcal pericarditis reported since 1900. Preceding pneumonia was present in 93%, and empyema was present in 66%. Pericarditis was thought to be a late event resulting from delay in administering appropriate therapy for pneumonia.
S. aureus is the organism most commonly responsible for purulent pericarditis in children. Most cases are the result of hematogenous seeding of the pericardium from staphylococcal pneumonia with empyema, acute osteomyelitis, or soft tissue abscesses. Among 117 children with S. aureus pneumonia at Texas Children’s Hospital, 13 children had an echocardiogram; one had a large pericardial effusion. Occasionally, the pericardium is infected during the course of staphylococcal endocarditis. S. aureus is the most frequently recovered organism when purulent pericarditis develops within 3 months after the patient has undergone open heart surgery. The clinical course of acute staphylococcal pericarditis is dominated by severe toxemia. In addition to the necrotizing infection produced by S. aureus, the organism may release exotoxins, which produce shock and contribute to the high mortality. Community-associated methicillin-resistant S. aureus isolates have been recovered from some patients with acute pericarditis.
S. aureus was isolated from 73% of infants who died of purulent pericarditis in the series reported by Gersony and McCracken. It was responsible for 50% of cases in children 1 to 4 years old in the review by Feldman. In seven patients younger than 1 month of age, S. aureus was isolated from four. This finding is corroborated in literature from other countries. Thebaud and colleagues reported 19 patients with purulent pericarditis in a children’s hospital in Paris between 1979 and 1994. The mean age of the children was 3 years (range, 3 months to 10 years). The organisms isolated were S. aureus (three cases), H. influenzae (four cases), group A streptococci (three cases), S. pneumoniae (three cases), and N. meningitidis (one case). Concomitant infections included pneumonia (six cases), osteomyelitis (three cases), cellulitis (one case), and sinusitis (one case). In the series from Turkey, S. aureus was isolated from five patients, and S. pneumoniae was isolated from one patient. S. aureus pericarditis as a complication of varicella has been reported in several children. S. aureus has also caused pericarditis associated with disseminated infection in a child with IRAK-4 deficiency.
In the prevaccine era, the second most frequently encountered organism was H. influenzae type b. It was responsible for 22% (35 of 163) of the cases in Feldman’s review. A single site of coexisting infection, the lung, was identified in 16 of the 35 cases. Meningitis as a single other site of infection was found in five of 35 patients, and multiple involvement was found in seven of 35. Echeverria and colleagues summarized 33 cases from the literature. Pulmonary infiltrates and empyema were seen in 64% of patients. In countries where the H. influenzae type b conjugate vaccine is administered to infants routinely, this organism has been eliminated as a cause of pericarditis.
Pneumococcal, streptococcal, and meningococcal pericarditis have diminished in frequency since the introduction of penicillin. Go and coworkers summarized the 15 reported cases of pneumococcal pericarditis from 1980 to 1998. One was a child. Only four cases did not have an underlying risk factor. In a surveillance study of invasive pneumococcal infections in eight pediatric hospitals, only three cases of pericarditis have been observed in more than 2500 cases of systemic pneumococcal infection during the 6-year period of 1993 through 1999. Nevertheless, S. pneumoniae remains an important, although rare, cause of acute bacterial pericarditis. The routine administration of the pneumococcal conjugate vaccine to young children has likely resulted in S. pneumoniae being an even less common cause of acute pericarditis.
Pericardial involvement occurs in approximately 5% of young adults with meningococcemia. The clinical course generally is milder than that observed with other types of purulent pericarditis. Pericardial involvement rarely is detected at the time of hospital admission. Pericarditis became apparent by the third day in 13 of 17 patients reported by Dixon and Sanford. In some patients, it did not occur until late in the course of therapy. In a multicenter study involving 159 children with meningococcal infections in children from 2001 through 2005, pericarditis was not encountered. Whether this late-onset pericardial effusion is a part of the meningococcal infection or is related to immune complexes is unclear. Primary meningococcal pericarditis that occurs without clinical evidence of meningococcemia, meningitis, or any other focal infection has been reported in 16 patients, including six children 18 years old or younger (range, 2 to 18 years). Meningococcal serogroup C was identified in 11 (79%) of 14 cases for which the serogroup was known. Cardiac tamponade developed in 88% of the patients. Pericarditis also has been reported in two children with W135 meningococcal infection.
Occasionally, other microorganisms cause acute purulent pericarditis. Feldman reported that 11 (8%) of 146 cases of pericarditis in children were caused by Pseudomonas aeruginosa. P. aeruginosa caused pericarditis in an immunocompetent adult with cystic fibrosis. Pericarditis can occur with pneumonic tularemia, salmonellosis, sepsis from enteric bacilli, listeriosis, and disseminated gonococcal disease. Anaerobic bacteria should be suspected when pericarditis develops in association with lung abscess, intraabdominal infection including ruptured appendicitis, or a penetrating wound. Callanan and colleagues reported the rapid development of constrictive pericarditis after purulent pericarditis caused by anaerobic streptococcal infection. The child had a history of blunt trauma to the chest with no evidence of a penetrating wound 3 weeks before cardiac tamponade developed. The incidence of anaerobic infection may be underestimated because of improper handling of specimens for culture. Prolonged symptoms related to pericarditis can be associated with Mycoplasma pneumoniae infection.
Mycobacterium tuberculosis, previously a common cause of acute pericarditis in the United States, now is responsible more often for chronic pericardial disease. This infection is a complication of miliary tuberculosis and rarely a primary infection. In the series of 2500 children with tuberculosis reported by Lincoln and Savell, pericarditis was diagnosed in 0.4% and found at necropsy in 5% of patients. A review of 100 cases of tuberculous pericarditis in South Africa by Desai revealed a marked male predominance (72%). The duration of symptoms, consisting of cough and peripheral edema, in most patients was 0 to 120 days. Most patients were febrile and had congestive heart failure. Generalized lymphadenopathy occurred in nearly 30% of patients, pulsus paradoxus occurred in 50%, and a friction rub was audible in 25%. Of the 52 patients who had pericardiocentesis, 40% yielded fluid, but none was positive for acid-fast bacilli. Pericardial effusion was shown in 82 patients, 16 of whom died of tamponade and another 16 of whom developed constricting pericarditis.
The four stages of tuberculous pericarditis have been described as dry, effusive, absorptive, and constrictive. Granulomas usually are found in the dry stage and heal with no sequelae. The effusive stage occurs commonly with tuberculous lymphadenitis, and 15 to 200 mL of fluid usually accumulates in the pericardial space. The absorptive stage is characterized by thickening of the pericardium with fibrin deposition. Further fibrin deposition and calcification occur during the constrictive phase. The disease may progress through all stages or remain in one stage.
Latent infection in the mediastinal lymph nodes with spread directly into the pericardium is thought to be the mode of involvement with M. tuberculosis. The lymph nodes at the tracheal bifurcation often are the source.
Histoplasma pericarditis generally occurs with pulmonary, rather than disseminated, disease. Coccidioidomycosis also may cause pericardial disease. Aspergillus and Candida are more serious considerations in patients who are immunosuppressed, have serious burns, or are receiving long-term, broad-spectrum antibiotics after undergoing cardiac surgery.
Finally, several parasites such as Trypanosoma cruzi and Toxoplasma gondii can attack the pericardium.
Pathology and Pathogenesis
Pericarditis begins with fine deposits of fibrin adjacent to the great vessels; it causes the pericardial membrane to lose its smoothness and translucency. Numerous granulocytes may extend into the myocardium.
Bacterial pericarditis most commonly results from direct extension of infection from involved lung and pleura. Pulmonary infections may spread to the pericardium through the bronchial circulation. Pericarditis also can develop through hematogenous dissemination from infection elsewhere, and it also may be the result of an immunologically induced response to a primary infection.
As pericardial fluid accumulates, intrapericardial pressure increases. The rate of increase is a function of the speed of accumulation and the compliance of the pericardium. With slow accumulation of fluid, large volumes can be accommodated because of the gradual expansion of the parietal pericardium. As the compliance of the pericardium reaches its maximum, however, further accumulation of even small volumes of fluid results in an abrupt increase in intrapericardial pressure. If pericardial fluid accumulates at a rapid rate, marked elevation in intrapericardial pressure may occur with much smaller volumes of fluid. In a small child, 100 mL can cause severe tamponade, whereas 3 L may accumulate slowly in an older child and not result in tamponade.
The most significant hemodynamic effect of pericardial effusion is restriction of ventricular filling. Ventricular end-diastolic, atrial, and venous pressures increase on the right and left sides of the heart equally. When restriction of ventricular filling becomes more pronounced, the ventricular stroke volume and cardiac output decrease. In an attempt to maintain cardiac output, tachycardia and peripheral vasoconstriction occur. Systemic arterial blood pressure and pulse pressure are reduced markedly. Tamponade occurs when these compensatory mechanisms fail to maintain adequate cardiac output.
Clinical Manifestations
A diagnosis of purulent pericarditis should be suspected in any patient with septicemia who develops cardiomegaly. The classic signs and symptoms of pericarditis are precordial pain, pericardial friction rub, evidence of cardiac fluid, and muffled heart sounds. Chest pain is not a common symptom, especially in small children; the reported rates vary from 15% to 80%. However, in one study focusing on 22 children (aged 6 to 17 years old) who presented to an emergency center and ultimately were found to have acute pericarditis, 95% had chest pain. Acute abdominal symptoms may be the presenting complaints of some children.
The most common symptoms and signs of pericarditis are fever, tachypnea, and tachycardia, which also are presenting features of associated systemic infection. If the cardiac shadow is radiographically enlarged, with or without a friction rub, and the tachypnea and tachycardia are out of proportion to the fever, myocardial dysfunction or pericarditis should be suspected.
An evanescent or ubiquitous rub may be detected. The typical sound of a rub is that of a high-frequency murmur, which may have a to-and-fro or triphasic pattern but may not have any correlation with the cardiac cycle. Frequently the rub is heard better with the patient leaning forward or kneeling. A rub may be differentiated from a murmur by pressing the diaphragm of the stethoscope firmly against the chest wall; this pressure amplifies the rub, and the typical scratchy quality becomes more apparent as the examiner opposes the visceral and parietal pericardium by compression of the chest. Rubs have been known to increase with inspiration. Although a rub is less likely to be heard in the presence of a large effusion, it still may exist. The heart sounds usually are muffled, and the palpable ventricular impulse generally is diminished. Both findings may be present in congestive heart failure, but they may be absent with tamponade.
Cardiac tamponade may be an early complication of pericarditis associated with a systemic infection. Cardiac tamponade means that there is compression of the heart by a tense pericardial sac, usually full of fluid, resulting in a decrease in venous return to the cardiac chambers and a decrease in cardiac output. During inspiration, the intrathoracic pressure decreases and venous return to the venae cavae increases. The tense pericardial sac limits the amount of blood that can enter the right atrium because of diastolic compression; a paradoxical increase in jugular venous pressure occurs during inspiration (i.e., Kussmaul sign) ( Fig. 27.1 ).
During inspiration, a small decrease in systolic blood pressure and cardiac output normally occurs and is caused by an increase in pulmonary venous capacitance. It is exaggerated with pericardial tamponade (>10 mm Hg decrease in blood pressure) because of the restricted inflow into the cardiac chambers. This clinical sign has been called paradoxical pulse, but it actually is an exaggeration of the normal respiratory cycle ( Fig. 27.2 ).
Diagnosis
The radiographic appearance of a rapidly increasing cardiothoracic ratio without increasing pulmonary vascular markings is more suggestive of pericardial effusion than of congestive heart failure caused by myocardial dysfunction ( Fig. 27.3 ). Fluoroscopy alone generally is of little value; myocardial dysfunction and pericarditis can impair cardiac contractility.
The size of the pericardial shadow does not indicate the severity of hemodynamic effects. It is a function of the rapidity of accumulation and the volume of pericardial fluid. When acute infection results in sudden cardiac tamponade, the heart size may be normal. A large, globular heart shadow with no evidence of increased pulmonary vasculature, particularly in a patient who has signs of right-sided heart failure, is strong evidence for pericardial disease. The lack of pulmonary overcirculation helps to distinguish this condition from myocarditis; however, determining whether pulmonary infiltrates also exist may be difficult.
A plain lateral chest radiograph may show findings consistent with a pericardial effusion. Separation of more than 2 mm between the anterior mediastinal and subepithelial “fat stripes” suggests an effusion. Obliteration of the retrosternal space without evidence of thymic or right ventricular enlargement also indicates pericarditis.
The extent of electrocardiographic abnormalities may be explained by the amount of pericardial effusion and the presence of superficial myocardial injury or myocarditis. Pericardial effusion gives rise to low-voltage QRS complexes as a result of the damping effect of pericardial fluid between the chest wall and the myocardium. Accumulation of fluid and fibrin under pressure also may produce an injury pattern manifested by ST-segment deviation. More than 90% of patients have elevation of the ST segment, which occurs most frequently in leads I, II, V 5 , and V 6 . Widespread T-wave inversion indicative of epicarditis may be seen in the same leads in which ST-segment elevation occurs.
Spodick described four stages of electrocardiographic changes in acute pericarditis. In stage I, ST-segment elevation is pronounced and the PR segment may be depressed. In stage II, the ST segment begins to return to the isoelectric line, the amplitude of the T wave diminishes, and the PR segment is depressed. By stage III, the ST segment has returned to the isoelectric line, and the T-wave inversion occurs. An incompletely inverted T wave (i.e., a diphasic wave or an upright T wave with a notched summit) sometimes is observed. In stage IV, these changes may resolve completely. T-wave abnormalities may persist for life, however, and do not indicate active disease.
Electrical alternans is seen in a large pericardial effusion. Electrical alternans refers to the alternation in electric amplitude of the T wave and the QRS complex with each cardiac cycle. It is thought to result from the rotational and pendular motion of the heart suspended in pericardial fluid.
Deviations from classic patterns occasionally occur, and single electrocardiographic changes are common findings. All 12 children reported by Okoroma and colleagues had ST-segment elevation, whereas only 3 had concomitant low voltage. Dysrhythmias with pericarditis are unusual in the absence of coexisting heart disease.
M-mode echocardiography is the most sensitive method for diagnosing significant pericardial effusion ( Fig. 27.4 ). With a small to moderate effusion, only a “fluid space” is seen posteriorly ( Fig. 27.4B ). With a larger effusion, fluid is seen anteriorly and posteriorly, and the septal motion becomes grossly abnormal. The heart may give the appearance of freely swinging ( Fig. 27.4A ). Newer echocardiographic techniques, such as two-dimensional sector scanning, are not more useful than the conventional M-mode. Pericarditis may be detected uncommonly by echocardiography in children with S. aureus bacteremia but without clinical evidence of pericardial or endocardial involvement.
