Right heart endocarditis: clinical and echocardiographic features

Delayed diagnosis of right-sided valve endocarditis causing recurrent pulmonary abscesses: a case report

BACKGROUND

Pulmonary valve infective endocarditis is a rare diagnosis that is usually associated with immunocompromised states or structurally abnormal hearts. It is unusual for it to occur in structurally normal hearts or to cause recurrent symptoms after targeted antibiotics. Although guidelines suggest follow-up with repeat echocardiography and inflammatory marker surveillance, this case demonstrates that these are not always useful investigations, and instead imaging of the chest may be more appropriate.

CASE PRESENTATION

We describe a case of a 74-year-old man who presented with respiratory symptoms and was originally misdiagnosed with pneumonia but later found to have a large pulmonary valve vegetation caused by Streptococcus mitis. Despite initially responding to antibiotic therapy, the vegetation continued to cause pulmonary emboli and cavitating lung abscesses months later, necessitating pulmonary valve replacement.

CONCLUSIONS

This case demonstrates that pulmonary valve endocarditis can present atypically with recurrent respiratory symptoms, and in such cases, echocardiography should be considered to investigate for right-sided infective endocarditis. In addition, despite correct treatment, with normalization of inflammatory markers and improvement in vegetation size, infective endocarditis can continue to cause systemic symptoms. Finally, clinicians should consider chest computed tomography routinely as part of right-sided infective endocarditis follow-up.

Isolated native tricuspid valve endocarditis due to group A β-hemolytic Streptococcus without drug addiction

We discuss a case of tricuspid valve endocarditis to group A Streptococcus in a middle-age man without a history of intravenous drug use.

Infective endocarditis at autopsy: a review of pathologic manifestations and clinical correlates

The frequency of autopsies appears to be declining, and the usefulness has been challenged. We reviewed cases of autopsied active infective endocarditis (IE) during 2 periods based on the availability of high-tech 2-dimensional echocardiograms: Period 1 (P1) included 40 cases studied from 1970 to 1985, and Period 2 (P2) included 28 cases seen from 1986 to 2008--that is, before and after the introduction of echocardiograms in our institution. We conducted the study to reassess the pathology of IE and to determine how frequently diagnosis is not made during life.The age of patients increased 10 years on average between the 2 periods, and comorbidities were significantly more frequent in P2. While the frequency of rheumatic valve disease and prosthetic valve endocarditis (PVE) decreased, degenerative valve disease increased. Isolated mitral or aortic valve IE was most common. Right-sided IE was observed in patients with Staphylococcus aureus bacteremia from infected venous lines. In most cases IE involved only the cusps of cardiac valves. "Virulent" microorganisms caused ulcerations, rupture, and perforation of the cusps and necrosis of chordae tendiniae and perivalvular apparatus. In PVE the lesions were located behind the site of attachment, and vegetations were seen on the sewing ring in both metallic and biologic prostheses. Infection spread to adjacent structures and myocardium with ring abscess observed in 88% of cases. Prosthetic detachment causing valve regurgitation was associated with abscesses in 76% of cases; these patients developed persistent sepsis and severe cardiac failure. Obstruction occurred in patients with PVE of the mitral valve. Acute purulent pericarditis was observed in 22% of cases, mainly in patients with aortic valve IE and myocardial abscesses.Gross infarcts were seen in 63% of cases but were asymptomatic in most instances. The spleen, kidneys, and mesentery were the sites most frequently involved. Myocardial infarctions were found in less than 10% of cases. Abscesses were also frequently found and were a common source of persistent fever and bacteremia. Glomerulonephritis was more common in the first period. Brain pathology consisted of ischemic and hemorrhagic infarcts and abscesses. Cerebral bleeding was more frequent in patients with PVE on anticoagulant therapy. Neutrophilic meningitis was observed in S. aureus IE.Diagnosis of IE was not made during life in 14 (35%) cases during P1 and 12 (42.8%) cases in P2. Overall, diagnosis was missed until autopsy in 38.2% of cases. IE was hospital acquired in 28 instances. While a clinical diagnosis was made in all but 4 cases of early-onset PVE (23.5%), the diagnosis was not made during life in 22 of 51 patients with native-valve IE (43.1%). Of these 22 patients, IE was hospital acquired in 11 (50%). The absence of fever, cardiac murmurs, and many of the typical stigmata of endocarditis may have led to the diagnosis being overlooked clinically.Brain bleeding, cardiac failure and less frequently acute myocardial infarct were the most common causes of death.IE continues to be missed frequently until autopsy. Postmortem examination is an important tool for evaluating the quality of care, and for guiding teaching and research related to cardiovascular infections.

Isolated pulmonic valve endocarditis in an adult patient with ventricular septal defect and infundibular pulmonary stenosis

Ventricular septal defect associated with infundibular pulmonary stenosis is a relatively uncommon congenital cardiac defect. We report the first case of a patient with perimembranous small ventricular septal defect and infundibular stenosis suffered from pulmonary valve endocarditis and septic pulmonary embolism.

Endocarditis caused by Staphylococcus aureus: A reappraisal of the epidemiologic, clinical, and pathologic manifestations with analysis of factors determining outcome

Staphylococcus aureus is the leading cause of infectious endocarditis and its mortality has remained high despite better diagnostic and therapeutic procedures over time. We conducted a retrospective review of 133 cases of definite S. aureus endocarditis seen at a single tertiary care hospital over 22 years to assess changes in the epidemiology and incidence of the infection, manifestations, outcome, risk factors for mortality, and impact of cardiac surgery on prognosis.Patients were classified into 2 groups: 1) right-sided endocarditis (64 patients) and 2) left-sided endocarditis (69 patients). While the number of cases of left-sided endocarditis remained steady at 1-3 cases per 10,000 admissions, the incidence of right-sided endocarditis, after a peak in the early 1990s, declined to almost disappear in 2001. Among the cases of right-sided endocarditis, we found 2 subsets of patients with different clinical features and prognosis: the first subset comprised 53 intravenous drug abusers, and the second subset comprised 11 patients with catheter-associated S. aureus bacteremia and endocarditis. Fifty-one patients were human immunodeficiency virus (HIV)-positive drug abusers, most of whom (80.3%) had right-sided endocarditis. We did not find differences in mortality between HIV-positive and HIV-negative individuals; mortality seemed to depend more on the site of the heart involved than on HIV status.Among the cases of left-sided endocarditis, the mitral valve was more commonly involved than the aortic valve (61% vs. 30%). Overall, 74% of patients with left-sided endocarditis developed 1 or more cardiac or extracardiac complication. In comparison, only 23.4% of patients with right-sided endocarditis developed complications.Prosthetic valve endocarditis (PVE) was hospital-acquired more frequently than native valve endocarditis (NVE). Patients with PVE had a shorter duration of symptoms until diagnosis and presented with or developed cardiac murmurs less frequently than patients with NVE. Cardiac failure (49%), renal failure (43%) and central nervous system (CNS) events (35%) were frequently observed in patients with both PVE and NVE. Valve replacement was more frequently needed and more rapidly performed in patients with PVE than in their counterparts with NVE.The overall mortality of patients with right-sided endocarditis was 17%. While the mortality of right-sided endocarditis in injection drug users was 3.7%, the mortality of patients with right-sided endocarditis associated with infected intravenous catheters was 82% (odds ratio [OR], 0.01; 95% confidence interval [CI], 0.001-0.07). For left-sided endocarditis mortality was 38% and was not significantly different in patients with NVE or PVE (OR, 0.65; 95% CI, 0.23-1.87). CNS complications were associated with mortality in both NVE (OR, 6.55; 95% CI, 1.78-24.04) and PVE (OR, 32; 95% CI, 2.63-465.40). Development of 2 or 3 complications was associated with an increased risk of mortality (OR, 5.59; 95% CI, 1.08-28.80 and OR, 9.25; 95% CI, 1.36-62.72 for 2 vs. 1 complication and for 3 vs. 2 complications, respectively).Surgical treatment did not significantly influence mortality in cases of NVE, (OR, 3.19; 95% CI, 0.76-13.38) but significantly improved the prognosis of patients with PVE (OR, 69; 95% CI, 2.89-1647.18).S. aureus endocarditis is an aggressive, often fatal, infection. The results of the current study suggest that valve replacement will improve the outcome of infection, particularly in patients with PVE.

Isolated native tricuspid valve endocarditis caused by viridans streptococcus

The present report describes a case of native tricuspid valve endocarditis caused by viridans group streptococcus in a 43-year-old man who had recently undergone dental extraction. The patient had no history of intravenous drug use, heart disease or right heart catheterization. Although there have been scattered reports of unusual organisms, to the authors' knowledge, this is the first case of viridans group streptococcal endocarditis involving only the tricuspid valve after dental manipulation.

Isolated pulmonic valve endocarditis caused by group B streprococcus (Streptococcus agalactiae)--a case report and literature review

The pulmonic valve is the least commonly involved valve in infective endocarditis. Pulmonic valve endocarditis is usually associated with tricuspid valve endocarditis, and isolated pulmonic valve endocarditis is exceedingly rare. The predisposing factors for developing pulmonic valve endocarditis include a congenitally anomalous pulmonic valve, intravenous drug abuse, and the presence of indwelling intravenous or flow-directed pulmonary artery catheters. More cases of group B streptococcus endocarditis are being reported. The risk factors for group B streptococcus endocarditis include diabetes mellitus, cancer, alcoholism, malnutrition, immunocompromised status, intravenous drug abuse, postpartum and postabortion states, and underlying valvular disease. The vegetations of this type of endocarditis are usually large and have a higher tendency to result in embolism. The presentation of group B streptococcus endocarditis is usually acute and may result in rapid valve destruction if not treated promptly. A case of isolated pulmonic valve endocarditis caused by group B streptococcus, Streptococcus agalactiae, is presented that was diagnosed with multiplane transesophageal echocardiography in a 40-year old, alcoholic, malnourished man, who was successfully treated with intravenous penicillin G. The literature on the isolated pulmonic valve endocarditis caused by group B streptococcus is reviewed.

An unusual case of enterococcal tricuspid valve endocarditis

A 52-year-old male smoker presented with a 10-week history of weight loss and malaise, together with a 1-week history of left-sided pleuritic chest pain, haemoptysis and mild dyspnoea. He had used intravenous drugs for a short time 30 years previously although he denied any intravenous drug use since. There was no other past medical history of note.

On examination, he was thin and appeared chronically unwell. He was apyrexial. There was a left pleural rub. There were no murmurs or stigmata of endocarditis. There were no other findings of note.

Full blood screen was normal apart from a white cell count of 11.2x109/litre (normal range 4.0–11.0x109/litre). Erythrocyte sedimentation rate was 52 mm/hr and C-reactive protein was 16 mg/litre (normal range <7.0 mg/litre). Urinalysis and urine culture were normal. The chest X-ray showed a circumscribed left lower zone lesion (Figure 1). Figure 2 shows the computed tomography appearance of the lesion.

At this stage, pulmonary malignancy was suspected (either a primary or secondary). The following day, two sets of blood cultures were taken in view of a low grade pyrexia. Enterococcus faecalis grew from all four bottles and the patient was started on intravenous amoxycillin.

Five days after admission a new soft pansystolic murmur at the left sternal edge was noted. Intravenous gentamicin was added. Transthoracic echocardiogram was normal but was repeated after an interval of 10 days in view of continuing low grade pyrexia and at this stage showed a vegetation adherent to the tricuspid valve (Figure 3).

The patient was treated with intravenous amoxycillin and gentamicin for a total of 6 weeks. He did not develop any further complications and has remained well at follow up.

Systemic infection related to endocarditis on pacemaker leads: clinical presentation and management

BACKGROUND

Endocarditis related to pacemaker (PM)-lead infection is a rare but serious complication of permanent transvenous pacing. To determine in which situations the diagnosis should be evoked and to determine optimal management, we reviewed our experience with endocarditis related to PM-lead infection.

METHODS AND RESULTS

Fifty-two patients were admitted for endocarditis related to PM-lead infection. The presentation was acute in 14 patients, with onset of symptoms in the first 6 weeks after the last procedure on the implant site, and chronic in 38 patients. Fever occurred in 86.5%. Clinical and/or radiological evidences of pulmonary involvement were observed in 38.4%. Pulmonary scintigraphy disclosed pulmonary infarcts in 31.2%. Local complications were found in 51.9%. Elevated C-reactive protein was found in 96.2%. A germ was isolated in 88.4% of patients and was a Staphylococcus in 93.5%. Transthoracic echocardiography demonstrated vegetations in only 23% of patients, whereas transesophageal echocardiography disclosed abnormal appearances on the PM lead in 94%. We systematically tried to ablate all the material. Two techniques were used: percutaneous ablation or surgical removal during extracorporeal circulation. All patients were treated with antibiotics after removal of the infected material. Two patients died before lead removal and 2 after surgical removal; the predischarge mortality was 7.6%, and the overall mortality was 26.9% after a follow-up of 20.1+/-13 months.

CONCLUSIONS

The diagnosis of endocarditis related to PM-lead infection should be suspected in the presence of fever, complications, or pulmonary lesions after PM insertion. Transesophageal echocardiography should be performed to look for vegetations. Staphylococci are involved in the majority of these infections. The endocardial system must be entirely removed and appropriate antibiotic therapy pursued for 6 weeks.

Has transesophageal echocardiography changed the approach to patients with suspected or known infective endocarditis?

Infective endocarditis is still a great clinical challenge. Its diagnosis is difficult to establish, and mortality has remained around 30%. Early diagnosis and optimal treatment are crucial fo prognosis improvement. Echocardiography plays an indispensable role in the management of this disease, especially with the recently introduced approach, transesophageal echocardiography (TEE). TEE can overcome the limitations of transthoracic echocardiography (TTE) and is superior to TTE in almost every way in providing earlier and more information for the diagnosis and treatment of infective endocarditis. TEE detects valve vegetations with much higher sensitivity and specificity than TTE. It can demonstrate smaller vegetations in the early stage of the disease and vegetations on atypical locations (e.g., mitral valve annulus), and provides detailed characterization of vegetations (e.g., location, size, mobility, and changes during treatment). Such information is of great prognostic value and may help in selecting proper treatment. TEE is more sensitive for detecting complications, such as mitral valve perforation, abscess, and subaortic complications, which respond poorly to medicine and for which timely surgery may be the best treatment. For those with prosthetic valve endocarditis, TEE is especially useful because TTE is greatly limited by the acoustic shadow of prostheses. Both positive and negative results of TEE examination are valuable for confirming or excluding infective endocarditis. TEE also plays a unique role in intraoperative monitoring and can assess surgical results before the chest is closed. TEE has become an invaluable tool for the diagnosis and management of patients with suspected or known infective endocarditis.

Staphylococcus aureus endocarditis in Danish intravenous drug users: high proportion of left-sided endocarditis

In a retrospective study covering the years 1982-1989 episodes of Staphylococcus aureus endocarditis in 51 intravenous drug users were studied. Tricuspid involvement dominated (34/51), but the frequency of left-sided involvement (33.3%) was greater than in earlier reports. Involvement of both sides of the heart was not detected, but 27.8% of the left-sided endocarditis cases had multiple pulmonary infiltrates, indicating that some of them might have had a concomitant right-sided endocarditis. The 2 groups were compared: patients with left-sided endocarditis were significantly older and with a longer time of intravenous drug use. The complication rate was the same (44.1%) as was the duration of antibiotic treatment (median 42 days). In total, five patients underwent surgery, two (5.8%) due to right-sided failure and three (29.4%) because of left-sided endocarditis. The mortality of tricuspid endocarditis was low (2.9%), whereas 5 patients (29.4%) with left-sided involvement died. The patients who died were significantly older and had a shorter duration of symptoms before hospitalization.

Isolated pulmonary valve endocarditis: a rare or an underdiagnosed disease?

A 48 year old patient with resistant coeliac disease developed prolonged unexplained pyrexia after surgery for small bowel volvulus. Despite extensive investigations and intensive antibiotic therapy, he deteriorated and died eight weeks postoperatively and significant isolated pulmonary valve endocarditis was discovered at autopsy. This diagnosis should be considered in all critically ill patients with unexplained pyrexia even in the absence of clinical features of endocarditis and transoesophageal echocardiography performed to exclude or confirm this lesion.

Right-sided endocarditis in the non-drug addict

Fifteen patients with right-sided infective endocarditis during a 5 year period (1985-1990) were retrospectively reviewed. Isolated tricuspid valve involvement occurred in nine patients. Staphylococcus aureus was the causative organism in seven cases; four were culture negative. The diagnosis was established by two-dimensional echocardiography in 11 patients and at postmortem in the remaining four patients who succumbed shortly after admission. Fever, tachypnoea and pneumonia were universal features. A successful outcome ensued in eight patients with medical therapy alone and in two patients who were submitted to valve replacement. Five patients died, two from uncontrolled infection with repeated pulmonary emboli. Right-sided infective endocarditis should be suspected in any pneumonic illness that complicates post-abortal infection or other inadequately treated sepsis. Two-dimensional echocardiography is important in diagnosis since cardiac signs are minimal at presentation.

Inability to validate a predictive score for infective endocarditis in intravenous drug users

We sought to identify presenting features that should increase the accuracy of diagnosis of endocarditis in symptomatic intravenous drug use (IVDU) patients. We used two data sets of IVDU patients to develop and validate a score for endocarditis. A retrospective analysis of admitted IVDU patients was conducted with subsequent validation of endocarditis score on consecutive admitted IVDU patients at the same urban teaching hospital emergency department. Statistical comparison was made of presenting clinical features in patients with and without positive blood cultures or vegetation on their echocardiogram. Multivariable analysis of significant features was carried out. A clinical score was developed using a likelihood ratio to determine weighting. Validation of the score was tested by application to a second set of admitted symptomatic IVDU patients. The performance of the score was assessed by comparison of receiver operating characteristic curves for the two data sets. Factors associated with endocarditis on multivariable analysis were past history of endocarditis (negative correlation), total white blood cell (WBC) count, percentage neutrophils and bands on differential WBC count, infiltrate on chest x-ray, and arterial oxygenation (negative correlation). Prospective validation showed poor predictive performance of the endocarditis score. Presenting clinical, radiographic, and laboratory features do not appear helpful in estimating the clinical likelihood of endocarditis in symptomatic IVDU patients.

Spectrum of right-sided infective endocarditis: an Indian experience

We studied retrospectively 23 consecutive patients seen at our centre with right heart endocarditis. None of the patients had a history of intravenous drug abuse. All patients were found to have underlying congenital heart disease as a predisposing factor, of which ventricular septal defect (26%) and Fallot's tetralogy (26%) were the commonest. Postoperative endocarditis (26%) also constituted an important clinical subset. Fever (100%) and predominant pulmonary symptoms (69.5%) were the important presenting features. Congestive heart failure was present in 15 patients (65.2%) and predicted an adverse in-hospital outcome. Both the pulmonary and the tricuspid valves were affected equally with presence of vegetations at multiple sites in 10 patients (43.4%). Seven patients (30%) also had concomitant left-sided endocarditis. Medical therapy alone was successful in 15 patients (68.1%) with an overall in-hospital mortality of 31.8%. Five of 6 patients with postoperative endocarditis died, signifying an ominous prognosis of this subgroup when treated medically. The clinical spectrum of right-sided endocarditis in our country differs from the West. The frequent presence of underlying congenital heart disease, the rarity of drug abuse as a predisposing factor, equal involvement of the tricuspid and pulmonary valves and a greater incidence of congestive heart failure are some of these differences.

Pulmonic valve endocarditis as an underdiagnosed disease: role of transesophageal echocardiography

Pulmonic valve endocarditis is a rare clinical entity. In spite of an increase in the frequency of right-sided endocarditis, primarily it is the tricuspid valve that is involved. Two-dimensional transthoracic echocardiography has improved our ability to diagnose infective endocarditis but has not identified many cases of pulmonic valve endocarditis. With the use of transesophageal echocardiography, three recent cases of pulmonic valve endocarditis were diagnosed by our laboratory. Each of these patients had clinical evidence of right-sided endocarditis, yet routine transthoracic echocardiograms failed to identify any pulmonic valve abnormalities. The true incidence of pulmonic valve endocarditis may be higher than previously reported, and the transesophageal echocardiogram is the preferred method for identifying and evaluating pulmonic valve endocarditis in adults.

Profile of right-sided endocarditis: an Indian experience

The clinical profile of right-sided infective endocarditis in India was studied from a review of records of patients with infective endocarditis admitted to this hospital. From November 1982 to November 1989, 109 patients with infective endocarditis showed vegetations on cross-sectional echocardiography confirming the diagnosis of infective endocarditis. In 19 (17.4%) patients, only the right side of the heart was involved: specifically the tricuspid valve alone in 10; tricuspid and pulmonary valves in 4; tricuspid valve and right ventricular outflow tract in 1; tricuspid valve and right ventricular free wall in 1; pulmonary valve alone in 2; and bifurcation of pulmonary trunk in 1. Eleven patients (57.9%) had underlying congenital heart disease whereas the remaining 8 patients (42.1%) did not have any underlying heart disease. The latter group, therefore, had isolated right-sided infective endocarditis. Previous illnesses leading to isolated right-sided infective endocarditis were: puerperal sepsis in 4; septic abortion in 1; staphylococcal pneumonia in 2; and epididymoorchitis in one. Eight out of 11 patients with congenital heart disease did not report any previous illness. In the remaining 3, right-sided endocarditis followed cardiac surgery in one; dental extraction without prophylaxis in one; and pulmonary balloon valvoplasty in one. All patients with isolated right-sided infective endocarditis had features of septicaemia, but a murmur of tricuspid regurgitation was audible in only 4 (50%) of them. We conclude that, unlike western reports, the pattern of right-sided infective endocarditis in India is different. No drug addict with right-sided infective endocarditis was seen; puerperal sepsis and septic abortion were the commonest causes of isolated right-sided infective endocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Septic pulmonary arteriovenous fistula. An unusual conduit for systemic embolization in right-sided valvular endocarditis

Right-sided valvular (tricuspid, pulmonic) endocarditis is frequently complicated by septic pulmonary embolization. Systemic embolization may also rarely occur due to associated left-sided endocarditis or right-to-left shunting in patients with septal defects. This report documents the occurrence of systemic embolization causing a cerebrovascular accident in an intravenous drug abuser with recurrent tricuspid valve endocarditis due to an isolated peripheral septic pulmonary arteriovenous fistula. Noninvasive diagnosis of the fistula by cardiac auscultation, contrast echocardiography, and nuclear magnetic resonance imaging was confirmed by selective pulmonary angiography. Subselective balloon embolization of the pulmonary arteries feeding this fistula was accomplished.

Echocardiographic detection of an infected superior vena caval thrombus presenting as a right atrial mass

A patient was found to have a large mobile right atrial mass by two-dimensional echocardiography after developing sepsis due to prolonged central hyperalimentation. Contrast echocardiography was helpful in localizing the origin of the mass. A large infected thrombus emanating from the superior vena cava was removed at operation. The discussion includes a review of the literature on the echocardiography of right atrial masses.

Tricuspid valve endocarditis

TVE is mainly a disease of intravenous drug abusers. Although the infecting organisms are often highly virulent, they frequently respond to medical treatment. The prognosis for patients with TVE is fairly good. About 25% of TVE patients require surgical intervention. Persistent sepsis and intractable congestive heart failure are indications for surgery. Tricuspid valvulectomy without prosthetic replacement is the surgical intervention of choice. Right-sided heart failure is the principal complication after valvulectomy without a prosthesis. A significant percentage of patients require insertion of prosthetic valves at a future date.

Prognostic significance of vegetations detected by two-dimensional echocardiography in infective endocarditis

Although 2DE is considered the most sensitive method for detecting vegetations in infective endocarditis, the independent clinical significance of these vegetations continues to be debated. To further examine this, we identified 74 patients who were diagnosed as having infective endocarditis over a 54-month period. The 50 patients who underwent 2DE examination form the basis of this report. Definite vegetations were present in 21 (42%) patients and measured 1.2 +/- 0.2 cm2. The vegetation was localized to the aortic valve in 10 patients, the mitral valve in eight, and the tricuspid valve in three. A major complication, defined as death, new-onset congestive heart failure, major arterial embolus, or valve surgery occurred in 86% of the vegetative endocarditis patients compared to 62% of those without vegetations. Among those patients with vegetations, death occurred in 24%, heart failure in 38%, arterial embolus in 48%, and surgery in 43%. This compared to 7%, 21%, 21%, and 24%, respectively, in those patients without vegetations. These data support the concept that 2DE detection of a vegetation defines a high-risk subgroup of patients with infective endocarditis in whom careful monitoring and aggressive management are warranted.

Right-sided valvular endocarditis: etiology, diagnosis, and an approach to therapy

Right- and left-sided endocarditis are two distinct entities, both clinically and experimentally. As such, they require different clinical approaches. The accurate diagnosis of right-sided endocarditis rests largely on a high index of suspicion which is often raised in the case of an intravenous drug abuser with fever, especially when pulmonary infiltrates are detected. Two-dimensional echocardiography can be expected to confirm the diagnosis in approximately 80% of the cases. Measurement of the echocardiographically visualized vegetation provides both prognostic and therapeutic information. When the vegetation is less than 1.0 cm in diameter, antibiotic therapy can be reasonably expected to cure the infection. Despite a prolonged fever, we recommend continued medical management in these cases, as lack of response to medical management is almost exclusively seen in cases in which echocardiographically determined vegetation size is greater than or equal to 1.0 cm, perhaps because of the slower metabolic rate of bacterial colonies within these large vegetations. If, however, after 3 weeks of antibiotic therapy, fevers persist in a patient in whom two-dimensional echocardiography reveals a vegetation of greater than or equal to 1.0 cm, surgical intervention should be contemplated. Prior to such intervention, the physician must be careful to exclude other sources of fever, such as abscesses, phlebitis, and drug reactions, as indicated in Table III. Also, adequate antibiotic levels should be documented prior to surgical intervention. Because of the adverse effect on vegetation size upon the response to antibiotics, there may be a role for anticoagulation in order to potentiate the effects of the antibiotic therapy; however, this is purely speculative at present.(ABSTRACT TRUNCATED AT 250 WORDS)