Isolated native pulmonary valve endocarditis in a child: Navigating diagnostic and therapeutic challenges with limited resources

Abstract

Isolated native pulmonary valve endocarditis (INPVE) is a rare form of infective endocarditis, accounting for <2% of cases. It typically affects the individuals with predisposing factors, including congenital heart defects, intravenous drug use, or indwelling catheters. Pediatric cases without such risk factors are extremely uncommon. Diagnosis is often delayed due to nonspecific symptoms that resemble pneumonia, sepsis, or heart failure and is further complicated by culture-negative results from prior antibiotic use. We present the case of a previously healthy 9-year-old boy with prolonged fever, respiratory distress, and malnutrition. Initial treatment for pneumonia was ineffective, prompting further workup that revealed pulmonary valve vegetations, functional valve stenosis and insufficiency, and right heart dilation. Blood cultures were negative, but empirical antibiotic therapy led to clinical improvement. This case underscores the need for early suspicion, timely imaging, and empirical treatment in suspected INPVE, especially in the resource-limited settings where diagnostic and surgical options are restricted.

INTRODUCTION

Right-sided infective endocarditis (IE) is less common than left-sided IE, comprising just 5%–10% of all the instances of endocarditis.[1] The pulmonary valve (PV) is the least frequently affected, involved in fewer than 2% of cases. Isolated native PV endocarditis (INPVE) is extremely rare, with only 70 cases reported up to 2013.[2] Literature on INPVE is limited, mostly consisting of adult case reports, often associated with intravenous drug use or congenital heart disease (CHD).[3] This report presents possibly the first documented pediatric INPVE case in Indonesia, highlighting diagnostic and management challenges in a resource-limited setting.

CASE REPORT

A 9-year-old child without preexisting cardiac conditions was referred to our hospital with a 4-month history of fever, nausea, vomiting, anorexia, malaise, and malnutrition. Upon admission, he had experienced prolonged fever, shortness of breath, pale skin, and generalized swelling for 3 weeks before hospitalization. One month prior, he was hospitalized for pneumonia and septicemia and commenced on intravenous antibiotics; nevertheless, the symptoms were only partially relieved. Physical examination revealed pale conjunctiva, tachycardia, tachypnea, accompanied by coarse breath sounds in bilateral lung areas, a systolic murmur predominant in the PV area, hepatomegaly, and generalized edema. He had a low leukocyte count (2500/mm³) with a low absolute neutrophil count (1670), hemoglobin 5.6 g/dL, hypochromic microcytic cells, and a low platelet count (37,000/mm³). Peripheral blood smear revealed leukopenia, shift to the left, toxic granules, and thrombocytopenia. Urine drug screening and human immunodeficiency virus test were negative. Blood chemical examination revealed potassium 2.50 mEq/dL, calcium 6.2 mg/dL, and albumin 2.4 g/dL. The chest X-ray indicated cardiomegaly and bilateral pulmonary infiltration [Figure 1]. Transthoracic echocardiography (TTE) showed numerous hyperechoic mobile masses, with the biggest measuring 8 mm × 5 mm, suggestive of vegetation attached to the PV leaflet [Figure 2]. This resulted in both left and anterior leaflets being flail, leading to functional stenosis (peak gradient of 40 mmHg) and mild-to-moderate regurgitation, with no evidence of other anatomical or structural abnormalities or CHD. However, the systolic functions of both left and right ventricles were within the normal ranges. Subsequent chest computed tomography (CT) indicated cardiomegaly and a hypoattenuating lesion, which suggested vegetation in PV, without evidence of pulmonary embolism [Figure 3]. There was dilatation of the right ventricle, right atrium, and main pulmonary artery owing to the functional stenosis and regurgitation of the PV. The blood cultures were obtained with no pathogen identified. The patient was diagnosed with INPVE and subsequently started on an antibiotic course of ampicillin 4 g/day, ceftriaxone 1 g/day, and gentamicin 60 mg/day before the availability of blood culture findings.

Figure 1.

Anteroposterior chest X-ray demonstrating cardiomegaly and patchy infiltrate in the bilateral lungs

Figure 2.

Parasternal short-axis aortic level transthoracic echocardiography shows: (a) Multiple vegetations on the flail pulmonary valves (thick arrow), causing (b). Functional stenosis (peak gradient of 40 mmHg) and mild-moderate regurgitation (mosaic coloration, arrowhead). The star indicates the aorta, and the diamond indicates the main pulmonary artery

Figure 3.

Chest computed tomography showing cardiomegaly and an attenuating lesion suggested vegetations on the pulmonary valve (red arrow)

On the second day of admission, he experienced acute respiratory distress necessitating transfer to the pediatric intensive care unit (PICU). Physical examination revealed tachycardia (heart rate 120 bpm), tachypnea (respiratory rate 45 times/min), high-grade fever (39.5°C), auscultatory findings of systolic murmur in the pulmonary area and S3 gallop, along with elevated jugular venous pressure. Despite clinical indication, arterial blood gas analysis could not be performed due to the unavailability of instrumentation in our hospital. Blood cultures were repeated upon PICU admission, along with empirical antibiotics. We administered a packed red cell transfusion for anemia, a continuous furosemide infusion (0.2 mg/kg/h) for volume overload, electrolyte repletion (IV potassium chloride and calcium gluconate), and albumin 25% for hypoalbuminemia. On the seventh day of admission, respiratory distress resolved with normalization of electrolytes and inflammatory markers. Repeated blood cultures were sterile. Empirical antibiotic therapy continued until the 10^th day of hospitalization. Due to inadequate caregiver capacity for outpatient medication adherence monitoring and significant geographical barriers to healthcare access, therapy was prolonged to 6 weeks under direct inpatient supervision in the hospital.

At the 2-week follow-up, there was significant improvement in the signs and symptoms of infection and heart failure, as well as in growth, development, and nutritional status, evidenced by a 1.2 kg increase in body weight over 2 weeks following hospitalization. There were no disease-related complications found in this patient. Ongoing caregiver education focused on proper medication to prevent complications and optimization of growth and developmental outcomes through nutritional and environmental enrichment strategies.

CASE DISCUSSION

Right-sided IE, particularly with PV involvement, is a rare clinical entity in the pediatric population.[4] INPVE often occurs in younger male patients associated with established risk factors, including CHD, intravenous drug abuse, and indwelling vascular access devices. INPVE accounts for <2% of all IE cases when associated with no established risk factors and has been documented in only a limited number of case reports.[5] Pediatric INPVE is even less common and typically linked to underlying CHD or surgical interventions.[2] In our case, the patient had no identifiable predisposing factors.

The majority of INPVE cases presented with prolonged febrile illness and had received a minimum of 2–3 weeks of antibiotic therapy before referral to the hospital.[3] The other clinical manifestations commonly reported comprise chills, respiratory symptoms, loss of appetite, malaise, growth retardation, and even heart failure. Diagnostic evaluation through imaging modalities primarily relies on TTE, chest X-ray, and CT scan.[6] Blood cultures represent a backbone in the diagnosis of IE, along with clinical examination and echocardiographic findings. Nevertheless, 5%–7% of IE cases yield negative blood cultures. Polymerase chain reaction-based methods targeting bacterial DNA offer improved diagnosis establishment.[7] In this case, the patient initially presented with nonspecific complaints, including dyspnea, nausea, vomiting, and pallor, over the last 4 months. In the previous hospitalization in our hospital, the clinical manifestation resembled severe pneumonia with acute respiratory distress, potentially as a complication of right-sided IE involving the PV due to septic embolism. However, embolization could not be confirmed, as the patient’s symptoms did not indicate pulmonary embolism and chest imaging revealed no wedge-shaped infarcts or other embolic lesions.[8] In addition, other contributing factors, including malnutrition and hospital-acquired pneumonia, may have played a role in the patient’s condition. TTE remains the first-line imaging modality, which in this case confirms the presence of mobile vegetations with flail leaflets of the PV. Thorax CT-scan demonstrated attenuating lesions on PV, suggesting vegetation. Imaging reassessment was planned after completing antibiotic therapy. However, the patient was lost to follow-up after 2 weeks, and re-evaluation could not be carried out. Blood cultures drawn from three extremities yielded negative results, which may be attributed to prior intravenous antibiotic administration, infection caused by fastidious bacteria, or suboptimal microbiological techniques; thus, blood culture-negative IE.

The diagnostic workup followed the 2023 European Society of Cardiology (ESC) Modified Duke Criteria for IE, with one major (pulmonic valve vegetations on TTE and CT) and one minor criterion (fever >38°C), classifying this as possible IE.[4,7] The patient presented with persistent fever, new-onset systolic murmur, and acute heart failure, fulfilling clinical indications for initiation of empirical antibiotic therapy. In accordance with ESC guidelines, we initiated a combination regimen of ampicillin, ceftriaxone, and gentamicin as empirical antimicrobial therapy. Right-sided IE generally demonstrates more favorable hemodynamic tolerance compared to left-sided IE, often permitting conservative medical management. Surgical intervention in right-sided IE is indicated for symptomatic severe valve dysfunction, large vegetations, persistent infection indicated by ongoing bacteremia or fever exceeding 5–7 days postinitiation of antimicrobial therapy, and signs of septic pulmonary embolism.[2,9] Following 48 h of empirical antibiotic therapy for IE, the patient demonstrated significant clinical improvement, including resolution of febrile symptoms and heart failure manifestations. Managing IE surgically is needed for future reference in this case, if the patient develops clinical deterioration or echocardiographic evidence of worsening right ventricular function. However, this was not indicated due to a favorable response to antimicrobial therapy.

CONCLUSIONS

This case highlights the rarity and diagnostic complexity of INPVE in children, particularly in the absence of common predisposing factors, including CHD or intravenous drug use. The diagnosis was particularly challenging due to the nonspecific clinical presentation, negative blood cultures, and limited diagnostic resources, requiring reliance on imaging and clinical criteria. Empirical antibiotic therapy guided by the ESC guidelines led to significant clinical improvement without the need for surgical intervention. This case highlights the necessity of sustaining a high clinical suspicion, conducting early echocardiographic evaluations, and implementing customized treatment approaches in the resource-constrained environments to enhance the outcomes in pediatric INPVE.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.