Isolated Pulmonic Valve Endocarditis.

Isolated pulmonic valve infective endocarditis (PV-IE) is a rare form of endocarditis. The authors report a case of giant vegetations detected by transthoracic echocardiography (TTE) on PV in a young patient, 33-year-old, with drug abuse history. The patient underwent surgical intervention by pulmonary valved bioconduit implantation. After operation, a pulmonary embolism episode was treated by a direct oral anticoagulant. The final outcome was favorable. The difficulty in diagnosing PV-IE is due to the inability to properly visualize the PV by echocardiography. In this case, with such large vegetations, TTE allowed a correct diagnosis and an effective surgical planning, confirming its importance as a diagnostic tool. Copyright:

INTRODUCTION

Isolated pulmonic valve infective endocarditis (PV-IE) is a rare disease affecting less than 2% of patients with IE.[1] Low-pressure gradient within the right heart may be the main reason of its rarety. The difficulty in diagnosing PV-IE is due to the inability to properly visualize the PV by echocardiography. In cases with large vegetations, transthoracic echocardiography (TTE) can allow a correct diagnosis and an effective surgical planning.

CASE REPORT

We report a case of a 33-year-old man with intravenous drug abuse history, immuodepression, and HCV-positive cirrhosis.

He presented to emergency department because of fever started 2 weeks before and associated with malaise and chills.

Physical examination was unremarkable. Blood Pressure was 110/60 mmHg, and temperature was 38°C.

Electrocardiogram demonstrated sinus rhythm with a heart rate of 88 bpm.

Lab-data revealed erythrocyte sedimentation rate of 45 mm/h (normal 0–22 mm/h) and C-reactive protein of 10.1 (normal <3 mg/L).

Complete blood count revealed a severe anemia (Hb: 8 g/dL) and thrombocytopenia (30,000/mm3), while metabolic panel was normal. Chest X-ray demonstrated multiple-site basal pneumonia and chest computed tomography (CT) scan revealed strange masses inside the pulmonary truncus [Figure 1]. Bloodcultures resulted positive for Methicilline-Susceptible Staphylococcus aureus.

Figure 1

Chest angio-computed tomography image revealing huge masses inside the pulmonary truncus

First TTE, performed in the emergency room, was negative, but since the suspicion of IE was high, it was repeated on day 2. Second TTE revealed at parasternal long-axis view, floating masses inside the right ventricle (RV) [Video 1], while, at four chamber view, an enlarged RV with reduced fractional area change (RV: 32%). Left ventricle was normal in size and function [Video 2]. The parasternal short-axis view showed two giant, elongated, and highly mobile PV vegetations, and the largest one was 5 cm × 1 cm [Figure 2 and Videos 3 and 4. The picture was complicated by a torrential pulmonic regurgitation [Video 5]. Torrential PV regurgitation can be considered as the most serious type of the disease, in which the valve leaflets are flailed so that it cannot hold the leakage anymore.

Figure 2

Transthoracic echocardiography, parasternal short-axis view image demonstrating two giant, elongated vegetations on two pulmonic cusps (largest-one: 1 cm × 5 cm)

All echo-projections revealed no involvement of any other heart valve.

A tailored (antibiogram-based) antibiotic therapy based on intravenous daptomycin 500 mg OD plus levofloxacin 500 mg BID was started. Moreover, blood transfusions were administered.

One week later, chest CT scan demonstrated multiple septic emboli as cavitary and precavitary lesions [Figure 3].

Figure 3

Chest computed tomography scan image demonstrating multiple septic emboli as cavitary and precavitary lesions

Two weeks after admission, the patient underwent surgical treatment by Shelhigh biological valved conduit model NR-2000C (Shelhigh, Inc., Milburn, NJ, USA) implantation.

Transesophageal echocardiography (TEE) was performed as intraoperative guiding procedure and it excluded additional complications or other valves involvement.

A TTE performed 6 days after operation [Video 6] showed a good result of the surgical procedure.

The final postoperative outcome was good, but, 4 weeks after discharge, the patient was re-hospitalized because of worsening dyspnea associated with arterial hypotension (brachial systolic pressure: 80 mmHg). Chest CT angiography demonstrated a subsegmental pulmonary embolism. A direct oral anticoagulant therapy (rivaroxaban 15 mg BID for 3 weeks, then 20 mg OD) was started with a complete thrombotic burden resolution at chest CT angiography in 3 months.

DISCUSSION

Overall incidence of IE is 3–10 per 100.000 patient-years.

Right-Sided IE (RSIE) is less common than left-sided involvement and accounts for 5%–10% of IE cases, most of these cases involve the tricuspid valve.

Isolated PV endocarditis (PV-IE) affects <2% of patients with IE.[12]

From 1979 to 2013, Chowdhury and Moukarbel[1] found only 70 reported cases of PVE.

Several authors pointed out that PV-IE is a rare condition, accounting around 1.1% of autopsies with valvular endocarditis, based on an article published by Cassling in 1985.[3]

Dhakam and Jafary reported that only 38 cases of structurally normal native PV-IE have been published in the literature, between 1960 and 2000, which account for 1.5%–2.0% of all cases of endocarditis.[4] Reviewing literature from 1960 to 1999, only 36 cases of PV-IE were reported by Ramadan et al.[5]

Many theories were used to explain the rarity of PV-IE: low-pressure gradient within the right heart, lower oxygen content of venous blood, and differences in the covering and vascularization of the right heart endothelium.[5] However, existing risk factors for RSIE, such as intravenous drugs abuse, central venous catheter, pacemaker implantation, congenital heart disease, and liver or kidney transplantation,[6] are very important to suspect of tricuspid valve endocarditis and/or PV IE in the presence of multiple lung lesions compatible with septic emboli.

The usual presentation of the patient with PV IE is fever, pleuritic chest pain, hemoptysis, shortness of breath, and cough due to pulmonary septic emboli. Schroeder in 2005 reported that the pulmonic regurgitant murmur is often a late feature.[7]

The difficulty in diagnosing PV-IE is due to the inability to properly visualize the PV.

Sometimes, initial TTE fails in diagnosing IE. In these cases, as it is recommended by the latest guidelines,[2] it is mandatory to repeating the procedure few days later. This happened for our patient.

TEE of PV is challenging due to its position, which is the most anterior and farthest from the TEE probe in comparison to other heart valves. While the TEE failed to detect one case of PV-IE from all nine cases reported in the literature review by Mayo Clinic, TTE was diagnostic in all isolated cases.[8]

However, about the diagnostic tools, Evangelista and Gonzalez-Alujas[9] reported that TTE sensitivity is 25% when vegetations are <5 mm and 70% for vegetations between 6 and 10 mm. For TEE, sensitivity is 90%–100% but, when vegetations are larger than 10 mm, TTE and TEE have similar sensitivity. However, TEE should be performed in order to exclude an involvement of other cardiac structures and therefore for better surgical decision planning. In our case, after discussion with the patient, it was postponed to the surgical procedure time.

Current guidelines identify the specific indication for surgical intervention. These include valvular regurgitation resulting in acute heart failure, the presence of multi-drug resistant organisms or fungi, IE complicated by heart block or abscess formation, persistent bacteremia or recurrent emboli despite appropriate antibiotic therapy, and severe regurgitation with mobile vegetations >10 mm.[210] It should be noted that these indications are based on studies in patients with left-sided native and prosthetic valve IE. No specific indications are reported for RSIE. In our case the indications to surgery were derived from the patient's clinical status and high sizing of vegetations causing a torrential regurgitation and pulmonary embolization. An additional postoperative complication (acute pulmonary thrombo-embolism) was solved by a direct oral anticoagulant. The relation between the pulmonary thromboembolism and PV-IE or drug-abuser status is uncertain. Tomashefski and Hirsch,[11] from 70 autopsies of drug abusers, found thrombotic changes of pulmonary vessels that are tipically induced by intravenous injections of solutions derived from tablets or capsules that ethically are intended for oral consumption because oral pharmaceutical preparations usually contain insoluble microcrystals such as talc, starch, or cellulose. A persisting drug abuse after discharge could have been the main cause of pulmonary thromboembolism in our patient.

CONCLUSIONS

Isolated PV endocarditis is a rare disease, and the diagnosis is challenging. In this case, with such large vegetations, TTE allowed a correct diagnosis and an effective surgical planning.

Regarding surgical treatment, no specific indications are reported from the latest guidelines[2] for RSIE. Our patient underwent surgery on the basis of (1) critical clinical status and (2) high sizing of vegetations causing a torrential regurgitation and pulmonary embolization.

Learning points

Despite PV-IE is a rare disease (2% of all endocarditis cases), it is mandatory to rule it out, especially in patients with a high risk of RSIE

In patients with a drug abuse history and suspected IE, it is recommended to accurately focusing on PV, using TTE as first choice technique, since TTE has a high sensitivity, especially when vegetations are larger than 10 mm

It is recommended to repeat TTE if the initial exam is negative and a high suspicion of PV-IE is persistent.

Patient consent

The patient provided informed consent for the case publication.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.