An Unusual Case of Endocarditis - A Rare Occurrence with Unique Etiology

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Abstract

The seeding of endocarditis directly to the non-valvular areas of the heart is extremely rare. We report a case of a 36-year-old woman presenting with sudden-onset lower-extremity pain and swelling, who was found to have mitral valve endocarditis with pulmonary vein vegetation. Echocardiography showed a large linear mitral valve mass coming into contact with the base of the left inferior pulmonary vein with each ventricular contraction. Spread into the atrium from mitral valve endocarditis is generally thought to be caused by jet lesions, whereas direct seeding as in this case is not well described. The location in the pulmonary vein is also unique, with no case reports being found in the literature, although the significance remains to be ascertained.

Acknowledgment: The authors would like to thank Dawn Chovanec for her help in the preparation of the manuscript.

Correspondence
Vishal Gupta, MD, MPH, Assistant Professor, Michigan State University, Associate Program Director, Interventional Cardiology Fellowship, and Director, Medical Device Research Laboratory, Borgess Medical Center, 1521 Gull Rd, Kalamazoo, MI 49048. E: vishalgupta@borgess.com
DOI
https://doi.org/10.15420/ahhj.2010.8.2.128

A 36-year-old woman with a history of complicated cholecystectomy several months previously experienced sudden onset of severe left leg pain and numbness. She was taken to the emergency department, where her pain and numbness subsided over three hours. On examination, she was afebrile with no peripheral stigmata of endocarditis. Cardiac auscultation revealed a new III/VI holosystolic murmur radiating to the axilla. Her left lower extremity was edematous and tender with diminished pulses (1+). A lower-extremity venous duplex was negative for deep venous thrombosis. A computed tomography angiogram ruled out pulmonary embolism but revealed mild splenomegaly with a few infarcts.

Owing to persistent pain, a lower-extremity arterial Doppler was performed, revealing an acute thrombus in the left proximal superficial femoral artery and popliteal artery. A transthoracic echocardiogram revealed a small mass on the mitral valve. For better visualization, a transesophageal echocardiogram (TEE) was performed, which revealed a linear vegetation (4cm) on the mitral valve attached to the posterior leaflet on the lateral aspect of the coaptation (see Figure1A). Severe mitral regurgitation was also observed through the perforation posterior leaflet of the mitral valve (see Figure 1B). Interestingly, another linear mass (2cm) was seen in the left inferior pulmonary vein, originating at the junction of the inferior pulmonary vein and left atrium (see Figure 2). There also appeared to be an annular abscess with a possible fistulous tract into the left atrium. With every contraction of the heart, the linear mass was in direct contact with the left inferior pulmonary vein. Blood cultures were drawn and the patient was started on ampicillin and gentamicin. Blood cultures were eventually positive for Enterococci faecalis and the antibiotics were changed to daptomycin and gentamicin. Cardiothoracic and vascular surgeons were consulted. The patient was transferred to a tertiary care center, where she underwent debridement of the pulmonary vein endocarditis along with prosthetic mitral valve replacement. Her antibiotics were continued and she was also started on anticoagulation. Deep tissue cultures obtained during the procedure were negative for growth. She did extremely well after the procedure and was discharged on the seventh post-operative day. Follow up at one, three, and six months was satisfactory with no recurrence of symptoms.

Discussion

Non-valvular endocarditis is uncommon, but it may occur on the chordae and mural atrial and ventricular endocardium. Many cases of vegetations in the atrium or ‘atrial endocarditis’ have been reported with various etiologies. Endocardial injury in each of these cases was through direct instrumentation, jet lesions, or direct primary vegetation contact, allowing for secondary vegetation growth.

There are two unique aspects of this case; the first is the location of the vegetation in the pulmonary vein junction and the second is the direct extension of the mitral valve endocarditis to the left inferior pulmonary vein. Mitral valve endocarditis leading to atrial vegetations is well described, but to the best of our knowledge there are no published cases involving the pulmonary vein. Atrial involvement is thought to increase the risk for embolic complications and is also included as a minor criterion for surgery,1 but the risks and significance of pulmonary vein endocarditis are unknown. In our patient, the primary presentation with multiple distal emboli raised concern for complications associated with large mitral and pulmonary vein vegetations. This being the first case of such vegetation in the literature, more cases would need to be reported before any further statements could be made regarding the significance of the location.

Atrial spread from mitral valve endocarditis is most often attributed to jet lesions.2 Jet lesions remain a remote plausible cause of this pulmonary vein extension, but direct seeding is most likely when considering this patient’s echocardiography. Although published case reports discuss, in detail, direct vegetation touch (kissing) in aortic valve endocarditis causing mitral valve vegetations,3 direct seeding into the atrium from mitral valve endocarditis is not well described. Piper et al. found that only vegetations large enough to traverse the distance between the mitral and aortic valves resulted in mitral kissing vegetations.4

Echocardiography in this case shows a large flailing mitral valve vegetation that traverses the distance from the mitral valve and comes into direct contact with the base of the left inferior pulmonary vein with each ventricular contraction. Such striking images on echocardiography led the authors to believe that the primary mitral vegetation had grown large enough in a linear fashion to directly seed at a distal point such as the pulmonary vein, as described in our case.

References
  1. Kim JH, Wiseman A, Kisslo J, Durack DT, Echocardiographic detection and clinical significance of left atrial vegetations in active infective endocarditis, Am J Cardiology, 1989;64:950–52.
  2. Gregory SA, Yepes CB, Byrne JG, et al., Atrial endocarditis—the importance of the regurgitant jet lesion, Echocardiography, 2005;22:426–30.
  3. Bhattacharyya S, Hickman M, Lythall D, Mitral valve ‘kissing’ vegetation, Heart, 2005;91:e43.
  4. Piper C, Hetzer R, Körfer R, et al., The importance of secondary mitral valve involvement in primary aortic valve endocarditis; the mitral kissing vegetation, Eur Heart J, 2002;23:79–86.