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Tex Heart Inst J. 2009; 36(3): 250–251.
PMCID: PMC2696495

Endomyocardial Fibrosis Mimicking Ebstein's Anomaly

A Diagnostic Challenge

Abstract

Endomyocardial fibrosis is a rare disease that is seen most commonly in tropical countries. It usually presents with characteristics of right-heart failure. Herein, we report the case of a 14-year-old adolescent boy who experienced endomyocardial fibrosis. Upon transthoracic echocardiography, the condition was mistakenly diagnosed as Ebstein's anomaly of the tricuspid valve. Sixteen months after undergoing tricuspid annuloplasty and receiving a bidirectional Glenn shunt, the patient showed no echocardiographic evidence of valvular regurgitation. We discuss imaging and surgical techniques that enable the diagnosis and treatment of endomyocardial fibrosis.

Key words: Adolescent, arteriovenous shunt, surgical, diagnosis, differential, diagnostic imaging/methods, endomyocardial fibrosis/complications/diagnosis/pathology/radiology/surgery, heart ventricles/radiography, prognosis, treatment outcome, tricuspid valve insufficiency/diagnosis/surgery, ventricular dysfunction, right/etiology

Endomyocardial fibrosis (EMF) is a rare disease that is seen most commonly in tropical countries. It usually presents with characteristics of right-heart failure. A 14-year-old adolescent boy's case of EMF was mistakenly diagnosed upon transthoracic echocardiography as Ebstein's anomaly of the tricuspid valve. Here, we discuss the case of this patient, along with imaging and surgical techniques for the diagnosis and treatment of EMF.

Case Report

In March 2007, a 14-year-old adolescent boy presented with a 1-year history of New York Heart Association (NYHA) functional class I–III dyspnea and worsening cyanosis. His oxygen saturation level was 82% on room air. His cardiovascular examination showed nothing unusual except for a displaced apical impulse that suggested cardiomegaly. Chest radiography revealed marked cardiomegaly. Electrocardiographic results indicated right atrial enlargement. No delta waves were seen, and the P–R interval was normal. A diagnosis of Ebstein's anomaly, which had been reached elsewhere by use of transthoracic echocardiography, was confirmed at our center. The patient's right atrium was markedly enlarged, the right ventricle (RV) was markedly hypoplastic, and a 15.6-mm displacement of the septal leaflet of the tricuspid valve was noted (Fig. 1). There was moderate tricuspid-valve regurgitation, a patent foramen ovale (PFO) shunting bidirectionally, and biventricular dysfunction. The patient was scheduled for elective repair of Ebstein's anomaly with use of a bidirectional Glenn shunt.

figure 15FF1
Fig. 1 Two-dimensional echocardiography (apical 4-chamber view) shows a marked displacement of the septal leaflet of the tricuspid valve (arrow), a hypoplastic right ventricle (RV), and a large right atrium (RA).

A median sternotomy was performed. Cardiopulmonary bypass was instituted via aorto–bicaval cannulation. There was no obviously atrialized portion of the RV, but the right atrium was markedly enlarged. When the right atrium was opened, we found that the tricuspid valve was morphologically normal, with no displacement of the leaflets. The RV cavity was small, the apical portion was obliterated, and the endocardium was white and thickened. An intraoperative diagnosis of EMF was made. Tricuspid annuloplasty was performed, the PFO was closed, and a bidirectional Glenn shunt was constructed. The patient's postoperative recovery was uneventful. At 16 months' follow-up, he was in NYHA functional class I, with no echocardiographic evidence of valvular regurgitation.

Discussion

Endomyocardial fibrosis is a uni- or biventricular disease of uncertain origin. It can be mistaken for other common conditions, such as apical hypertrophic cardiomyopathy, constrictive pericarditis, rheumatic valve disease, or Ebstein's anomaly.1 The initial manifestation in most patients is RV failure. The characteristic features of EMF upon echocardiography are obliteration of the apex of the involved ventricle and dilation of the corresponding atrium.1 The initial event in the pathogenesis of EMF appears to be some form of subendocardial inflammation. This in turn leads to the spread of the process to the endocardium, which results in the formation of mural thrombus. This thrombus becomes organized and, over time, undergoes fibrosis, which heralds the formation of secondary thrombus and further organization.2 Usually beginning in the delicate inflow tract, fibrosis in most cases of right ventricular EMF involves the apex. Apical obliteration, combined with subvalvular fibrosis, reduces the size of the RV cavity and also leads to an apparent downward displacement of the tricuspid valve that is exaggerated by a giant right atrium. This mimics Ebstein's anomaly. A PFO stretched by tricuspid regurgitation can be mistaken for an atrial septal defect associated with Ebstein's anomaly. Although an endomyocardial biopsy can be diagnostic of EMF, it is an invasive procedure, and the specimen can sometimes be inadequate. Hence, biopsy is not always necessary.1 The angiographic or echocardiographic features of EMF are typical but may need to be supplemented by advanced imaging methods, especially in cases of diagnostic dilemmas. Computed tomography and magnetic resonance imaging (MRI) have both been useful in this regard. Hyperenhancement and delayed enhancement on contrast MRI and high-intensity signals on T2-weighted images are diagnostic of myocardial fibrosis.3,4

Surgical treatment of EMF involves the excision of fibrotic plaques by coring, along with atrioventricular valve repair or replacement. The operative mortality rate for such a procedure is high (18%), and the progressive nature of the disease is not altered by surgical excision.5 The palliative bidirectional Glenn procedure that we performed in our patient is associated with a low operative mortality rate. Mishra and colleagues reported a case of an elective bidirectional Glenn shunt, and their patient exhibited no progression of the disease at 8 years' follow-up.6 Off-loading the RV can probably delay progression of the disease, but the long-term outcome of this approach in comparison with a more aggressive approach is unknown. Otherwise, the addition of a bidirectional Glenn shunt has chiefly been reported as a salvage procedure in patients who could not be weaned from cardiopulmonary bypass after extensive resection.7 Other surgical options are total cavopulmonary connection8 and “one-and-a-half ventricle” repair.9 Our plans for our patient involve regular follow-up with serial echocardiography, with the option of either a tricuspid-valve replacement if regurgitation develops, or conversion to a total cavopulmonary connection if ventricular involvement progresses and causes right-heart failure.

Supplementary Material

Video for Fig. 1:

Footnotes

Address for reprints: Karthik Vaidyanathan, R MS, Frontier Lifeline, Dr. KM Cherian Heart Foundation, R 30 C Ambattur Industrial Estate Rd., Chennai 600101, India. E-mail: moc.liamffider@codvkr

References

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