A 54-year-old Mexican American woman was admitted to the Erie County Medical Center, Buffalo, NY, with the general symptoms of tiredness, weight loss with loss of appetite, leg weakness, and low blood pressure (80/60 mm Hg). The patient denied any paroxysmal nocturnal dyspnea, orthopnea, or leg edema. She did have some facial swelling, a skin rash on both hands, and joint swelling, which was consistent with a previous diagnosis of polymyositis and dermatomyositis. The patient also had evidence of septic arthritis of the left elbow. Physical examination revealed extensive wheezing and a grade 2/3 systolic ejection murmur, heard predominantly over the tricuspid valve area.
Laboratory workup revealed pancytopenia and an elevation in liver function tests. All the markers for autoimmune disease were negative. Biopsies and computerized tomographic scans performed to search for visceral malignancy were negative. Blood cultures grew methicillin-sensitive Staphylococcus aureus. Electrocardiography revealed normal sinus rhythm with evidence of right atrial enlargement. Radiography revealed cardiomegaly and a “hugely” dilated right heart. Cardiac catheterization revealed normal coronary arteries with no evidence of pulmonary hypertension, but a greatly enlarged right ventricle compressed the left ventricular septum. Echocardiography revealed a markedly dilated (20-cm diameter) right ventricle with atrialization of the right ventricle and poor right ventricular function. Severe tricuspid valve regurgitation was associated with apically displaced septal and free-wall tricuspid valve leaflets and a massively dilated right atrium. Left ventricular function and aortic valve structure were normal. No vegetations were seen on either the transthoracic or the transesophageal echocardiogram.
The patient's family history was negative for coronary artery disease, hypertension, diabetes mellitus, cancer, arthritis, or connective tissue disorder. She did not smoke or drink, and had no history of intravenous drug abuse.
She continued to deteriorate and died 11 days after her final hospital admission. On examination of the heart at autopsy, the tricuspid valve was displaced away from the atrioventricular junction and into the right ventricular cavity, with the anterosuperior leaflet tethered to the underlying endocardium (Figure 1, arrow). The right atrium was massively dilated. The inflow tract of the right ventricle had been incorporated into the right atrium, resulting in a massively dilated right atrium and a small right ventricle. An atrial septal defect (secundum type) was located in the septum primum floor of the fossa ovalis and measured 2.1 cm in diameter (Figure 2, arrow).
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Pathologic Diagnosis: Ebstein Anomaly of the Heart
Abstract
Ebstein anomaly is an uncommon form of congenital heart disease, primarily of the tricuspid valve. It is usually diagnosed by observing displacement of the annular attachment of the septal, and often mural, leaflets of the tricuspid valve into the right ventricle with dysplasia of the valvular leaflets, although there are multiple variations with a spectrum of pathologic features. Cross-sectional echocardiography is the method of choice for the diagnosis of this rare cardiac malformation. Most patients with this condition also have an abnormal chest radiograph with globular cardiomegaly resulting from right atrial enlargement. Associated cardiac anomalies are present in many patients, with atrial septal defect being the most common. It is important to recognize the pathologic features of this disorder because they might influence the approach to surgical treatment, clinical course, and prognosis. The method of surgical treatment of patients who require surgery remains controversial.
Ebstein anomaly was first described by Wilhelm Ebstein in 18661 as a condition in which the annular attachment of the septal, and usually the mural, leaflets of the tricuspid valve are displaced into the right ventricle, and the valvular orifice is formed in the ventricular cavity at the junction of the atrialized right ventricle and the true functional right ventricular cavity. In essence, all or part of the ventricular inlet portion becomes physiologically part of the right atrium, thus representing the so-called atrialized component of the right ventricle.2 The anterosuperior leaflet of the tricuspid valve is always attached in its appropriate position to the atrioventricular annulus, but it is considerably larger than normal, with a linear muscularized attachment to an apical shelf between the ventricular inlet and apical components. The septal and mural leaflets always show downward displacement and dysplasia. When the right ventricle contracts, these tricuspid valve abnormalities result in leakage of blood back into the right atrium. Consequently, the right atrium becomes enlarged and, if the leakage is severe, congestive heart failure occurs. The size of the dilated right atrium and atrialized portion of the right ventricle makes the functional right ventricle appear very small, although the right ventricle approximates normal size when its length is compared with the left ventricle.3 In all cases, there is marked dilatation of the atrioventricular ring. Although considerable clinical variability is recognized, the autopsy findings in Ebstein malformation are definitive and are often associated with other cardiac anomalies, the most common being atrial septal defect.4
Clinically, both the anatomy and the severity of the malformation can be well defined through echocardiographic and hemodynamic studies. The apical displacement of the septal leaflet insertion, a redundant and elongated anterior leaflet, and right ventricular thinning are diagnostic features of Ebstein anomaly. Additional supportive features may include tethering of the tricuspid valve leaflet(s) to the underlying endocardium, fenestration of the anterior tricuspid valve leaflet, aneurysmal enlargement of the right atrium, secundum atrial septal defect or patent foramen ovale, or the presence of an accessory bypass conduction tract.5 The principal determinant of severity by echocardiography is the degree of inferior displacement of the proximal attachment of the tricuspid valve leaflets from the atrioventricular ring, and the extent to which the right ventricle has been atrialized.6 The chest radiograph reveals globular cardiomegaly (balloon-shaped) with a narrow pedicle, caused primarily by right atrial enlargement associated with normal or reduced pulmonary vascularity.
In patients with Ebstein anomaly, the clinical course may be variable. Traditionally, adults will have mild forms and a good prognosis, and symptomatic neonates experience a high morbidity and mortality.7 However, complete understanding of its course is still far from complete because this is a rare condition (less than 1% of all congenital heart diseases) and there is great variation in the anatomy and, consequently, in the hemodynamic profile in affected patients.
The data on long-term outcome in adult patients who have not undergone corrective surgery is limited. The most appropriate therapeutic approach and, particularly, the selection of surgical candidates are controversial.
References
The authors have no relevant financial interest in the products or companies described in this article.
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