1356932 - Right ventricular failure in an infant: Absence of the myocardium of the right ventricle

A male infant was admitted to the Ignacio Chavez national institute of cardiology aged 16 months with signs of heart failure. There was nothing outstanding about his prenatal, birth and family history.  Two months before his admission, the parents notice dyspnea and sweating with feeding. Numerous episodes of peripheral cyanosis and laboured breathing had been observed.

The infant was admitted to the hospital with the presumptive diagnosis of Ebstein’s anomaly.

Transthoracic echocardiography and cardiac magnetic resonance was performed, revealing severe dilation of the right atrium and right ventricle an extremely thin-walled RV with almost complete absence of the right ventricular free wall myocardium and impaired systolic function. These findings were compatible with Uhl’s anomaly.

 


 

Diagnostic Techniques and Their Most Important Findings:

Chest x-ray showed conspicuous cardiac enlargement with no pulmonary artery dilatation. Transthoracic echocardiography showed severe dilation of the right chambers, impaired right ventricular systolic function, a tricuspid valve with normal implantation and severe regurgitation; an estimated pulmonary artery systolic pressure of 19 mmHg; a normal pulmonary artery diameter and a atrial septal defect of 3.5mm.

Cardiac magnetic resonance imaging was performed, revealing severe dilation of the right atrium (38 x 36 mm) and right ventricle (end-diastolic volume 63 ml, 153.6 ml/m2), an extremely thin-walled RV with almost complete absence of the right ventricular free wall myocardium, a paucity of apical trabeculations and impaired systolic function of 21%. The left ventricle was normal and an systolic function of 40%. Late gadolinium enhancement was observed in the right ventricle and right atrium walls. 


Learning Points from this Case:

Uhl’s anomaly of the right ventricle is an unusual cardiac disorder with almost complete absence of right ventricular myocardium and the direct apposition of endocardium to epicardium without a myocardial layer in between, resulting in right ventricular failure, normal tricuspid valve, and preserved septal and left ventricular myocardium.

The exact cause of Uhl’s anomaly is unknow. Selective but unrestrained apoptosis of right ventricular myocytes after complete cardiac development has been postulated to explain it.  

In severe forms, like the present case, right ventricular failure develops during childhood. Previous to the advent of current imaging methods, diagnosis was performed during autopsy. Currently, cardiac magnetic resonance is the technique of choice for identification, as well as for morphologic and functional assessment.

In cardiac magnetic resonance, Uhl’s disease is described by an exceptionally dilated thin-walled RV with severe hypokinesis, a lack of trabeculations and no fat signal in the RV wall. This case shows that clinical symptoms, and imaging findings must be thoroughly reviewed in congenital heart disease in order to enable correct diagnosis. Primary right ventricular disease should be considered when RV failure is present.