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Concealed left atrial membrane: pitfalls in the diagnosis of cor triatriatum and supravalve mitral ring
Insights
Congenital left atrial membranes, like cor triatriatum, can obstruct blood flow. In children with other heart defects, pulmonary venous obstruction was unexpectedly absent due to specific anatomical and physiological factors.
Area of Science:
- Pediatric Cardiology
- Congenital Heart Disease
- Cardiac Surgery
Background:
- Cor triatriatum and supravalvular mitral ring are congenital left atrial membranes causing left ventricular inflow obstruction.
- These defects typically present with pulmonary venous obstruction as isolated anomalies.
Observation:
- Four pediatric cases are presented where left atrial membranes were associated with other significant cardiac defects.
- Associated defects included coarctation of the aorta, sinus venosus atrial septal defect, and tricuspid atresia.
- One patient had undergone prior pulmonary arterial banding for complex coarctation of the aorta syndrome.
Findings:
- None of the patients demonstrated significant pulmonary venous obstruction during cardiac catheterization.
- Pulmonary arterial diastolic and wedge pressures were within normal limits for all patients.
- Absence of pulmonary venous obstruction was attributed to large membrane openings, a pulmonary venous chamber-decompressing atrial septal defect, or decreased pulmonary blood flow.
Implications:
- Two-dimensional echocardiography facilitated diagnosis of these complex congenital heart defects.
- Accurate diagnosis is crucial as pulmonary venous obstruction can arise post-operatively for associated cardiac defects.
- Understanding these mechanisms is vital for surgical planning and management of pediatric patients with complex congenital heart disease.
Abstract:
Cor triatriatum and supravalve mitral ring are forms of congenital left ventricular inflow obstruction produced by membranes within the left atrium. Typically, these defects occur as isolated anomalies with manifestations of pulmonary venous obstruction. Four children are presented whose left atrial membrane was associated with other significant cardiac defects, including, in one patient each, simple coarctation of the aorta, sinus venosus atrial septal defect, tricuspid atresia and complex coarctation of the aorta syndrome. The patient with the latter defect had undergone previous pulmonary arterial banding. None of these patients demonstrated significant pulmonary venous obstruction at cardiac catheterization. All patients had a normal value for either pulmonary arterial diastolic or pulmonary arterial wedge pressure. Three mechanisms explained the lack of pulmonary venous obstruction: (1) a large cross-sectional area of membrane openings, (2) an atrial septal defect that was confined to the pulmonary venous chamber and decompressed it by allowing blood to escape into the right atrium, and (3) decreased pulmonary blood flow. The diagnosis was facilitated by two dimensional echocardiography. Accurate diagnosis of left atrial membrane in the setting of other cardiac defects is of practical significance because pulmonary venous obstruction may occur after surgery for the associated defects.