Discussion
Cor triatriatum sinistrum is an infrequent cardiac anomaly that accounts for 0.1 to
0.4% of congenital heart diseases[1] and was first described by Church in 1868. In this condition, the left atrium is
bisected by an anomalous fibromuscular membrane into a proximal chamber or the common
embryonic pulmonary vein and a distal chamber or the embryonic left atrium giving
rise to the atrial appendage and the AV valve.[2] The two chambers generally communicate with each other through fenestrations in
this inter-atrial membrane. The simplest classification was laid down by Loefller
in 1949, where group one was defined as having no opening, group two as having one
or additional small openings, and group three as having a single, large opening.[3] Group one patients present early in infancy with pulmonary edema and other features
of left heart obstruction, while group two and three patients are usually asymptomatic.
It is mostly detected incidentally in adult population. Large fenestrations can become
obstructed later in life due to fibrosis and calcification, which can then cause symptoms
such as dyspnea, orthopnea, and hemoptysis.[4] Associated cardiac conditions include atrial and ventricular septal defect, anomalous
pulmonary vein return, bicuspid aortic and right AV valve, coarctation of aorta, and
persistent left superior vena cava.[4]
[5]
Echocardiography depicts the interatrial membrane beautifully while the fenestrations
in the membrane can sometimes be visualized as a jet of increased velocity on color
Doppler. CT scan and magnetic resonance imaging (MRI) help in assessing the membrane,
cardiac anatomy, and associated congenital anomalies with oblique reformats being
extremely useful in visualizing the lesion in entirety. Sometimes, a jet can be seen
on CT while MRI can evaluate the flow through the fenestrations and assess other functional
parameters including mitral regurgitation.
Treatment in CTS depends on the severity of the patient's symptoms. Incidentally detected
lesions in asymptomatic patients do not warrant any active management. Significant
dyspnea and pulmonary congestion are treated by diuretics, digoxin, and preload reduction,
while surgical intervention is reserved for highly symptomatic patients with significant
obstruction.[5]
