Cor Triatriatum Sinistrum (Panel A)
CASE REPORT: LATE PRESENTATION OF SYMPTOMATIC COR TRIATRIATUM SINISTRUM
Dr Gurunathan Sothinathan
A 67 year old lady was referred to our institution 3 years ago with a heart murmur, having had an ASD repair with a Dacron patch 20 years previously. Trans-thoracic echocardiography demonstrated a linear echo-density in the left atrium. On TOE (Panel A), a septum (white arrows) divided the left atrium into 2 chambers connected by a visible channel (PVC – pulmonary venous chamber, LA – left atrium, LV – left ventricle, RV – right ventricle). Doppler echocardiography revealed minimal trans-membrane gradient suggesting a non-obstructive form of cor triatriatum sinistrum.
During follow up, she developed exertional dyspnoea and peripheral oedema, associated with elevated right heart pressures. Cine MR images (Panel B) demonstrated a sizable transverse septum dividing the left atrium (black arrow-heads) with turbulent flow on the pulmonary venous side.
Although she had haemodynamically significant obstruction, she declined referral for corrective surgery.
DISCUSSION
In classical Cor triatriatum sinistrum, a fibromuscular membrane separates the left atrium into a common pulmonary venous chamber (receiving blood from the pulmonary veins), and the true left atrium (communicating with the mitral valve and left atrial appendage). The membrane may contain one or more restrictive orifices. Most cases present in the neonatal period or infancy, and 70-80% of cases are associated with an ASD.
When there is a large communication between the chambers, presentation can occur in adulthood, and may be found incidentally on cardiac imaging. Late conversion to a symptomatic state, may be caused by fibrosis and calcification in the orifice of the separating diaphragm.
Cor triatriatum sinistrum may be missed on trans-oesophageal echocardiography due to poor spatial resolution in the posterior left atrium, close to the transducer. CMR is useful for imaging Cor triatriatum. In general, it provides better spatial resolution and superior tissue contrast compared to echocardiography and imaging is easily performed in multiple planes.
Pre-operatively CMR provides excellent delineation of the dividing membrane and guides the surgical approach. Cine imaging clearly depicts fenestrations in the membrane and is useful for demonstrating any turbulent flow across it.
REFERENCES
- Nelson Alphonso, Martin A, Norgaard, MD, Andrew Newcomb. Cor Triatriatum: Presentation, Diagnosis and Long-Term Surgical Results. Ann Thorac Surg 2005;80:1666-1671
- Amyn Malik, Daniel Fram, Amir Mohani. Cor triatriatum: A multimodality imaging approach. Can J Cardiol. 2008 March; 24(3): e19–e20
- Sakamoto I, Matsynaga N, Hayashi K, Ogawa Y, Fukui J. Cine-magnetic resonance imaging of cor triatriatum. Chest 1994; 106:1586-1589
- Ono Y, Fukui K, Munakata M, et al. Usefulness of the preoperative MRI for diagnosis and operative method in a case of cor triatriatum. Kyobu Geka 1996; 49:921-923