Cor Triatriatum
Cor Triatriatum is a rare congenital heart defect characterized by a fibromuscular membrane that divides one of the atria into separate chambers. This abnormal septation can obstruct normal blood flow, leading to hemodynamic consequences that depend on the size of the communication between the two chambers.
Types:
Cor Triatriatum Sinistrum (Left Atria) - Most Common:
A fibrous membrane divides the left atrium into a proximal and distal chambers. There is commonly a thin fibromuscular membrane partitioning the atriums into three distinct atrial compartments (here the left atrium is divided in 2 chambers and the right atrium is undivided).
The atrium is divided into an upper (pulmonary venous) compartment and a lower (vestibular) compartment. The upper compartment receives blood from the pulmonary veins, while the atrial appendage is typically associated with the lower compartment.
The pulmonary veins drain into the proximal chamber, while the distal chamber communicates with the mitral valve.
If the communication is restrictive, it can mimic severe mitral stenosis, causing pulmonary hypertension and heart failure.
2. Cor Triatriatum Dextrum (Right Atria) - Rare Variant:
The right atrium is divided by a membrane, resembling a persistent embryologic right valve of the sinus venosus.
Often associated with other congenital anomalies, such as atrial septal defects (ASDs).
Sweep in the short axis view. One may appreciate that there are some pleural effusions on the left and right bases of the lungs (bilateraly). We can appreciate the fibrous membrane dividing the left atrium into a proximal and distal chamber.
Subcostal view. One may appreciate the filling through the mitral valve. There are restrictive shunts (blue and red jets) from the orifces 3 atrial compartments.
Dilated subhepatic veins secondary to the high right atrial pressure due to the RV dysfunction and high end-diastolic pressure. This is seen in the context of post-capillary pulmonary hypertension.
Subcostal sweep. one may appreciate that the RV is dilated and has decreased systolic function. There is significant tricuspid insufficiency reaching the roof of the right atrium. The inter-atrial shunt (ASD secundum) is right to left into the distal
Fibrous membrane divides the left atrium into a proximal and distal chamber (red arrow).
SVC and IVC flow in the subcostal short axis view
Parasternal long axis view. Significant underfilling of the left ventricle and of the left atrium. The RV is significantly dilated due to the increased post-capillary pulmonary hypertension.
Parasternal view demonstrating an underfilled left ventricle, which appears partially compressed ("pancaked") due to the pressure-overloaded right ventricle and the overall reduced left ventricular preload.
Dilatation of the pulmonary artery, right ventricle and right atrium.
Dilatation of the pulmonary artery. Secondary to that, there is pulmonary insufficiency on the colour mode of the parasternal long-axis view.
One may appreciate the restrictive shunt through the membrane seperating the left atrium.
Small shunt from the right atrium to the left atrial distal chamber. The shunt is right to left due to the high right ventricular end-diastolic pressure, and the low left atrial distal chamber filling.
Tricuspid insufficieny. Dilatation of the RA and of the RV in the apical view.
Sweep in the apical view.
Tricuspid regurgitation. SVC fills into the right atrium.
Peak gradient here obtained at 27 mmHg through one of the orifices.
Mean gradient through the fenestration of the membrane at 9 mmHg.
Flow through the RA to LA shunt (right to left).
RV-RA gradient of 63 mmHg. Suprasystemic in this particular context (sBP at 50 mmHg).