Cor triatriatum is a very rare congenital heart defect where the formation of the atria, the two upper chambers of the heart, is not normal. Instead, either the right or left atrium are divided in two by different things like membranes, tissues that are folded, or bits of fibrous matter. The disease is further identified by where the additional atrium occurs and can be called cor triatriatum dextrum or sinistrum (right or left). Essentially, the person with this condition has three atria, and many people with it have other structural heart defects.
Not all people are aware they have cor triatriatum. It depends on the degree of communication between the primary and extra atrium and on presence of other heart defects. With this condition, blood returning to the heart mostly goes to the extra chamber, and if there’s complete closure between that extra chamber and the primary atrium, the condition can be serious immediately. With very little blood getting to the appropriate part of the heart, congestive heart failure could occur almost directly after birth.
On the other hand, some people have ample communication between extra and primary atria, which means the blood is simply going through an extra step before being pumped either to the body or lungs. There are some cases where people don’t realize they have cor triatriatum until they’re middle-aged. This extra step can be wearing on the heart eventually and bring on signs of failure.
An early or late surgical repair of cor triatriatum could have varied results. The goal is to minimize the work the heart must do to receive its needed blood supply. In infants who do have multiple heart defects, it may be necessary to do a variety of reparative steps, including fixing any additional defects. Sometimes additional defects are functional and their presence actually makes having an extra atrium survivable. In this case, careful planning would be required to effect repairs that deal with all defects at once or in a way that prevents heart failure.
It’s difficult to comment on survivability of cor triatriatum because the defect can vary so much in severity. Children at most risk are usually those with complexly disordered hearts, where more than one defect is present. Even with complex defects, surgery improves continuously, and many things once thought irreparable are now reparable and survivable with very little impact on life span or quality of life. Severe cases of a third atrium where no surgery is attempted are often fatal, though again there are some people with this condition that survive to adulthood. It can generally be said that a child who shows signs of heart failure from cor triatriatum would probably not be expected to live without treatment.