“Why does lithium cause Ebstein anomaly?”

Added: 2026-05-25

[00:00:00]Why does lithium cause Ebstein anomaly?

[00:00:02]Okay, so I'll ask you guys watching this, do you know who normally takes lithium? Possible question if you're a Sim Man.

[00:00:10]Patients with bipolar disorder, it's a mood stabilizer, fine. So, it's a teratogen if taken by the mother during pregnancy, it can cause Ebstein anomaly in the fetus, which is AKA atrialization of the right ventricle. And we have that phrasing because you have a small right ventricle and a large right atrium. Part of the right ventricle that was supposed to form that didn't becomes more right atrium instead. Now, the student's asking why this occurs. It's something obscure about how lithium interferes with delamination if we want to sound sophisticated. Delamination of the tricuspid valve from the primitive right ventricle. In other words, when we normally have our right atrium and right ventricle separated by the tricuspid valve, the valve is going to function with normal chordae tendineae, papillary muscle, but in embryologic development, the early tricuspid valve is affixed.

[00:01:11]It's part of the wall of the right ventricle and that normal separation, that delamination, cannot occur if lithium is there. We get an interference with various cellular pathways. Wnt, GSK3, which you as a Sim Man will not ask you. So, what they want for the exam is simply that lithium can cause Ebstein anomaly in the fetus, easy, and of course, not in pregnancy, things like tremor, hypothyroidism, ECG changes, that's it.