eteisväliseinän

Eteisväliseinän refers to the wall separating the atrium and the ventricle in the heart. In a typical mammalian heart, there are two atria and two ventricles, divided by these septa. The atrial septum separates the left atrium from the right atrium, and the ventricular septum separates the left ventricle from the right ventricle.

The atrial septum is a thin wall, while the ventricular septum is much thicker due to the greater workload of the ventricles. These septa are crucial for maintaining the unidirectional flow of blood through the heart and for ensuring that oxygenated and deoxygenated blood do not mix.

Congenital heart defects can involve abnormalities in the atrial or ventricular septa. Atrial septal defects (ASDs) involve a hole in the atrial septum, allowing blood to flow between the atria. Ventricular septal defects (VSDs) involve a hole in the ventricular septum, leading to blood flow between the ventricles. These conditions can have significant impacts on the heart's ability to pump blood effectively.

During fetal development, a structure called the foramen ovale within the atrial septum allows blood to bypass the lungs. This opening typically closes shortly after birth, forming a depression known as the fossa ovalis. If it fails to close completely, it results in a patent foramen ovale (PFO), which is a common type of ASD.