Herzscheidewand

The Herzscheidewand, commonly referred to as the heart septum, is the wall that divides the heart into its right and left sides. It prevents mixing of oxygen-poor and oxygen-rich blood and is essential for the heart’s orderly function.

The heart contains two main septa: the interatrial septum, which separates the right and left atria, and the interventricular septum, which separates the right and left ventricles. The interatrial septum includes the fossa ovalis, a remnant of the fetal foramen ovale. The interventricular septum is primarily muscular, with a small membranous portion near the base of the heart.

Embryologically, the atrial septum forms from the septum primum and septum secundum, while the ventricular septum develops from growing ventricular walls and from endocardial cushions that contribute the membranous part. Proper formation and closure of the septa are essential for separating the systemic and pulmonary circulations after birth.

Functionally, the septa ensure that the right and left sides of the heart operate in parallel circuits with distinct pressures and oxygen content. The interventricular septum also plays a role in the conduction system, housing portions of the bundle branches that coordinate ventricular contraction.

Clinical relevance includes congenital septal defects, most notably atrial septal defects (ASD) and ventricular septal defects (VSD). VSDs, in particular, are among the most common congenital heart defects and can lead to left-to-right shunting, heart failure symptoms, or, if untreated, pulmonary hypertension and Eisenmenger syndrome. Treatment ranges from observation to medical management and surgical or device closure, depending on size and hemodynamic impact.