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The interventricular septum is more than just a wall separating the heart’s chambers; it helps the heart pump efficiently and ensures correct blood flow. Without the development of the interventricular septum, the two ventricles could not function as separate pumps, and this would have deadly consequences.
To fully understand the role of this structure, we need to look at its origin, function, anatomy, blood supply, and how health or disease affect it.
Interventricular Septum Development
The interventricular septum is formed through coordinated development in the embryonic heart. The primitive heart tube first loops and forms chambers. The septum starts as a muscular ridge and grows upwards from the apex of the developing ventricles. Subsequently, membranes grow into the muscular part to form a complete separation between the right and left ventricles.
Mistakes in this process can cause congenital malformations, including a common congenital heart defect: ventricular septal defect (VSD), one of the most frequent cardiac malformations. Knowledge of its embryologic derivation clarifies why abnormalities occur.
Interventricular Septum Function
The primary job of the interventricular septum is to provide a barrier that prevents high-oxygen blood from the left ventricle from mixing with the low-oxygen blood from the right ventricle.
In addition to its function as a partition, the septum also aids in the pumping activity to the heart. In systole, the contractile part of the myocardium contracts in conjunction with the ventricular walls, helping to eject blood into the systemic and pulmonary circuits.
Interventricular Septum Thickness
The septum has an uneven composition. Its thickness in dimensions change with site and function. The muscular portion (especially around the left ventricle) is thicker to accommodate the greater pressure that the left side of the heart needs to generate to pump blood throughout systemic circulation.
Some diseases influence this thickness. One example is the septum thickens abnormally in hypertrophic cardiomyopathy and inhibits the flow of blood from the left ventricle to the aorta, often causing chest pain, fainting, and arrhythmias.
Interventricular Septum Location
Located in the center of the heart, it separates the left and right heart structures. It lies from the base of the heart, near the atrioventricular valves, to the apex of the heart. Because it is relatively near the center, it communicates with other structures such as the atrioventricular and interatrial septa (which divide the atria from the ventricles and from each other, respectively). This orientation highlights it as the central to heart structure.
Interventricular Septum Blood Supply
The septum is primarily supplied with blood by the right and left coronary arteries. The anterior two-thirds, including the region containing the conduction system, are provided predominantly by the left anterior descending artery. Branches of the right or circumflex artery perfuse the bottom one-third. Occlusion of these arteries results in ischemia or infarction of the septal muscle, impairing both mechanical pumping and electrical conduction.
Interventricular Septum Parts
The septum consists of the muscular part, which contributes to the contractile force, and the membranous part, a thinner segment necessary for structural separation around the valve.
- The muscular septum comprises the majority, contributing significantly to the contractile strength of the ventricles.
- The membranous septum is thinner and located near the atrioventricular valves. Due to its delicate nature, defects in this area are more likely to result in VSDs.
Both components have specific clinical relevance to whether a developmental or acquired disease occurs in one or the other portion.
Atrioventricular and Interatrial Septum
While the atrioventricular septum (also known as the membranous part) is separate from the interventricular septum, the two play a role in allowing complete septation of the heart chambers: Atrioventricular and Interatrial Septa.
The atrioventricular septum separates atria from ventricles, and the interatrial septum divides right and left chambers. Together with the interventricular septum, these structures form a cardiac barrier ensuring unidirectional blood flow and preventing abnormal connections.
Interventricular Septum in Health and Disease
In a normal functioning heart, the septum allows for blood to pass and contract in unison. Its structure or function, however, may deteriorate in disease. Acquired septal thickening or thinning can also result in significant heart disease.
For example, suppose the septum is weakened in dilated cardiomyopathy and does not contract properly. In that case, it can fail to contribute adequately to contraction, leading to more severe symptoms of heart failure.
Ventricular Septal Defect: Symptoms and Causes
If a defect in the septum (or wall) that divides the two ventricles is present, blood can flow from a high-pressure left ventricle to a low-pressure right ventricle.
Symptoms vary depending on the size of the defect and may include shortness of breath, failure to thrive in infancy, fatigue, or frequent respiratory infections. Larger defects are typically associated with heart enlargement and pulmonary hypertension. These can occur due to errors in embryogenesis or may be secondary to trauma or infarction.
Separation of Ventricles and Heart Defects.
Separation of the two ventricles by this septum is necessary for normal heart action. Without it, the mixing of oxygenated and deoxygenated blood diminishes the performance and puts a strain on both the pulmonary and systemic circulations. This division explains why septal defects directly affect heart function.
Anatomy and Heart Wall
The septum is a vital feature of the heart wall. The wall is divided into three layers:
- Endocardium
- Myocardium
- Epicardium
These layers merge with the septum and are continuous with the adjacent ventricular walls. Its location allows both pumping chambers to work in tandem smoothly.
Heart Blood Flow and Cardiac Septum
An intact septum is necessary for normal blood flow through the heart. The heart’s right ventricle pumps the deoxygenated blood to the lungs; its left side sends oxygenated blood to the body. In this way, the septum provides a complete independent structure for these two circulations. Even minimal defects of the septum may impair this system and result in volume overload of the chambers.
Heart Partition and Clinical Implications
The interventricular septum is the major division of the heart, and must be able to withstand high pressures in both ventricles, especially the left. Occasionally, an underlying condition, such as a myocardial infarction, may weaken the septum, resulting in rupture of the septum with subsequent development of this serious complication.
Early detection of these conditions is crucial for maintaining proper circulation and preventing heart failure.
The Interventricular Septum in Perspective
When viewed in the context of heart anatomy, the interventricular septum presents a complex puzzle, from prenatal life to adult pathology. It bridges mechanical, electrical, and vascular functions, making it indispensable.
Advances in imaging and surgical techniques enable clinicians to diagnose and treat septal disorders more effectively, resulting in improved outcomes for patients with congenital or acquired septal conditions.
Conclusion
The septum separates the two halves of the heart, but does not have a passive wall between them, instead acting as an active interface that plays a dynamic role in blood pumping through the heart and in determining how well it pumps. Its anatomy, thickness, localization, and vascular supply, as well as its relation to other heart structures, all highlight the complexity and significance of this tissue. When altered or distorted, it is implicated in a variety of pathologies from ventricular septal defects to heart failure, in both health and disease.
At BaleDoneen, we emphasize the importance of understanding these vital truths about heart anatomy to promote the prevention, early detection, and treatment of cardiovascular disease.
FAQs
What is the importance of the interventricular septum?
The interventricular septum separates the right and left ventricles so that oxygenated blood does not mix with deoxygenated blood. It aids in contraction and facilitates the transmission of electrical impulses, which are synchronized to create a heartbeat.
What happens if the interventricular septum is damaged?
Damage to the septum can result in an abnormal flow of blood between the ventricles, leading to decreased circulation and impaired oxygen transmission. It can cause heart failure, arrhythmia, or serious complications such as a ventricular septal defect.
What is the purpose of the ventricular septum?
The ventricular septum serves as a dividing wall between the ventricles, contributing to their ability to pump blood in the heart. It is a site of important conduction pathways that permit synchronised cardiac contractions.
Why is the septum important to the heart?
It does so by ensuring that oxygen-rich and oxygen-poor blood do not mix. Its architecture provides the conductive and pump functions, both of which are essential for the heart’s function.
About the Author: Randy Kembel
