The muscular interventricular septum is a wall of tissue that separates the lower two chambers of the heart, known as the ventricles. Its proper formation and function are fundamental for maintaining the heart’s ability to circulate blood efficiently throughout the body.
Anatomy and Position
The muscular interventricular septum is primarily composed of cardiac muscle cells, or cardiomyocytes. It is the thicker and more substantial part of the interventricular septum, forming the majority of this dividing wall. In adults, its thickness typically ranges from 8 to 10 millimeters, though it tends to be thinner towards the heart’s apex.
This muscular structure is situated between the heart’s two lower chambers, the right and left ventricles. It extends from the heart’s apex, or tip, upwards towards its base. The septum is curved, with its convex side facing the right ventricle, and it forms parts of the walls for both the right and left ventricles.
Essential Function
The primary role of the muscular interventricular septum is to maintain the distinct separation between the left and right ventricles of the heart. This separation is necessary to prevent the mixing of oxygen-rich blood, which is destined for the body, with oxygen-poor blood, which is on its way to the lungs. By keeping these blood supplies separate, the septum ensures that the circulatory system operates with maximum efficiency.
The muscular septum contributes to the heart’s pumping action and helps regulate pressure differences within the ventricles. During systole, the septum shortens longitudinally and thickens, shifting towards the left side of the heart to support the right ventricle’s pumping action. This coordinated movement helps direct blood flow properly. The septum also houses parts of the heart’s electrical conduction system, including the bundle of His, which helps coordinate ventricular contractions.
Common Conditions Affecting the Septum
Ventricular Septal Defect (VSD) is a hole in the septum that allows blood to flow between the left and right ventricles. The size and location of these holes can vary, with smaller defects sometimes closing spontaneously, particularly those located in the muscular part of the septum. Larger VSDs can lead to symptoms like shortness of breath and difficulty feeding in infants due to increased blood flow to the lungs and extra work for the heart.
Hypertrophy, or thickening of the heart muscle, is an acquired condition affecting the septum. This can occur in conditions like hypertrophic cardiomyopathy (HCM), a genetic disease where the heart muscle, often including the septum, thickens. This thickening can make the ventricle stiff, impeding its ability to relax and fill with blood, and in some cases, the thickened septum can bulge into the left ventricle, partially blocking blood flow out to the body. High blood pressure can also lead to left ventricular hypertrophy, where strain causes the heart muscle, including the septum, to thicken.
Diagnosis and Management
Diagnosing conditions related to the muscular interventricular septum typically involves various imaging techniques. Echocardiography is the most frequently used test, employing sound waves to generate real-time images of the heart’s structure and blood flow. This allows healthcare professionals to determine the size and precise location of defects, as well as assess how well blood is moving through the heart. Magnetic resonance imaging (MRI) can also provide detailed images of the heart’s structures and can be used to evaluate ventricular function and blood flow, often supplementing information gathered from echocardiograms.
Management approaches for septum-related conditions vary depending on the specific diagnosis and severity. For small Ventricular Septal Defects, regular monitoring may be sufficient, as many close on their own, especially muscular VSDs. Larger defects or those causing significant symptoms may require medical therapy to manage heart failure symptoms, which can include medications like diuretics to reduce fluid. In some cases, surgical intervention may be necessary to close the defect, often involving open-heart surgery to patch the hole. For hypertrophic cardiomyopathy, treatment focuses on reducing symptoms and preventing complications through medications, lifestyle changes, and in some instances, surgical myectomy or alcohol septal ablation to reduce the thickened muscle.