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Interventricular Septum

The interventricular septum (IVS) is a thick muscular wall that separates the right and left ventricles of the heart. It extends from the atrioventricular septum superiorly to the apex of the heart inferiorly. The septum has two main parts: a muscular portion (thicker, forming the majority) and a membranous portion (thin, near the aortic valve). The IVS plays a critical role in maintaining ventricular independence, ensuring unidirectional blood flow, and providing the structural framework for coordinated cardiac contraction. It is a common site of congenital and acquired pathologies, including ventricular septal defects (VSDs), hypertrophy in hypertrophic cardiomyopathy, and ischemic injury.

Synonyms

  • IVS

  • Ventricular septum

  • Septum cordis

Function

  • Separates the right and left ventricles, preventing blood mixing

  • Contributes to synchronous ventricular contraction via conduction fibers (bundle branches)

  • Provides the structural base for the bundle of His and Purkinje fibers, essential for cardiac conduction

  • Maintains ventricular pressure balance during systole

  • Serves as a diagnostic landmark for congenital and acquired cardiac disease

MRI Appearance

T1-weighted images:

  • IVS myocardium shows intermediate signal intensity, similar to other cardiac walls

  • Provides good delineation from the blood pool (low signal on spin echo)

  • Useful for anatomical evaluation of septal thickness

T2-weighted images:

  • Myocardium appears intermediate signal intensity

  • Edema from ischemia, myocarditis, or trauma appears hyperintense in the septum

  • Useful for detecting acute pathology

Cine MRI (SSFP / T2-weighted dynamic sequences):

  • Allows real-time visualization of septal motion during systole and diastole

  • Normal septum moves toward the left ventricle during systole

  • Abnormal motion patterns: paradoxical septal motion (RV overload or post-surgery), septal flattening (pulmonary hypertension), or septal hypertrophy (HCM)

  • Enables accurate measurement of septal thickness, contractility, and wall motion abnormalities

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Late gadolinium enhancement (LGE) detects fibrosis, infarction, or scar within the septum

  • Essential in ischemic heart disease, cardiomyopathies, and infiltrative diseases (e.g., amyloidosis, sarcoidosis)

CT Appearance

Non-contrast CT:

  • IVS appears as a thick muscular wall with soft tissue attenuation

  • Calcifications (rare) may be seen in chronic disease or post-surgical changes

Contrast-enhanced CT (Cardiac CTA):

  • Provides clear delineation of septal thickness, relation to chambers, and coronary arterial supply (LAD branch to septum)

  • Detects septal hypertrophy, ventricular septal defects, ischemic wall thinning, or aneurysm formation

  • Multiplanar reconstructions help in preoperative planning and congenital heart disease evaluation

MRI images

Interventricular septum mri image

MRI images

mri image Interventricular Septum anatomy

CT image

Interventricular septum ct axial image -img-00000-00000