[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Chest](https://durgical.com/en/anatomy/region/chest/) › Interventricular septum [Cardiovascular system](https://durgical.com/en/anatomy/system/cardiovascular-system/) · [Chest](https://durgical.com/en/anatomy/region/chest/) # Interventricular septum The interventricular septum is the wall between the two lower chambers of the heart; it keeps oxygen-rich and oxygen-poor blood apart. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=thorax&select=interventricular_septum&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The thick muscular wall between the two ventricles, with a thin membranous part near the top. ## What it does Separates oxygen-rich from oxygen-poor blood and carries the bundle branches of the conduction system. ## Key points - The membranous part sits just below the commissure of the [aortic right coronary cusp](https://durgical.com/en/anatomy/right-coronary-leaflet/) and [aortic non-coronary cusp](https://durgical.com/en/anatomy/non-coronary-leaflet-of-aortic-valve/); perimembranous defects are the commonest ventricular septal defects - The [Bundle of His](https://durgical.com/en/anatomy/atrioventricular-bundle/) runs along the lower edge of the membranous part, then splits into the bundle branches on either side of the muscular septum - Septal rupture after infarction gives a new harsh holosystolic murmur and sudden heart failure, usually within the first days ## Key facts **Where** Between ventricles; thick muscular part and small membranous part just below aortic valve **Function** Separates ventricles; carries bundle branches; supplied by LAD septals (anterior 2/3) and PDA (posterior 1/3); membranous part = commonest VSD site ## Relations **In front** Anterior interventricular groove with the [LAD (anterior descending artery)](https://durgical.com/en/anatomy/anterior-interventricular-artery/), which sends septal perforating branches into it **Behind** Posterior interventricular groove with the [posterior descending artery (PDA)](https://durgical.com/en/anatomy/inferior-interventricular-artery/) and the [middle cardiac vein](https://durgical.com/en/anatomy/middle-cardiac-vein/) **Above** Aortic valve above the membranous part; the [tricuspid septal leaflet](https://durgical.com/en/anatomy/septal-leaflet-of-right-atrioventricular-valve/) attaches across the membranous septum on its right side **Contents** The left bundle branch fans out under the left ventricular endocardium; the [right bundle branch](https://durgical.com/en/anatomy/right-bundle-branch/) runs down to the moderator band ## How to find it It cannot be felt. A ventricular septal defect gives a loud, harsh holosystolic murmur at the left lower sternal border, often with a thrill; small defects are typically the loudest. ## On imaging Echocardiography: parasternal long and short [axis](https://durgical.com/en/anatomy/axis/) and apical four-chamber views measure its thickness and show defects with colour Doppler. Septal motion becomes paradoxical with left bundle branch block or after heart surgery. Cardiac MRI shows septal scar. ## Common problems - A hole from birth (ventricular septal defect). - Can rupture after a large heart attack (rare). ## How it is diagnosed ECG, blood tests (troponin) for a heart attack; echocardiogram for ejection fraction and wall movement; cardiac MRI. ## Treatment - Opening the blocked artery fast in a heart attack (angioplasty and stent). - Heart-failure medicines, and devices such as a defibrillator or resynchronization pacemaker. - Bypass surgery when several arteries are narrowed. ## Clinical notes - Many small muscular defects close by themselves in childhood; large defects cause heart failure in infancy and, left alone, Eisenmenger syndrome - Post-infarct rupture is apical after anterior infarcts and basal-inferior after inferior infarcts - Hypertrophic cardiomyopathy thickens the septum asymmetrically and can narrow the left ventricular outflow tract - Closing a perimembranous defect risks the bundle of His at its lower rim, causing heart block - The septal tricuspid leaflet hinges below the top of the membranous septum, so its upper (atrioventricular) part lies between the [left ventricle](https://durgical.com/en/anatomy/left-ventricle/) and the [right atrium](https://durgical.com/en/anatomy/right-atrium/); a defect there shunts left ventricle to right atrium (Gerbode defect) ## Development The muscular part grows up from the floor of the primitive ventricle; the membranous part closes last, from the endocardial cushions and the outflow ridges, which is why defects cluster there. ## Related conditions - [Hypertrophic cardiomyopathy](https://durgical.com/en/conditions/hypertrophic-cardiomyopathy/) - [Mechanical complications of myocardial infarction](https://durgical.com/en/conditions/mechanical-complications-of-myocardial-infarction/) - [Eisenmenger syndrome](https://durgical.com/en/conditions/eisenmenger-syndrome/) - [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/) - [Rubella and congenital rubella syndrome](https://durgical.com/en/conditions/rubella-and-congenital-rubella-syndrome/) - [Trisomy 18 (Edwards) and trisomy 13 (Patau)](https://durgical.com/en/conditions/trisomy-18-and-trisomy-13/) - [Hypertensive heart disease](https://durgical.com/en/conditions/hypertensive-heart-disease/) - [Ventricular septal defect](https://durgical.com/en/conditions/ventricular-septal-defect/) - [Tetralogy of Fallot](https://durgical.com/en/conditions/tetralogy-of-fallot/) - [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/) ## Test yourself Think of the answer, then tap the question to see it. ## Where is the commonest ventricular septal defect located? In the membranous part of the interventricular septum (perimembranous), just below the aortic valve, which closes last in development. ## What murmur does a ventricular septal defect produce? A loud, harsh holosystolic murmur at the left lower sternal border, often with a thrill; small defects are typically the loudest. ## How does post-infarction rupture of the interventricular septum present? A new harsh holosystolic murmur and sudden heart failure, usually within the first days after the infarct. ## Which arteries supply the interventricular septum? Septal perforators of the LAD supply the anterior 2/3; the posterior descending artery supplies the posterior 1/3. ## Why does closing a perimembranous ventricular septal defect risk heart block? The bundle of His runs along the lower edge of the membranous septum, at the lower rim of the defect. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/anatomy/interventricular-septum/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** septum interventriculare TA2 3970 **Official Spanish (DeCS)** Tabique interventricular DeCS D054088 **English (TA2)** Interventricular septum **Also called** ventricular septum · septum ventriculorum ## Related - [Bundle branches](https://durgical.com/en/anatomy/right-bundle-branch/) - [LAD (anterior descending artery)](https://durgical.com/en/anatomy/anterior-interventricular-artery/) - [Posterior descending artery (PDA)](https://durgical.com/en/anatomy/inferior-interventricular-artery/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=52518); [Anatomy, Thorax, Heart](https://www.ncbi.nlm.nih.gov/books/NBK470256/); [Anatomy, Thorax, Heart and Pericardial Cavity](https://www.ncbi.nlm.nih.gov/books/NBK482452/); Tratado de anatomía humana (9.ª ed.), tomo II, Libro IV Angiología, sección 1, capítulo 1: Corazón, artículos I–VI. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/interventricular-septum/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/interventricular-septum/