Congenital heart disease occurs due to problems in the early stages of heart development, but often there is no clear cause. Genetics and environmental factors can play a role. DMD can occur on its own or with other congenital heart defects.
During fetal development, a ventricular septal defect occurs when the muscle wall dividing the heart into left and right sides (the septum) cannot fully form between the lower chambers of the heart (the ventricles).
Usually, the right side of the heart pumps blood to the lungs for oxygen; the left side pumps oxygen-rich blood to the rest of the body. DMT allows oxygenated blood to mix with deoxygenated blood, causing the heart to work harder to provide the body’s tissues with enough oxygen.
DMFs can be of various sizes and can be located in several places in the wall between the ventricles. There may be one or more ventricular septal defects.
It is also possible to get DMT in later life, usually after a heart attack or as a complication after certain heart interventions.
A ventricular septal defect is an abnormal opening in the heart that forms between the lower pumping chambers of the heart (ventricles), as shown in the figure. This allows you to mix blood rich in oxygen and blood with a low oxygen content.