A congenital heart defect is an abnormality in the structure of the heart that is present at birth. There are several different types of heart defects. Some are simple and do not require treatment, and others are more complicated and may require multiple surgeries performed over several years. Learning the facts about your child’s heart defect will help you understand the condition and prepare you for what you can expect in the months and years that follow.
The heart begins to form at the end of the third week of pregnancy and this process continues for several more weeks during the first trimester. Of particular importance during this time is the development of the ventricular septum. This is the wall between the two lower chambers of the heart which are called the ventricles.
The aorta is also formed about this time, and this gradually joins near the left ventricle. In close proximity to this, tissue in the central heart separates into mitral and tricuspid valves. This leads to a separation between the right and left atrium. Eventually the septum closes and when this occurs, the critical stages of anatomic cardiac development are thought to be complete.
Some birth defects occur when the septum does not close completely. There are both atrial and ventricular septal defects. An atrial septal defects (ASD) is a birth defect of the heart where there is a hole in the wall (septum) that divides the upper chambers of the heart (the atria). This hole can vary in size and may close on its own or may require surgery. A ventricular septal defect (VSD) occurs when there is a hole in the wall, or septum, that separates the two lower chambers of the heart (the ventricles). There are several sub-categories of both atrial and ventricular septal birth defects.
A recent paper by Danish researches studying the children of mothers who took Zofran (ondansetron) during the first trimester of pregnancy reported a significantly increased risk of cardiac malformations. In particular, they found a much higher risk of septum defects in these children. The authors concluded their paper by recommending at this time that Zofran (ondansetron) should not be used off-label to treat nausea and vomiting in early pregnancy.