Septal defects are "holes" which punctuate the endocardial septal tissue, thus forming an illicit communication between the heart's chambers. As such, blood is "leaked" from one side of the heart to the other to a degree that can range from clinically insignificant to severe, depending on the size of the lesion(s) involved. These holes appear when the endocardial tissue fails to fuse completely in-utero. They can affect the atrial septum (the "wall" dividing the heart's upper chambers), the ventricular septum (the wall dividing the heart's lower chambers), or a combination of both. They may be isolated, or adjunct to a series of more complex malformations.
Septal defects are acyanotic in nature, meaning that blood is leaked from the left side of the heart to the right. As such, blood that has already been oxygenated by the lungs returns there instead of being distributed throughout the body as it should. This can lead to several complications, which will be discussed below. In this article, I will explore the frequency, effects, and risk factors inherent to the various forms of this disease.
Septal Defects- A Basic Overview:
Septal defects are collectively termed "holes in the heart". This is one case in which the lay term does justice to the medical jargon. Research indicates that congenital heart malformations collectively constitute the most common form of birth defect, affecting one out of every hundred live births. Septal defects are frequently the culprit, with ventricular septal defects accounting for half of all CHDs. Hence, the fact that cardiothoracic surgeons consider the surgical repair of isolated septal defects as "run-of-the-mill" should come as no surprise. This, of course, does not serve to minimize their severity: open-heart surgery is no walk through the park, and a defect significant enough to warrant invasive intervention will obviously cause problems for the affected individual if it is left untreated. The good news is that most of these holes do not necessitate such drastic measures. Indeed, an estimated 60 to 70% of VSDs will resolve spontaneously, either closing up altogether or becoming small enough with time so as to be considered clinically insignificant.
There are three primary types of septal defects: ventricular septal defects (VSDs), atrial septal defects (ASDs) and atrioventricular canal defects (AV canal defects or AVSDs). Each type of malformation has its own specific range of possible complications, but share many issues in common as well. The following section will serve to outline and explain two of these three major categories, the ASD and the VSD. Because AVSDs are more complex, I will discuss this condition at a later date.
