Atrioventricular canal defect
| Atrioventricular septal defect | |
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| Illustration of a atrioventricular septal defect | |
| Classification and external resources | |
| Specialty | medical genetics |
| ICD-10 | Q21.2 |
| ICD-9-CM | 745.6 |
| DiseasesDB | 31910 |
| eMedicine | med/670 |
| MeSH | C14.240.400.560.350 |
Atrioventricular septal defect (AVSD) or atrioventricular canal defect (AVCD), previously known as "common atrioventricular canal" (CAVC) or "endocardial cushion defect", is characterized by a deficiency of the atrioventricular septum of the heart. It is caused by an abnormal or inadequate fusion of the superior and inferior endocardial cushions with the mid portion of the atrial septum and the muscular portion of the ventricular septum.
A variety of different classifications have been used, but the defects are usefully divided into "partial" and "complete" forms.
Symptoms include difficulty breathing (dyspnea) and bluish discoloration on skin and lips (cyanosis). A newborn baby will show signs of heart failure such as edema, fatigue, wheezing, sweating and irregular heartbeat.
If there is a defect in the septum, it is possible for blood to travel from the left side of the heart to the right side of the heart, or the other way around. Since the right side of the heart contains venous blood with a low oxygen content, and the left side of the heart contains arterial blood with a high oxygen content, it is beneficial to prevent any communication between the two sides of the heart and prevent the blood from the two sides of the heart from mixing with each other.
Down syndrome is often associated with AVCD. Other risk factors include: having a parent with a congenital heart defect, alcohol use while pregnant, uncontrolled diabetes treatment during pregnancy and some medications during pregnancy.
This type of congenital heart defect is associated with patients with Down syndrome (trisomy 21) or heterotaxy syndromes. 45% of children with Down syndrome have congenital heart disease. Of these, 35–40% have AV septal defects. Similarly, one-third of all children born with AVSDs also have Down syndrome.
A study also showed that there is also an increased risk of atrioventricular canal in patients who suffer from Noonan syndrome. The pattern seen in those patients with Noonan syndrome differ from those patients who have Down syndrome in that "partial" AVCD is more prevalent in those who suffer from NS, where as those who suffer from down syndrome show a prevalence of the "complete" form of AVCD.
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