In addition, levo transpositions of the great arteries can accompany CHB but this is less common than the first one.These developmental abnormalities can impair the conduction system of the heart by disrupting its anatomical structure. Diagnosis
There is  a difference in diagnosis between low risk pregnancies where mothers do not have (or are not aware of) any autoimmune disease, and the high risk ones where mothers are known to have a specific autoimmune disease and / or are positive to anti Ro/La autoanitbodies and / or had a CHB-affected pregnancy previously.In low risk pregnancies, testing the mothers serum is not part of the routine prenatal tests. Therefore, the congenital heart block is usually diagnosed during a routine obstetrical ultra sound. The first symptom in most cases is a slow heart rate which can be detected using fetal echocardiogram and Doppler ultra sound techniques between the weeks 18 - 30. The Doppler is very important to assess the level of AV block as well as to check for other cardiac structural abnormalities that might be associated with CHB such as left atrial isomerism, valvular damages and big arteries inversion, while the echocardiogram is useful to detect other complications such as the hydrops fetalis. In the absence of cardiac structural diseases, the second step to confirm the diagnosis is to test the serum of the mother for anti Ro/La autoantibodies using the enzyme-linked immunosorbent assay (ELISA).In high risk pregnancies, the diagnosis is relatively easier as fetal and maternal screenings are part of the routine monitoring of the pregnancy.
The majority of CHB-related deaths occur in the first 3 months after birth followed by fetal death, and it is less common to occur after the third month of age.Mortality rate is very high when the disease is diagnosed prenatally, and declines dramatically with older diagnosis ages.Around 60% - 70% of the patients will need pace-maker implantation regardless of the age of diagnosis.The disease seems to affect both males and females equally.The survival rate is heavily affected by the associated diseases, and it is higher in autoimmune-mediated CHB patients compared to CHB patients with congenital cardiac structural problems.Recurrence rate: mothers who had pregnancies associated with CHB, have a 16 - 18% chance of having kids with heart block in the following pregnancy.A study in the United States showed that the vast majority of the affected mothers are of a Caucasian ethnicity, despite the fact that Systemic Lupus Erythematosus (SLE) is more common among minorities. == References ==