History: Patient came at 12– 13 weeks ultrasound scan

Findings and Description:

●     Four-chamber view on fetal echocardiogram: Demonstrates a common atrioventricular (AV) valve with communication between both atria and ventricles, consistent with a complete AVSD.

●     Fetal heart enlargement (cardiomegaly) due to increased cardiac load.

(Color Doppler ultrasound will show: Shows abnormal flow across the AV valve, suggesting regurgitation.

M-mode Doppler: Detects fetal arrhythmia, most notably atrial flutter with atrial rates exceeding 300 beats per minute, and possible atrioventricular dissociation.)

Diagnosis:

Atrioventricular Septal Defect (AVSD) with Fetal Arrhythmia.

Differential Diagnosis:

1. Complete AVSD: Common AV valve with large defects in both atrial and ventricular septa, best assessed with fetal echocardiography.

2. Partial AVSD: A smaller atrial defect with a cleft in the mitral valve; less common in this presentation but should be considered.

3. Unbalanced AVSD: One ventricle is significantly smaller, leading to disproportionate blood flow, which may result in worsening fetal outcomes.

4. Congenital Heart Block: May occur in the setting of structural heart defects, especially when the fetal heart rhythm is irregular.

5. Fetal Atrial Flutter: Rapid atrial contractions detected on Doppler with slow ventricular response.

Discussion:

●     AVSD is a congenital heart defect often associated with chromosomal abnormalities like Down syndrome (Trisomy 21).

●     Fetal arrhythmias, such as atrial flutter or complete heart block, are significant complications, especially when associated with structural heart defects.

●     Ongoing fetal echocardiographic monitoring is essential to track the severity of the AVSD and arrhythmia progression.

●     Genetic counseling is recommended to discuss the potential for chromosomal abnormalities.

●     Prenatal interventions, including maternal administration of antiarrhythmic drugs (e.g., digoxin or sotalol), may be necessary if the arrhythmia is hemodynamically significant.

●     A multidisciplinary team approach, including pediatric cardiologists, neonatologists, and maternal-fetal specialists, is crucial for planning delivery and postnatal care.

Conclusions:

●     The fetus has a Complete AVSD with associated arrhythmia (likely atrial flutter or heart block).

●     Continued surveillance and potential pharmacologic treatment for arrhythmia are advised.

●     Delivery planning should include a center with neonatal cardiac surgery capabilities.