Type and significance of fetal arrhythmias

Fetal echocardiography was undertaken in 350 high risk pregnant females between 14 to 36 weeks of gestation at our institution. Significant fetal arrhythmias were diagnosed with the help of M-mode and pulsed Doppler echocardiography in 24 pregnant females. Three categories of arrhythmias were observed: (i) atrial or ventricular extrasystoles in 17, (ii) supraventricular tachycardia in 4, and (iii) congenital complete atrioventricular block in 3. The first category of arrhythmia was benign in 100 percent of cases with complete resolution before or just after birth. The second category was completely treatable with antiarrhythmic drugs given to the mother, thus preventing complications of heart failure and hydrops. In the third category, one fetus who had associated severe structural cardiac malformation, died in utero. The other two are doing well postnatally and are on medical follow up. Recognition of arrhythmias and appropriate prenatal treatment will prevent intrauterine death and also help avoid unnecessary operative or premature deliveries.