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.

Fetal echocardiography--norms for M-mode measurements.

M-mode echocardiography was performed in 110 normal fetuses to study the norms for various cardiac parameters at varying gestational ages. The measurements were done in normal pregnancies with gestation varying from 14-38 weeks. The parameters studied were aortic root diameter, left atrial and right ventricular outflow tract dimensions, left and right ventricular cavity dimensions, and left ventricular, septal and right ventricular wall thickness. The values were analysed statistically by linear regression analysis and 95 per cent confidence limits were derived. It was found that values for right and left ventricles increased with gestation such that at term both ventricles were equal in size. The aorta and left atrium also increased with increasing gestation but the value for left atrium increased more than that of aorta giving increased left atrium to aorta ratio. These values could be utilised as norms for Indian fetuses and could help in detecting abnormalities of size.