Congenital heart disease (or CHD) is a range of heart disorders, of varying degrees of severity, which are present at birth. CHD affects about eight in every one thousand live babies that are born and is caused by factors operating early in pregnancy. These factors include viral infections (e.g. Rubella), diabetes, maternal radiation and drugs (such as thalidomide, warfarin and phenytoin). CHD is also a feature of Downs syndrome (approximately 30% of sufferers have CHD) and other chromosomal defects. The 'diseases' include the 'hole in the heart' (septal defects), patent ductus arteriosus, pulmonary stenosis (valve narrowing), aortic stenosis and fallots tetralogy.
             In the developing embryo, two endothelial tubes run in the belly and fuse in the neck region to form the single heart tube. Venous inflow and arterial outflow are at the caudal (tail) and cephalic (head) ends of the heart tube, respectively. The tube is divided into five segments: sinus venosus, atrium, ventricular inlet component, ventricular outlet component and arterial segment. During the fourth week of gestation, complex looping of the heart tube provides the basis of adult cardiac structure, with the ventricle lying beneath the atrium. The four-chambered structure requires separation of the atrial and ventricular components (and also the division of the arterial segment into the aorta and pulmonary artery). These separations occur during the fifth and sixth weeks of gestation and it is this process which is most prone to erroneous development. By the end of the eighth week, cardiovascular development is complete and no further changes take place until birth.
             CHD offers many clinical manifestations, heart failure being the most obvious. If this occurs in the neonatal period/ first month of independent life, it presents a medical emergency and may be caused by almost any major cardiac defect. In the preterm baby, heart failure is usually the result of a persisten...