Congenital Heart Diseases

No sysle~natic surveys hiive been conducted to estimate the incidence of CHD at birth in India and other developing countries. As a result there really is no iformation available about the CHD incidence at birth in India.There are examples 01 studies that have surveyed school going children for CHD.School survey data fro111 the Amrita lnstitutc of Medical Sciences suggest a CHD prevalence of 2 per 1000. Clearly such studies cannot be use to determine the magnititude of CHD in the population because it does not account for the very high attrition of CHD.

Extrapolation of data from develope countries may give us a rough estimate of CHD prevalellce at birth. Using slatislics from the developed nations. It call be estinlated that betwecn 130,000 to 270,000 children are born with CllD each year in India. Approximately 80,000 newborns with CHD would require intervention during the neonatal period or illfancy each year. Between 3-10 per cent of the present inljnt mortality [nay be accounted Ibr by CHD.

Ventricular Septal Defect

Venlriculnr septum anatomy - Anatonmical
location af
various VSD's

Indications for Surgery

Some VSDs close spontaneously or become smaller in size. This has to be taken into consideration before surgery is advised. Spontruleous closure can be complete by one year of age or the defece nrmowed considerably. There is an inverse relationship between the probability of closure and age at which the patient is seen. SO per cent of patients with la-ge VSD seen at one month of age ]nay close spontaneo'usly. 60 per cent of those seen at three months and 50 per cent seen at six l~lonrPls and 25 per cent of those presenting at 12 months.

A luge VSD will have a diameter equal to aorta and a moderate one about 50 per cent a10 a small one Iess than one third of its diarneler. When infants with large VSDs have severe and intractable heart failure or respiratory syrnptonls during the first three months. prompt zlosure is advised. Most often these babies have other a..sociattd cardiac anomalies eha~ are also col~ected. Operation is not advised in the first three months, if the syn~ptoms: are not serious, as spontaneous closure may occur. 111 ini'ants older than three months significant growth failure and increase in for surgery. AII in1;~fllt presenting st pulmonary vascular resistance alc i~ldicatio~ls six months with severe synlptoins and a pulrnonary'vasculru- resistance index of 4-8 Wood units/m2 needs early repair. 3n children having pulmonary resistance (Rp) less ttlnn 4 unitslnl' surgery could be postponed up to one year. There is no
advantage in waiting fulrher as 11le results of surgery at one year is as good as at a later stage in experienced centers.

Pulmonary Artery Banding

Banding of pulmonary trunk is done to reduce pulmonary flow in a baby. It is seldom done for isolated ventricular septa] defect. MultipIe muscular ventricular septal defects (Swiss cheese defects) are difficult to close in infancy and so pulmonay artery banding may treat thern. It is also the procedure of choice for tricuspid atresia with VSD and other types of univentricular hearts without pulmonary stenosis. Pulmonary artery banding is done with a view to Fonton type of correction at a later stage.

Technique

The operation may be performed through a small left anterollitera1 #horacotomy or median sternotomy. The latter approach is preferable. Pe~icslrdiiim is opened and aorta and pulmonary trunk are dissected and a right-angled clamp passed around it.A 3 to 4 mrn wide polyester tape impregnated with silicon is used for banding. The tightness of bmcl depends on the circumference of the band applied. According to Tnrsler's formula, the circumferential length of the band is 20 nun + weight of the baby in kilograms (taken as millimeters). For a complex cardiac rmomaly like univentricular heart the measurement is 24mnt + weight of the baby in Kg (taken as millimeters). While tightening the band, aortic pressure and lel't p~~l~nonary artery pressures are monitored. Properly banded, the pulmonary artery pressure should fall to less than 50 per cent of aortic pressure. Systemic arterial oxygen saturation (SAO,) should be maintained at 80-85 per cenl. Haernoclips are applied to tighten the b&d to the correct level. Haernoclips are useful as they can be removed and re-applied at the desired levels. After banding, the bnnd is anchored at two places by prolene sutr~res to the adventitia of the pulmonary artery.

Results

Results of surgery for ventricular septa1 defects are excellent. Though the mortality is not 0 per cent, in a Iarge series it was 1.3 per cent. Complications like complete heart block and recurrent ventricular septa1 defect have become extremely rare (less than one per cent).