“Hole in the Heart”- Atrial and Ventricular Septal Defects:

A hole in the heart implies an abnormal connection between either the left and right atrium (atrial septal defect), or between the right and left ventricles (ventricular septal defect).

Atrial septal defect:
Before a baby is born, the lungs have no specific function, so the foetal circulation bypasses them by an open communication between the two atria. When the baby is born, certain physiological effects result in this open communication shutting. It appears commoner in the babies of diabetic mothers. If the communication persists after the birth, this is called an atrial septal defect. This can occur in different locations within the septum that separates both atria (sinus venosus, ostium primum, and septum secundum). These defects are often picked up routinely in young baby checks. Sometimes they are missed until later in childhood. The increased turbulence that these defects cause may result in an audible murmur.

Echocardiography is usually undertaken to detect this. Defects may be small or large. In many children, the smaller defects may spontaneously close overtime, but it is wise to monitor them to confirm this. Sometimes, the defects are not detected till adulthood, when a murmur is eventually heard or a patient may complain of shortness of breath or effort intolerance. In such cases, an echocardiogram can measure the degree of abnormal flow (referred to as a “shunt”). Large defects or those with a shunt ratio of 2:1 will need to be repaired. More recently, there is a tendency to intervene with less significant shunts (>1.5:1). Transoesophageal echocardiography (see under Cardiac Tests) is used to determine the suitability of defect closure using an umbrella device.

The advantage of this technique is that it obviates open heart surgery, and can be done via tubes and the folded umbrella being introduced via the veins in the leg. This is referred to as a “percutaneous technique” (i.e introduced through the skin and vein). If the defect is too close too other cardiac structures or there is not enough space around the defect, then open heart surgery maybe more appropriate.

The main worry with unrepaired defects is that eventually the right side of the heart enlarges due to the increased volume of recirculating blood. This can cause palpitations. Over a longer period of time the right heart pressures exceed that of the left heart, and results in blood bypassing the lungs leaving blood un-oxygenated and causing cyanosis (blue lips). At this stage the changes are irreversible.

Ventricular Septal Defect:
This occurs when one or more imperfections are present in the wall connecting the right and ventricles. In most cases this occurs from birth, but occasionally they can occur after a heart attack affects the wall of the ventricular septum, causing a hole to appear. In the defects present from birth, some of them will seal themselves off in later childhood.

Residual defects after that period tend to remain. Small defects may not necessarily need repairing, but at least should be monitored to avoid the same right heart pressure changes as described for atrial defects. Asymptomatic patients are monitored with echocardiography, and only repaired if the defect is large, or if the right heart starts to enlarge. Even un-repaired defects need yearly echocardiographic monitoring. Repairs usually involve open surgery, but increasingly catheter based techniques are being employed that obviate the need for major surgery.