Congenital heart disease

In the case of children, most heart problems are congenital-that is, they are problems the child is born with, as opposed to problems that arise from lifestyle or later activities. Congenital heart problems usually stem from abnormalities or defects in the structure of the heart. In such cases, the heart will not have formed properly. (Another term for a congenital heart defect is a 'lesion.') Some defects require treatment, while others will lessen in severity as the child grows and may not have to be treated.

Some pediatric cardiac surgical procedures can produce as close to a normal heart as is possible (for example, repairs of atrial or ventricular septal defects). Other operations cannot make the heart normal. The most that cardiac surgery can do for children with some congenital heart defects or lesions is to correct the blood circulation to ensure that most of the 'blue blood' (deoxygenated blood) goes to the lungs and most of the 'red blood' (oxygenated blood) goes to the body. However, the heart's structure post-operatively can be far from normal. Therefore, while corrective heart surgery can allow for a significant improvement in lifestyle, it is not always usually curative in the sense of making the heart normal.

Ventricular failure

One of the main threats that children with these heart defects face is from heart failure. Heart failure occurs when the pumping capability of the heart is impaired and the ventricles are unable to pump an adequate volume of blood to the body and/or the lungs. This can affect either the left ventricle or the right ventricle or both (as in biventricular failure).

Left ventricular failure

With left-sided heart failure, blood backs up in the left ventricle and then progressively into the left atrium and into the lungs. Fluid will then build up in the lungs, making it more difficult for the blood to pick up oxygen. The patient will often be short of breath and breathe rapidly but shallowly, and may cough. Also, because the left ventricle is not pumping enough oxygenated blood out to the body, the skin may be cool and appear bluish, and pulses will feel weak. There may be insufficient blood flow and oxygen delivery to the organs, which may also start to fail. For example, the kidneys may start to produce less urine and the patient may retain fluid and appear to gain weight.

Right ventricular failure

With right-sided heart failure, fluid builds up in the right ventricle, and then backs up into the right atrium and into the great veins (the IVC and the SVC). This leads to swelling, which may be seen in the ankles and across the backs of the hands and feet. The liver also often becomes swollen and enlarges so that it can be felt below the ribs of the right side of the chest.

Biventricular failure

Sometimes left-sided heart failure can lead to failure of the right side of the heart, as blood backs up through the lungs and into the right side of the heart. This places a strain on the right heart, which may then also fail.

Shunting

Shunting is the term applied when blood from the left and right sides of the circulation becomes mixed. The site at which shunting occurs and the amount of mixing will determine how much oxygenated blood is supplied to the tissues of the body. Normally, shunting is primarily from the side with the higher pressure to the side with the lower pressure: that is, from left to right. This may lead to changes in the right side, which then develops an increase in resistance to flow. The result is that the pressures on the left and right sides then become equal. This situation may become irreversible, preventing surgical corrections from being successfully undertaken.