Pulmonary Hypertension

Pulmonary hypertension is one of the results that may occur because of extra blood being pumped through the lungs and at an excessive pressure. This may occur when the normal separation between the right sided (lung) and left sided (body) circulation is incomplete, as when there is a hole or holes in the central wall of the heart (VSD), or when there is a connection between the aorta and the pulmonary artery (PDA). Pulmonary hypertension may also occur in many other conditions, for example if there is obstruction to the blood flow coming back to the heart from the lungs, or if there is upper airway obstruction.

Description

In the normal heart the right side pumps blood to the lungs, which is a relatively easy task, whilst the left side has the more difficult job of pumping blood all around the body. As a result the pressure in the left ventricle (pumping chamber) is generally about four times that in the right ventricle, and the wall of the left ventricle is thicker than that of the right.

Many defects that involve holes in the septum (central heart wall) allow blood to flow (shunt) from the high pressure left side of the heart to the lower pressure right side. This results in an increase in the pressure on the right, and causes too much blood to be pumped to the lungs. The body's natural reaction to this, is to constrict (narrow) the blood vessels in the lungs in an effort to limit this excess blood flow.

Over a period of time, this narrowing of the pulmonary (lung) arteries increases due to thickening in the surrounding muscle due to the increased workload, and also the closure of smaller lung arteries. These changes reduce the blood flow into the lungs, and increase the pressure needed by the right ventricle to pump blood into the lungs to be oxygenated.

As the resistance to flow increases, there is less left to right shunting (blood flow) within the heart, and eventually the pressure is such that the shunt is reversed, i.e.. right to left shunting occurs. This process is called Pulmonary Vascular Disease, and ultimately results in low oxygen levels and therefore cyanosis (blueness) and increased haemoglobin levels in the blood of the patient.

It is the damage caused by prolonged pulmonary hypertension that generally prohibits late repair of cardiac defects. As patients with Down's Syndrome have a propensity to develop Pulmonary Vascular Disease due to the fact that they tend to have larger holes in the heart and smaller airways, surgical repair is generally carried out fairly early in life, although timing will vary depending on the exact heart defect.

Special attention should be paid to treating obstructed breathing (e.g. inhalations, nose drops, antibiotics, ENT surgeon), as long term obstruction may aggravate the condition.

The rate of development of pulmonary vascular disease depends on the nature and size of the defect, but varies greatly from patient to patient, even between those with the same cardiac problem. Routine checks that the patient has at clinic appointments, such as echocardiograms, help the cardiologist to monitor the patient's pulmonary artery pressure.

Treatment

Successful surgery will usually prevent the continuance of pulmonary hypertension, and the development of Pulmonary Vascular Disease. This is usually performed before 6 months of age.

In a young child with abnormally elevated pressure in the pulmonary artery due to a left to right shunt, corrective surgery is rarely considered too dangerous, but pulmonary artery banding (pa banding / banding) may be effective. This procedure requires the surgeon to place a restrictive band around the artery, thus reducing the blood flow into the lungs, and preventing the need for the body to form its own restriction. If successful, the development of pulmonary vascular disease may be slowed or stopped, and surgical repair of the hole(s) may be possible at a later date.

In cases where banding is not successful or inappropriate, treatment includes the use of oxygen and certain medication which relax the pulmonary vessels and increase the blood flow into the lungs. There are some new drugs being tried which may prove effective at reducing the pulmonary artery pressure.

Follow Up Advice

Most patients with a cardiac defect, whether repaired or not, will require antibiotic cover during any dental treatment to prevent any bacteria entering the blood stream from where they can reach the heart causing bacterial endocarditis (infection of the heart lining), which can be very serious. It is best, therefore, to encourage good dental care and avoid too many sweet drinks etc. while the child is young.

"The doctor explained that my baby had pulmonary hypertension and that if the pressure is very high, like my daughter's, it is too dangerous to operate. I'd met a couple of other mothers whose babies had had surgery and were doing well, and one whose son was older and hadn't had an operation. He wasn't too well, and I'd already decided to go ahead with surgery to give my baby a chance - now I was being told she couldn't have it done. Then the doctor told me about an operation to put a band around the lung artery, which would protect her lungs from damage and hopefully give her the chance for surgery later on. She had the banding done at four weeks, and it worked. When she was ten months, her pulmonary pressure had reduced and she had a complete repair and she's doing well now. I still don't understand why her pressures were so high so soon, but at least they were able to do something about it.".