Heart and lungs

Although the heart and lungs are separate organs, they are intimately linked; they are packed neatly together within the chest, and interact functionally together to pump the oxygen supply around the body.

Key points

• 1 in 1,000 babies have a slow pulse (heart block)

• Heart murmurs occur in some patients

• 'Sticky blood' can cause lung clots

• Pericarditis and pleurisy respond to treatment

Structure of the heart

The heart is a muscular pump. It has three main layers: an outer sausage skin (the pericardium), the muscle layer (the myocardium) and the inside lining, including the valves (the endocardium). All three layers can be attacked by lupus.

An active muscular organ such as the heart depends critically on a good blood supply. This is provided by the coronary arteries. It is here that things can go dramatically awry: the three main branches of the coronary artery can become blocked or cut off. This can give rise to chest pain (ie, angina) or, worse, a more severe blockage leading to a heart attack (ie, a lack of oxygen to a portion of the heart muscle).

Coronary artery disease and heart attacks are among the epidemics of western society and lupus patients, unfortunately, are particularly at risk.

Pericarditis

Inflammation of the surrounding of the heart (pericarditis) is a common feature of lupus, particularly in the early acute stage or in a flare-up.

The classical symptom is chest pain - often sharp and situated in the centre of the chest. Sometimes it is worse in certain positions. The pain is usually different from the crushing pain of angina, but not always so.

Associated with the chest pain is shortness of breath. When the double sausage skin of the pericardium is inflamed, the usual smooth surfaces become roughened and rub together. Often, doctors can hear this rub through the stethoscope as a characteristic scratching noise with each heart beat. The inflammation then creates fluid (as it does in the skin with a blister) and this fluid can accumulate between the two layers of the pericardium - this is known as a pericardial effusion. In extreme cases, this fluid accumulation can impair the heart beat and lead to extreme distress, shortness of breath, and pump failure with accumulation of fluid throughout the body.

Heart muscle

Fortunately, a direct attack on the heart muscle in lupus is unusual. A more common, and an important problem, is coronary artery thrombosis and furring (atheroma). Now that survival in lupus is hugely improved, with patients leading full lives and having normal life spans, a new problem has been recognised. A second disease peak has been picked up in lupus patients in their 40s and 50s - blood vessel problems, notably heart attack and stroke.

The cause of this increased propensity to atheroma and heart attack in some patients is now the focus of intensive study, but the solution remains elusive. The usual suspects include prolonged steroid use, kidney disease and raised blood pressure, but in reality none of these fully explains the phenomenon.

One suspect is sticky blood due to Hughes syndrome (also called antiphospholipid syndrome). Studies have shown a tendency in some Hughes syndrome patients to develop constrictions, or stenosis, of certain arteries including the coronary arteries.

Logically therefore, the appropriate use of low dose aspirin (as well as good control of cholesterol) may reduce the risk of later artery clots and heart attacks.

The valves

It has been known for many decades that the heart valves can be affected in a small number of patients with lupus. Indeed, the unusual condition of heart valve thickening with blood clots on their surfaces is widely known as Libman-Sacks endocarditis.

Recently, however, with the discovery of the antiphospholipid syndrome, it appears likely that valve problems in lupus are more closely linked to this condition.

The main symptom of heart valve involvement is shortness of breath. The 'whooshing' noise made by a leaky heart valve can usually be heard through a stethoscope, though more detailed heart tests are needed to determine the size of the leak.

Benign murmurs, requiring no specific therapy, are common - not only in lupus but also in the population at large. Severe valve disease requiring surgery is rare.

Congenital heart block

A rare heart defect, congenital heart block, has been noted in I in 1,000 infants born of lupus (and Sjögren's syndrome) mothers.

This defect in the heart's conduction tissue results in a slow pulse rate (around 40 per minute) in the offspring. It is a serious manifestation and more often than not requires the insertion of a pacemaker into the young infant's heart.

The condition is limited to children of mothers carrying the antibody called anti-Ro and is thought to be due to the mother's antibody crossing the placenta and reacting with the fetus' heart conduction tissue.

Pleurisy

One of the most common manifestations of active lupus is pleurisy which is due to inflammation of the lining of the lungs. Like the heart, the lungs are surrounded by two thin 'sausage skin' layers called the pleura. These normally move together painlessly during breathing. When the pleura become inflamed, they become roughened, stick together, and cause pain on inspiration (breathing in). This rubbing together can sometimes be heard as a pleural rub through the stethoscope.

Lung clots

One of the serious complications of a blood clot (eg, a deep vein thrombosis in the leg or pelvis) is a pulmonary embolus, that is, a broken-off piece of clot travelling to the lung. This is usually a dramatic and life threatening event, associated with chest pain and collapse. However, in some cases (notably again in those patients with Hughes syndrome and its clotting tendency), the lung clots may go relatively unnoticed. An untreated build up of lung clots over a period of months and years is one of the causes of the serious medical condition known as pulmonary hypertension.

Pulmonary hypertension

Hypertension means raised blood pressure. In pulmonary hypertension the pressure is on the right side of the heart, the side which pumps blood around the lungs. The main clinical effect of pressure build-up is shortness of breath. This serious condition, measured by a series of cardiology tests, was once considered untreatable. Now, however, there is more optimism with a group of exciting new medications coming on stream.

Pulmonary fibrosis

Another cause of shortness of breath, though completely distinct from the clotting conditions described above, is pulmonary fibrosis.

In this condition, the normally soft, delicate lung tissue becomes scarred. I liken it to the effect you get when you lick freshly spun candy floss - the edges become stuck together and less mobile.

Pulmonary fibrosis has many causes, and is seen as an unusual complication in a number of diseases including rheumatoid arthritis. It is, in fact, very unusual in lupus.

Infection

No account of the lung in lupus would be complete without mentioning infection of the chest. Individuals with impaired immune defences or those on strong immunosuppressive drugs are more prone to infection. These infections include tuberculosis, an infection once again on the increase. In any patient with unexplained recurrent cough or chest problems, the doctor should be on the alert for a lurking infection.