Pericarditis

The normal pericardium

This contains about 50ml of fluid, and help lubricate the movement of the heart. It helps to:

-          Limit distension of the heart

-          Protect the heart from infection / damage

-          Aids the filling of the ventricles

However – congenital defects of the pericardium do not appear to have much impact on heart function.

Acute Pericarditis

Causes

-          Infection (most commonly viral, but often not identified). The most common causatory factors are coxsackie B virusand echovirus.

-          Acute MI – post MI pericarditis occurs in about 20% of MI patients. It occurs most commonly withanterior MI’s and MI’s with massive ST elevation.

o   The incidence is actually reduced by 5-6% with thrombolysis

o   It can be difficult to differentiate this pain from angina pain within the first couple of days after an MI

o   Dressler’s syndrome is pericarditis that occurs secondary to myocardial or pericardial damage, and occurs at least 2 weeks after the MI. this makes it different from the normal post MI pericarditis described above. Dressler’s occurs in about 7% of MI patients.The symptoms can arise anywhere between a few weeks and 2 years after an MI, and will usually subside within a few days. Typical time of onset is 1 to 4 weeks after the MI.

§    It is an auto-immune condition whereby the body auto-reacts against damaged myocardial tissue. Antimyocardial antibodies are often found.

§    Recurrence is common

§    May also occur after episodes of unstable angina

§    Presents with massively raised ESR

-          Less common causes

o   Autoimmune reaction

o   Trauma

o   Neoplasm

o   Idiopathic

o   Bacterial infection

o   TB

o   Rheumatic fever

o   HIV – these patient may get staphylococcal pericarditis – which is often fatal

-          Pericarditis and myocarditis often co-exist

Signs/Symptoms

-          Sharp pain – this can vary in site and severity, however is usually retrosternal. It often radiates to the shoulders and neck, and is aggravated by deep breathing (pleuritic), movement, change of position, exercise and swallowing.

o   The pain is typically relieved by leaning forwards

o   The differentials for this type of pain are basically pleurisy and pericarditis

-          Fever – a low grade fever may be present

-          Pericrdial effusion – this is present whatever the cause. However, it can be a result of different factors (depening on the cause); e.g. serous, purulent, haemorrhagic, fibrinous

o   Fibrinous exudates – can eventually lead to adhesion

o   Serous – this produces a large amount of straw-coloured fluid, with a very high protein content

o   Haemorrhagic – usually due to malignant disease, most commonly carcinoma of the breast, bronchus, and lymphoma.

o   Purulent – this is rare, and may be a complication of septicaemia.

o   Pericardial effusion may press on the surrounding tissues, particularly the bronchi, resulting in dyspnoea

-          Pericardial friction rub – this is a high pitched superficial scratching or crunching sound, that is produced by movement of the pericardium. It is diagnostic for pericarditis. Usually heard in systolebut may also be heard in diastole.

o   It is classically heard in three, or two (‘to and fro’ rub) phases – i.e. this menas it is heard 3 times or twice during one cardiac cycle

o   The rubs are typically heard best with the diaphragm at the left lower sternal edge at full expiration

Investigations

-          ECG – this will show widespread saddle shaped ST elevation. There may also be PR interval depression – and if both of these are present it is pretty much diagnostic for pericarditis

o   Later there may also be T wave inversion – especially if myocarditis is also present. This will eventually resolve

o   The ST elevation is often distributed in both inferior and anterior leads – thus this helps to distinguish it from MI

-          FBC – there may be leukocytosis or lymphocytosis due to viral or bacterial infection

-          CXR, echo, radionucleotide scans – these are all of little use in uncomplicated disease

Treatment

-          Treat the underlying cause!

-          Bed-rest and oral NSAID’s. however – do not use NSAID’s in the first few days after MI – as they associated with increased risk of myocardial rupture.

-          Corticosteroids may be given as symptomatic relief, but there is no evidence that they increase the speed of cure

Complications

-          If pericarditis lasts more than 6-12 months, then chronic pericarditis is said to exist. In these cases, it is possible for the pericardium to thicken, and this can restrict ventricular filling, and then restrictive pericarditis is present