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Pericardial Diseases

Pericardial Disease

The Pericardium

First, we draw the heart and great vessels in context with the diaphragm and lungs.

The fibrous pericardium forms a loose "bag" around the heart; it is attached to the central tendon of the diaphragm.

The serous pericardium comprises two layers and a space: – The parietal layer lines the fibrous pericardium. – The visceral layer, which is the outer covering of the heart; thus, the visceral layer of the pericardium is the epicardium of the heart.

The pericardial cavity is between the parietal and visceral layers; this small space typically contains less than 50 mL of fluid, which allows for free movement of the heart.

The pericardium has a limited ability to respond to injury, which is often key to its pathology: – In response to injury, the pericardium increases fluid production; this fluid can contain fibrin and inflammatory cells. – The pericardium can distend to hold this fluid, but only up to a point.

Pericarditis - Inflammation

The most common pericardial disease, and, it can lead to others. Pericarditis is inflammation ('itis') of the pericardium.

Signs & Symptoms

Sharp chest pain, which may radiate to the shoulder. Pain is often relieved upon sitting up or leaning forward. Pericardial friction rub, which is often characterized as a squeaking or scratching sound. Elevated biomarkers: white blood cells, erythrocyte sedimentation rate (ESR), C-reactive protein, and, in some cases, cardiac troponin.

ECG changes in 4 stages ECG Can help distinguish pericarditis from myocardial infarction.

Stage I: Diffuse concave ST-segment elevation and PR-segment depression, which can be seen in most leads (all except for aVR). Recall that, in myocardial infarction, the ST segments are typically convex and not diffuse.

Stage II: Normalization of the ST and PR segments, and flattened T-waves.

Stage III: Inverted T-waves.

Stage IV: T-waves either normalize or persist as inverted waves.

Treatment Aspirin, NSAIDs, and NSAIDs; corticosteroids may be considered if these drugs fail.

Causes of Pericarditis Many cases are idiopathic. Causes of pericarditis vary by population. For example, in richer countries, viral and post-surgical causes prevail; in poorer countries, tuberculosis is a significant cause of pericarditis. Some causes are associated specific types of pericarditis; for example, some bacteria can cause purulent pericarditis.

Pathogens, especially HIV, Coxsackie virus, Streptococcus, Staphylococcus, and Tuberculosis, can cause pericarditis. It is thought that many idiopathic cases are caused by viruses.

Metabolic disorders, such as occurs in kidney failure (uremic pericarditis)

Autoimmune disorders, particularly Rheumatoid Arthritis and Systemic Lupus Erythematosus

Cancers, especially of the breast or lung, and Hodgkin lymphoma

Drugs, including penicillin and some anticoagulants

Myocardial infarction

Cardiac surgery or trauma

Radiation therapy

Constrictive pericarditis can occur when chronic inflammation leads to fibrosis or calcification of the pericardium. – This produces a tough, inelastic shell around the heart that impairs diastolic filling. – Impaired diastolic filling can lead to peripheral venous congestion and Kussmaul's sign.

Kussmaul's sign is characterized by increased jugular venous pressure during inspiration.

Pericardial Effusion - Fluid accumulation

Fluid accumulation (in some cases, 100s of mL) in the pericardial cavity.

Causes of pericardial effusion are similar to, and include, pericarditis. Recall that increased fluid production is one way that the pericardium responds to injury.

Hemorrhagic effusions can also occur, and tend to result from trauma, myocardial infarctions, and vessel rupture.

Diagnosis often entails echocardiogram, CT, or MRI, which allows us to see the quantity and location of excess pericardial fluid.

If pericardial effusion occurs in the absence of pericarditis, the patient may not experience any symptoms. Pericardial friction rub may be heard (but not necessarily).

ECG changes include tachycardia, electrical alternans, and low QRS voltage.

Cardiac Tamponade - Fluid from effusion impedes filling

Also called pericardial tamponade

Occurs when the pressure from the pericardial effusion impedes filling. – Recall that the pericardium can distend to hold excess fluid only up to a point; cardiac tamponade occurs when the elastic limit of the pericardium is surpassed, and the accumulating pericardial fluid exerts pressure on the heart.

Most likely to occur when fluid accumulates rapidly, but can also occur when a large volume of fluid accumulates over time.

When the pressures on the heart that impede filling are too high, cardiac tamponade can lead to shock.

Key clinical indications:

Key clinical indications to look out include Beck's Triad and pulsus paradox. Beck's triad includes hypotension, distension of the jugular neck veins, and distant or muffled heart sounds. Pulsus paradoxus is characterized by a 10 mmHg or more drop in arterial blood pressure upon inspiration.

Treatment: Drainage of the excess fluid from the pericardial cavity.

For references, see Pericardial Diseases tutorial.

Pericardial Diseases

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