Notes
Pericardial Disease
Sections
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
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.
Clinical Cases
Case 1: Cardiac Tamponade
A 78-year-old male presents to the emergency department via ambulance. He is a resident at a long-term acute care (LTAC) facility, and was diagnosed six months ago with metastatic small cell lung cancer likely secondary to a 60 pack-year history of smoking. Paramedics report they were called because the patient developed hypotension earlier this afternoon, and staff at the facility were concerned because he was "very dehydrated" and had not eaten breakfast or lunch. There was reportedly no don't resuscitate and/or do not intubate (DNR/DNI) orders on file. Intravenous (IV) access was established enroute to the hospital and the patient has thus far received approximately 200 ml of normal saline.
On arrival, his blood pressure is 70/55 mm Hg, heart rate is 110/min, respiratory rate is 20/min, and his oxygen saturation is 88 percent on 2L of oxygen. Physical examination demonstrates dilated and bulging jugular veins bilaterally, muffled and distant heart sounds, and poor inspiratory and expiratory effort. Decreased breath sounds were noted in the right upper lobe. You order a STAT chest x-ray, which shows a large cardiac silhouette and electrocardiogram (EKG), which shows electrical alternans.
Based on the information you have at this point in time, what is the most appropriate next step?
Answer
- Pericardiocentesis
Explanation
This patient has cardiac tamponade secondary to a large pericardial effusion. Beck's Triad is the hallmark of cardiac tamponade and consists of low blood pressure (hypotension), bulging neck veins, and distant or "muffled" heart sounds. Additionally, a large cardiac silhouette may be seen on chest x-ray (CXR), as in this scenario. A right upper lobe mass (likely small cell carcinoma) is also seen on his CXR.
Echocardiographic assessment (echocardiogram) is the diagnostic treatment of choice. Electrical alternans (beat-to-beat variation in the amplitude of the P and R waves unrelated to the respiratory cycles) is a classic but uncommon finding on EKG (see image below). Pulsus paradoxus (a fall in systolic blood pressure greater than 10 mm Hg during the inspiratory phase of respiration) is also seen with cardiac tamponade.
Pericardiocentesis is a procedure performed to remove fluid that has built up in the heart sac (pericardium). It is indicated, as in this scenario, when the pericardial effusion is large enough to cause cardiac tamponade and hemodynamic instability. Ideally, the procedure is performed using ultrasound or fluoroscopy to prevent complications such as laceration of a coronary artery or vein, though it may be performed at the bedside under life-threatening conditions.
Board Review
Pericardial Disease
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USMLE & COMLEX-USA
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References
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