MM: Mediastinum, Pericardial Effusion

• Pericardial effusion is an acute or chronic accumulation of fluid above 50mL within the pericardial space.
• Chemotherapy also can increase the risk of opportunistic viral or bacterial infections.
• Among patients with known cancer disease, pericardial effusion may arise from cancer treatment, most frequently radiation therapy.
• There is normally 10-50 mL of serous fluid in the pericardial cavity.
• Any disease that affects the pericardium or causes pericarditis can result in pericardial effusion.
• Some common conditions that can lead to pericardial effusion include infections, neoplasms, autoimmune diseases, radiation, and myocardial infarction.
• Acute pericarditis is often associated with viral infections or surgical procedures involving the heart, such as coronary interventions and pacemaker lead implants.
• Disease processes that increase capillary filtration or reduce lymph drainage can also lead to pericardial effusion.
• Hypotension is caused when the fluid in the pericardial cavity begins to compress the heart, reducing its capacity to expand between contractions, leading to a reduced stroke volume and blood pressure.
• Muffled heart sounds are caused by the fluid between the heart and the stethoscope.
• The needle may be inserted through the left 5th or 6th intercostal space near the sternum due to the cardiac notch in the left lung and the shallower notch in the left pleural sac, which exposes an area of the pericardium.
• Other fluids that can accumulate within the pericardial space include blood, air, and fluid from the pleural cavity.
• All three types of fluid buildup can progress to cardiac tamponade.
• The needle will pass through the structures of the body wall (skin, subcutaneous tissue/superficial fascia, deep fascia, anterior thoracic wall muscles, endothoracic fascia), fibrous pericardium, parietal layer of serous pericardium, and then into the pericardial space.
• Alternatively, a pericardiocentesis can be guided by ultrasound or CT imaging to define the needle path and display needle progress in real-time to ensure it only enters the pericardial cavity.
• A lead can be attached to the needle and the ECG detects when the needle touches the epicardium.
• Pericardial effusion is not guaranteed to progress into cardiac tamponade, nor is cardiac tamponade caused exclusively by pericardial effusion.
• A pericardiocentesis is a procedure that seeks to sample or drain fluid from the pericardial cavity, which is usually necessary to relieve cardiac tamponade.
• Jugular vein distention is caused by impaired blood flow through the heart and blood accumulates in the veins, resulting in visible distention, often first noticed in the neck and jugular veins.
• These symptoms, known as Beck’s Triad, indicate that the pericardial effusion has transitioned into cardiac tamponade.
• Around 2/3rds of pericarditis cases are considered idiopathic or attributed to viral infections.
• Most pericarditis cases are self-limiting with a relatively benign clinical course.
• Hemopericardium is an emergency due to the rapid progression to cardiac tamponade because of high pressure arterial blood entering the pericardial space.
• Plausible mechanisms linking cancer to the development of pericarditis include direct infiltration by malignant cancer cells from proximate structures, pericardial hemorrhage, or spread of cancer cells through the bloodstream.
• Other risk factors for pericarditis include recent cardiothoracic surgery, myocardial infarction, and bacterial infection (e.g., tuberculosis), as well as autoimmune disease and cancer (lung cancer most common; breast, ovary/prostate, gastric, kidney).
• Pericardial effusion can be caused by lung cancer and/or radiation therapy.
• The pericardium can adapt to a stretching load if it is applied slowly, but there is a limit to this stretching capacity because the fibrous pericardium will become stiff at higher volumes.
• Coronary artery rupture, aortic dissection, trauma, or anything that causes damage to the pericardium can result in hemopericardium, a condition where blood accumulates in the pericardial space.
• Pericardial effusion is a condition where fluid accumulates in the pericardial space.
• Cardiac tamponade is a (often lethal) situation where heart expansion, stroke volume, and blood flow through the heart is reduced or compromised by increased pericardial cavity pressure.
• When pressure inside the pericardial cavity increases, the pressure necessary to move blood into the heart must also increase, which results in a reduced cardiac output (the cardiac output curve shifts to the right).
• The word “tamponade” means “stoppage of blood flow.” Therefore, cardiac tamponade is the stoppage of blood flow through the heart.