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For a perspective: When excess fluid collects in the sac (pericardium) surrounding the heart, doctors refer to this as pericardial effusion. It may be caused by inflammation of the pericardium (pericarditits). Signs and symptoms of pericardial effusion may include:
Fluid retention (edema)
...LOW BLOOD PRESSURE... High pb is not a factor, but that doesn't rule out the medical condition, shortness of breath, dizziness or fainting, chest pain, cough, fast heart rate or heart palpitations. Sore back and legs are not symptomatic of pericardial effusion (may be a different issue). Without the symptoms listed, the condition may not be serious!
Causes of pericardial effusion include:
Infection, inflammatory disorder such as lupus, etc. does not include flu like symptoms. So it is likely fluids accumulated slowly, and the pericardium (sac surrounding the heart) may have and is stretched enough to accommodate it without symptoms and the signs and symptoms may not occurred until a large amount of fluid collects over time. But a rapid fluid accumulation...even if the fluid amount is relatively small...can severely impair the function of the heart. Cardiac symptoms occurs when the pericardial effusion compresses the heart and prevents effective pumping of blood to the body. This can be life-threatening.
Has the doctor may confirmed a diagnosis by an echo? CT or MRI scan?