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A Dave Hanson, RN, MSN, CCRN, CNS, replies:
Despite advances with percutaneous catheter interventions, cardiac surgical procedures continue to be widely used as a definitive therapy for patients with significant coronary and valvular disease. Coronary artery bypass graft surgery is a well established treatment for myocardial revascularization and more than 300000 patients undergo this surgical procedure annually in the United States.1 Pericardial effusion can occur after open heart surgery and contributes to postoperative morbidity and mortality.2
Pathophysiology
The diagnosis of pericardial effusion is made by the presence of an abnormal amount and/or character of fluid in the pericardial space. The pericardial space normally contains 15 to 50 mL of fluid, which serves as lubrication for the visceral and parietal layers of the pericardium. This fluid is thought to originate from the visceral pericardium and is essentially an ultrafiltrate of plasma. Total protein levels are generally low; however, the concentration of albumin is increased in pericardial fluids owing to its low molecular weight.3
The cause of abnormal fluid production depends on the underlying etiology, but usually it is secondary to injury or insult to the pericardium (ie, pericarditis). Clinical manifestations of pericardial effusion are highly dependent upon the rate of accumulation of fluid in the pericardial sac. Rapid accumulation of pericardial fluid may cause elevated intrapericardial pressures with as little as 80 mL of fluid, while slowly progressing effusions can grow to 2 L without symptoms.
Pericardial effusions can be acute or chronic, and the time course of development has a great impact on the patient’s symptoms. Treatment varies, and is directed at both removal of the pericardial fluid and alleviation of the underlying cause, which usually is determined by a combination of fluid analysis and correlation with comorbid illnesses.4 Pericardial effusion can often be the cause of a number of distinct clinical syndromes and echocardiography can rapidly confirm the presence and hemodynamic impact of an effusion.
Detection of Pericardial Effusion in Cardiac Surgery
Typically, the occurrence of pericardial effusion shortly after cardiac surgery is clinically detected when a patient develops right and/or left sided heart failure, often accompanied by chest discomfort, a pericardial rub, fever, and an abnormally large increase in the number of white blood cells in the blood. This condition is often referred to as postpericardiotomy syndrome because of the buildup of excess fluid in-between the heart and the membrane surrounding the myocardium. This pathology occurs because of inflammation following coronary artery bypass surgery.
Treatment
The decision to drain a pericardial effusion must take into account not only the echocardiographic findings, but also the clinical presentation and the risk-benefit ratio of the procedure. The vast majority of patients recover from cardiac surgery without any symptoms (chest discomfort, pericardial rub, fever, and leukocytosis) of pericardial effusion and subsequently do not require diagnostic effort to confirm the presence of pericardial effusion. However, postoperative pericardial effusion is considerably more common than clinically apparent, and occurs in as many as 85% of patients. Although anti-inflammatory agents may be useful to facilitate resolution, postoperative pericardial effusion is usually transient and the clinical course benign.5
References
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