Today's Veterinary Practice

SEP-OCT 2015

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tvpjournal.com | September/October 2015 | TOday'S VeTerinary PracTice TOday'S TecHnician Peer reviewed 69 Pericardial effusion is considered a cardiac emergency situation that is most commonly seen in canine patients. it is very important, especially for veterinary technicians in emergency care facilities, to be able to recognize the signs of pericardial effusion and quickly respond. PATHOPHYSIOLOGY The normal pericardium has an outer fbrous pericardium and inner serous pericardium, which consists of a parietal and visceral layer (Figure 1). The pericardial cavity—the area between these 2 layers of the serous pericardium—normally contains 1 to 15 mL of a plasma ultrafltrate. 1 even though animals can survive and function normally without an intact pericardium, the pericardium serves many important purposes. The pericardium: • Structurally supports the heart in the thorax, preventing excessive motion of the heart • Protects the heart from neoplasia and infections. Pericardial Effusion excessive fuid in the pericardial space is called pericardial effusion. When effusion accumulates slowly, the pericardium can enlarge to accommodate this increase in volume and, if intrapericardial pressure is low, clinical signs may not be present and cardiac function remains relatively normal. When effusion accumulates quickly or intrapericardial pressure rises quickly, intrapericardial pressure surpasses the normal diastolic pressure in the right ventricle and cardiac tamponade occurs. 2 Pericardial effusions of large volumes can also compress the lungs and trachea, causing respiratory diffculties and coughing. When the esophagus is compressed by excess fuid buildup, dysphagia or regurgitation may occur. 3 Cardiac Tamponade Cardiac tamponade results in a decrease in venous return, stroke volume, cardiac output, and ventricular flling. Therefore: • The body tries to compensate by increasing heart rate and peripheral vascular resistance to help maintain normal blood pressure. • as intrapericardial pressure continues to rise, it causes collapse of the right side of the heart, preventing cardiac output into the pulmonary artery. • Since blood is no longer leaving the right side of the heart, there is no venous return to the left atrium and ventricle, 2 eventually resulting in cardiogenic shock manifested by lethargy, hypotension, poor pulse quality, and tachycardia. CAUSES Congenital Causes congenital causes of pericardial effusion may include: 1 • Peritoneopericardial diaphragmatic hernia: a condition in which the septum transversum fuses with the pleuroperitoneal folds, creating an incomplete separation of the abdominal and thoracic cavities and usually resulting in a small amount of fluid accumulation. However, gastrointestinal signs are more commonly noted due to the presence of abdominal organs within the pericardial cavity. • Pericardial cysts: another congenital cause of pericardial effusion, but they are much rarer and often asymptomatic. Acquired Causes an acquired cause of pericardial effusion is pericarditis, which stems from neoplastic, immune, infammatory, and, occasionally, infectious disease processes. • neoplastic processes are the most common cause of pericardial effusion and cardiac tamponade: » Hemangiosarcoma is commonly found in responding to a cardiac emergency: Pericardial effusion in canine Patients Oriana D. Scislowicz, BS, LVT CVCA - Cardiac Care for Pets, Richmond, Virginia FIGURE 1. Diagram depicting relationship between the pericardium and heart.

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