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Basics ⬇

Basics

Overview

  • Pericardial disease accounts for about 5% of cardiovascular disease in dogs (far less in cats), but it is a common cause of emergency presentation, since dogs with pericardial disease often experience serious clinical signs. Clinical signs of pericardial disease are usually caused by cardiac tamponade, which occurs when fluid accumulates in the pericardial space fast enough to increase the intrapericardial pressure above the central venous pressure during part of the respiratory cycle. If the intrapericardial pressure exceeds the central venous pressure continuously for more than a few minutes, death occurs. Pericardial constriction (elevated intrapericardial pressure in the absence of significant effusion) is fortunately rare in both dogs and cats, and occurs most often as a long-term complication of infectious or effusive pericarditis.
  • Clinical signs of pericardial disease generally depend on the severity of tamponade (or rarely, constriction), and are independent of the underlying disease (i.e., inflammatory pericardial diseases (pericarditis) cannot usually be distinguished from neoplastic pericardial diseases based on the clinical signs they produce).

Signalment

  • Idiopathic hemorrhagic pericarditis is more common in young to middle-aged, largebreed dogs (e.g., Great Pyrenees, Great Dane, Saint Bernard, golden retriever).
  • Infectious pericarditis is relatively rare, but it occurs most often in young, active dogs (occasionally cats), associated with a penetrating injury (e.g., twig, plant awn).
  • Pericarditis is rare as an important cause of clinical signs in cats, but the most common cause is feline infectious peritonitis (FIP), which has a “dual peak” age incidence in young and old cats.
  • Small amounts of pericardial effusion in the absence of cardiac tamponade occur commonly in cats with hypertrophic cardiomyopathy, most often with other signs of heart failure-this should not be confused with pericarditis.

Signs

  • Cats-clinical signs are rare, but similar to dogs when they occur.
  • Dogs-clinical signs are caused by tamponade, and include signs of low cardiac output (e.g., collapse, weakness, anorexia, prerenal azotemia) as well as those caused by high central venous pressure (e.g., ascites). Diminished arterial pulse strength with noticeable weakening of the pulse on inspiration is called pulsus paradoxus, a physical finding highly suggestive of tamponade. Dogs with tamponade also commonly have muffled or distant heart sounds, jugular venous distension, and rapid heart rates (tachycardia), but these findings are not pathognomonic.
  • Clinical signs of pericardial constriction tend to be more chronic, with ascites prominent among them. Rarely, dogs with chronically elevated central venous pressures develop intestinal lymphangectasia, with subsequent protein-losing enteropathy.

Causes & Risk Factors

  • The cause of idiopathic hemorrhagic pericarditis is unknown; it may constitute the benign end of a spectrum that on its malignant end may include mesothelioma, when mesothelial cells that line the pericardium (or other body cavity) become malignant.
  • Infectious pericarditis can be caused by either bacterial or fungal infection (e.g., tuberculosis, coccidioidomycosis, actinomycosis, nocardiosis, and infection with Pasteurella spp.). Infectious pericarditis may result from migrating porcupine quills, plant awns, projectiles, or other objects introduced into the chest.
  • Cats-trauma or infection (e.g., FIP, Staphylococcus aureus, Escherichia coli, Streptococcus, Actinomyces, Cryptococcus, and possibly Toxoplasma).

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

  • Other causes of pericardial effusion and tamponade (e.g., neoplasia, left atrial rupture, heart failure, peritoneal-pericardial diaphragmatic hernia, and pericardial cysts).
  • Other causes of heart failure (e.g., cardiomyopathy, myocarditis, tricuspid or pulmonary valve disease, congenital heart disease, cor pulmonale, and severe left-sided CHF).
  • Other causes of abdominal effusion (e.g., neoplasia, hemorrhage, severe hypoalbuminemia).
  • Other causes of weak arterial pulse or collapse (e.g., cardiomyopathy, shock, hypoadrenocorticism, arrhythmias).

CBC/Biochemistry/Urinalysis

Most often unhelpful, with nonspecific changes common to many chronic conditions, including mild anemia, relatively nonreactive neutrophilia, and monocytosis.

Imaging

Thoracic Radiography

Often unhelpful, although a rounded cardiac silhouette may suggest pericardial effusion, particularly when the slow accumulation of chronic effusion permits significant expansion of the pericardium before the onset of tamponade; absence of this finding does not rule out pericardial effusion or pericarditis.

Echocardiography

The best single test to rule out pericardial effusion. Two-dimensional echocardiography reveals an echo-free space inside the parietal pericardium when effusion is present. Cardiac tamponade is recognized by the diastolic collapse of the right atrium, which is relieved during inspiration. The identification of intracardiac neoplasia is best left to highly trained and experienced echocardiographers.

Hemodynamic Measurements

  • In the absence of volume contraction or treatment with diuretics, cardiac tamponade is associated with high central venous pressures (>10 mmHg), and even if marginally elevated (e.g., 5–10 mmHg), these pressures spike to high levels (>10 mmHg) and remain elevated on fluid challenge (e.g., 10 mL/kg IV bolus of LRS administered IV in less than 5 minutes).
  • Constrictive pericardial physiology is rare and difficult to diagnose even by simultaneous pressure measurements from the right and left ventricles showing pressure equalization at an elevated end-diastolic pressure. Atrial pressure tracings classically show a rapid drop in pressure in early diastole followed by an early rise to a plateau at an elevated end-diastolic pressure.

Diagnostic Procedures

Electrocardiographic Findings

Potentially, low-voltage QRS complexes (<0.9 mV in all leads in the dog), electrical alternans, ST segment elevation in the caudal and leftward leads (e.g., II, aVF, V3, I), P-mitrale (even in the absence of left atrial enlargement) and occasionally, arrhythmias. These changes lack sensitivity, and are not pathognomonic even when present.

Fluid Analysis

Cytologic examination of pericardial effusion cannot reliably differentiate among the common neoplastic (e.g., hemangiosarcoma, mesothelioma) and idiopathic causes of effusion. Cytology can identify (and thus rule out if they are not present) some potential causes of effusion (e.g., lymphosarcoma, FIP, sepsis).

Other Procedures

  • If an infectious agent is suspected, aerobic and anaerobic cultures of the effusion are indicated.
  • Histopathologic examination of the pericardium.
  • Significant elevation of serum cardiac troponin I is not typical of benign effusion and suggests hemangiosarcoma.

Treatment ⬆ ⬇

Treatment

Medications ⬆ ⬇

Medications

Drug(s)

  • Treat infectious disease with appropriate antibiotics or antifungals based on culture and sensitivity testing.
  • While anti-inflammatory, immunosuppressive, or anti-fibrotic strategies have been tried in dogs (e.g., therapy with corticosteroids, azothiaprine, or colchicine) the efficacy of these strategies for preventing recurrent effusion is unknown.

Contraindications/Possible Interactions

  • Diuretics and preload reducers are contraindicated in tamponade.
  • Corticosteroids or other immunosuppressive agents may exacerbate infection.

Follow-Up ⬆ ⬇

Follow-Up

Pericardial effusion may recur if the pericardium is intact. Pleural effusion may occur months or even years after pericardiocentesis or pericardectomy, often associated with mesothelioma; periodic echocardiographic monitoring following treatment is recommended.

Miscellaneous ⬆

Miscellaneous

Abbreviations

  • CHF = congestive heart failure
  • FIP = feline infections peritonitis

Suggested Reading

Case JB, Maxwell M, Aman A, Monnet EL. Outcome evaluation of a thoracoscopic pericardial window procedure or subtotal pericardectomy via thoracotomy for the treatment of pericardial effusion in dogs. J Am Vet Med Assoc 2013, 242(4):493–498.

Chun R, Kellihan HB, Henik RA, et al. Comparison of plasma cardiac troponin I concentrations among dogs with cardiac hemangiosarcoma, noncardiac hemangiosarcoma, other neoplasms, and pericardial effusion of nonhemangiosarcoma origin. J Am Vet Med Assoc 2010, 237(7):806–811.

Nelson OL, Ware W. Pericardial effusion. In: Bonagura JD and Twedt DC (eds), Kirk's Current Veterinary Therapy XV St. Louis, MO: Elsevier, 2014, pp. 816–823.

Tse YC, Rush JE, Cunningham SM, Bulmer BJ, Freeman LM, Rozanski EA. Evaluation of a training course in focused echocardiography for noncardiology house officers. J Vet Emerg Crit Care (San Antonio) 2013, 23(3):268–273.

Author Bruce W. Keene

Consulting Editors Larry P. Tilley and Francis W.K. Smith, Jr.

Acknowledgment The author and editors acknowledge the prior contribution of Donald J. Brown.