Hydropericardium

Introduction

This is a condition where excessive fluid accumulates in the pericardial cavity.
Fluid accumulation within the pericardial sac may lead to fibrous thickening and opacity of the pericardium if prolonged. Villous proliferation of the serosa will occur due to the irritation caused by the presence of the fluid.
Large volumes of fluid within the pericardial sac may cause cardiac tamponade, a compression of the heart. Side effects associated with the build up of fluid, such as degrees of embarrassment of the function of the heart, depend on the length of time build up of the fluid occurs.

Serous transudate can be seen in the pericardial sac due to congestive heart failure. This will cause a low cellular and high protein content in the fluid. Other conditions producing transudate in the pericardial sac of this consistency include neoplasia such as heart base tumours or secondary metastasis to the pericardium. Other debilitatinf diseases also can also contribute to this.

A serous transudate with a high cell and protein count may be caused by an acute toxeamia or by Mulberry Heart disease and Gut Oedema of pigs. As these disease cause damage to the endothelium, the fluid containing cells of the endothelium demonstrates just how severe the disease has been. There may also be firinous clots within the pericardial sac.

Clinical Signs

If fluid build up is slow, then signs will include grdaually worsening right sided heart failure, due to compression of the heart, the right ventricle will compress causing right sided failure. Signs will include ascites, hepatomegaly, jugular distension, jugular pulses and lethargy. If fluid build up is sudden e.g. in toxaemias, then the only clinical sign may be sudden death.

Diagnosis

History and clinical signs can be characteristic of the disease and may lead to a presumptive diagnosis.

Diagnostic imaging can be performed. An ultrasound can show fluid surrounding the heart and the presence of fibrinous clots if any exist. It can also show compression of the right ventricle. Radiography may show an enlarged cardiac silhouette, which is suggestive of a pericardial disease and fluid lines may be seen within the pericardial sac. Pericardicentesis can be performed to demonstrate the type of fluid in the pericardium so as to aid diagnosis.

Treatment

The only effective way to treat animals with pericardial effusions is pericardicentesis. This will relieve clinical signs even when only one thrid of the fluid is drained. This requires ECG moitoring throughout and for it to be ultrasound guided if possible.
In cases of recurrent pericardial effusion, a pericardectomy can be performed as a palliative measure to reduce the amount of recurrence.

Prognosis

This is dependent on the cause of the hydropericardium. If neoplastic then prognosis is guraded. If due to heart failure, medical treatment of this is important.

References

Boswood, A. (2008) Cardiovascular System Study Guide, Royal Veterinary College.
Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition), W.B. Saunders Company.
Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition), Mosby Elsevier.
Taylor, D.J. (2006) Pig Diseases (Eighth edition), St Edmunsdbury Press ltd.