pericardial disease

• The pericardium is the sac surrounding heart and consists of an inner "visceral” layer and an outer “parietal” layer with no significant lumen.

  • Visceral layer is so close to the heart it is almost like the endocardium
  • Parietal layer is contiguous (in connection) with the blood vessels adventitial layer
• The function of the pericardium is not essential but includes…

  • Keeping the heart anatomically fixed
  • Reduce friction
  • Equalize gravitational forces (pericardial fluid)
  • Prevention of over dilation
  • Regulation between stroke volumes of both ventricles
  • Metabolically active
• The sterno-pericardial ligament connects to the sternum while the phrenico-pericardial ligament connects to the diaphragm, both these ligaments prevents distension
• 3 things can go wrong with the pericardium…

  • The pericardial sac can fill with fluid e.g.,
  • Blood
  • Transudate
  • Exudate occurs due to a thoracic trauma e.g. a dog bite that punctures the pericardium and causes an infection
  • Mass can be present within the pericardial space, heart or the pericardium
  • Neoplasia
  • Pericardial peritoneal diaphragmatic hernias –cats (often not symptomatic)
  • Pericardial cysts –congenital
  • The pericardium can become stiff –‘constrictive’
  • Restriction of pericardial filling secondary to reduced pericardial compliance
• Impaired ventricular filling can occur as a consequence of increased intrapericardial pressures (which can occur due to fluid accumulation, the presence of a mass or pericardial constriction). This becomes significant as it can cause cardiac tamponade…

  • Intrapericardial pressure equilibrates with the right atrial and right ventricular filling pressures
  • There is a continuum that ranges from subclinical to fulminant heart failure
  • Congestive right heart failure results from chronic tamponade
  • Low cardiac output and shock results from acute tamponade
• The right sided heart pressure is lower than the left hand side and the intrapericardial pressure, this causes the right side of the heart to collapse and hence cant fill. This means that there is less blood going through the pulmonary vessels so less back to the left atrium so fall in left-hand side preload and an acute fall in cardiac output
• The typical History depends on the pathophysiology but there are two common types of presentation…

  • Acute cases – Sudden onset exercise intolerance, weakness, collapse, shock, rapid death if untreated
  • This is one of the few causes of cardiogenic shock
  • Chronic cases - 2 week history of ascites, progressive exercise intolerance, lethargy, GIT signs, collapse.
  • Most common
• Clinical signs include…

  • Jugular distension
  • Positive hepatojugular reflex
  • Ascites
  • Tachycardia
  • Muffled heart sounds
  • However, some cases you can hear the heart so this is not a guaranteed sign
  • Weak femoral pulses
  • Pale mucous membranes
  • Tachypnoea/dyspnoea
  • GIT signs
• Diagnosis involves the triad of clinical signs (Jugular distension, poor pulses, right sided heart failure) and also….

  • ECG
  • This shows tachycardia with small complexes and electrical alternans
  • Echocardiography (Gold standard)
  • This can identify is there is an effusion, mass, hernia or cyst present.
  • Radiography
• signs of RHS heart failure include

  • Jugular distension
  • Positive hepatojugular reflex
  • Ascites
• treatment is often emergency care (oxygen and IV fluids possibly) and a pericardiocentesis/pericardial strip if there is an effusion (in a dog).

  • If the animal is in shock rain quick if not take your time to drain.

  DO NOT give diuretics, they have a fall in supply to the left side of the heart causing output to decrease which consequently affects blood pressure.

  • By providing diuretics, you remove more of the circulating volume and make these patients worse
  • They are dependent on preload!
• do not drain pericardial effusions in cats, treatment of the cause will remove the effusion
• Congenital disorders of the pericardium include…

  • Pericardial peritoneal diaphragmatic hernia (PPDH)
  • weimaraners and Persians are overrepresented. It is the communication between the pericardial and the peritoneal cavities that allow for the herniation of abdominal contents
  • Abnormal fusion of the septum transversum with the pleuroperitoneal folds / Post natal injuries
  • Associated to umbilical hernias or abnormal sternebrae
  • Clinical signs vary with the herniated structures and the onset ranges from 4 weeks to 15 years and if needed then can get a surgical correction
  • Pericardial cyst
• what are the causes of pericardial effusions in cats?

  congestive heart failure and FIP
• Causes of pericardial effusion in dogs

  • Cardiac neoplasia (most common)
  • Hemangiosarcoma
  • Heart base tumours
  • Mesotheliomas (tumours of the lining of the body cavity)
  • Lymphosarcoma
  • Idiopathic (haemorrhagic)
  • Left atrial rupture
  • NO Pericardiocentesis
  • Coagulopathies, uremic, infection (bacterial and fungal)
  • Often fatal but in these cases do not drain
• Hemangiosarcomas commonly affects the right atrial/right auricular appendage and the spleen - metastatic disease is common

  • Acute tamponade(haemorrhage) – can be a small volume if an acute bleed
  • Can present with forward failure
  • Requires surgical resection but if it’s a solitary lesion you do not need to open the heart
• Chemodectomas/Ectopic thyroid carcinomas occur in older brachycephalic dogs. These dogs are in a state of constant hypoxaemia meaning the aortic arch is stimulated a lot causing proliferation and hence benign tumours. They are not often removed but can cause chronic tamponade and are presented in right sided failure.
• Mesotheliomas (tumours of the lining of the body cavity) arise from the serous membranes e.g. Pericardium, pleura, peritoneum and the tunica vaginalis of the testes

  • They cause a severe pleural & pericardial effusion, chronic tamponade and presented in RHF
  • They require a histopathological diagnosis and is treated with a pericardiectomy
• idiopathic (haemorrhagic) pericardial effusions commonly affect large breed dogs like the saint Bernard and Golden retriever. It causes chronic tamponade and these cases are presented in RHF.

  • To treat perform a pericardiocentesis. These usually re-occur so may need to drain again, after the third recurrence refer for a pericardiectomy if the owner can afford it (often successful)
• Left atrial rupture is secondary to chronic valvular disease (severe mitral regurgitation and jet lesions), and this often affects small breed dogs (CKCS). This causes acute tamponade and they present in forward failure.
• Indications or a pericardiectomy include…

  • Severe chronic pericardial disease
  • Restrictive pericardial disease
  • Palliative surgery for neoplastic aetiologies of pericardial effusion
• Recurrence may happen, it depends on aetiology but most with a neoplastic origin will recur.  Some

  idiopathic cases will also recur. In these cases you can…

  • Repeat pericardiocentesis
  • Risk of constrictive pericardial disease developing
  • Risk of the procedure
  • For neoplastic aetiology can use a balloon to make a pericardial window –palliative procedure only
  • Pericardial strip
• Complications of pericardiocentesis include…

  • Cardiac puncture
  • Arrhythmias
  • The right atrium (and hence the right ventricle) suddenly fills and dilates thus causing atrial dysrhythmias)
  • Dissemination of infection or neoplasia
  • Atrial fibrillation
  • Likely to occur post drainage (also ventricular arrhythmias can happen)
  • Myocardial stunning
  • There is a poor systolic function for a few days post drainage.
• Pericardiocentesis can be therapeutic and diagnostic. To perform, the animal is placed in left lateral recumbence, it is done this way to avoid laceration of main coronary vessels as the right side has a larger cardiac notch (bigger gap between the lungs). The site is prepared surgically and then local anaesthetic is applied. Several different catheter types may be used and are inserted between the 4th and 6th intercostal space at the level of the costochondral junction (elbow crosses the costochondral junction).
• pericardiocentesis is a relatively safe procedure with the risk inversely related to the amount of effusion
• Blood in body cavities does not clot, if it clots you are in the heart (or a vessel)