Pericardial disease

• What is the pericardium?

  Sac surrounding the heart

  Inner - visceral layer (surface of the heart)

  Outer - parietal layer

  No significant lumen.

  Small amount of pericardial fluid between the 2 layers
• Pericardium

  Visceral layer = epicardium

  Parietal layer contiguous with BV adventital layer.

  Sterno-pericardial ligament

  Phrenico-pericardial ligament

  Prevents distension.
• Function of the pericardium

  Not essential.

  Fixes the heart anatomically.

  Reduces friction.

  Equalsies gravitational forces (pericardial fluid)

  Prevention of overdialtion (pericardial restraint).

  Regulation between stroke volumes of both ventricles (ventricular coupling).
• What can go wrong with the pericardium?

  • Pericardial sac can fill with fluid
  • Blood
  • Transudate
  • Exudate
  • Mass can be present within the pericardial space, heart or the pericardium:
  • Neoplasia - Haemangiosarcoma, mesothelioma ect.
  • Pericardial peritoneal diaphragmatic hernias - cats (often not symptomatic).
  • Pericardial cysts - congenital.
  • The pericardium becomes stiff - constrictive.
• What is pericardial disease?

  Impaired ventricular filling as a consequence of increased intrapericardial pressures (not volume).

  Fluid accumulation - most common

  Presence of a mass

  Pericardial constriction - fibrous
• Cardiac tamponade

  The intrapericardial pressure exceeds the filling pressure of the right side, so the right side collapses and it can’t fill. The pressure in the systemic veins and capilliaries goes up so we end up with ascites and right sided congestive heart failure.

  Chronic tamponade - congestive right heart failure

  Acute tamponade - low cardiac output and shock.
• Clinical signs of pericardial disease

  Jugular distension (sign of RSHF)

  Positive hepatojugular reflex.

  Ascites.

  Tachycardia - in some cases you can still hear the heart quite and others you can’t.

  Weak femoral pulses.

  Pale mucous membranes

  Tachypnoea/ dyspnoea

  GIT signs.
• Pericardial disease clinical presentation

  Triad of clinical signs:

  1. Muffled heart sounds.
  2. Right sided heart failure;
  3. Ascites
  4. Distended jugular veins
  5. Positive hepatojugualr reflex
  6. Forward failure
  7. Poor peripheral pulses.
• ECG for pericardial disease

  Not that helpful.

  Shows tachycardia, small complexes

  Electrical alternans - not important, the QRS complex signs varies regularly from big to small, most likely because the heart is sitting in a bag of fluid it’s bouncing back and forth.

  
• Pericardial effusion in dogs

  Cardiac neoplasia (most common)

  Haemangiosarcomas - tumours of the blood vessels, almost always on the right atrium.

  Heart base tumours

  Mesotheliomas

  Lymphosarcoma

  Idiopathic (haemorrhagic)

  Left atrial rupture - don’t drain them as you want the pressure to go up, and you hope that the tear resolves itself, most of these are fatal.

  Coagulopathies, uremic, infection (bacterial and fungal).
• Peritoneal pericardial diaphragmatic hernia

  Most common

  Communication between the pericardial and the peritoneal cavities allowing herniation of abdominal contents.

  Abnormal fusion of the septum transverse with the pleurperitoneal folds/ post natal injuries.

  Associated with umbilical hernias or abnormal sternebrae.

  Clinical signs vary with the herniated structures and the onset ranges from 4 weeks to 15 years.

  Incidental finding

  Surgical correction.