Pericardial disease Flashcards
Anatomy of the pericardium
Fibrinous pericardium (outer)
Serous pericardium (inner)
- Parietal layer
- Pericardial fluid
- Visceral layer
Fibrinous pericardium (outer)
Thin, tough sac that is continuours with the adventitia of the great vessels dorsally and with the sterno-pericardial ligament ventrally
Serous pericardium (inner)
Consists of two layers and the pericardial fluid between them.
A thin layer of mesothelial cells is present in the inner aspects of the layers
Parietal layer: inner surface of the fibrinous pericardium, composed of collagenous fibers
Pericardial fluid: between the layers, small volume, serous, thin, clear fluid
Visceral layer: forms the epicardium
Blood supply to the pericardium
Via branches of the aorta, internal thoracic artery, and musculophrenic arteries
Lymphatic drainage from the pericardium
Cardiac, mediastinal, and pre-sternal lymph nodes
Function of the pericardium
Prevention of overdilation
Protection from infection
Maintain the heart in a fixed position within the thorax
Coordinates the left and right ventricular function
NOT VITAL
Congenital pericardial disease
Peritoneopericardial diaphragmatic hernia (PPDH)
Pericardial cysts
Peritoneopericardial diaphragmatic hernia (PPDH)
Defect in the ventral diaphragm and pericardium during embryonic development
Incomplete sepration of the thoracic and abdominal cavities
Most common congenital defect
Weimeraners and Persian cats
Often asymptomatic
Can be GI signs or less commonly resp signs
Surgical correction can be curative
Pericardial cysts
Rare
Result from the entrapment of the omentum or falciform ligament in the pericardium
Often asymptomatic but can cause pericardial effusion and cardiac tamponade
Surgical removal is possible
Acquired pericardial diseases
Pericardial effusion
Categories of pericardial effusion
Haemorrhagic
Transudate
Exudate
Causes of haemorrhagic pericardial effusion
Neoplastic
Idiopathic
Left atrial rupture
Coagulopathy
Trauma
Causes of transudate pericardial effusion
Congestive heart failure
Neoplasia
PPDH
(Less common: hypoproteinaemia, uraemia with renal failure)
Causes of exudate pericardial effusion
FIP
Infection
Foreign bodies
Neoplastic pericardial effusions
Haemangiosarcoma
Chemodectomas (heart base tumour)
Mesothelioma
Pericardial effusion caused by haemangiosarcoma
Most common
Predilection site: right atrial appendage and right atrium
GSDs and Golden retrievers
High rate of metastasis (sleen/liver common)
Rapid recurrence following pericardiocentesis
Grave prognosis
Surgical excision rarely feasible, chemotherapy not generally advised
Pericardial effusion caused by chemodectomas (heart base tumour)
Second most common
Arise from chemoreceptors in the pulmonary artery and ascending aorta
Predisposed: brachycephalics, older dogs
Benign, typically slow growing with slow metastatic rate - but can be locally invasive
Clinical signs due to compression of the great vessels
Pericardiectomy can prolong survival with good QOL
Pericardial effusion caused by mesothelioma
Low-grade malignancy originating from mesothelial cells lining coelomic cavities
Malignanacy uncommon in dogs
Predilection site: pleura +/- pericardium
Often large volume pericardial effusion
Pericardiectomy palliative
Intracavity chemo an option
Paragangliomas
Another form of aortic body tumour
Functional - secrete catecholamines
Idiopathic pericardial effusion
Diagnosis of exclusion - neoplasia more common in older dog
Second most common cause of pericardial effusion
Unknwon aetiology
Large breeds over-represented
50% recurrence rate - pericardiectomy is indicated
Pericardial fibrosis with a mixed inflammatory response and no vasculitis
Left atrial rupture
Rare
Typically older, small breed dogs
Secondary to severe myxamatosus mitral valve associated with severe left atrial dilation and jet lesions
Guarded prognosis
Right-sided congestive heart failure
CHF is most common cause of pericardial effusion in cats
Effusion occurs due to passive congestion and decreased drainage
It rarely results in a volume large enough to cause tamponade
Treatment: CHF therapy
Guarded prognosis
Septic pericardial effusions
Rare
May be associated with penetrating or migrating foreign bodies
Cytology and culture and sensitivity
Aggressive antibiosis, exploratory thoracotomy often required
FIP in cats
Clinical signs usually associated with cardiac tamponade
Constrictive pericarditis
Uncommon
Thickened, fibrotic pericardium
Can be idiopathic, neoplastic or occur secondary to recurrent pericardial effusions
Signs of right sided heart failure
Pericardiectomy required
Guarded prognosis
Cardiac tamponade
Once intrapericardial pressures exceed right atrial, and subsequently right ventricular, pressures, this results in diastolic collapse of the right atrium +/- ventricle
Impedes ventricular filling and so reduced stroke volume and cardiac output
Pulsus paradox
During pericardial effusion
Increase in right ventricular filling on inspiration causing the interventricular septum to shift toward left ventricle (reducing stroke volume)
Variation in pulses quality with the respiratory cycle
Signalment and history of a patient with pericardial effusion
Often large breed, older dogs
Collapse
Exercise intolerance
Lethargy
Abdominal distension
Cough
Polydipsia
Hyporexia
Acute pericardial effusion is more likely to result in signs of reduced cardiac output while chronic effusions are more likely to present with signs of right sided congestive heart failure (ascites)
Clinical examination of pericardial effusion
Muffled heart sounds
Weak femoral pulse, pulses paradoxus
Tachycardia
Ascites
Jugular distension
Positive hepatojugular reflux
Hepatomegaly/splenomegaly
+/- respiratory signs
Diagnostics of pericardial effusion
Echocardiography
Blood pressure
ECG
Radiography
Clinical pathology
Pericardial fluid analysis
Echocardiography of pericardial effusion
Best non-invasive method
Easy to identify (hypoechoic fluid, contained within bright hyperechoic pericardium)
Also look for pleural effusion and ascites
Ideally do a thorough search for a cardiac or heart base mass
Blood pressure - pericardial effusion
Assess degree of haemodynamic compromise.
Hypotension with forward failure
ECG - pericardial effusion
Often sinus tachycardia
Electrical alternans a common finding
Radiography of pericardial effusion
Inferior to thoracic ultrasound
Globoid, enlarged cardiac silhouette with very distinct margins
Dilated CdVC
Abdominal effusion
Small pulmonary vessels
Clear lung fields
Clin path of pericardial effusion
Pre-renal azotaemia common finding
Mildly elevated liver enzymes
Albumin may be low
Anaemia
Cardiac troponin I often elevated
Pericardial fluid analysis
Assess volume, gross appearance
PCV
Cytology - low diagnostic yield for neoplastic effusions, useful for diagnosis of septic pericarditis
C&S if suspicion of septic pericarditis
Key treatment points for pericardial effusion
If tamponade is present, pericardiocentesis should be performed (unless left atrial tear)
If haemodynamically unstable patients - high rate IV fluids
DO NOT give furosemide
Pericardiocentesis
Essential if cardiac tamponade
Often palliative rather than curative
Owner must know that the effusion may recur
Patient prep for pericardiocentesis
Mild sedation
Sternal or left lateral recumbency
Pericardiocentesis performed via the right side to avoid the large coronary artery
Place IV catheter and give IVFT if required
Connect ECG
Aseptic preparation 3rd-8th ICS, ventral half of the right chest
Technique for pericardiocentesis
Use US to find best point of entry, or 5-6th ICS at level of costochondral junction
Local anaesthetic infiltration
Small stab incision through skin
Over-needle catheter (14G) approach:
- advance catheter over needle and remove needle once in pericardium
Modified Seldinger technique:
- Advance introducer catherter into pericardium over the needle, withdraw needle, then thread the guidewire through and remove introducer catheter
Attach 3-way tap
Aspirate fluid, maintain some for analysis
Ensure it does not clot
Monitor ECG
Once fully drained, remove catheter
Complications of pericardiocentesis
Haemorrhage and catastrophic bleeding
Arrhythmias
Pneumothorax
Pulmonary oedema
Pericardiectomy
If more than 3 pericardiocentesis are required
Pericardium should be sent for histopathology
Subtotal pericardiectomy preferred to a pericardial window
May be curative in cases in cases of idiopathic pericardial effusion but in most cases palliative
