254 Pericardial Diseases Flashcards
1
Q
What is the function of the pericardium?
A
- prohibit cardiac over dilation
- protect from infection and forming adhesions
- maintain heart in fixed position in thorax
- regulated interrelationship between stroke volume of two ventricles
- Prevent tricuspid regurgitation when ventricular diastolic pressure is increased
2
Q
What is the anatomy and physiology of the pericardium?
A
- 2 membranes: outer, fibrous, parietal membrane, and inner, serous, visceral membrane (epicardium)
- Small volume 0.3-1ml is present to reduce friction between two membranes
- parietal layer composed of mesothelial cells and connective tissues including compactly arranged collagen fibres in multilayer orientation, interspersed wit less abundant elastin fibres.
- the pericardium is able to stretch for chronic increases in volume.
3
Q
What is peritoneopericardial diaphragmatic hernia (PPDH)? What are their signs and how is it diagnosed and treated?
A
- Peritoneoparicardial diaphragmatic hernia PPDH
= a defect where the pericardium allows abdominal organs to enter the pericardial space while keeping the pleural space in tact
- can be symptomatic
- clinical signs can include tachypnoea, resp distress, vomiting, and anorexia. Other signs such as lethargy, weight loss, diarrhoea, exercise intolerance, and coughing.
- Thoracic radiographs: increased dose of cardiac silhouette, no distinction between heart and diaphragm.
- Echo: abdominal organs adjacent to heart
- Treated by surgical correction
4
Q
What do pericardial cysts normally present in? What is their pathology? What can they cause?
A
- rare in dogs, not reported in cats
- mostly young dogs so may be congenital.
- Cysts often represent cystic hematomas.
- pathologic abnormalities includes encapsulation within adipose tissue wth extensive haemorrhage and necrosis, or organising cystic
- can cause cardiac tamponade by infect compression and associated effusion.
- Treat: surgical removal of cyst, its associated pedicure, pericardectomy, and herniorrhaphy for cases that develop PPDH
5
Q
What causes pericardial effusion?
A
- most common is hemangiosarcoma, idiopathic pericarditis, mesothelioma, and chemodectoma.
- Other less common causes are thyroid gland adenocarcinoma, infective pericarditis, lymphoma, sarcoma, and carcinomatosis, ruptured left atrium secondary to severe mitral valve regurgitation, sterile foreign body, and granulomas
6
Q
Explain the pathophysiology of pericardial effusion and cardiac tamponade
A
- Pericardial effusion increasesintrapericardial pressure which is spread equally to al chambers during diastole and systole. The thin walled right heart bears the pressure resulting in cardiac tamponade.
- Cardiac tamponade = impaired ventricular filling due to accumulation of fluid within pericardial space -> lead to reduced SV and CO.
- acute tamponade - rapid fluid accumulation leads to rapid increase in intrapericardial pressure. Additional fluid accumulates chronically and stretches pericardium without increasing intrapericardial pressure. Collapse of right atrium and ventricle increases right atrial and ventricular diastolic pressures. Diastolic collapse of right heart decreases right ventricular filling and right ventricular stroke volume, thereby reducing venous return to left heart. LV SV is decreased which decreases CO and causes atrial hypotension and cardiogenic shock.
- Chronic tamponade - manifests as elevated right heart diastolic pressures and right sided congestive heart failure. The increase diastolic pressure required to cause leaking of systemic capillaries is lower (10-15mmHg) than for pulmonary capillaries (25-30mmHg), so right heart failure is seen.
7
Q
What is pulses paradoxes?
A
= fall of systolic arterial blood pressure >10mHg during the inspiratory phase of normal breathing.
- pulses simultaneously slight and irregular, disappears during inspiration and returns during expiration
- an accentuation of normal small decline of LV SV an systemic arterial blood pressure that occurs with inspiration.
8
Q
What are the common heart base masses?
A
Heart base masses grow on the ascending aorta at aortic body, and caused by:
- neuroendocrine tumour
- chemodectoma
- non-chromaffin paragangliomas
- thyroid gland adenocarcinoma
- mesothelioma -> mesothelioma often seeds on serosa surface of pericardium and pleura without causing a discrete mass.
Less common tumours:
- lymphoma and sarcoma (undifferentiated, rhabdomysarcoma, fibrosarcoma)
9
Q
How common is idiopathic pericarditis? What is the hypothesised pathogenesis?
A
- second most common to HSA (20-75% aetiology)
- postulated to be secondary to viral or immune mediated disease.
Pathogenesis= mononuclear cellular inflammation and fibrosis -> target pericardial blood vessels and lymphatic. Damaged pericardial blood vessels are likely source of the heamorrhagic effusion. - Can resolve after pericardiocentesis in half of cases, and remaining half suffer from recurrent pericardial effusion in days to years and require subtotal pericardectomy.
10
Q
What is aetiology of infective pericarditis?
A
- common Indus of infection is migrating grass awns or other intrapericardial penetrating foreign body.
- Bacterial or fungal agents reported: Bacteroides spp., actinomycetes spp. Streptococcus canis, pasteurella spp. Peptostreptococcus spp., and coccidiodes imitis
- Pericardial effusion typically is flocculent and suppurative grossly,
11
Q
Explain the pathophysiology of LA rupture causing pericardial effusion.
A
- less common cause
- severe MMVD causing severe LA pressure and dilation, accompanied by high velocity jet lesions hitting LA wall.
- present with acute cardiac tamponade, weakness, cardiogenic hock, and often acute death.
- Small breed dogs with severe mitral valve degeneration at greater risk: Shetland sheepdogs, male poodles, daschunds, and cocker spaniels have higher predilection for left atrial rupture.
12
Q
What are the metabolic and toxic causes of pericardial effusion?
A
- pericardial effusion secondary to uremia and cholesterol based pericardial effusion associated with hypothyroidism.
- coagulation disorders lead to pericardial effusion occur with anticoagulant rodenticide intoxication and secondary to DIC, warfarin intoxication, and other coagulopathies.
13
Q
Explain difference in clinical scenarios with patients having pericardial effusion
A
- Acute =
- acute cardiac tamponade = rapid onset weakness/collapse - Chronic =
- Chronic tamponade = innappetance, lethargy, exercise intolerance, progressive abdominal distension, and respiratory abnormalities such as tachypnoea or dyspnea
14
Q
What are the expected physical examination findings of a patient with pericardial effusion?
A
Hallmark signs:
- muffles heart sounds
- weak pulse
- tachycardia
- pale MM
Other signs:
- +/- lung sounds
- right heart failure, distended jugular veins or pulse, a positive hepatojugular reflux test, hepatomegaly and ascites with ballotable fluid.
15
Q
How is pericardial effusion diagnosed?
A
- Echo - essential and differentiates aetiologies of pericardial effusion.
- T-rads are insensitive: see globooid cardiomegaly with crisp cardiac margin.
- CT: increases sensitivity to detect pulmonary metastasis
- MRI: does not increase yield for detecting masses
- ECG; electrical alternate is beat-to-beat variation in QRS amplitude caused by heart swinging back and forth in large volume of pericardial effusion
- Pericardial fluid analysis; differentiate heamorrhagic, suppurative inflammatory (infective), pyogranulomatous inflammatory, modified transudate, or chylous. May also be able to detect neoplastic causes.
- Aerobc and anaerobic cute should also be submitted
