Pericardial surgery

Question 1

What are the 2 layers of the pericardium?

Answer 1

• Outer fibrous layer
• Inner serous layer (closed mesothelial lined sac with parietal and visceral layers)

Question 2

List the functions of the pericardium

Answer 2

• Keeps the heart in position
• Restrains cardiac filling
• Enhances diastolic ventricular couplig
• Protects against atrial rupture
• Prevent spread of infection or neoplasia to heart from pleural cavity
• Provides a gliding surface for heart motion

Question 3

What does pericardial fluid contain?
What is a normal volume?

Answer 3

Pericardial fluid is an ultrafiltrate of the serum
- phospholipids for lubrication
- Protein 1.7-3.6g/dL
- Colloid osmotic pressure approx 25% of serum

Normal volume 1-15ml

Question 4

What are the physiologic effects of cardiac tamponade?

Answer 4

• Decreased cardiac output
• Increased central venous pressure
• Activation of compensatory RAAS and sympathetic adrenomedullary catecholamine release
• As atrial wall stretching is limited, atrial natriuretic peptide is not produced and therefore does not counteract effects of RAAS
• Increase in systemic venous and portal pressures causing jugular vein distention, liver congenstion, ascites and peripheral oedema
• Compression of coronary arteries causes poor myocardial perfusion
• Cardiogenic shock and death

Question 5

What is pulsus paradoxus?

Answer 5

A variation in systolic arterial pressures up to 10mmHg from increasing venous return during inspiration in a relatively nonexpandable heart (due to pericardial effusion) causing intraventricular septal shift to the left, reducing CO

Can also be seen with obstructive lung disease, restrictive cardiomyopathy or hypovolaemic shock and is therefore not pathognomonic for pericardial effusion

Question 6

What is the risk associated with partial pericardial defects?

Answer 6

Cardiac herniation

Question 7

What have pericardial cysts been associated with?

Answer 7

• PPDH
• Other cases have been on a stalk at the apex of the pericardium
• Suggests they result from entrapment of omentum, falciform ligament or liver in pericardium during development

Question 8

What 2 syndromes can be associated with pericardial rupture?

Answer 8

During healing, a stricture can develop causing vena caval compression
- Budd Chiari Syndrome: ascites and hepatomegaly
- Caval syndrome: Swelling of head and neck

Caval angiography for diagnosis. RIght 5/6th IC thoracotomy for resection of fibrotic sac +/- angioplasty with pericardial patch graft

Question 9

What are the most common neoplastic causes of pericardial effusion?

Answer 9

• HSA of right atrial appendage
• Chemodectoma, usually along ascending aorta (brachycephalics most common)

Question 10

What breed is overrepresented for pericardial effusion?

Answer 10

Golder Retrievers

Question 11

What is an expected central venous pressure of a dog with pericardial effusion?

Answer 11

10-12mmHg

Question 12

Describe the following ECG

Answer 12

Electrical alternans
- Amplitude of QRS and ST-T complexes changes from 1 complex to another due to heart swinging in fluid filled pericardial sac
- Strongly suggestive of pericardial effusion

Question 13

What is the sentivity and specificity of echocardiogram for cardiac mass detection?

Answer 13

• 82 and 100%

Question 14

What can be measured in the plasma of dogs with pericardial effusion which is assoc with HSA?

Answer 14

Cardiac troponin I
- Conc over 0.25ng/ml 82% senstivite and 100% specific for cardiac HSA

Question 15

Where do you perform a pericardiocentesis?

Answer 15

RIght 5/6th ICS with a 20g needle/catheter

Question 16

What are the surgical options for pericardial effusion?

Answer 16

Pericardiectomy
- Subtotal or complete (complete does not improve outcomes)

Thoracoscopic pericardial window
- 3x3cm window in large breed dogs (too large risk cardiac herniation)
- Transdiaphragmatic (with right 4th and 7th ICS or right and left 7th ICS) or intercostal approach

Thoracoscopic subtotal pericardiectomy
- Transdiaphragmatic approach with instrument cannulas in left and right 9th ICS

Question 17

What is the prognosis for pericardial effusion?

Answer 17

Neoplastic:
- HSA MST 16d
- Aortic body tumours, MST 730d with Sx vs 42d
- Mesothelioma usually deveolps unremitting pleural effusions 1.5-5m post pericardiectomy. MST 10.5-13.6m

Idiopathic
- Excellent
- Subtotal pericardiectomy 100% surviva at 3yr (Dunning et al)
- Another study 12% dies periop, 16% died within 1 yr, 72% long term survival
- Pericardial window MST 13.1m, 35% survival at 3yr
- MST 22m

Question 18

What is the Kussmaul sign?

Answer 18

Paradoxical, persistent increase in jugular venous pressure during inspiration
- Assoc with constrictive pericarditis
- Negative intrathoracic pressure during inspiration is not transmitted to the cardial chambers

Question 19

How is restrictive pericarditis diagnoses?

Answer 19

Cardiac catheterisation
- Measurement of pulmonary capillary wedge, atrial and ventricular pressures
- Increased and equilibration or near-equilibration of diastolic filling pressures in all chambers

Question 20

What is the Tx and prognosis for constrictive pericarditis?

Answer 20

Subtotal pericardiectomy
- Relieved clinical signs in 6/10 dogs
- Prognosis more guarded if epicardium involved - required decortication
- Prognosis poor if develops after treatment of pericardial effusion