Ch 107 - Pericardial surgery Flashcards
What are the 2 layers of the pericardium?
- Outer fibrous layer
- Inner serous layer (closed mesothelial lined sac with parietal and visceral layers)
List the functions of the pericardium
- 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
What does pericardial fluid contain?
What is a normal volume?
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
What are the physiologic effects of cardiac tamponade?
- 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
What is pulsus paradoxus?
Pulsus paradoxus refers to an exaggerated fall in a patient’s blood pressure during inspiration by greater than 10 mm Hg.
Normally, the systolic blood pressure decreases by less than 10 mmHg during inspiration, facilitating venous return to the right atrium and ventricle and pulmonary blood flow. However, because heart volume is limited by the pericardium during tamponade, the intraventricular septum shifts to the left. Consequently, left ventricular end-diastolic volume, left heart output, and arterial pressure are further decreased during inspiration, resulting in variation of systolic arterial pressures often greater than 10 mm Hg.
This phenomenon, known as pulsus paradoxus, can also occur with obstructive lung disease, restrictive cardiomyopathy, or hypovolemic shock and is therefore not pathognomonic for cardiac tamponade.
What is the risk associated with partial pericardial defects?
Cardiac herniation
What have pericardial cysts been associated with?
- 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
What 2 syndromes can be associated with pericardial rupture?
During healing, a stricture can develop causing vena caval compression (cranial, caudal or both)
- Budd Chiari Syndrome: ascites and hepatomegaly (compression of the caudal vena cava)
- Cranial vena cava syndrome: Swelling of head and neck (compression of the cranial vena cava)
Caval angiography for diagnosis. RIght 5/6th intercostal thoracotomy for resection of fibrotic sac +/- angioplasty with oval inlay pericardial patch graft
What are the most common neoplastic causes of pericardial effusion?
- HSA of right atrial appendage
- Chemodectoma, usually along ascending aorta (brachycephalics most common)
What breed is overrepresented for pericardial effusion?
Golder Retrievers
What is an expected central venous pressure of a dog with pericardial effusion?
10-12mmHg
Describe the following ECG
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
What is the sentivity and specificity of echocardiogram for cardiac mass detection?
- 82 and 100%
What can be measured in the plasma of dogs with pericardial effusion which is assoc with HSA?
Cardiac troponin I
Is an indicator of myocardial damage
- Conc over 0.25ng/ml 82% senstivite and 100% specific for cardiac HSA
Where do you perform a pericardiocentesis?
RIght 5/6th intercostal with a 20g needle/catheter
What are the surgical options for pericardial effusion?
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
What is the prognosis for pericardial effusion?
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
What is the Kussmaul sign?
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
How is restrictive pericarditis diagnosed?
Cardiac catheterisation
- Measurement of pulmonary capillary wedge, atrial and ventricular pressures
- Increased and equilibration or near-equilibration of diastolic filling pressures in all chambers
What is the Tx and prognosis for constrictive pericarditis?
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
