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
