Pericardial Diseases Flashcards
describe normal pericardial anatomy
- parietal pericardium: tough, outer fibro-serous membrane
- visceral pericardium (epicardium)
-delicate, inner serous membrane
-single layer of mesothelial cells adhered to myocardium - pericardial cavity (potential space), contains small amount of fluid
-1/4ml/kg body weight
-protein: 1.7-3.5g/dL
-low cellularity
describe the functions of the pericardium
- anatomical fixation of the heart!!!!
-prevents excessive movement with changes in body position - helps to maintain optimal functional shape of the heart
- prevents chamber over distension (pericardial restraint)
- supports ventricular coupling: interdependence
- reduces friction
- provides physical barrier to infection and malignancy
in theory nonessential, because surgical removal of the pericardium does not cause clinically significant hemodynamic alterations in the NORMAL heart
describe properties of the normal pericardium
- normal pressure in pericardial space is approx zero or negative and varies with respiration (parallels that of pleural space)
-minimal effect on cardiac filling - the pericardium has a small reserve volume (relatively noncompliant)
-when volume of pericardial contents > reserve volume, compliance decreases dramatically, causing intra-pericardial pressure to rise
-pressure will then be directed inward and start to compress the heart
define pericardial effusion (4)
- excessive, abnormal fluid accumulation in the pericardial space
- most common pericardial disorder affecting veterinary patients
-condition most likely to lead to tamponade and CHF - effusion greater than pericardial reserve volume can increase intrapericardial pressure, compress the heart, and impair its function
-most susceptible = right atrium/right ventricle in DIASTOLE (lower pressure chambers in the lowest pressure portion of the cardiac cycle)
- cardiac tamponade:
-occurs when intrapericardial pressure is high enough to impair venous return to right heart
describe the consequences of cardiac tamponade (3)
- right sided CHF
-due to increased diastolic filling pressures
-leads to ascites and pleural effusion - cardiogenic shock when impairment severe enough
-decreased preload, stroke volume, and cardiac ouput - death if untreated!
describe pericardial effusion
with respect to hemodynamic effects, intrapericardial pressure matters more than volume!
- once PE > 2-7ml/kg (reserve volume), pressure rise depends on rate of fluid buildup
- the pericardium can hypertrophy/stretch to accommodate a large volume of fluid without significant elevations in pressure IF accumulation is SLOW (like with a tumor, will reach tamponade at a much higher volume)
-but tamponade QUICK and at lower volume if add fluid too fast
-so fluid volume of an animal in tamponade can clue you into to how acute or chronic a condition is
describe clinical consequences of acute versus chronic pericardial effusion
chronic PE/tamponade: like with slowly-developing neoplastic effusion
- compensatory responses possible
-pericardial dilation (hypertrophy)
-activation of RAAS - gradual onset of clinical signs
- right sided CHF predominates!!
acute PE/tamponade: like with acute hemorrhage
- no time for long-term compensatory responses
- acute onset, rapidly progressive
- decreased cardiac output, cardiogenic shock predominates
describe PE findings of pericardial effusion/cardiac tamponade (4)
- beck’s triad:
-jugular venous distension/pulsation
-muffled heart sounds: encased in fluid sac
-systemic hypotension: poor diastolic filling decreases CO - tachycardia
- abdominal distension
- pulsus paradoxus
because findings are variable and inconsistent, index of suspicion is very important!!
describe pulsus paradoxus in dogs
- a phasic variation in arterial pulse quality in dogs:
-inspiratory pressure decreases >10 mmHg - exaggeration of normal phenomenon!!
-during inhalation (vs exhalation):
–decreased intra-thoracic pressure causes bigger venous return to right heart, greater right sided filling, and leftward shift of interventricular system,
–blood pools in pulmonary vessels
–result: decreased filling of left ventricle and weaker pulse on those beats (inhalation)
- pericardial effusion exaggerates this ventricular interdependence, making pulse variation detectable (imperceptible in health)
- not very sensitive (not present in every patient with PE, but VERY specific for pericardial effusion!!!
describe thoracic radiographs with pericardial effusion
- globoid cardiac silhouette without specific chamber enlargement patterns
-basketball in the chest - sharply delineated (crisp) margins of cardiac silhouette
- bilateral contact between the cardiac silhouette and the thoracic wall (DV or VD)
- small pulmonary vasculature
NOT PRESENT IN ALL CASES (absent in up to 50%)
-ULTRASOUND is best dx to look for fluid in pericardial space!!!
describe echocardiography of pericardial effusion
used to:
- confirm presence of effusion
- assess for tamponade (right atrium or ventricular walls collapsing in, no longer concave)
- look for cardiac/pericardial tumors
fluid in pericardial space = best time to detect tumors since they are outline by the dark anechoic space
describe neoplastic and non neoplastis causes of pericardial effusion in dogs
neoplastic:
- right atrial hemongiosarcoma*
- heart base tumors:*
-chemodectoma/aortic body tumor
-ectopic thyroid carcinoma - mesothelioma
- lymphoma
- other primary and metastatic sarcomas/carcinomas
non-neoplastic:
1. idiopathic hemorrhagic PE*
- infectious (bacterial/fungal)
- coagulopathy (ex. warfarin toxicity)
- left atrial rupture
- small volumes seen with: uremia, hypoalbuminemia, and CHF
canine PE are typically hemorrhagic/serosanguinous, non/mildly inflammatory, non-septic
- = accounts for >90% of canine cases
describe neoplastic and non-neoplastic causes of pericardial effusion in cats
neoplastic:
1. lymphoma!!
2. primary cardiac tumors (rare)
non-neoplastic:
1. left sided CHF!!
2. FIP (wet form)!!
3. sepsis, idiopathic pericarditis, toxoplasmosis, uremia
PE of enough volume to cause tamponade is VERY rare in the cat!!
describe neoplastic and non-neoplastic causes of pericardial effusion in horses
neoplastic:
lymphoma and mesothelioma, both rate
non-neoplastic:
1. idiopathic pericarditis!!
2. bacterial/viral pericarditis!!
3. trauma, vessel rupture, penetrating foreign bodies (rare)
PE in horses typically fibrinous, inflammatory, and often septic!
describe neoplastic and non-neoplastic causes of pericardial effusion in cows
neoplastic:
lymphoma
non-neoplastic:
1. traumatic reticulopericarditis/hardware disease!!!
2. idiopathic hemorrhagic pericarditis
3. septicemia, extension of pleural/pulmonary infection
PE in cows typically fibrinous, inflammatory, and often septic!
