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What are potential causes of a heart murmur when advanced diagnostics are normal? (3)
- innocent murmur
- physiologic murmur (fever, dehydration)
- mild congenital causes
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What are congenital differentials for a patient with a systolic murmur and cyanosis? (3)
- tetralogy of fallot
- pulmonary hypertension
- reversed PDA/ VSD/ASD
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What are congenital differentials for a left-sided systolic heart murmur with no cyanosis? (4)
- pulmonary stenosis (heart base PMI)
- atrial septal defect (heart base PMI)
- sub-aortic stenosis
- mitral dysplasia (apex PMI)
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What are congenital differentials for a right-sided systolic heart murmur with no cyanosis? (4)
- ventricular septal defect
- endocardial cushion defect
- tricuspid dysplasia
- sub-aortic stenosis
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What are types and congenital causes (3) of systolic+ diastolic heart murmurs?
- continuous murmur- PDA
- to and fro murmur- sub-aortic stenosis and aortic insufficiency or ventricular septal defect and aortic insufficiency
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Describe eccentric myocardial hypertrophy.
- dilation of the chamber to accommodate volume
- usually radiographically identifiable
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Describe concentric myocardial hypertrophy.
- thickening of the myocardium to accommodate pressure
- may or may not be radiographically identifiable
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What are the most common congenital causes of heart murmurs in dogs and cats? (4 each)
- Dogs: pulmonic stenosis, PDA, aortic stenosis, VSD
- Cats: VSD, aortic stenosis, pulmonic stenosis, HCM with OLVOT (<--is that really congenital tho?)
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What breeds are predisposed to pulmonic stenosis? (7)
- English bulldog (esp males; correlated with coronary anomalies)
- Beagle
- Chihuahua
- Mastiff
- Samoyed
- Keeshond
- Fox terrier
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Describe the specific location and pathophysiology of pulmonic stenosis. (3)
- valvular stenosis (unlike SAS)
- concentric myocardial hypertrophy first d/t increased pressure in right heart THEN eccentric hypertrophy
- post-stenotic dilatation of main pulmonary artery
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What are radiographic findings associated with pulmonic stenosis? (3)
- right atrial and ventricular enlargement- Reverse D on VD projection
- bulge at pulmonary trunk (post-stenotic dilatation)
- pulmonary vasculature is normal to under-circulated
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What are breed dispositions for sub-aortic stenosis?
generally large breed dogs
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What is the specific location and pathophysiology of sub-aortic stenosis?
- sub-aortic stenosis (below the valves, within the LV); fibrous ridge in the LV outflow tract
- concentric myocardial hypertrophy first d/t pressure overload in left heart then eccentric hypertrophy
- post-stenotic dilatation of the aorta
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What are radiographic findings with sub-aortic stenosis? (4)
- prominent "cranial waist" on lateral projections (enlarged/ dilated aortic arch)
- widening of the cranial mediastinum on VD
- LV enlargement +/- LA enlargement
- normal pulmonary vasculature
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What is the specific location of a PDA?
- normal fetal structure b/w the descending aorta and pulmonary artery
- becomes a PDA when it fails to close within 72hr of birth (should become ligamentum arteriosus)
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What is the pathophysiology of a PDA?
connection b/w high pressure systemic circulation and low pressure pulmonary circulation--> volume overload
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What are radiographic findings with PDA? (4)
- three notches: aortic arch, main pulmonary artery, and left auricle
- LA and LV enlargement
- +/- increased width of cardiac silhouette
- enlarged pulmonary arteries and veins (over-circulation)
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What is Eisenmenger Syndrome?
- systemic to pulmonary circulation connection and left-to-right shunting of blood
- --> increased pulmonary blood flow, irreversible pulmonary vasculature injury, irreversible pulmonary vasculature resistance--> REVERSAL OF SHUNT, begins shunting right-to left--> cyanosis, hypoxia, and erythrocytosis
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What is the most common congenital heart defect in cats?
VSD
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What is the specific location and pathophysiology of VSDs?
- most commonly high in the membranous septum
- small defects make a loud noise but may be non-symptomatic
- large defects may be quieter but shunt from high-pressure left to low-pressure right--> volume overload
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What are radiographic findings associated with VSDs? (7)
- enlarged pulmonary arteries and veins
- +/- RV enlargement
- +/- dilated pulmonary trunk
- cats: cardiomegaly on lateral rads, dilated/ tortuous pulmonary vessels, enlarged CVC, +/- pulmonary edema
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What are some possible locations of atrial septal defects? (2)
- ostium secundum: foramen ovale (middle)
- ostium primum: base of atrial septum at endocardial cushion (may be associated with tricuspid or mitral dysplasia)
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Describe the pathophysiology of ASD.
- small defects may be non-symptomatic
- large defects shunt from high pressure left to low pressure right
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What are radiographic findings associated with ASDs? (4)
- enlarged pulmonary arteries and veins
- RA enlargement
- +/- RV enlargement
- +/- MPA dilation
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Great vessel defects are often found as a result of...
regurgitation or "vomiting" (what the client thinks) after eating d/t extraluminal stricture at heart base
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What are the different vascular ring anomalies?
- persistent right aortic arch (most common) with left ductus arteriosus
- aberrant right subclavian artery
- double aortic arch
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