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C & R II - wk1 > congenital heart disease in SA > Flashcards

congenital heart disease in SA Flashcards

1
Q

pressure -overload

what are the causes of outflow obstruction

A

congenital outflow tract obstruction

  • pulmonic stenosis
  • sub-aortic stenosis

high afterload

combo of both

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2
Q

what is pressure overload

A
  • consequence of outflow tract obstruction: (sub-) valvular stenosis
  • increased reistance to the ventricular systolic outflow
  • proportionate increase in ventricular pressure if flow remains constant
  • pressure = flow x resistance
  • increased wall stress leads to increased ventricular muscle mass (hypertrophy) - eccentric
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3
Q

what are the clinical signs due to outflow tract obstruction

A
  • secondary to ventricular hypertrophy leads to reduced ventricular filling capacity
  • during exercise when heart rate is high, the filling is even more impaired
  • when cardiac output drops to a critical amount, cerebral hypoperfusion ensues (weakness or fainting)
  • ventricular or atrial arrhythmias due to ischemic scars in myocardium (fainting, sudden death)
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4
Q

what is pulmonic stenosis

A

a dynamic or fixed anatomic obstruction to flow from the right ventricle to the pulmonary arterial vasculature

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5
Q

what breeds are predisposed to pulmonic stenosis

A
  • bullmastif
  • beagle
  • bulldog
  • spaniel
  • keeshond
  • schnauzer
  • chihuahua
  • terrier breed
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6
Q

what can pulmonic stenosis be due to

A
  • isolated valvular (majority) obstruction
  • subvalvular obstruction
  • suprevalvular obstruction
  • may be found in association with more complicated congenital heart disorders
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7
Q

what is type A valvular stenosis

A

lack of division of valve leaflets (fusion)

normal dimension of annulus

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8
Q

what is type B valvular stenosis

A

hypoplastic valve annulus and thickened leaflets

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9
Q

what is coronary malformation

A
  • engl. bulldog
  • aberrant left coronary artery encircles PA-causing narrowing
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10
Q

what are the clinical signs of PS

A
  • none: diagnosis incidental during puppy well visit
  • exercise intolerance
  • syncope
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11
Q

what are the physical exam findings of patient with PS

A
  • systolic murmur 4-6/6 loudest over left 3rd ICS
  • arterial pulses: normal
  • mucous membranes: pink
  • ascites (rare)
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12
Q

what are the 3 diseases that can be associated with a systolic ejection murmur that is diamond shaped

A
  • aortic stenosis
  • pulmonic stenosis
  • ventricular septal defect
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13
Q

what are the characteristics of PS on chest x-ray

A
  • “reverse D” due to enlargement of the right ventricle (hypertrophy from chronic pressure overload)
  • enlarge PA (post stenotic bulge)
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14
Q

what diagnostic plan provides a definitive diagnosis for PS

A

echocardiography

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15
Q

what are characteristics of PS on echo

A
  • RV hypertrophy and dilation
  • fused or thickened and relatively immobile pulmonic valve cusps
  • turbulent blood flow across the stenosis
  • post stenotic pulmonary artery dilation
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16
Q

PS

what does doppler allow us to estimate

A
  • intra-cardiac pressure
  • calculation of pressure difference (gradient) between the right ventricle and pulmonary artery
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17
Q

what is the Bernoulli equation

A

pressure gradient: 4 x velocity^2

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18
Q

how is the velocity of blood flow across the stenosis measured

A

by echo and used to asses the severity of disease

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19
Q

what are characteristics of PS using angiography

contrast

A
  • hypertrophy of RV walls
  • post-stenotic dilation of the main pulmonary artery
  • filling defect at level of pulmonary valves
20
Q

what is the prognosis of PS

A
  • mild (0-50mmHg) - may need no intervention, good long term prognosis
  • moderate (50-85mmHg) - may or may not need valvuloplasty
  • severe (>85mmHg) - baloon dilation valvuloplasty -or for moderate with more than mild TR or R-L atrial shunt
21
Q

how to tx PS

A
  • beta blocker therapy (atenolol) to decrease HR during excercise and reduce RV hypertrophy; reduce myocardial O2 consumption
  • baloon valvuloplasty
22
Q

what is pulmonic stenosis coronary anomaly

A
  • engl. bulldogs and some boxers may have an anamolous left main coronary artery arising from a single right coronary artery associated with the stenosis
  • associated with an increased risk of balloon valvuloplasty b/c of the risk of avulsion of the left coronary artery during insufflation of the balloon and subsequent rupture of the left coronary
23
Q

what is breeding advice for PS

A
  • affected individuals and their parents should not be used for breeding
  • siblings should only be used after careful screening
  • if any affected offspring are born, breeding of the parents should be discontinued
24
Q

key points

PS most commonly occurs due to:

A
  • commissural fusion
  • dysplasia of valve leaflets
25
Q

key points

what type of murmur is heard with PS and where is it located

A
  • loud systolic ejection murmur
  • left base of the heart
26
Q

key points

how is the difinitive diagnosis of PS achieved

A

echo

27
Q

key points

when should balloon valvuloplasty be considered with PS

A

in moderate to severe cases

28
Q

what is subaortic/aortic stenosis (SAS/AS)

A
  • 1st or 2nd most common defect in dogs
  • subvalvular > valvular > supravalvular
  • breed predisposition: golden retriever, newfoundland, boxer, german shepard, rottweiler, bull terrier, bloodhound
29
Q

what is subvalvular aortic stenosis

ridge

A
  • ridge and may not be apparent at birthbut may become more obvious between 4 and 12 months of age
  • ridge increases “work” of heart and causes permanent damage to muscle
30
Q

what are the clinical signs of SAS

A
  • none: diagnosis incidental during puppy well visit
  • or exercise intolerance, syncope, sudden death
31
Q

what are the PE findings with SAS

A
  • systolic murmur 1-6/6 loudest over left 3rd or 4th ICS, may radiate to right side and up carotid arteries
  • murmur appears/increases until 1 yr old
  • femoral pulses can be weak if stenosis is severe
32
Q

what diagnostic plan to use for a definitive diagnosis or AS

A

echocardiography

33
Q

characteristics of AS on echo

A
  • may demonstrate LV hypertrophy
  • subaortic ridge or ring may be visible
  • turbulent blood flow across the stenosis
  • may observe post-stenotic aortic buldge
34
Q

what is the prognosis of SAS

A
  • mild (<50mmHg): no innervention needed, good prognosis
  • moderate (50-80): likely normal
  • servere (80-130): survival: 2.8 years vs 8.3 yrs if gradient less than <133
  • servere SAS (>130): 2.8yrs, high risk for sudden death in the first 3 yrs of life - 70% mortality
35
Q

what are 3 complications of SAS

A
  • sudden death
  • infective endocarditis of the aortic valve
  • congestive heart failure (usually late in life)
36
Q

what is the medical management of SAS

A

beta blockers

  • HR reduction: reduce myocardial O2 consumption
  • suppress arrhythmias
  • but no benefits on survival shown
37
Q

what are the interventional options for management of SAS

A
  • subvalvular ridge is not as amendable to standard balloon dilation
  • cutting balloon
38
Q

what is PDA

A

smooth muscle hypoplasia in ductus - failure of ductus to close

39
Q

what does PDA result in

A

significant shunting of blood from the descending aorta to the pulmonary artery (left to right)

40
Q

what breeds are predisposed to PDA

A
  • small dogs (bichon, chihuahua, small mixed, yorkie, poodle, etc)
  • german shepard, newphoundland, boxer, bullmastif, etc
  • females > males
41
Q

what is the clinical presentation of PDA

A
  • 75% cases are asymptomatic
  • 25% - coughing, exercise intolerance (CHF)
42
Q

what are the PE findings of PDA

A
  • continous murmur
  • loudest over left heart base
  • systolic and diastolic aortic pressures normally exceed pulmonary artery presssures, shunting is continuous throughout cardiac cycle
43
Q

what type of pulses are found with PDA

A

bounding femoral pulses

44
Q

how to definitively diagnose PDA

A

echo

45
Q

what are the characteristics of PDA on rads

A
  • cardiomegaly: LA and LV
  • pulmonary over-circulation (increased size of lobar vessels - arteries and veins) and increased vascularity
46
Q

what is the management of PDA

A
  • ductus should be closed to stop volume overload: prevent heart failure
  • minimally invasive (catheter based) - ACDO, coil embolization
  • surgical ligation (toy breeds and german shepards)

C & R II - wk1 (13 decks)

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