congenital heart disease

Question 1

patent ductus arteriosus cause

Answer 1

lack of inhibition of local prostaglandins

normally prostaglandins would cause an increase in smooth muscle proliferation and contraction leading to closure of the duct

Question 2

pathophysiology of PDA

Answer 2

continuous murmur

increased pulmonary flow and increased venous return via the pulmonic veins to the left side of the heart

volume overload on left side causes atrial and ventricular eccentric hypertrophy & increases left ventricular diastolic pressure

pulmonary edema

hyperkinetic pulse

dilation of proximal aorta and main pulmonary artery

Question 3

right to left shunting PDA

Answer 3

extremely rare

in dogs <6 months old

pressures in pulmonary artery and aorta tend to be similar

pulses not hyperkinetic

concurrent pulmonary hypertension

Question 4

what breeds are most commonly affected with PDA?

Answer 4

chihuahuas, collies, Maltese, other poodles, toy pomeraninans, shelties

Question 5

are males or females more likely to have PDA?

Answer 5

females 2x

Question 6

clinical findings of PDA

Answer 6

left sided congestive heart failure signs (tachypnea, coughing, etc)

arterial pulses-hyperkinetic

continuous thrill at left CD heart base

continuous murmur

point of maximal intensity of PDA-far cranial and high over left heart base

soft systolic mumur over mitral valve (secondary to increase in left ventricular size)

Question 7

ECG findings in PDA

Answer 7

may be normal

change consistent with left atrial and left ventricular enlargement (P wave prolonged)

R wave amplitude increased

+/- atrial and ventricular tachyarrhythmias in advanced cases (atrial fibrillation)

Question 8

thoracic radiograph findings of PDA

Answer 8

pulmonary overcirculation

dilation of main pulmonary artery and proximal aorta

left atrial and ventricular enlargement

Question 9

ECHO findings of PDA

Answer 9

perform to confirm dx and exclude other concurrent congenital heart defects

left atrial and ventricular dilation

spectral/color flow Doppler: abnormal retrograde flow via ductus into pulmonary artery

Question 10

natural history of PDA

Answer 10

64% will die within 1 year-remaining are likely to develop complications, some live full lives

px with correction for uncomplicated PDA cases: confers an outstanding long term px, considered to be curative

Question 11

treatment of PDA

Answer 11

ductal closure via surgical ligation or placement of transcatheter ductal occluder

perform ASAP

stabilize patients before sx

Question 12

subaortic stenosis

Answer 12

common and important congenital malformation of K9 heart

Newfoundlands!

develops progressively

usually subvalvular stenosis

Question 13

what happens following PDA occlusion?

Answer 13

the heart returns to normal

Question 14

clinical signs of Right to left PDA

Answer 14

hypoxemia

differential cyanosis

hind limb weakness

polycythemia

auscultation: no murmur, split S2 sound

Question 15

therapy for right to left PDA

Answer 15

don’t occlude

phlebomtomy-maintain PCV below 65% to prevent hypervisocity of blood

sildenafil, propranolol

Question 16

how does sildenafil work?

Answer 16

phosphodiesterase 5 inhibitor: increased cGMP and NO signaling

vasodilation of pulmonary arteries-reduction of pulmonary hypertension, decreased right to left shunt

Question 17

how does propranolol work?

Answer 17

non-selective beta-blocker

prevent exercised induced systemic vasodilation

Question 18

what is the first line of therapy for pulmonary hypertension?

Answer 18

sildenafil

Question 19

pathophysiology of pulmonic stenosis

Answer 19

primary malformation of pulmonic valve

causes right ventricular outflow tract obstructions from the muscular ridges and fibrous membranes

arterial obstructions

concentric hypertrophy

Question 20

signalment of pulmonic stenosis

Answer 20

dogs: english bulldog, scottish terrier, fox terrier, mini schnauzer, chihuahua

feline-rare

Question 21

clinical signs of pulmonic stenosis

Answer 21

most are asymptomatic during first year

syncope

exercise intolerance

cyanosis

abdominal distension

sudden death

Question 22

PE finding of pulmonic stenosis

Answer 22

left sided ejection (systolic) basilar murmur over pulmonic valve

prominent jugular pulse

prominent apex beat on right hemithorax

murmur of tricupsid regurgitation

Question 23

ECG finding of pulmonic stenosis

Answer 23

right ventricular enlargement

shift in MEA to right side

QRS complex negative

Tall p waves due to right atrial enlargement

Question 24

thoracic radiographs of pulmonic stenosis

Answer 24

right ventricular enlargement

prominent post-stenotic dilatation of main pulmonary artery

Question 25

Echo findings of pulmonic stenosis

Answer 25

confirm dx of pulmonic stenosis and evaluate severity of defect

concentric right ventricular hypertrophy with prominent papillary muscles and flattening/displacement of setpum towards the left

post stenotic dilation of pulmonary artery

doppler: Benoulli equation (change in P=4V²)

mild <50 mg, moderate (50 to 100), severe >100

Question 26

px of pulmonic stenosis

Answer 26

mild, moderate cases-can live a normal life

moderate to severe: exercise intolerance, extertional syncope, cardiac arrhythmias, secondary tricupsid regurgitation with right sided congestive heart failure and/or atrial fibrillation, sudden death

Question 27

therapy of pulmonic stenosis

Answer 27

balloon valvuloplasty: usually won’t re-restrict

Question 28

english bulldogs and pulmonic stenosis

Answer 28

no Left coronary arteries, a branch from right coronary artery runs over pulmonic artery leading to pulmonic stenosis

dont try balloon valvulopasty

Question 29

medical management of pulmonic stenosis

Answer 29

fish oil with omega 3 fatty aicds

beta blockers: atenolol or propanolol

patients with right sided CHF: diuretics, ACE inhibitors, abdominocentesis, positive inotropic drugs are CI (ie digoxin, pimendoben)

Question 30

subaortic stenosis

Answer 30

progressive

subvalvular stenotic ring consists of loosely arranged reticular fibers, mucopolysaccharide ground substance, and elastic fibers

coronary circulation can be abnormal

focal areas of myocardial infarction and fibrosis

Question 31

pathophysiology of subaortic stenosis

Answer 31

left ventricular outflow obstruction

left ventricular systolic pressure increases and systolic pressure gradient across outflow tract

concentric hypertrophyof LV

late and slow rising arterial pulse

systolic murmur and post stenotic dilatation of ascending aorta and aortic arch

left atrial concentric hypertrophy

severe: left sided heart failure

Question 32

signalment of subaortic stenosis

Answer 32

newfoundland, boxer, german shepherd and golden retriever, rottweilers, german short-haired pointers

Question 33

clinical findings of subaortic stenosis

Answer 33

asymptomatic

soft to moderately intense systolic murmur over aortic valve

sudden death

severe: exertional tiring, syncope or left side congestive heart failure

Question 34

PE of pulmonic stenosis

Answer 34

left systolic murmur: radiates to right cranial thorax, radiate through carotids

to and fro murmur-systolic and diastolic

arrhythmias

weak femoral pulses: late peak

Question 35

ECG of pulmonic stenosis

Answer 35

normal

left ventricular enlargement

significant S-T segment depression-indicator of myocardial ischemia and fibrosis

any ventricular arrhythmias should be considered important