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Flashcards in Congenital heart diseases Deck (47):
1

Patent ductus arteriosus (PDA)

Pathophysiology

 

  • Hereditary hypoplasia of the ductal smooth muscle causes the duct to remain open instead of colapsing at birth
  • Pulmonary artery resistance is lower than systemic resistance, blood shunts through the PDA from the aorta to the pulmonary artery (L to R shunt) --> volume overload of the L heart, eccentric hypertrophy, CHF
  • In very large PDAs, over circulation of the lungs may lead to inc. pulmonary vascular resistance --> flow in PDA shifts from L-R to R-L (usually ~6-8wks)
  • R to L shunting:
    • Over-circulation of the R heart which might lead to hypertrophy and R sided CHF
    • Blood in descending aorta has low PaO2 --> kidneys produce EPO --> erythrocytosis, hyperviscosity

2

Patent ductus arteriosus

Signalment

  • Seen commonly in toy and mini poodles, GSDs, and collies
  • Detected in puppies coming in for their first vaccine
  • More common in females
  • Cats die w/in a few weeks after birth with PDA

3

PDA

Probable owner complaint/usual history

Usualy asymptomatic; incidental finding during puppy vaccines

4

PDA

Common abnormalities on PE

  • Continuous machinery murmur--heard more in the dorsal 1/3 of the chest
    • Remember where defect is--have to listen under triceps
    • Murmur can sometimes only be heard at the thoracic inlet
    • Percordial thrill, bounding, water-hammer femoral pulse
  • Animals with R-L shunts may not have an audible murmur
    • Caudal cyanosis (vulva, penis)

5

PDA

Abnormalities found on special exam

  • Blood gas
    • Normal for L-R
    • Decreased caudal PaO2 and erythrocytosis in R-L
  • Rads
    • May see signs of L/R heart enlargement based on direction of shunt
    • May be able to see ductus diverticulum--best seen on DV
    • Prominent lung vessels in L-R shunts
      • Appear under-perfused in R-L
  • Echo
    • Signs of L/R heart enlargement
    • May see signs of elongated coniacl shape of the duct
  • Doppler--turbulence in the pulmonary artery distal to the pulmonic valve
  • Angiography
    • Aortic root or L heart injection to demonstrate L-R shunt
    • Jugular or R heart inj to see R-L shunt
    • Medium will fill pulmonary artries and aorta at the same time and allow for visualization of chamber enlargement
  • ECG--signs of L or R heart enlargement, arrhythmias if present

6

PDA

DDx

  • Concurrent aortic stenosis and aortic insufficiency
  • Pulmonic stenosis with regurg
  • VSD with aortic regurg
  • Aorticopulmonary window
  • Truncus arteriosus

7

PDA

Treatments

  • L-R
    • Surgical closure--isolated and tied closed with umbilical tape or closed with embolization coils or Amplatz canine duct occluders (ACDO)
    • Close ASAP if detected at young age (stabilize heart failure patients first)
  • R-L
    • Cannot surgically close--acute right heart failure
    • Treat clinical signs with medication

8

PDA

Prognosis

Prevention

  • Prognosis
    • W/o treatment 65% die w/in a year--most in heart failure by 16 months
    • 95% survive after surgery--excellent prognosis post-op
    • R-L shunts can be medically maintanined for 3-5 years at very low levels of activity
  • Prevention
    • Do not breed affected animals

9

Aortic stenosis

Pathophysiology

  • Fibrocartilaginous CT that completely or partially encircles aortic outflow tract
  • May be subvalvular (95% of dogs), valvular, or supervalvular
  • Increases afterload --> left ventricular concentric hypertrophy
  • Decreases diastolic filling and CO
  • Predisposes to ventricular dysrhythmias 

10

Aortic stenosis

Signalment

Probable owner complaint/usual history

  • Signalment
    • Genetically transmitted in Newfoundlands
    • Other predisposed breeds: boxers, rotts, retrievers, GSDs, GSHPs
  • Complaint/history
    • Incidental finding in asymptomatic dogs at puppy vaccines
    • Most common signs are syncope or sudden death
    • May not develop murmur until ~3 months of age

11

Aortic stenosis

Common abnormalities on PE

  • Systolic murmur loudest over L heart base, radiates up carotid
  • Hypokinetic femoral pulses
  • To-and-fro murmur and hyperkinetic pulses if aortic insufficiency and regurg present
  • Possible ventricular heave--apical impulse
  • VPDs

12

Aortic stenosis

Abnormalities found on special exam

  • Rads--appear normal
    • Concentric hypertrophy hard to detect
    • Dilation of ascending aorta (lateral view)
  • Angio--small left ventricular cavity, post-stenotic dilation of the aorta
  • Echo--concentric left ventricular hypertrophy, subvalvular echogenic ridge/band, narrowing of L ventricular outflow tract
  • M-mode--left ventricular hypertrophy
  • Dopler--inc. velocity across aortic valve w/ regurg
    • 1.5-3m/s = mild
    • 3-4.5m/s = moderate
    • 4.5-5m/s = severe
    • <2.4m/s and no abnormalities seen = uncertain--recheck 
  • Catheterization--pressure gradient across the aortic valve
    • <40mmHg = mild
    • >80mmHg = severe and high left ventricular end-diastolic pressure
  • ECG--usually normal
    • L ventricular enlargement
    • ST depression
    • VPD

13

Aortic stenosis

DDx

  • Atrial setal defect
  • Other causes of continuous murmurs or syncope
  • Physiological murmurs
  • Bact. endocarditis of aortic valve

14

Aortic stenosis

Treatment

  • Beta-blockers
    • Recommended in cases of syncope, moderate-severe gradients (~4m/s), ventricular arrhythmias or ST changes
    • Do not change pressure gradient, but reduce clinical signs and decrease risk of sudden death (antiarrhythmic, dec. myocardial O2 demand)
    • Warn owners that these drugs cannot be stopped abruptly--must titrate
    • Maximum safe dose 
    • May improve diasstolic function--improve distensibility and diastolic filling
    • Caution: (-) inotropic/chronotropic effects 
  • Sx correction or balloon valvulolasty--lowers pressure gradient, but does not inc. survival rate
  • Positive inotropes contraindicated
  • Dogs w/ CHF: standard therapy w/ diuretics and vasodilators should be used

15

Aortic stenosis

Prognosis

Prevention

  • Prognosis
    • Progressive (rapid in young dogs)
    • ~20% die suddenly before 3yrs of age
    • Depends on severity of lesion:
      • Severe: ~70% die before age 3
    • >3yrs old--usually mild lesion
      • Dependent on severity of outflow velocity and pressure gradient
        • <4m/s = normal life
        • >5m/s = likely to succumb 
    • Predisposed to endocarditis
  • Prevention--do not breed affected dogs (dogs >12mo can be certified free of congenital heart dz)

16

Pulmonic stenosis

Pathophysiology

  • Stenosis may be subvalvular, valvular (88%), or supravalvular
  • Valve cusps may be fused
  • Commonly dysplastic--thickened and asymmetrical
  • Sometimes hypoplastic--valve annulus
  • Causes concentric hypertrophy of the R ventricle
  • High velocity through stenotic valve causes post-stenotic dilation of the pulmonary artery trunk
  • R atrium enlarged due to R ventricular filling ressures
  • May predispose to arrhythmias

17

Pulmonic stenosis

Signlament

Probable owner complaint/usual history

  • Signalment
    • Most common in English bulldogs, Scottish terriers, mini schnauzers, and wirehaired fox terriers
    • Polygenic in beagles
  • Complaint/history
    • Incidental finding during pupy vaccines
    • If clinical signs are present the lesion is more severe and forward heart signs are seen

18

Pulmonic stenosis

Common abnormalities on PE

  • Systolic heart murmur of L heart base
    • Radiates up the neck
  • Possible R CHF signs
  • Pulses and mm mostly normal

19

Pulmonic stenosis

Abnormalities found on special exams

  • Rads
    • R ventricular enlargement (inc. sternal contacton lat view) w/ post-stenotic dilation of the pulmonary trunk (1:00) on VD/DV views
    • Possible ascites and hepatomegaly
  • Echo
    • R ventricular hypertorphy, flattened sternum, large R atrium, restricted motion of the pulmonic valve
    • Post-stenotic dilation
  • M-mode--thickened septum and R ventricular free wall
  • Doppler
    • Velocity across pulmonic valve >1.2m/s suggests pulmonic stenosis (esp. if >2.0m/s)
    • Inc. pressure gradient
      • >80mmHg = severe
      • 10-50mmHg = mild
      • Pulmonic regurg
  • Angio
    • Narrowed passage in valve area
    • Thickened valves, post-stnotic dilation
  • Catheterization--gradient across pulmonary valve region
  • ECG--R ventricular enlargement; occasionally arrhythmias

20

Pulmonic stenosis

DDx

 

  • Subaortic stenosis
  • Aortic septal defects

21

Pulmonic stenosis

Treatment

  • Balloon valvuloplasty
    • Recommended for dogs with severe to moderate stenosis, those with clinical signs, or with moderat to severe right ventricular concentric hypertrophy/fibrosis/ischemia
    • Balloon catheter inserted via jugular vein, inflated at stenotic valve--tears stenotic tissue and reduces narrowing
    • Post-dilation pressures should be <50mmHg
    • Control heart failure and dysrhythmias as necessary pre-op
  • Annular ring hypoplasia or infundibular hypertrophy--patchgraft valvuloplasty
  • Single right coronary type R2A (bulldogs, boxers)--right ventricular to pulmonary artery conduit
  • Atenolol can be used to try and imrove diastolic function and arrhythmias if sx not possible

22

Ventricular setal defect (VSD)

Pathophysiology

  • Failure of development of the setum between the ventricles
  • Severity depens on size of defect
  • Most occur in the membranous part of the septum allowing blood to flow from the L ventricle directly to the pulmonary arteries--> minimal effects of the R ventricle
  • Volume overload of the L ventricle results from increased venous return--L heart enlargement and poss. failure
  • Larger openings and those lower down the septum can increase the pressure in the R ventricle and lead to R heart enlargement as well

23

VSD

Signalment

Probable owner complaint/history

  • Signlament
    • More common in cats
    • English bulldogs and keeshonds predisposed, but can occur w/o familial history
  • Complaint/history
    • Smaller defects usually incidental findings during pediatric vaccinations
    • Animals w/ larger defects may be stundted and exhibiting signs of L sided heart failure (syncope, organ dysfunction, exercise intolerance)

24

VSD

Common abnormalities on PE

  • Systolic murmur--loudest over R sternal border
  • Smaller defects will have louder murmurs
  • Possible thrill over R hemithorax

25

VSD

Abnormalities found on special exams

  • Rads
    • Prominent pulmonary vessels
    • Signs of L heart enlargement--'tracheal bump'
    • Trachea in line w/ spinal column
    • If R heart enlarged may see inc. sternal contact
  • Echo
    • Can be seen and measured--need to distinguish from 'septal drop out' (common artifact)
      • Contrast can be used 
    • Enlargement
  • Doppler
    • Definitive diagnosis by documenting L-4 flow
    • Can calculate size of the defect
  • Angio
    • Dye injected into L heart will enter R ventricle during systole
    • Die inj. into R heart will appear diluted after dye-free blood enters during systole
  • ECG
    • May show L/R heart enlargement
    • oss. right bundle branch block

26

VSD

DDx

Prognosis

Prevention

  • DDx
    • Loud R-sided murmur possibly diagnostic
  • Prognosis
    • Mild-moderate = good to excellent
    • Occasionally defect will spontaneously close
    • Development of pulmonary hypertension w/ R-L shunting results in a poorer prognosis (6 mo)
  • Prevention
    • Do not breed animals w/ defect

27

VSD

Treatment

  • Small VSDs--no treatment required, some may spontaneously close
  • Severe VSDs
    • Surgical repair is an otion but will require bypass--open heart surgery
    • Pulmonary banding--decreases the diameter of the pulmonary arteries --> increase resistance and decrease shunting across the defect --> less volume overload
  • Arterial vasodilators--asymptomatic animals with L heart enlargement
    • Reduce degree of L-R shunting
    • Hydralazine used--beware of GI upset, monitor BP closely

28

Tetralogy of Fallot

Pathophysiology

  • Lesion includes: pulmonic stenosis, overriding aorta (dextropositioning), VSD, hypertrophy of the R ventricle
  • Hemodynamic consequences depend on size of VSD and extent of pulmonic stenosis
    • Less severe stenosis will result in a presentation similar to VSD
    • L-R shunting--rare
    • Severe stenosis more common, and R-L shunting occurs
    • Deoxegenateed blood is nnot pumped into the lungs and instead goes out into circulation --> cyanosis and kidney EPO prod.
    • CHF rarely occurs b/c the R-L shunting allows both ventricles to share the increase pressure 
  • Right ventricular hypertrophy predisposes to arrhythmias

29

Tetralogy of Fallot

Signalment

Probable owner complaint/history

  • Signalment
    • Autosomal recessive in Keeshond
    • Wirehaired terriers and English bulldogs predisposed
  • Complaint/history
    • Stunted growth
    • Exercise intolerance
    • Shortness of breath
    • Syncope

30

Tetralogy of Fallot

Common abnormalities on PE

  • Murmur heard during 1st vaccine visit (both sides of chest) and most patients are cyanotic
  • Might be a systolic murmur of pulmonic stenosis at the L heart base and a VSD murmur on the right
  • Murmurs may be very soft if there is erythrocytosis, severe stenosis, or minimal flow through the VSD

31

Tetralogy of Fallot

Abnormalities found on special exams

  • Lab--erythrocytosis, inc. PCV 60-70%
  • Rads--R heart enlargement, small pulmonary vessels
  • Echo
    • Overriding aorta and VSD
    • Hypertrophy of R ventricle
  • Doppler--inc. peak flow across pulmonary valve, shunting through VSD
  • Angio--ID's the VSD, R ventricular hypertrophy, pulmonic stenosis, and direction of the shunt
  • Catheterization--measurement of the pressure gradient across the VSD
  • ECG--possible R ventricular enlargement

32

Tetralogy of Fallot

DDx

Prevention

  • DDx = other causes of cyanosis
  • Prevention = do not breed animals w/ this defect

33

Tetralogy of Fallot

Treatment

Prognosis

  • Surgical procedures to re-route blood--variable success
    • Subclavian attached to pulmonary artery to increase oxygenation or connect aorta to pulmonary artery--like PDA
  • Beta blockers--possibly lessen MVO2 of R ventricle or imrove distensibility
  • Hydroxurea--anti-cancer drug, blocks RBC production
  • Phlebotomies and replace blood with sterile saline; low dose aspirin to prevent thromboembolism
  • Vasodilators are contraindicated--will make R-L shunting worse and increase hypoxia
  • Prognosis--depends on the severity; some dogs live a long (though inactive) life

34

Atrial septal defect

Pathophysiology

  • "Common atrium"
  • Blood flows to right atrium because of its thinner, distensible walls
  • R ventricular enlargement due to volume overload
  • Enlarged pulmonary vessels
  • L-R shunt

35

Atrial septal defect

Signalment

Probable owner complaint/history

  • Signalment--found in younger animals during pediatric vaccinations
  • Complaint/history
    • Small defects present asymptomatically
    • Larger defects may present with heart failure signs

36

Atrial septal defect

Common abnormalities seen on PE

Abnormalities found on special exam

DDx

  • PE
    • Possible murmur heard over L heart base
    • May hear splitting of S2
  • Rads--R heart enlargement, prominent pulmonary vessels
  • DDx--pulmonic or aortic stenosis

37

Atrial septal defect

Treatment

Prognosis

Prevention

  • Treatment
    • Dependent on size of the defect--most with small defects will remain asymtomatic
    • Surgical correction of large defects will require bypass
  • Prognosis--depends on size; worse if tricuspid stenosis is also involved
  • Prevention--don't breed

38

Atrioventricular valve malformations

Pathophysiology

  • Thickened or fused valves
  • Papillary muscles that are malpositioned, partially developed, or absent
  • Chordae tendinae that are too long, too short, or absent
  • Valvular insufficiency most commonly seen with dyslastic valves failing to meet during systole--> regurg and volume overload
  • Valvular stenosis (rare)--stenotic valves decrease ventricular filling during diastole --> inc. atrial pressure and CHF

39

Atrioventricular valve malformations

Signalment

Probable owner complaint/history

  • Signalment
    • Most common congenital malformation in cats
    • Large breed dogs may be predisposed
  • History
    • Signs depend on the valve involved--L or R CHF signs

40

Atrioventricular valve malformations

Common abnormalities seen on PE

Abnormalities seen on special exam

Valve insufficiency--depend on valve affected

41

Atrioventricular valve malformations

DDx

Prevention

  • DDx
    • Other causes of diastolic murmurs--PDA, possible aortic stenosis
  • Prevention--don't breed

42

Atrioventricular valve malformations

Treatment

Prognosis

  • Treatment
    • Furosemide and an ACE inhibitor
    • Arterial vasodilators may be helpful by reducing regurg and promoting forward flow
    • Low sodium diet may be helpful
  • Prognosis
    • Depends on severity of defects

43

Endocardial fibroelastosis

All the things

 

  • Seen more in Burmese and Siamese kittens
  • Fibrosis of ventricular endocardium--> stiffening of walls--> decrease ability to dilate and fill during diastole
  • Left CHF by the time the animal is 2-4mo
  • No treatment

44

Persistent right aortic arch (PRAA)

Pathophysiology

Signlament

  • Vascular ring formed by the ligamentum arteriosus dorsally, aorta to the right, pulmonary artery to the left, and cardiac base ventrally--constricts esophagus and trachea
  • Signalment: common occurrence in GSDs

45

PRAA

Signs

Abnormalities on special exam

  • Signs
    • Megaesophagus cranial to the constriction = regurg of solid food
    • Asymptomatic at young age (liquid diet)
  • Rads: esophageal dilation cranial to the heart base

46

PRAA

Treatment

Prognosis

DDx

  • Treatment--surgical ligation and transection of LA
  • Guarded prognosis--esophageal fx may remain abnormal
    • Animals at risk for aspiration pneumonia
  • DDx: congenital megaesophagus

47

Inherited ventricular arrhythmias in GSDs

All the things

  • Possible genetic link in some lines of GSDs, otherwise idiopathic
  • Starting at 3 months, animals may be affected w/ mild VPDs or eisodes of VT and poss. sudden death
  • Severity will inc. until 7mo and then decreases
    • By 18mo risk of sudden death is markedly dec.
  • Severely affected animals can be given sotalol and mexiletine to dec. episodes of VT (does not prevent sudden death)
    • Sotalol alone is roarrhythmogenic and mexiletine alone has no affect
    • Drug trtmt until animals are 18 mo to 2 yrs