Congenital Heart Diseases Flashcards
What is a congenital heart disease?
persistent fetal circulation after birth or failure of normal cardiac development
- FETAL CIRCULATION = PDA, patent foramen ovale
- POOR NORMAL DEVELOPMENT = valvular dysplasia, ASD, VSD
What are the 3 ways blood can flow through the fetal RA?
- FORAMEN OVALE - shunts RA to LA to aorta since lung circulation is not as important in utero (closes at birth when LA pressure rises)
- DUCTUS ARTERIOSUS - shunts blood from PA to descending aorta (constricts after birth)
- PULMONARY ARTERY - RA to RV to PA, but high pressure tends to shunt less to the lungs
What 4 things happen to the CVS of fetuses when they are born?
- lung expansion - decreases pulmonary resistance, regresses right heart, remodels pulmonary arterioles
- left heart expansion
- closure of FO due to increasing LA pressure
- closure of DA with decreased PGE2 and increased oxygen tension
What are important questions for diagnosing congenital heart disease in dogs and cats?
- Is there a murmur in a young animal or is the history suggestive of CHD?
- What are the characteristics of the murmur? (location, timing, pulse quality)
- Is signalment supportive? (male vs. female, breed, age)
- Is the full history of the littermates, dam, sire, or relatives available?
- Do signs suggest CHD? (lethargy, exercise intolerance, respiratory signs, collapse, cyanosis, high PCV)
- Does patient need to be stabilized before transfer to specialist?
- What are the next steps for imaging? (rads, echo)
- Is watching and waiting an option?
- Is medical management indicated?
- Are surgical, catheter-based, or hybrid treatment options available?
- What is the prognosis with and without treatment?
- Can the animal have anesthesia for an elective procedure?
What genetic and sex predilection is associated with PDA?
SMALL BREEDS - Poodles, Yorkies, Maltese, Pomeranian, Bichon, Chihuahua, Cocker
mostly female (2:1)
What is the normal function of the ductus arteriosus? What likely causes it to remain patent?
shunts fetal blood away from nonfunctional lungs by connecting MPA to the descending aorta (should close within a few hours or birth and securely closed by 7-10 days)
lack of smooth muscle responsible for closing it
What results from a PDA? What does this cause?
left (systemic) to right (pulmonary) shunting
left-sided volume overload —> pulmonary over circulation, LA and LV dilation
What 2 physical exam findings are indicative of a PDA?
- heart murmur - PMI in left basilar region, continuous machinery sounding (continuous L to R shunting)
- hyperkinetic, water hammer, bounding pulses
How do most puppies present with PDA? What are clinical signs associated with?
asymptomatic (64% die of complications within 1 year)
size of shunt —> once tachypnea, coughing, exercise intolerance, and syncope develop, there is a high risk of death unless therapy can be initiated
What is seen on thoracic radiographs in cases of PDA?
- LA and LV enlargement
- ductal bump - bulge in descending aorta
- dilated MPA
- pulmonary venous and arterial distension
+/- pulmonary edema
What is occurring in this radiograph?
- enlarged LA
- ductal bump
- elongated cardiac silhouette
- congested pulmonary veins compared to arteries
PDA, radiographs:
- 3 knuckle sign - enlarged ductus diverticulum, descending aorta, and MPA/left auricle
- enlarged pulmonary veins/arteries
What 3 things are seen on echocardiography in cases of PDA?
- continuous retrograde flow into the PA
- LA and LV enlargement
- mitral regurgitation
What surgical treatment is available for PDA? What needs to be done prior?
- transarterial occlusion with Amplatz ductal occlude or coil embolization
- surgical ligation - smaller dogs/cats
(prognosis excellent with treatment)
treat CHF
What is reverse PDA? What does this result in?
persistent fetal pulmonary circulation causes pulmonary hypertension and a large DA causes no resistance to blood flow
pulmonary pressure rises dramatically due to pulmonary hypertension, which causes blood to flow from MPA into the descending aorta (Eisenmenger physiology)
What is the ultimate result of reverse PDA? What are 4 signs?
right to left shunt (less blood goes into lungs, deoxygenated blood enters systemic circulation)
- differential cyanosis of caudal mucous membranes and normal pink cranial membranes
- RV hypertrophy
- polycythemia secondary to hypoxia
- collapse with exercise, hind limb weakness
How does diagnosis of reverse PDA compare to normal PDA? What is commonly seen on echo?
typical murmur is absent, diagnosis is based on clinical suspicion and diagnostic tests
evidence of pulmonary hypertension and bubbles in descending aorta with agitated saline contrast (blood goes into systemic circulation rather than into the lungs, which would normally clear the bubbles)
How does treatment compare with reverse PDA? What are 3 options? What is prognosis like?
CANNOT occlude PDA
- Sildenafil - vasodilator treats pulmonary hypertension
- phlebotomy - done when PCV > 70% to get to a target of 60-65% (remove 10-20 mL/kg and replace same amount with fluids)
- Hydroxyurea, Cyclophosphamide - suppress erythropoiesis (may cause excessive BM suppression)
3-5 years
What is the cause of pulmonic stenosis? What is the most common location?
genetic/mutation —> varying degree of narrowing (thickened/fused leaflets, hypoplastic/narrow valve annulus)
valvular - dysplastic valve leaflets obstruct outflow where increased pressure is required to push through (RV hypertrophy)
What can cause subvalvular pulmonic stenosis?
- coronary artery anomalies
- concurrent abnormality in certain breeds - English Bulldogs, Boxers
What breeds are predisposed to developing pulmonic stenosis? What breed has a sex predilection?
SMALL BREEDS > large breeds
- Beagles, Boxers, Bulldogs
- Chihuahua
- Labs
- Chow Chow
- Mini Pin
Bulldogs - M>F
What does pulmonic stenosis lead to?
dysplastic valve leaflets cause pressure overload because more pressure is needed to push blood through —> RV hypertrophy with secondary RA enlargement
What 3 things are seen on radiographs and echo in cases of pulmonic stenosis?
- RV hypertrophy
- post-stenotic dilation - pulmonary artery dilated due to high velocity of blood hitting the wall
- severely high velocity of blood (> 80 mmHg) with Doppler
What history is associated with pulmonic stenosis? What 2 things are seen on PE?
- asymptomatic to right-sided CHF
- exercise intolerance
- syncope
- murmur - systolic, left basilar PMI (most cranial valve!)
- normal pulses
What are 3 late changes associated with pulmonic stenosis?
- right-sided CHF
- jugular venous distension
- distended abdomen
What 3 things are seen on thoracic radiographs in cases of pulmonic stenosis?
- RA and RV enlargement
- dilated MPA
- pulmonary underperfusion
+/- right-sided CHF —> ascites or pleural effusion
What is commonly seen on ECG with pulmonic stenosis?
tall P waves (P pulmonale) due to RA enlargement
Pulmonic stenosis, radiograph:
heart base bulge of MPA
Pulmonic stenosis, radiograph:
bulging MPA
What 4 things are seen on echo in cases of pulmonic stenosis?
- thickened, immobile PV leaflets
- turbulent, high velocity flow across PV
- post-stenotic dilation
- RV hypertrophy
+/- patent FO
What are the 3 severities of pulmonic stenosis?
- severe = >80 mmHg - right-sided CHF, exertional syncope, serious arrhythmias
- moderate = 50-80 mmHg
- mild = 30-50 mmHg - asymptomatic, normal life span)
How does pulmonic stenosis compare to aortic stenosis?
animal born with it and it does not typically worsen —> prognosis can be determined when full grown
aortic stenosis is progressive —> not present at birth, develops over first 4-8 weeks, may not hear a murmur until 2 y/o
What treatments are recommended for the 3 severities of pulmonic stenosis?
- MILD = no treatment
- MODERATE = Atenolol (decreases O2 consumption and obstruction from hypertrophy) +/- balloon valvuloplasty
- SEVERE = Atenolol, balloon valvuloplasty
In what 2 situations are balloon valvuloplasties contraindicated in cases of severe pulmonic stenosis?
- concurrent balanced shunts - VSD, ASD
- coronary anomaly
What is the most common congenital cardiac malformation in large-breed dogs?
subaortic stenosis —> subvalvular ridge or ring of fibrous tissue can cause dynamic obstruction of LV outflow or SAM
What breeds predilection is seen with subaortic stenosis? Is it seen in cats?
LARGE BREED DOGS - Newfoundlands, Goldens, GSDs, Rottweilers, Boxers, Bouvier des Flander, Bull Terrier
seen in cats with HOCM causing LVOT obstruction (dynamic, not associated with valve)
What 5 things result from subaortic stenosis?
- outflow tract obstruction causes pressure overload to LV - fibrous/fibromuscular subvalvular
- concentric hypertrophy - poor ventricular filling and coronary perfusion
- secondary mitral regurgitation
- arrhytmias
- low output failure = exercise intolerance, syncope, sudden death
What is the sequelae of mild-moderate and severe subaortic stenosis?
MILD-MODERATE = 30-80 mmHg, normal life span
SEVERE = >125 mmHg, signs within first 3 years due to LVOT obstruction causing LV concentric hypertrophy - ischemia, ventricular arrhythmias, sudden cardiac death, LS-CHF, exertional syncope
What are dogs with subaortic stenosis predisposed to?
endocarditis
How do most patients present with subaortic stenosis?
- murmur- systolic crescendo/decrescendo, left basilar PMI
- decreased pulses
- pulsus parvus et tardus - weak and late pulses
What 4 things are seen on radiographs in cases of subaortic stenosis?
- post-stenotic dilation of ascending aorta
- loss of cranial waist on lateral views
- widened mediastinum on DV views
- LV and LA enlargement +/- pulmonary edema
Subaortic stenosis, radiograph:
post-stenotic dilation
What are 4 signs on ECG in cases of subaortic stenosis?
- tall R waves due to ventricular enlargement
- depression/elevation of ST segments indicative of ischemia
- wide P waves (P mitrale) due to LA enlargement
- ventricular or atrial arrhythmias
What 4 things are seen in echos in cases of subaortic stenosis?
- turbulent/elevated flow in LVOT
- visible subaortic ridge/ring
- LV concentric hypertrophy
- mitral regurgitation
Subaortic stenosis, echo:
LVOT obstruction
What treatments are recommended for the 3 severities of subaortic stenosis? What can be done prophylactically?
- MILD = no treatment
- MODERATE = exercise restriction +/- Atenolol to decrease HR, myocardial O2 demand, and afterload
- SEVERE = Atenolol, cutting balloon valvuloplasty, treat CHF if present, exercise restriction
broad spectrum antibiotics to prevent endocarditis
Congenital heart defects:
What are the 3 most common types of septal defects?
- ASD - PFO, secundum defect, primum defect, sinus venosus defect, coronary sinus defect
- VSD - membranous, perimembranous, muscular
- AV septal defect
What genetic risk factors are associated with ASD, VSD, and AVSD?
ASD - Poodles, Boxers, uncommon!
VCS - cats, small ruminants > Keeshond
AVSD = endocardial cushion defect in cats
What is the degree of shunting with septal defects associated with? What do they cause?
size of defect —> larger hole = larger defect
left to right shunting - blood goes into the lungs (lower pressure) and cause pulmonary overcirculation, and ultimately LS-CHF
- cats with AVSD can develop right AND left CHF very early
What occurs with ASDs? What causes an associated murmur?
blood shunts from LA to RA and into low-pressure RV, then LUNGS = overcirculation
increased preload in the RV and into the pulmonary system (turbulent flow!) = left basilar systolic murmur
What portion of the ventricular septum is most commonly associated with defects? What 2 results are seen?
membranous portion —> just below aortic valve, top of septum
- systolic murmur loudest on right side (L to R shunt of blood)
- volume overload into RV = hypertrophy, pulmonary overflow
How does a large VSD compare to a smaller one?
- large = softer murmur due to pressure equilibriating
- large = more severe
What 2 signs are indicative of VSD on radiographs?
- right side enlargement secondary to volume overload (smaller shunts)
- pulmonary overcirculation and left sided cardiomegaly (large shunts)
- usually normal!
What treatment is recommended for small shunts resulting from VSDs?
hemodynamically insignificant - no therapy requires, may close by 2 y/o
What interventions are available for larger shunts resulting from VSDs? Surgery?
- ASD and VSD devices available, but must be in a fixable location
- occlusion devices
- pulmonary banding
- not commonly possible for cats
typically not available
What is Eisenmenger’s syndrome?
severe pneumonia in young animals with VSD resulting from pulmonary circulation —> pulmonary hypertension —> shunt reversal (R to L)
- cyanosis, polycythmia
What breed has a predilection for developing Tetralogy of Fallot? What 4 cardiac changes are seen?
Keeshonds, English Bulldogs
- VSD
- pulmonic stenosis - valvular/infundibular
- RV hypertrophy
- overrriding (dextrapositioned) aorta - sits above septum
What signs are associated with Tetralogy of Fallot?
- exertional weakness
- dyspnea
- syncope
- cyanosis due to R to L shunt (VSD)
What does Tetralogy of Fallot result in? What is seen on PE?
right to left shunting —> less oxygenation
- holosystolic right sternal murmur
- systolic ejection murmur at left base
- polycythemia - due to hypoxia, hyperviscosity
What imaging is used to diagnose Tetralogy of Fallot?
RADIOGRAPHY - underperfused lungs, reduced pulmonary vasculature, RV hypertrophy
ECHO - visualize defects, Doppler
What is the consequence of Tetralogy of Fallot? What surgical and medical treatment is recommended?
shunting of unoxygenated blood to systemic circulation causes cyanosis, polycythemia, and right-sided CHF
- SX = open heart bypass, subclavian anastomosis between aorta and pulmonary artery, conservative balloon valvulopasty to balance VSD
- MEDICAL = phlebotomy or bone marrow suppression for polycythemia, beta-blockers for outflow obstruction
What is valvular dysplasia? What 2 are most common? What do they lead to?
any malformation of the valve leaflets, chordae tendineae or papillary muscles, resulting in regurgitation
- mitral valve = left-sided CHF
- tricuspid valve = right-sided CHF (Labradors)
- both can result in stenosis and impedance of ventricular filling (stenosismitra)
What dogs are predisposed to mitral dysplasia? How are the valves most commonly affected?
- Bull Terriers
- GSDs
- Great Danes
- M>F
shortened/elongated chordae, abnormal attachment of leaflet/cup to chordae
What are the 2 most common results of mitral valve dysplasia?
- mitral valve regurgitation - left-sided, systolic murmur
- mitral stenosis - left-sided, diastolic murmur
(clinical signs like CVD, but in younger patients)
What dogs are predisposed to tricuspid dysplasia?
- Labrador
- GSD
- Boxer
- Weimeraner
- Great Danes
- OESD
- Goldens
- M>F
What are the 3 most common results of tricuspid dysplasia?
- tricuspid regurgitation - right-sided, systolic murmur
- right heart enlargement and CHF
- tricuspid stenosis - right-sided, diastolic murmur
What is seen on ECGs in cases of tricuspid dysplasia?
splintered QRS complex
Tricuspid dysplasia, radiograph:
- rounded cranial and right lateral margins of cardiac silhouette
- RA and RV enlargement
- leftward displacement of apex
What is a double chamber right ventricle?
abnormal muscle bundle within the RV subdivides it into 2 chambers
- surgical correction possible
What is cor triatriatum? What are the 2 types? What signs are associated?
thin, fibro-muscular membrane subdividing either the left or the right atrium into 3 chambers
- dexter (dogs) - persistent valve of sinus venosus forms a membrane that divides RA into 2 subchambers —> ascites without jugular venous distension
- sinister (cats) - abnormal membrane subdivides LA into 2 subchambers —> LS-CHF
