Congenital heart diseases Flashcards
What are differential diagnoses for heart murmurs?
- Innocent “flow” murmurs
- Anaemia etc.
- Congenital heart disease: differential diagnosis refined by:
– Timing of the murmur
– Point of maximal intensity (PMI) of the murmur
– Radiation of the murmur
– Pulse quality
– Precordial impulse
What is patent ductus arteriosus?
- Blood shunted from aorta to pulmonary artery
- Continuous “run-off” of blood into pulm. circ.
- Pulmonary over-circulation
- Volume overload of LA & LV
- Dilation of Mitral valve annulus: secondary MR
- Increased LA & LV EDP results in LHF
- Myocardial failure is a common consequence
What animals is PDA seen in?
- Common defects in dogs (Females>males)
- GSD
- Collies
- Bichon Frise
- Poodles
- CKCS
- Irish setter
CS of PDA?
- Asymptomatic initially
- Continuous murmur - very localised
- Secondary murmur of Mitral regurgitation (MR)
- collapsing femoral pulse = tapping
- if untreated = CHF by 7y/o
What is seen radiographically of PDA?
- Left atrial & LV enlargement
- “Apparent” right sided enlargement
- On DV, may have pathognomic “triple knuckle”
(Aortic, pulmonic and left auricular appendage bulges). - Pulmonary over-circulation (arteries & veins increased)
- +/- Radiographic evidence of LHF
How is PDA treated?
- Should be corrected before CHF develops
- Surgery - thoracotomy, ligation of ductus
- Catheterisation occlusion of PDA
- Early Tx = cure
- Once CHF - guarded prognosis
What is the most common congenital defect in dogs?
- Aortic stenosis
What breeds are predisposed to aortic stenosis?
- Boxers
- Newfoundlands
- Golden retrievers
- Rottweilers
- Bull terriers
- Miniature bull terrier
What is the pathophysiology of aortic stenosis?
- Fixed (or dynamic) obstruction at aortic valve
- Increased afterload on LV: develops concentric hypertrophy (LVH) (Pressure overload)
- Increased aortic velocities
- Coronary perfusion compromised (poor coronary filling and increased wall stress; coronaries do not “keep up” with LVH)
- Myocardial ischaemia may result in ventricular arrhythmias
What are CS of aortic stenosis?
- Harsh, ejection type mid to holosystolic heart murmur
- Grade of heart murmur corresponds to severity of stenosis
- Radiates up carotids and on right chest
- Weak femoral pulses
How would you grade severity of aortic stenosis?
0-50mmHG = mild
50-80mmHG = moderate
>80mmHG = severe
(Pressure gradient = 4 x Velocity x Velocity)
How would you treat aortic stenosis?
- No surgical tx
- If CHF = diuretics
What breeds tend to get pulmonic stenosis?
- Rare in cats
- Common in dogs
- Cocker spaniels
- CKCS
- Terriers
- Beagle
- Bulldog
- Bull mastiff
- Boxer
What are CS of pulmonic stenosis?
- Incidental heart murmur
- Exercise intolerance
- Syncope
- Mid - holo-systolic murmur cranially left heart base
- Grade of murmur correlates severity
- Deep S waves on ECG on lead I, II + aVF
What is the pathophysiology of pulmonic stenosis?
- Fixed obstruction at pulmonic valve
- Increased afterload on RV: concentric RVH
- Increased velocity of pulmonic outflow
- If RV pressures equal / exceed LV pressures, altered IVS motion (may be paradoxical) and LV can appear “squashed”.
- RV hypertrophy may lead to myocardial ischaemia; ventricular arrhythmias may result
What is treatment of pulmonic stenosis?
- Cardiac catheterisation - balloon valvuloplasty of valvular stenosis
What does a murmur suggest with ventricular septal defects?
- Inversely proportional - louder murmur = lower grade
What is VSD?
- Left to right shunt LV to RV in systole
- Volume overload of RV
- Pulmonary over-circulation
- Volume overload of LA & LV
- Left sided heart failure may result
What can VSD lead to?
- Can be asymptomatic
- Left sided heart failure with large defects
- May close with growth
- Aortic valve leaflets may prolapse into VSD; VSD functionally “closed” but Aortic regurg’n develops
- If pulmonary hypertension is associated with the VSD, high RV pressures may result in shunt reversal (right to left)
What dog breeds are mitral dysplasia seen in?
- Bull terriers
- Golden retrievers
- Great danes
- GSD
+ common in cats
- causes louder murmur than tricuspid as more pressure
What dog breeds are tricuspid dysplasia seen in?
- Labradors
+ common in cats
What is pathophysiology of mitral/tricuspid dysplasia?
- Incompetence of MV/TV, with M Regurgitation / TR
- Volume overload of LA/LV or RA/RV
- Left / Right sided heart failure
- Possible arrhythmias (especially atrial,
e.g. supraventricular tachycardia, AF) - severe decompensation if Atrial Fib develops
What is tetralogy of fallot?
- Pulmonic stenosis
- Right ventricular hypertrophy
- Ventricular septal defect
- Dextrapposed aorta
=cyanosis
What are other congenital cardiovascular lesions?
- Vascular ring anomaly - persistent right aortic arch (Jack russell terriers)
- Pericardio-Peritoneal Diaphragmatic Hernia (Weimaraner + Maine coon cat)
