Young Animal with a Murmur Flashcards
What is the first thing to consider when a young animal presents with a heart murmur? What signs may suggest one of the other?
Is it an “innocent” or flow murmur, or is it a pathological murmur? If there are clinical signs (e.g. signs of HF, poor growth, excercise intolerance) then there is likely to be significant underlying heart disease.
Why are young animals more likely to have innocent flow murmurs?
Young animals have less viscus blood, lower PCV and lower plasma protein and higher CO which predispose to the development of turbulence.
What characteristics would you expect an innocent flow murmur to have in comparison to a congenital defect murmur?
Tend not to exceed grade III/IV, and should become less audible with age. Usually they disappear by 6 months. Typically systolic and crescendo-decrescendo. Also not usually associated with clinical signs.
How should we investigate congenital heart disease in a young animal? Should we “wait and see”?
History, signalment, clinical exam etc. should help to narrow down. Diagnostic imaging is useful to help get a definitive diagnosis. Best time to manage is before development of clinical heart failure, therefore a wait and see policy is NOT GOOD.
What types of things on phyiscal exam may help you to narrow down types of congenital defects?
Location, timing and audibility of heart murmurs, pulse quality, is there any evidence of cyanosis?, are there any growth differences? Are there any signs of HF?
Are all heart murmurs in young animals pathological?
No, they may be innocent flow murmurs which will go away by themselves.
What types of further investigation/diagnostic tests might help you to narrow down the congenital heart defect in a young animal with a murmur?
ECG, Blood tests, Radiographs, Echocardiography
How can blood tests help you to narrow down the causes of a heart murmur in a young animal?
Is PCV normal? Abnormal right to left shunting (pulmonary to systemic) can be a stimulus for increased PCV (by production of red cells, polycythaemia)
How can ECG help you to narrow down the causes of a heart murmur in a young animal?
Cardiac rhythm normal? Is there normal QRS deflection suggesting enlargement of particular parts of the heart?
How can radiographs help you to narrow down the causes of a heart murmur in a young animal?
Is there cardiomegaly or can pulmonary vessels be seen on a radiograph? Any signs of HF?
How can echocardiography help you to narrow down the causes of a heart murmur in a young animal?
Which chambers are enlarged, is hypertrophy concentric or eccentric (pressure overload vs. volume overload)?
What five broad classes can congenital defects be put into?
Valvular malformations, Persistent foetal vessels, septal defects, malformation of vasculature, complex defects.
What type of overload do left to right shunts cause, volume overload or pressure overload?
Volume overload. (VO occurs along path of shunting erythrocyte).
What type of overload do stenoses of outflow valves cause, volume overload or pressure overload?
Pressure overload, due to increased resistance to ejection
What type of congenital heart defects is Cyanotic heart disease associated with? What do these congenital heart diseases have to do to the heart for right to left shunts to occur?
Occurs in RIGHT TO LEFT shunt. For a right to left shunt to occur, the heart must have the capacity to shunt, and also an increased pressure in the right side of the heart e.g. Tetralogy of Fallot.
