Approach to the Young Animal with a Murmur Flashcards
Describe the approach to a young animal with a murmur….
If pathological:
Primary cardiac disease or effects of another? e.g. anaemia
Majority will have a congenital heart disease, but not all
Young animals with murmur or heart failure may have acquired disease e.g. parvoviral myocarditis
What are flow murmurs?
Murmurs that may occur in normal young individuals due to:
High CO (growing animal)
Reduced blood viscosity (less RBC/plasma protein)
What are the characteristics of a flow murmur?
No associated clinical signs Low intensity (<3/6) Reduces in intensity and disappears with age
What do significant murmurs in young animals usually signify?
Presence of congenital heart disease
What are the types of congenital heart abnormalities seen in dogs?
Valvular malfunctions (dysplasia) - Stenosis/insufficiency of any heart valve
Persistent foetal vessels
- PDA
Malformation of vasculature
- Vascular ring anomaly
Septal defects
- VSD, tetralogy of fallot
What are the reasons for discovery of a murmur in young animals?
Incidental murmur Murmur with other clinical signs - Cyanosis, syncope, stunting - Overt congestive failure Non-cardiac signs - Hepatic encephalopathy with PSS - Regurg with VRA
How can you investigate cardiac congenital disease in small animals?
History Clinical exam ECG Radiography Echocardiography Doppler echo
Systolic murmur:
- Left side apex
- Left side base
- Right side sternal border
- Right side cranial
- Continuous
- AV valve closed = mitral insufficiency
- Outflow valves open = aortic and pulmonary stenosis
- LV pressure higher than RV pressure = flow through VSD
- AV valves close, outflow valves open = tricuspid insufficiency and aortic stenosis
- Aortic pressure > PA pressure = flow through PDA
What does cyanosis indicate?
Cyanotic heart disease = right to left shunting.
Deoxygenated blood shunts across into systemic circulation.
What does exaggerated pulse quality indicate in an animal with congenital heart disease?
What does poor pulse quality indicate?
Increased: PDA (higher systolic pressure and lower aortic diastolic pressure)
Decreased: Aortic stenosis (damping effect)
(Pulse = difference between systolic and diastolic pressure)
What do left-to-right shunts create?
Volume overload
What does stenosis lead to?
Pressure overload (increased resistance to ejection from ventricles)
Describe the path of the shunting erythrocyte when a VSD is present.
Pulmonary veins LA LV RV Pulmonary artery Pulmonary vein
Keeps cycling round the pulmonary circulation.
Pulmonic valve has to cope with shunting blood as well as normal volume = get murmur due to volume overload.
VSDs:
- Nature of defect
- Pathophysiology
- Physical exam
- Diagnostics
- Therapy
- Prognosis
- Failure of normal formation of interventricular septum
- Left to right shunt
- Intense systolic murmur usually loudest on right
- Volume overloaded left side and pulmonary circulation
- Definitive treatment not available
- Fair if defect small and pressure difference maintained
Is a louder VSD murmur poorer prognosis?
NO
Smaller pressure difference with larger septal defect = reduced velocity of flow, so murmur is quieter.
Larger defect = poorer prognosis = quieter murmur