Murmurs in Young Animals Flashcards
What causes innocent murmurs?
> v TP and v PCV - low viscosity blood
^ CO as animal growing
-> turbulent flow of blood in the absence of pathology
Characteristics of a flow or innocent murmur?
- no clinical signs
- low intensity <3/6
- reduces in intensity and disdappears with age (by 6 months)
Which species has highest incidence of congenital heart defects?
dogs 1/100 live births
What are the 4 main types of abnormality?
> valvular malformations or dysplasia - stenosis or insiffuiciency of any valves > persistence of foetal vessels - PDA > malformation of vasculature - vascular ring anomaly > Septal defects * complex defects eg. tetralogy of fallot involve multiple defects (pulmonic stenosis and septal defect)
What clinical signs may congential heart problems present as unrelated to CV system?
- hepatic encephalopathy with PSS
- regurgitation with VRA
What are potential causes of systolic murmurs?
> left - apex: mitral insufficiency - base: AS/PS > right - sternal border: VSD - cranial: triceps insusfficiency or aortic stenosis
Other than murmur, what clinical signs may indicate congential heart defects?
> cyanosis
- cyanotic heart disease where R-L shunt can occour (BAD)
Pulse quality
- exaggerated (may be PDA, waterhammer pulse)
- poor (may be aortic stenosis > damping effect)
What type of shunt creates volume overload?
Left -> Right
What type of shunt causes pressure overload?
Stenotic outflow tracts
See lecture for diagrams of the path of the shunting erythrocyte!
Which species are VSDs the most common defect in?
All except dog!
Dog - PDA `
What type of shunt does VSD cause? So where is murmur heard? Implications of this?
Left - right
- murmur heard loudest on RIGHT with palpable thrill on the R thoracic wall
- colume overloaded left side and pulmonary circulation
Tx and prognosis of VSD?
- no definitive Tx
- prognosis fair if defect is small and pressure difference maintained across defect
Where specifically is VSD likely to occour?
Near great vessels (near top)
How does relative pulmonic stenosis occour?
L-V shunt overloads pulmonary circulation as aortic CO is always maintained by homeostatic mechanisms
-> pulmonary artery is relatively too thin for volume of blood passing thorugh
What is the peak left and right ventricular pressure in systole?
LV: 120mmHg
RV: 35mmHG
What does speed of flow thorugh a defect indicate?
Faster the flow, smaller the defect, better the prognosis!
What is a small VSD termed?
Restrictive defect
What causes cyanotic congenital heart disease? PE findings?
- RV pressure overload and systemic hypoxia
- PE: poorly grown, may be no murmur or quiet murmur
Diagnositcs for cyanotic congential heart disease?
- RVH
- shunting defect
- polycythaemia may be present (abnormally ^ Hbg conc due to ^RBC or v volume)
Tx pulmonic hypertension or pulmonic stenosis (cyanotic congenital heart disease)?
no definitive tx
- palliative tx for certain defects
- control PCV
What is a potential RV systolic pressure with pulmonary hypertension?
140mmHg
Why may murmurs be less audible with more severe defects?
if RV pressure ^, pressure gradiant is less so velocity v and murmur less audible
What causes ^ RV pressure?
Pulmonic hypertension
What is the pathophysiology of tetralogy of fallot similar to?
VSD
How may VSD occour other than congenitally?
Traumatic eg. kicked by a horse
Which way does blood flow thorugh the DA in utero?
PA -> A
What is heard on PE with PDA?
continuous left base murmur
bounding pulses
How may PDA be diagnosed?
- three knuckles on DV rads (Ao, PA, LA)
- volume loaded left heart and pulmonary circulation
- doppler: ductal flow
Tx and prognosis for PDA?
Ligation or intra-vascular closure
- prognosis good if closed
What pathophysiology does aortic/pulmonic stenosis have?
Pressure overload LV or RV respectively
PE findings with aortic/pulmonic stenosis?
- left base systolic murmur
- poor pulses (less so with pulmonic)
- with pulmonic, apex beat may be on the right
Diagnostic findings with aortic/pulmonic stenosis?
> aortic - concentrically hypertrophied LV - ^ aortic outflow velocity with doppler > pulmonic - concentrically hypertophied RV - ^ pulmonary outflow velocity with doppler - pulmonary artery dilation
Management and potential outocmes of aortic stenosis?
- definitive cure not available
- medical management best option but evidence not strong
> sudden death can occour
Tx of pulmonic stenosis?
- balloon valvuloplasty (good evidence for efficacy)
- surgical patch grafting
How does VRA (vascular ring anomaly) often present?
- malformation of great vessels -> obstruction of thoracic oesophagus
- puppies weaned begin regurgitating
- NO murmur!
- massive distension of oesophagus on rads cranial to heart base
Tx and prognosis of VRA?
- surgical relief of compression
- prognosis guarded as persistnet malfunction of oesophagus often seen after
Are atrial septal defects often significant? PE findings?
Not really (usually found incidentally)
- left to right shunt possible
- PE may be normal or soft murmur over pulmonic valve due to relative or functional pulmonic stenosis
Tx of atrial septal defects?
Rarely required
Pathophysiology of mitral and tricuspid dysplasia?
- stenosis OR insufficiency of the valves
- > volume load of left (M) or right (T) side
PE findings of AV valve dysplasia? Diagnostic findings?
- murmurs or mitral regurge or tricusp regurge
- stenosis murmurs less audible
Dx - enlargement of L/R heart
Tx of atrial septal defects?
Surgical repair attempted but limited success
