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
Pulmonary hypertension/pulmonic stenosis and ventricular septal defect
- Pathophysiology
- Physical exam
- Diagnostics
- Treatment
- Cyanotic. RV pressure overload and systemic hypoxia (reverse flow of blood). Right to left shunt.
- Poorly grown, may be no/quiet murmur
- Right ventricular hypertrophy, shunting defect, polycythaemia
- No definitive therapy, some palliative therapy, need to control PCV
Describe the path of shunting erythrocyte when VSD and pulmonic stenosis is present…
- Systemic veins
- RA
- RV
- LV
- Aorta
- Systemic veins
Reduced pulmonary circulation. Right to left shunt means reduced oxygen and right ventricular hypertrophy.
Patent ductus arteriosis
- Defect
- Nature of defect
- Physical exam
- Diagnostics
- Treatment
- Prognosis
- Persistence of foetal connection
- Left to right shunt
- Continuous left base murmur and bounding pulses
- Volume loaded left side and pulmonary circulation
+ Ductal flow with doppler
+ Hypertrophy of aorta, PA, LA on radiograph - Surgical ligation or interventional closure
- Good if closed
Describe the path of the shunting erythrocyte when a PDA is present…
- Pulmonary veins
- LA
- LV
- Aorta
- Pulmonary artery
Huge amount of blood flowing through pulmonary artery AND aorta = hypertrophy of left side to cope with increased volume.
Aortic stenosis
- Nature of defect
- Pathophysiology
- Physical exam
- Diagnostics
- Management
- Prognosis
- Narrowing of left ventricular outflow tract
- Pressure overload of LV
- Left base systolic murmur, poor pulse
- Concentrically hypertrophied LV, increased aortic outflow velocity with Doppler
- Definitive cure not available. Medical management.
- Poor
Pulmonic stenosis
- Nature of defect
- Pathophysiology
- Physical exam
- Diagnostics
- Management
- Narrowing of right ventricular outflow tract
- Right ventricular pressure overload
- Left base systolic murmur, pulse less affected
- Right ventricular hypertrophy, pulmonary artery dilation, increased pulmonary ourtflow velocity with Doppler
- Balloon valvuloplasty and surgical patch grafting
Vascular ring anomaly
- Nature of defect
- Pathophysiology
- Physical exam
- Diagnostics
- Management
- Malformation of great vessels eg. PRAA
- Obstruction of thoracic oesophagus
- No murmur, signs of regurgitation
- Dilated oesophagus cranial to heart
- Surgical relief of compression BUT guarded prognosis (irreversible damage to oesophagus)
Atrial septal defects
- Nature of defect
- Pathophysiology
- Physical exam
- Diagnostics
- Treatment
- Failure of formation of atrial septum
- May have left to right shunt but often not significant (low pressure difference)
- May be normal, or soft murmur over pulmonic valve
- Found incidentally
- Usually not required
Path of shunting erythrocyte when atrial septal defect present
- Pulmonary veins
- LA
- RA
- RV
- Pulmonary artery
Value of blood shunting through defect is likely to be very low.
Mitral and tricuspid dysplasia
- Nature of defect
- Pathophysiology
- Physical exam
- Diagnostics
- Treatment
- Malformation fo one or both AV valves
- Stenosis/insufficiency of valve leads to volume load of left or right side
- Murmurs of mitral/tricuspid
- Enlargement of left/right side
- Definitive repair attempted surgically but limited success
