PATHOLOGY - Congenital Cardiac Disease Flashcards
What are the two classifications of heart murmurs in puppies and kittens?
Nonpathological murmurs
Pathological murmurs
What are the six characteristics of non-pathological murmurs?
- Murmurs are softer or absent at rest, with changes of position or phase of respiration
- Short duration
- Systolic murmur
- No other associated abnormal heart sounds or physical exam findings
- Murmur localised on the left side
- Grade I or II
What are the two classifications of non-pathological murmurs in puppies and kittens?
Functional mumur
Innocent murmur
What is a functional murmur?
A functional murmur is where there is no heart disease detected and there is a plausable physiological explanation for the murmur
What can cause a functional murmur?
Changes in blood viscosity
Increased cardiac output
Give an example of a condition that can cause a functional murmur and explain why
Anaemia decreases blood viscosity causing increased blood flow velocity and turbulent blood flow, resulting in a functional murmur
What is an innocent murmur?
An innocent murmur is when there is no heart disease detected however there is no obvious physiological explanation for the murmur
What is the likely cause of innocent murmurs?
The likely cause of innocent murmurs is the larger stroke volume in puppies and kittens relative to great vessel size
What are the three most common congenital heart diseases seen in dogs?
Pulmonic stenosis
Patent ductus arteriosus (PDA)
Subaortic stenosis
Which congenital heart diseases are Boxers predisposed to?
Pulmonic stenosis
Subaortic stenosis
Which congenital heart diseases are German Shepherds predisposed to?
Patent ductus arteriosus (PDA)
Persistent aortic arch
Which congenital heart disease are Bulldogs predisposed to?
Pulmonic stenosis
Which congenital heart disease are Labradors predisposed to?
Tricuspid valve dysplasia
Which congenital heart disease are Bull Terriers predisposed to?
Mitral valve dysplasia
What is the most common congenital heart disease in cats?
Ventricular septal defects
What is pulmonic stenosis?
Pulmonic stenosis is the structural malformation that causes an obstruction of blood flow from the right ventricular outflow tract into the pulmonary artery
Describe the pathophysiology of pulmonic stenosis
Pulmonic stenosis causes an obstruction of blood flow from the right ventricular outflow tract, resulting in pressure overload and compensatory right ventricular concentric hypertrophy. As the right ventricle hypertrophies, ventricular compliance diminishes, leading to impaired ventricular filling. This will further reduce blood flow into the pulmonary artery and consequently the blood flow to the left side of the heart, resulting in decreased stroke volume and cardiac output. Concentric hypertrophy increases the surface area of the myocardium resulting in the oxygen demand exceeding the oxygen supply from the coronary circulation, resulting in oxygen deficiency, resulting in systolic dysfunction and right-sided heart failure. This will eventually result in a backup of blood from the right side of the heart resulting in right-sided congestive heart failure
How does pulmonic stenosis result in a heart murmur?
Since the blood has to flow through a narrow opening, this results in turbulent blood flow and a heart murmur
How can you determine the severity of pulmonic stenosis on clinical exam?
The severity of the pulmonic stenosis corresponds with the intensity of the heart murmur heard on auscultation
What are the five clinical signs of pulmonic stenosis?
Asymptomatic
Left sided basal crescendo-decrescendo systolic murmur on auscultation
Exercise intolerance
Syncope
Signs of right-sided congestive heart failure
How can pulmonic stenosis present on an ECG?
Right bundle branch block (RBBB)
What are the four key signs of pulmonic stenosis on radiography?
Cardiomegaly
Increased sternal contact
Prominant pulmonary artery
Heart looks like an inverted ‘D’ on ventrodorsal radiograph
What are the two key signs of pulmonic stenosis on echocardiography?
Right ventricular concentric hypertrophy
Turbulent blood flow at the pulmonary valve (doppler)
What is the most common form of pulmonic stenosis?
Valvular pulmonic stenosis
What are the two classifications of valvular pulmonic stenosis?
Type A: Narrowed or fused heart valves
Type B: Narrowed annular ring
What can be done to treat type A valvular pulmonic stenosis?
Balloon valvuloplasty
What is a balloon valvuloplasty?
A balloon valvuloplasty is a procedure used to widen a narrow heart valve. A catheter is inserted into the jugular vein and guided into the right side of the heart to the pulmonary valve. When the pulmonary valve is reached and the balloon is in position, it is inflated to widen the valve