2.b Murmurs SDL

what is a cardiac murmur?

A cardiac murmur is an additional sound heard on auscultating the heart, often described as a 'whoosing' noise.

What causes a heart murmur?

It is caused by turbulent blood flow through the heart

How are murmurs graded?

On how loud they are

How do murmurs occur in small animals?

It can occur in either systole or diastole but in small animal practice the vast majority occur in systole between S1 and S2 (between the lub and dub sounds).

What is a grade 1 murmur?

Grade 1: The murmur is only just audible in perfect conditions - ie no dogs barking in the practice, no owner talking

What is a grade 2 murmur?

Grade 2: The murmur is audible but quieter than the normal heart sounds

What is a grade 3 murmur?

Grade 3: The murmur is the same volume as the normal heart sounds

What is a grade 4 murmur?

Grade 4: The murmur is louder than the normal heart sounds

What is a grade 5 murmur?

Grade 5: The murmur is loud and when you palpate the chest wall you can appreciate a vibration known as a palpable thrill

What is a grade 6 murmur?

Grade 6: The murmur is audible with the stethoscope off the chest wall

what are innocent murmurs?

Often heard in young patients (upto 3-6mo old) or rarely in very fit patients. Turbulent flow is created as the blood leaving the heart is ejected at such a high velocity it creates a noise. These are quiet murmurs (grade 1-2) and are heard over the left heart base

What would we suspect if a murmur grade reduces as a cat gets less stressed?

Stress-induced murmur POTENTIALLY

what are physiological murmurs?

Usually created due to stress (cats) or another issue within the body such as anaemia which changes the viscosity of the blood making it more prone to becoming turbulent.

what are pathological murmurs?

These occur due to underlying structural heart disease such as degenerative valvular disease, congenital disease etc.

what is the difference between acquired and congenital murmurs?

Murmurs can be acquired (occur later in life) or congenital (the patient is born with a murmur).

what is the PMI?

Where you hear the murmur the loudest is known as the point of maximal intensity (PMI). It can give an indication of what the underlying cause of the murmur is.

Base= dorsal and cranial

Apex = sits in sternum caudal and ventral

what murmurs can be heard at the base of the heart?

-physiological flow mumrmurs

-aortic/pulmonic stenosis

-PDAs (patent ductus arteriosusrmurs

what murmurs can be heard at the apex of the heart?

mitral regurgitation

right ventricle is in what position to the left?

Cranial to left

might be able to hear tricuspid regurgitation or VSDs

Non-pathological murmurs

how do they present?

-murmur is absent or much softer at rest than with excitement/exercise/stress

-no other abnormal heart or other physical exam anomalies associated with the cardiovascular system

-patient is less than 6mo old

-localised to left heart base- doesn't radiate

-grade 1-2/6

Pathological murmurs

how do they present?

-murmur is present at rest or with activity

-PMI left apex or right sided

-remains loud throughout most of systole

-gallops or arrhythmias audible

-radiates from PMI

-Grade 3+

-clinical signs consistent with cardiovascular disease

-patient is over 6 months old

If the PMI is left apex what is it likely to be a result of?

Mitral regurgitation

What is a continuous heart murmur?

A continuous heart murmur is heard throughout both systole and diastole

-Systolic murmur: occurs between S1 → S2

-Diastolic murmur: occurs between S2 → S1

-Continuous murmur: continues through S1 and S2

Give an example of a continuous murmur cause

result of a Patent Ductus Arteriosus (PDA) - a foetal vessel connecting the aorta and pulmonic artery that should have closed at birth.