Download CARDIAC MURMUR What does it mean?

CARDIAC MURMUR
What does it mean?
Kirstie A. Barrett, DVM, DACVIM
(cardiology)
Lynette D. Tsugawa, DVM, DACVIM
(cardiology)
Systolic Murmurs
Systolic murmur: heard between the first
and second heart sound (S1 and S2)
n  Due to turbulent blood flow during
systole– mitral regurgitation, turbulent
flow in aorta or pulmonary artery, VSD
when blood shunts across septum
n 
Functional Systolic Murmur
Usually soft and high frequency
n  Due to decreased blood viscosity or
increased cardiac output
n  Dogs/cats with anemia
n  Other functional murmurs due to
hypertension, fever, pregnancy,
hyperthyroidism
n 
Diastolic Murmur
Heard after the second heart sound
(between S2 and S1)
n  Aortic or pulmonary valve insufficiency so
retrograde blood flow during diastole
n  Mitral valve stenosis in mid-diastole due to
obstruction of blood flow into LV
n 
Continuous Murmur
PDA, pulmonary arteriovenous fistulas,
rupture of a coronary artery into the RA
n  PDA: intensity or murmur varies through
cardiac cycle
n  Loudest intensity near time of second
heart sound
n  Due to blood flow from high pressure
aorta into the lower pressure pulmonary
artery thru open ductus
n 
Do we keep the puppy?
Owner just received/bought/found puppy
n  Five minute rule
n  What is the significance of a murmur?
n  What do you tell them?
n 
Puppy/kitten innocent murmur
Soft systolic murmur grade I-II/VI
n  May vary in intensity with heart rate
n  Usually loudest over left heart base
n  Mid-systolic so able to hear heart sounds
clearly
n  No clinical signs
n  Normal pulses
n  Expect to resolve by 4-6 months of age
n 
Systolic murmur & disease
Systolic murmur usually louder (grade IIIIV/VI)
n  Longer duration – may obscure normal
heart sounds
n  Do NOT correlate intensity of murmur with
severity of defect (small VSD for example)
n 
Physical exam
Pulses: hypokinetic pulses with moderate
to severe left ventricular outflow
obstruction (SAS)
n  Cyanosis: usually due to right to left
shunt at level of heart or great vessels
n  Distended jugular veins: right sided
heart disease (PS or TV dysplasia)
n  If observe any of these abnormalities need
further diagnostics
n 
Radiographs
Severe cardiomegaly with TV dysplasia or
PDA (volume overload)
n  Careful! easy to over-interpret right sided
enlargement in young animals
n  Pressure overload (PS, SAS) more difficult
to determine cardiomegaly on radiograph
due to concentric hypertrophy
n 
Dilation of proximal ascending aorta (SAS)
n  Dilation of main pulmonary artery (PS, PDA)
n 
Radiographs
Pulmonary edema due to congestive heart
failure in a dog under 1 year of age
n  Cardiomegaly on radiographs
n  THINK PDA!!
n  If no continuous murmur then need to
rule-out other congenital lesion, DCM
n 
Right-sided cardiomegaly
Right-sided cardiomegaly
Continuous murmur…PDA
MUST LISTEN WAY UP UNDER LEFT
ARMPIT!!!
n  Can be very focal
n  Always listen for continuous murmur
especially if hear systolic murmur
n  Hyperkinetic or bounding pulses due to
diastolic runoff through ductus (or other
left to right shunt; aortic regurgitation)
n 
Puppy and kitten exams
Continuous murmur ausculted: definitely
indicated to pursue work-up
n  Radiographs
n  EKG
n  Echocardiogram
n  WHY? Because this is a defect we can
successfully treat
n 
PDA
Breeds at increased risk for having a PDA:
Chihuahua, collie, Maltese, poodle,
Pomeranian, springer spaniel, keeshond,
bichon frise, Cavalier, Shetland sheepdog
n  Some regions have higher frequency in
larger dogs: Labs, Newfoundlands,
German Shepherd
n  Clinical Signs: none, left CHF, thin body
condition, lethargy
n 
Radiographs
Puppy or kittens with a PDA can have
normal thoracic radiographs
n  Radiographic changes include:
n 
left-sided cardiomegaly
n  pulmonary hypervascularity
n  Prominent aortic arch (proximal descending
aorta) and pulmonary artery
n  Aortic bulge “ductus bump” at origin of
ductus
n 
EKG changes with PDA
Left ventricular enlargement indicated by
severe increased R wave amplitude in
leads II, III, aVF
n  Normal mean electrical axis
n  Wide P waves with left atrial enlargement
n 
EKG of puppy with PDA
Confirmation of PDA
Confirm presence of a PDA with echo
n  Surgery to ligate ductus vs catheterization
procedure
n  Either way need to stop blood flow
through ductus (as long as flowing left to
right)
n 
Pulmonic Stenosis
Stenosis or narrowing in the RVOT
creating a partial obstruction to blood flow
n  Most commonly due to pulmonic valve
dysplasia
n 
n 
n 
Also supra or sub-valvular
Severe or symptomatic patients are
possible candidates for balloon
valvuloplasty
Pulmonic Stenosis
Symptoms include: no clinical signs;
syncope/lethargy, right CHF
n  Typical breeds: beagle, Samoyed,
Chihuahua, bulldog, miniature Schnauzer,
Lab, mastiff, chow, Newfoundland, basset
hound, terrier/spaniel breeds
n 
Pulmonic Stenosis
Pulmonic Stenosis
Pulmonic Stenosis
Pulmonic Stenosis
PS and RV Hypertrophy
Subaortic Stenosis (SAS)
Subvalvular aortic stenosis (Newfies,
boxers, goldens, rottweilers, GSD)
n  Valvular aortic stenosis (bull terriers)
n  Stenosis or narrowing in the LVOT
creating a partial obstruction to blood flow
n  Ridge of fibrous tissue encircling the LVOT
below the aortic valve
n 
SAS Clinical Signs
Exercise fatigue, syncope, left sided CHF
n  Usually asymptomatic
n  Severe cases at risk for sudden death
usually between 1 and 3 years of age
n 
n 
No prevention possible
Systolic ejection murmur at left (or right)
heart base and radiates up carotid arteries
n  Progressively grows louder over time
n 
Ventricular Septal Defect (VSD)
Flow across ventricular septum primarily in
systole
n  Left to right flow because left sided
pressures are 4-5 times higher than right
n  High VSD eject blood directly into RVOT vs
low VSD into RV
n  Louder murmur with smaller defect
n  Bulldog, English springer spaniel, Westie
n  Kittens
n 
Feline VSD
Feline VSD
Adult dog
Systolic murmur over left heart base
n  Small breed? Large breed?
n  Pulse quality? Mucous membrane color?
n  Radiographs
n  EKG
n 
Small to Medium breed
Systolic murmur over left heart base
n  No clinical signs
n  Radiographs: look for cardiomegaly, left
atrial enlargement, pulmonary edema,
ascites, MPA dilation
n  Acquired: Think mitral valve disease, less
likely DCM (confirm with echo), rare HCM
n  Congenital: listen for continuous murmur,
rule-out PS or other with echo
n 
Left Atrial enlargement
Normal Left Atrium
Mitral Valve disease
Mitral Valve disease
Medium to Large breed
Dilated Cardiomyopathy (DCM)
n  “New” systolic murmur often low intensity
n  +/- Atrial fibrillation
n  +/- ascites indicating right heart failure
n  Radiographs indicated and if abnormal
recommend echo
n 
Cardiomegaly
DCM vs Pericardial Effusion
Muffled heart sounds
n  Weak pulses
n  Ascites
n  Distended jugular veins
n  Globoid cardiac silhouette on radiographs
n  THINK PERICARDIAL EFFUSION!
n  Echo indicated
n 
Feline cardiac murmurs
Continuous murmur– think PDA
n  Systolic murmur at left apex or just off
sternum to the right or left
n  +/- gallop rhythm
n  Radiographs indicated
n  Thyroid levels in older cats with a
murmur/gallop
n 
Cardiomegaly in a cat
Hypertrophic cardiomyopathy
(HCM)
Most common myocardial disease in cats
n  Mild to severe thickening of the left
ventricular (LV) wall and papillary muscles
n  Hypertrophy due to myocardial disease
not secondary to pressure or volume
overload
n 
Feline HCM
Hypertrophied Ventricle
n  Non-dilated ventricle
n  Septum or Free Wall
• greater than 6 mm
n  Associated with:
• hyperthyroidism
• hypertension
• P/V overload
• Chronic anemia
• Idiopathic HCM
n 
Hypertrophic Cardiomyopathy
Mitral regurgitation murmur
n  Gallop rhythm
n  Atrial or Ventricular Arrhythmia
n  ECG
n 
LA enlargement
n  LV enlargement
n  LBBB OR LAFB
n  Atrial Fibrillation
n  VPC’s or Ventricular tachycardia
n 
Maine coon cats
Inherited as simple autosomal
dominant trait
n  Humans: sarcomeric gene mutation
n  Progressive disease
n  Apparent at 2 years of age in males;
females affected at 3 years
n  Often do not see clinical signs until
6 to 7 years of age
n 
Normal vs HCM
Thrombus formation
If large left atrium possible risk to form a
thrombus and “throw a clot”
n  Aspirin therapy – ¼ of 81 mg tablet Mon,
Wed, Fri
n  Clopidogrel (Plavix) – ¼ of a 75 mg tablet
once a day
n  Poor prognosis associated with aortic
thromboembolism
n 
Dilated Cardiomyopathy (DCM)
Enlarged ventricular chamber size
n  Overall weight of heart is increased but
walls are thinner than normal
n  Secondary to taurine deficiency (30% of
deficient cats develop DCM)
n  Sulfur-containing amino acid
n  Conjugates bile acids (lost in bile)
n  Cats unable to synthesize adequate
quantities in liver so need in diet
n 
LV Fractional Shortening
on Echo
Abnormal radiographs
Enlarged heart on thoracic radiographs of
a cat, +/- pulmonary edema, recommend
echocardiogram
n  Rads can be normal especially with HCM
n 
And then there are always
surprises…
Mass
n  Other congenital defect (even in an older
dog)
n 
RA Hemangiosarcoma
LA Mass
Moderator Band in mid-LV
Moderator Band in LV
SUMMARY
Innocent vs significant murmur in puppy/
kitten
n  Listen carefully way up under left
armpit for continuous murmur!
n  Adult dog murmur– look for other physical
exam findings/clinical signs
n  Adult cat murmur-- always investigate
with radiographs
n  Arrhythmia and murmur– rads and echo
n 
THANK YOU!
Any Questions??