Page 32 - WSAVA2018
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 25-28 September, 2018 | Singapore
apex is the position on the left where the mitral valve will be most audible. On the right side the tricuspid valve is most clearly audible. VSD and PDA murmurs need not be at a valve position. PDA dorsal to the left heart base. VSD “diagonal” from the left heart apex to the right sternal border.
Intensity of murmur
Murmurs are graded out of six in terms of intensity
What else are we listening for?
Intensity of heart sounds. May be muffled with pleural or pericardial fluid. May be marked if there is gross cardiomegaly.
Listen for heart rhythm. Compare to pulse rate and rhythm. Always take the pulse at the same time as listening to the heart.
Finally listen to the lungs. Respiratory disease is often mistaken for heart disease due to similarity of the signs – breathlessness, coughing etc. A lot of older small breed dogs with lung disease will have incidental heart murmurs. Listen for wheezes and crackles over lung fields. Crackles may be evident if there is pulmonary oedema present.
A murmur has been discovered – what now?
Following the discovery of a murmur there are a number of important questions that should be considered which will help narrow down the likely nature of the underlying disease process.
How old is the dog?
Animals younger than 3-4 years of age are more likely to have congenital disease rather than acquired disease.
What breed and size is the dog?
Many congenital diseases have strong breed associations. With acquired heart disease, degenerative mitral valve disease is more likely to occur in small breed dogs whereas larger dogs tend to develop dilated cardiomyopathy.
How audible is the murmur?
Louder murmurs often, but not always, signify the presence of more serious disease.
Is the animal showing any clinical signs consistent with heart failure?
Signs such as increased respiratory rate and effort, exercise intolerance, lethargy and collapse episodes may occur as a consequence of heart disease leading to inadequate function of the cardiovascular system. If such signs are present it is more likely that an animal’s murmur indicates the presence of significant disease.
Are there other signs present suggestive of compromised function of the cardiovascular system these could include pallor, cyanosis, venous congestion, ascites, cold extremities, an audible arrhythmia etc.
  Audible after a long time listening in perfect conditions. Quiet room, amenable patient, good stethoscope.
  Clearly audible as soon as the stethoscope is placed over the point of maximal intensity.
  Clearly audible and as loud as the normal heart sounds.
   Audible louder than heart sounds but no thrill palpable, likely to radiate widely over the thorax.
 Thrill palpable over the point of maximal intensity at the skin surface
   Audible with the stethoscope lifted off the chest.
  Murmurs can also be described according to their radiation, pitch and shape. These characteristics are less important than the three already referred to.
When a murmur is audible at a site other than the point of maximal intensity it is said to radiate. It will radiate more loudly in certain directions due to the direction
of the turbulent jet giving rise to the murmur, or along structures adjacent to the site of origin of the murmur. Aortic stenosis murmurs tend to radiate up the carotid arteries and are sometimes audible over the head. Mitral murmurs radiate dorsally within the thorax.
High pitch murmurs may be more likely to be ejection murmurs and low pitch murmurs may suggest regurgitant flow. Fairly loose terms and probably more useful when trying to establish if a murmur has changed or if more than one murmur is present in the same animal.
Description from phonocardiogram diamond shape, crescendo, crescendo - decrescendo etc. Decrescendo murmurs get less intense over time the classic example of this being aortic regurgitation.

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