Page 855 - Cote clinical veterinary advisor dogs and cats 4th

412 Heart Murmur, Incidental Finding

(asymptomatic) mitral valve regurgitation. Technician Tips Count Respirations and Monitor Respiratory
Relevant inclusion criteria for the trial that Teaching owners to keep a log of their pet’s Effort)
VetBooks.ir heart sum > 10.5, an echocardiographic left of HF decompensation so that medications can SUGGESTED READING
resting respiratory rates can allow early detection
demonstrated this effect were a vertebral
be adjusted and hopefully hospitalization for
atrial–aortic ratio > 1.6, and left ventricular
Atkins C, et al: ACVIM consensus statement.
enlargement.
canine chronic valvular heart disease. J Vet Intern
• ACE inhibition may have a positive effect on acute HF can be avoided. Guidelines for the diagnosis and treatment of
the time to development of stage C HF in Client Education Med 23:1142-1150, 2009.
canine patients with left atrial enlargement Management of the veterinary patient with AUTHOR: Jonathan A. Abbott, DVM, DACVIM
due to mitral valve regurgitation. chronic HF requires careful monitoring and EDITOR: Meg M. Sleeper, VMD, DACVIM
• Evidence that medical therapy slows the relatively frequent adjustment of medical
progression of HCM is lacking. therapy (see client education sheet: How to

Heart Murmur, Incidental Finding Client Education
Sheet

BASIC INFORMATION rate or body posture), short (midsystolic), Initial Database
single (unaccompanied by other abnormal • Thoracic radiographs may be considered
Definition sounds), and small (not widely radiating). as the initial diagnostic test in small- to
A heart murmur that is detected in the process medium-breed dogs with systolic murmurs
of an examination that was not initially directed Etiology and Pathophysiology that are loudest over the mitral valve
at the cardiovascular system • A heart murmur is caused by turbulent blood region.
flow in the heart (p. 414). • An echocardiogram should be considered
Synonym • Identifying the timing, location, and intensity for any adult animal with one or more of
Asymptomatic heart murmur of the murmur may be straightforward or the following: uncertain or unusual murmur
challenging; uncertainty favors pursuing characteristics, murmur characteristics sug-
Epidemiology diagnostic testing. gesting a form of heart disease that requires
SPECIES, AGE, SEX • The presence of a heart murmur does not initiation of treatment, large-breed dog (aus-
Any species, all ages, both sexes warrant treatment. Rather, determining its cultation and thoracic radiographs have low
cause (definitively or presumptively) can lead to specificity for individual cardiac disorders),
GENETICS, BREED PREDISPOSITION an assessment of whether treatment is indicated. impending cardiovascular stress (e.g., plane
Predispositions mirror those of the causative travel, general anesthesia), breeding prospects,
cardiac diseases (pp. 263, 505, 657, 658, 764, DIAGNOSIS or owner who wishes to have confirmation
844, and 948). of the cause of the murmur.
Diagnostic Overview • An echocardiogram should be considered
RISK FACTORS First, an incidentally detected heart murmur for puppies and kittens with a murmur that
• Structural heart disease is pursued through careful characterization is grade 3/6 or louder, that is diastolic or
• Anemia of the murmur’s timing, grade, and point of continuous, that obscures the second (or
• Youth maximal intensity. Second, these characteristics, both) heart sounds, that radiates to the
combined with the patient’s signalment, may carotid region or is loudest over the left
Clinical Presentation provide a strong suspicion of a likely underlying apex or right hemithorax, or that is a direct
HISTORY, CHIEF COMPLAINT cause. If so and the veterinarian’s tentative diag- relative of an animal with congenital heart
• By definition: identified in patients that are nosis is of a benign process, the client is satisfied disease.
presented for noncardiovascular concerns, with this opinion without confirmation, and • NT-pro-BNP testing in cats can raise or lower
such as annual wellness exams, noncardiac the animal is not to be used for breeding nor the likelihood of structural heart disease
medical concerns, or preanesthetic evaluation. subjected to cardiovascular stress, diagnostic (notably cardiomyopathy) as the cause of
• Although no historical signs are associated testing is not essential. Otherwise, diagnostic the murmur.
with the murmur, misleading or overlapping testing should be pursued.
signs are common, including cough, exercise TREATMENT
intolerance, and others, which can be caused Differential Diagnosis
by unrelated comorbidities. Murmurs may be nonpathologic (the heart is Treatment Overview
structurally normal) or pathologic (caused by Because a murmur is a physical finding alone,
PHYSICAL EXAM FINDINGS a structural heart lesion): no treatment is warranted.
• Heart murmur (by definition), which is • Nonpathologic (benign) murmurs are further
described according to timing, grade, and described as functional if a plausible physi- Acute and Chronic Treatment
point of maximal intensity (p. 414) ologic cause is detectable (e.g., anemia) or as Initiation of treatment in the absence of a
• Auscultatory features of murmurs that are innocent if no cardiac or extracardiac cause diagnosis is not appropriate. It can lead to
nonpathologic (see Differential Diagnosis for the murmur can be identified. administration of medications a patient does
below) classically meet the six S criteria, which • Pathologic murmurs can be caused by any not need (or that are contraindicated), cause
are typically systolic, soft (grade 1-2/6), sensi- cardiac disorder of any degree and do not unnecessary expense, and cause adverse treat-
tive (prone to change in intensity with heart automatically indicate a severe condition. ment effects.

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