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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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