Page 20 - Feline Cardiology

10 Section A: Clinical Entities

Murmur character can change (e.g., become louder) due couragement of the patient, the client, or both—may
to physiologic changes in the patient that do not neces- compromise the willingness to pursue later treatment
sarily reflect the presence or progression of cardiac when it becomes indispensable (e.g., CHF, ATE; see
Clinical Entities beginning cardiac medications. A common conundrum healthy cat with an incidentally discovered heart murmur
Chapter 11).
disease.
Therefore, a reasonable approach to the overtly
The mere existence of a heart murmur does not justify
appears to be to
is the cat with an incidentally found heart murmur and
grossly apparent cardiac changes on radiographs—but
no evidence of congestive heart failure and no overt 1. Consider the context of the case, since preanesthetic
clinical signs—whose owner is unable or unwilling to evaluations or evaluations of breeding stock carry
pursue echocardiography. At least two approaches are greater implications for the cardiovascular health of
recognized by cardiologists in such cases, and each patients immediately or for many generations,
carries substantial advantages and drawbacks. First, it respectively (and echocardiography would be more
may be inferred that in a cat with a murmur and heart immediately important in such patients).
enlargement noted radiographically, cardiac medica- 2. Discuss the advantages and drawbacks of echocar-
tions (an angiotensin-converting enzyme inhibitor for diography with the cat’s owner, recommending echo-
concentric or eccentric hypertrophy suggested by gener- cardiography if it is feasible.
alized cardiomegaly and aspirin for blood stasis associ- 3. Pursue treatment if indicated based on diagnostic
ated with atrial enlargement) may be warranted because imaging findings following a realistic and compre-
these abnormalities suggest that cardiac remodeling has hensive discussion with the owner of advantages and
occurred. If bursts of tachycardia or an irregularly irreg- drawbacks of such treatment, particularly when
ular rhythm at an elevated heart rate is persistent, a drug cardiac morphology has not been determined.
such as atenolol may be beneficial. On the other hand,
echocardiography allows a noninvasive and detailed GALLOP HEART SOUNDS
assessment of cardiac structure and basic cardiac func-
tion. The advantages of deciding whether to pursue
treatment based on cardiac appearance on radiographs Key Point
alone are
The term gallop rhythm is a misnomer because the
• Simplicity of diagnostic testing underlying cardiac rhythm is most often sinus. The
• Lower expense additional heart sound, which results in a triple cadence in
conjunction with the normal first and second heart sounds,
is more accurately called a gallop heart sound.
The advantages of deciding on whether to pursue treat-
ment based on echocardiographic findings are
The third (S 3) and fourth (S 4 ) heart sounds are not nor-
• Elimination of misdiagnosis when the heart is in fact mally audible during cardiac auscultation in small
structurally normal (but peritoneopericardial dia- animals. When present in dogs or cats, the extra sound
phragmatic hernia, pericardial effusion, or an artifact results in a triple beat cadence reminiscent of a cantering
such as patient obliquity, expiratory-phase films, or horse. Because of this similarity, some refer to it as a
ventrodorsal projection instead of dorsoventral, give gallop rhythm; however, this term leads to confusion
the mistaken impression of cardiomegaly on because a true arrhythmia (change in the rhythm of
radiographs) cardiac electrical activity) is not present. In fact, gallop
• Quantification of structural lesions (e.g., atrial enlarge- sounds are usually associated with sinus rhythms. An
ment, outflow tract velocities associated with obstruc- extra heart sound (and this triple-sound, galloping char-
tion, Doppler assessment of diastolic function) that acter of each heartbeat) can be noted due to the presence
help in deciding whether to initiate treatment, and of auscultable S 3 or S 4 sounds, a systolic click, or a split
may help stratify risk and owner concern/monitoring heart sound, but only the diastolic sounds (S 3 and S 4)
for the future are correctly termed “gallop” sounds. The various extra
sounds occur secondary to differing abnormalities and
It must also be considered that the physical administra- mechanisms, so accurate identification is important. S 3
tion of medications to an asymptomatic cat for a period and S 4, as diastolic filling sounds, are best ausculted
commonly lasting months to years—and attendant dis- using the bell of the stethoscope (see Box 1.1).