Evaluation der systolischen und diastolischen Funktion bei der felinen hypertrophen Kardiomyopathie mittels Gewebedoppler

Hypertrophic cardiomyopathy (HCM) is the most common cardiac
disease in cats. The evaluation of the myocardial function of
feline HCM is crucial to be able to identify affected animals and
to judge the course of the disease. The development of diastolic
dysfunction is typical for the course of this disease. Clinical
symptoms usually emerge only when the cat is severly affected. The
myocardial changes can lead to congestive heart failure or to
sudden cardiac death. The gold standard to diagnose HCM is the
depiction of a myocardial hypertrophy using echocardiography. A
myocardial dysfunction, however, can already be present before a
hypertrophy develops which can be measured. Thus, the aim of this
study “evaluation of the systolic and diastolic function in
hypertrophic cardiomyopathy using Tissue Doppler Imaging” was to
examine myocardial function in various stages of HCM as well as to
compare the findings with those of healthy cats. The study
population consisted of 280 cats of different breeds. Based on the
degree of hypertrophy and the size of their atrium, cats were
classified as either healthy, equivocal, mildly, moderately, and
severely affected. Different ultrasound planes were compared
concerning their ability to detect a myocardial hypertrophy. The
findings revealed that the maximum diastolic wall thickness in
three ultrasound planes was superior to measurements that used only
the parasternal short axis view. In addition to the conventionally
used transmitral inflow profiles, myocardial strain and strain rate
were also evaluated for the first time in feline HCM, using colour
Tissue Doppler Imaging (TDI) in various stages of HCM. Systolic and
diastolic velocity was also measured. The two software programs for
TDI analysis EchoPAC 2D-Strain and EchoPAC Q-Analysis were
compared, but only EchoPAC Q-Analysis was a clinically useful
method. Whereas the conventionally used transmitral inflow profiles
were not able to detect a diastolic dysfunction in cats with HCM,
significant differences between the stages of disease were
frequently revealed when the measurement was conducted with TDI.
Using TDI, it was possible to detect myocardial dysfunctions even
in cats that were classified as equivocal as well as in
non-hypertrophic segments of the myocardial wall. The early
diastolic TDI velocity as well as the ratio to the early diastolic
transmitral flow velocity turned out to be a sensitive parameter
for the detection of a diastolic dysfunction. The fusion of E and A
waves demonstrated the influence of both singular waves in the
course of the various disease stages. This shows the importance of
examining singular and fused early- and late-diastolic parameters
separately. The systolic function was also affected with
progression of the disease. Strain measurements revealed
significant differences between HCM stages. With progression of the
disease, postsystolic shortening also occurred more frequently.
While strain rate revealed the same tendency across all stages of
disease, tissue velocity was superior in the detection of a
myocardial dysfunction. In conclusion, TDI can be used to support
the diagnosis of HCM already in a very early stage. TDI could be
useful to monitor disease progression and therapy to adjust for the
individual animal. Another potential use of TDI is to evaluate the
effect of new drugs designed to slow the progression of myocardial
dysfunction. Due to the similar causes, pathogenesis, and clinical
presentation, feline HCM can serve as a model for human HCM.