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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 3, May/June 2015
110
AFRICA
The exclusion criteriawere as follows: previous coronary artery
disease (patients who had a history of myocardial infarction,
unstable angina pectoris, angiographically proven significant
coronary artery stenosis or had undergone revascularisation),
congestive heart failure (left ventricular ejection fraction
≤
40%
or symptomatic heart failure), patients who had known or a
history of valvular heart disease, pulmonary disease, pulmonary
hypertension, left bundle branch block, a rhythm other than
sinus, and pericarditis. Chronic alcohol consumption (more than
20 g/day), serum hepatitis B antigen or anti-hepatitis C viral
antibody positivity, which are known to worsen NAFLD, were
the other exclusion criteria.
All medications were stopped 48 hours before the time of
echocardiography. Fasting venous blood samples were taken to
determine levels of blood glucose, electrolytes, total cholesterol,
high-density lipoprotein cholesterol, low-density lipoprotein
cholesterol and triglycerides.
Ultrasonography
Although liver biopsy is currently the gold standard for
distinguishing NAFLD forms, abdominal USG is the preferrred
method for qualitative assessment of NAFLD.
10
Abdominal
USG was performed on all study participants by a single
experienced physician who was blinded to the clinical and
laboratory results of the study groups.
The diagnosis of NAFLD was based on increased liver
echotexture on ultrasonography [Siemens Antares (Erlangen,
Germany)] compared with the kidneys, vascular blurring and
deep attenuation.
15
Fat infiltration in the liver was described in
three ultrasonographic stages using published criteria.
16,17
The
liver was considered to be normal if there was normal hepatic
echotexture and normal beam attenuation.
Mild steatosis (grade I) was identified as a minimal increase
in echogenicity of the liver parenchyma with a slight decrease
in definition of the portal vein walls and minimal or no
posterior beam attenuation. Severe steatosis (grade III) was
identified as grossly increased hepatic parenchymal echotexture
that permitted visualisation of the main portal vein walls alone.
Smaller venules were not visualised, and there was increased
posterior beam attenuation. Moderate steatosis (grade II) was
identified by hepatic echogenicity, portal venous definition
and beam attenuation between mild and severe parameters.
According to USG results, 59% grade I HS and 41% grade II–III
HS was found in the patients.
Echocardiography
All patients underwent a complete transthoracic echocardio-
graphic and tissue Doppler study using multiple views in the
left lateral decubitus position. Echocardiographic measurements
were calculated by two of three experienced cardiologists who
were blinded to the current study. In case of disagreement, an
opnion was obtained from the third cardiologist, and the final
decision was made by consensus.
This study was performed using a 3.5-Mhz transducer on
a Vivid 7 GE ultrasonographic system. Echocardiographic
measurements were made in accordance with the criteria
recommended by the American Society of Echocardiography.
All subjects were in sinus rhythm. The measurements were
done on three consecutive heartbeats, and the average of these
measurements was calculated.
In the apical four-chamber view, the sample volume (size 2
mm) of the pulsed-wave Doppler was placed between the tips
of the tricuspid leaflets. The tricuspid inflow velocity was traced
and the following variables were measured: peak velocity of early
(E) and late (A) filling and deceleration time (DT) of the E-wave
velocity.
In the parasternal long-axis view, the right ventricular (RV)
diameter was measured using Mmode from the RV anterior wall
to the right side of the interventricular septum on the R wave of
the electrocardiogram. RV longitudinal functions were assessed
by pulsed tissue Doppler imaging (TDI). Pulsed Doppler sample
volume (size 5 mm) was placed on the basal portion of the right
ventricle at the level of the lateral tricuspid annulus from the
apical four-chamber view. The Nyquist limit was set at 15 to 20
cm/s. For optimising the spectral display of myocardial velocities,
the monitor sweep speed was adjusted at 50 to 100 mm/s.
The pulsed TDI pattern has a positive myocardial systolic
velocity (Sa) and two negative diastolic velocities: early (Ea)
and late (Aa). The diastolic indices of myocardial early (Ea)
and atrial contraction (Aa) peak velocities and myocardial
systolic wave (Sa) velocity were measured and the ratio of
Em/Am was calculated. TDI-derived myocardial performance
index (MPI) of the right ventricle was measured by dividing
the difference between the time interval from the end to the
onset of the tricuspid annular velocity pattern during diastole
(
a
) and the duration of the tricuspid Sa (
b
) by the tricuspid Sa
duration (
b
).
RV MPI
=
(
a
–
b
)
____
b
.
Conventional and tissue Doppler echocardiographic
parameters and their implications on right ventricular systolic
and diastolic function are presented in Table 1.
Biochemical evaluation
Blood samples were drawn from each patient after a 12-hour
overnight fast for the determination of lipid profiles and glucose
levels. Plasma glucose level was determined with the glucose
oxidase/peroxidase method (Gordion Diagnostic, Ankara,
Turkey). Levels of total cholesterol, high-density lipoprotein
cholesterol (HDL-C), and triglycerides (TG) were determined
with enzymatic colorimetric assays by spectrophotometry.
Low-density lipoprotein cholesterol (LDL-C) was calculated
using the Friedewald formula.
Statistical analysis
The SPPS version 20.0 software package was used for
statistical analysis. All the data were expressed as mean
±
standard deviation. The Kolmogorov–Smirnov test was used
to determine normal disributions. Categorical variables were
compared with the chi-square or Fisher’s exact test. Normally
distributed variables were compared across groups by means
of the Student’s
t
-test whereas variables that did not normally
distribute were compared by means of the Mann–Whitney
U
-test. Spearman’s correlation analysis was used to evaluate
the relationship between the variables. A
p-
value
<
0.05 was
considered significant.