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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 5, September/October 2020
242
AFRICA
studies were performed in the left lateral decubitus position with
the conventional views (parasternal long- and short-axis, apical
four-chamber views). Right ventricular ejection fraction (RVEF)
from 2D methods was calculated as: (end-diastolic volume –
end-systolic volume)/end-diastolic volume.
Right ventricular M-mode, tissue Doppler records, isovolumic
acceleration (IVA) and myocardial performance index (MPI)
measurements were performed for right ventricular systolic and
diastolic function indicators. Peak myocardial speed during
isovolumic contraction was defined as isovolumetric contraction
velocity (IVV) (m/sec) and time elapsed to reach peak speed was
defined as acceleration time (AT). IVA was calculated with the
following formula: IVA = IVV/AT.
Right ventricular MPI was calculated as the ratio between the
sum of the isovolumic contraction time (ICT) and isovolumic
relaxation time (IRT) divided by the ejection time (ET): MPI
= (ICT + IRT)/ET. Right ventricular fractional area change
(RVFAC) was assessed in the four-chamber view and calculated
as: RVFAC = [RV end-diastolic area – RV end-systolic area]/RV
end-diastolic area × 100%. Pulsed tissue Doppler imaging (TDI)
was performed to measure systolic and diastolic myocardial
velocities at the basal level of the RV free wall. Peak myocardial
IVV, peak myocardial systolic velocity (Sm), peak early and
late diastolic velocities (Em and Am), ICT, IRT and ET were
measured.
We used M-mode scanning to measure tricuspid annular
plane systolic excursion (TAPSE) in the apical four-chamber
view with the cursor placed at the free wall side of the
tricuspid annulus to assess RV longitudinal function. TAPSE
was measured as the distance between the peak and trough of
the M-mode tracing curve, and at least three consecutive beats
were averaged. All Doppler measurements were performed at the
end of the expiration in order not to affect flow parameters with
respiration and to be more consistent.
Averages of measurements were used for comparison.
Measurements were generally consistent and this provided
more stable results. Inter-observer agreement was evaluated by
calculating the Pearson’s correlation coefficient (
r
= 0.93).
Statistical analysis
Statistical analysis was performed using the Statistical Package
for Social Sciences (SPSS) for Windows 20 (IBM SPSS
Inc, Chicago, IL) and Medcalc 11.4.2 (MedCalc Software,
Mariakerke, Belgium) programs. Compliance of the data to the
normal distribution was tested using the Kolmogorov–Smirnov
test. Normally distributed numeric variables are expressed
as mean
±
standard deviation and non-normally distributed
variables are expressed as medians. Categorical variables are
expressed as numbers and percentages.
For comparisons between the heroin and control groups, the
Student’s
t
-test was used for parametric variables and the Mann–
Whitney
U
-test for non-parametric variables. The chi-squared and
Fisher’s exact chi-squared tests were carried out for comparison
of categorical variables. Single-variate logistic regression analysis
was performed in order to determine the effects of potential
prognostic factors on right ventricular function. Significant risk
factors were included in the multivariate logistic regression and
independent predictors were determined. A
p
-value of < 0.05
was accepted as statistically significant.
Results
In the heroin group, the mean duration of heroin use was 4.6
years. The mean red cell distribution width (RDW) in the heroin
group was observed to be significantly higher compared to the
control group (15
±
1.6 vs 13.4
±
1.1%,
p
< 0.01). No significant
differences were found in other demographic and laboratory
characteristics between the groups (Table 1).
Comparison of the echocardiographic characteristics between
the groups revealed statistically larger right ventricular basal
(39.4
±
4.7 vs 35.6
±
4.3 mm,
p
< 0.01), mid (37.2
±
4.7 vs 31.8
±
3.6 mm,
p
< 0.01) and apicobasal (60.8
±
7.2 vs 53.6
±
11.1 mm,
p
= 0.01) diameters and pulmonary artery diameter (22.4
±
2.5
vs 20
±
2.5 mm,
p
< 0.01) in the heroin group compared to the
control group. Tricuspid pulsed wave E (PW E) (62.9
±
14.8 vs
52.6
±
12 cm/s,
p
= 0.01) and tissue Doppler e wave (17.2
±
4.5 vs
14.3
±
3 cm/s,
p
= 0.01) values in the heroin group were observed
to be statistically higher compared to the control group. The
MPI value was higher and abnormal in the heroin group (0.48
±
0.22 vs 0.39
±
0.11,
p
< 0.05), whereas the right IVA was observed
to be significantly reduced in the heroin group (2.92
±
0.69 vs 3.4
±
0.68 m/s
2
,
p
< 0.01). No significant differences were observed
between the groups with regard to RVEF (59.6
±
2.5 vs 60.6
±
2.3%,
p
= 0.08), TAPSE (24.1
±
4.2 vs 24.5
±
2.4 mm,
p
= 0.7),
TDI-S (13.7
±
2.1 vs 13.8
±
2.1 cm/s,
p
= 0.86) and RVFAC (42.7
±
8.3 vs 43.9
±
3.5%,
p
= 0.4) values (Table 2).
An independent correlation was observed between the RVIVA
and heroin use in univariate [0.36 (0.18–0.72),
p
< 0.01] and
multivariate [0.42 (0.19–0.88),
p
= 0.02] regression analyses.
Furthermore, an independent correlation was detected between
the pulmonary artery diameter and heroin use in univariate [1.49
(1.19–1.85),
p
< 0.01] and multivariate [1.43 (1.14–1.81),
p
< 0.05]
regression analyses (Table 3).
Discussion
Addiction to heroin-like drugs is currently an important health
problem however knowledge on the cardiac effects of heroin
addiction is limited. To our knowledge, the present study is the
first in the literature on the subject.
Table 1. Baseline characteristics and laboratory findings of the groups
Variables
Heroin (+)
(
n
= 45)
Heroin (–)
(n
= 40)
p-
value
Age (years), mean (SD)
29.6
±
9.6
30.1
±
8.1
0.81
Gender (female),
n
(%)
2 (4.4)
6 (15)
0.09
Diabetes mellitus,
n
(%)
0
0
–
Hypertension,
n
(%)
0
0
–
Coronary artery disease,
n
(%)
0
0
–
BMI, kg/m
2
26.5
±
2.7
27.5
±
2.7
0.11
WBC (× 10
3
cells/µl)
8.1
±
1.7
7.9
±
1.5
0.61
Haemoglobin (g/dl)
16.2
±
0.9
15.7
±
1
0.02
RDW (%)
15
±
1.6
13.4
±
1.1
< 0.01
Creatinine (mg/dl)
0.84
±
0.13
0.82
±
0.1
0.31
Platelet count (× 10³ cells/µl)
283.6
±
80.5
279.6
±
79.4
0.82
Sodium (mmol/dl; SD)
140.5
±
3.4
140.8
±
3.2
0.62
Potasium (mmol/dl; SD)
4.3
±
0.38
4.32
±
0.33
0.73
Calcium (mg/dl; SD)
9.2
±
0.5
9.3
±
0.4
0.84
p
< 0.05 is statistically significant. Continues variables are reported as mean
±
SD or median (IQR). Categorical variables are reported as
n
(%).
BMI: body mass ındex, WBC: white blood cells, RDW: red cell distribution
width.