CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 3, May/June 2011
AFRICA
125
Doppler and M-mode echocardiography. Adult hypertensive
subjects who were at least 18 years old and who were willing to
participate in the study were included.
Blood pressure was measured in the clinic with an Accosson’s
sphygmomanometer and hypertension was diagnosed when
blood pressure was persistently
≥
140 and/or
≥
90 mmHg and/
or the use of antihypertensive therapy according to standardised
procedures and guidelines.
13
Systolic and diastolic blood pres-
sure was taken as the first and fifth korotkoff sounds, respec-
tively. Other clinical information obtained included weight (in
kilograms), height (in metres), body mass index, age and gender.
Sixty-four normotensives were used as controls. They were
randomly recruited from patients’ relatives and hospital staff
who were willing to participate. They were well matched in age
and gender distribution with the hypertensive subjects. Patients
with diabetes mellitus or a history of heart or renal failure were
excluded from the study. Determinations of the Tei indices were
done differently without access to the clinical data of the subjects.
Echocardiography
All the subjects had transthoracic echocardiography done
according to the recommendation of the American Society
of Echocardiography.
14
Patients were placed in the left lateral
decubitus position. Left ventricular measurements such as wall
and chamber dimensions were obtained in systole and diastole.
They included left ventricular internal dimension in diastole
(LVIDd) and systole (LVIDs), posterior wall thickness in diastole
(PWTd), and interventricular septal thickness in diastole (IVSd).
Left ventricular mass (LVM) was calculated from the measure-
ments of the left ventricle (LV) using the equation:
LVM (g)
=
0.81 [1.04 (interventricular septal thickness
+
posterior wall thickness
+
LV end-diastolic internal dimension)
3
– (LV end-diastolic internal dimension)3]
+
0.6.
15
LVM index (LVMI) was calculated as LVM/height (m)
2.7
.
Correcting LVM for height
2.7
has been shown to minimise the
effect of gender, race, age and obesity on the validity of vari-
ous parameters for the diagnosis of left ventricular hypertrophy
(LVH), for which many parameters exist.
16
LVH was defined as
LVMI
>
51 g/m
2.7
.
LV geometry was determined after calculation of the relative
wall thickness (RWT) using the formula:
2
×
posterior wall thickness
LV end-diastolic internal dimension.
17
RWT was considered abnormal if it was
≥
0.45.17
Four left ventricular geometric patterns were described
based on RWT and left ventricular mass index (LVMI): normal
geometry, concentric remodelling, eccentric hypertrophy and
concentric hypertrophy. LV geometry was defined as concentric
hypertrophy (elevated LVMI and RWT), concentric remodel-
ling (normal LVMI and elevated RWT), eccentric hypertrophy
(increased LVMI and normal RWT) and normal geometry
(normal LVMI and RWT).
The Tei index reflects both systolic and diastolic function.
It was defined as the sum of the isovolumic relaxation time
and isovolumic contraction time divided by the ejection time
obtained from the left ventricular inflow and outflow.
11
The
isovolumic relaxation time was determined from the apical five-
chamber view as the time from the end of left ventricular ejection
to the beginning of the early mitral inflow (E) wave. Isovolumic
contraction time was defined as the time from the peak of the R
wave or the end of the late atrial filling (A) wave to the beginning
of left ventricular ejection.
Statistical analysis
The Statistical Package for Social Sciences, SPSS 16.0 (Chicago
Ill.) was used for the study. Quantitative data were summa-
rised using means
±
standard deviation (SD) while qualitative
data were summarised using percentages and proportions.
The Student’s
t
-test and chi-squares were used as appropriate
for intergroup comparisons. Correlation analysis was used for
univariate associations between numerical variables. Values with
p
<
0.05 were taken as statistically significant. Ethical approval
was obtained for the study.
Results
The clinical characteristics of the study population are shown in
Table 1. The hypertensives and the control population were well
matched in age and gender distribution. Left ventricular wall
thickness, isovolumic relaxation and contraction time, body mass
index, left ventricular mass index, relative wall thickness and Tei
index were significantly higher among the hypertensive subjects
than the controls. Left ventricular internal diastolic and systolic
dimensions and ejection times were however similar between the
hypertensive and control groups.
Table 2 shows the mean age and echocardiographic param-
eters among the four left ventricular geometric patterns.
Concentric hypertrophy was the commonest pattern of abnor-
mal geometry (41.4%), followed by concentric remodelling
(26.2%), and eccentric hypertrophy was demonstrated in 14.6%
of the hypertensive population. Only 17.7% of the hypertensive
population had normal geometry. Hypertensives with concentric
hypertrophy were likely to be older. The mean Tei index was
significantly higher in patients with each abnormal geometric
TABLE 1. CLINICALAND ECHOCARDIOGRAPHIC PARAMETERS
OF STUDY PARTICIPANTS
Variable
Hypertensives (164)
Controls (64)
p
Age (years)
56.6
±
12.5
55.2
±
7.8
0.408
Gender F (%)
78 (47.6%)
31 (48.3%)
0.675
SBP (mmHg)
147.9
±
24.0
125.1
±
15.1
0.000**
DBP (mmHg)
89.9
±
11.7
78.9
±
12.1
0.000**
LVIDd (mm)
45.9
±
9.0
45.3
±
8.8
0.660
LVIDs (mm)
31.0
±
11.1
32.4
±
8.0
0.389
IVSd (mm)
14.5
±
4.6
10.3
±
3.6
0.000**
PWTd (mm)
12.3
±
5.9
10.3
±
2.7
0.022*
ET (msec)
275.0
±
56.8
284.4
±
36.1
0.239
IVCT (msec)
101.1
±
46.6
88.0
±
25.6
0.012*
IVRT (msec)
99.4
±
28.6
79.9
±
14.2
0.000**
BMI (kg/m
2
)
26.1
±
5.3
23.3
±
4.1
0.000**
LVMI (g/m
2.7
)
106.5
±
55.3
42.3
±
19.8
0.038**
RWT
0.56
±
0.5
0.42
±
0.1
0.025*
Tei index
0.77
±
0.68
0.40
±
0.07
0.000**
*Statistically significant. SBP: systolic blood pressure, DBP: diastolic blood
pressure, LVIDd: left ventricular internal dimension in diastole, LVIDs: left
ventricular internal dimension in systole, PWTd: posterior wall thickness in
diastole, ET: ejection time, IVCT: isovolumic contraction time, IVRT: isovolu-
mic relaxation time, BMI: body mass index, LVMI: left ventricular mass index,
RWT: relative wall thickness, F: female.
