CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 1, January/February 2010
AFRICA
23
the commonest left ventricular geometric abnormalities in this
study. This was similar to the findings from the Atherosclerosis
Risk in Community (ARIC) study as reported by Fox
et al
.,
27
who demonstrated that 65% of their hypertensive cohort had
either concentric hypertrophy or concentric remodelling. Several
studies have shown that the increased prevalence of LVH among
blacks may be due to genetic susceptibility during their develop-
ment.
28-31
The association of hypertension with left ventricular
hypertrophy therefore calls for more aggressive treatment to
reverse the adverse cardiovascular risk associated with it.
Subjects with eccentric hypertrophy had the lowest ejection
fraction in this study. Others have reported similar associations
among hypertensive subjects.
27
The haemodynamic changes
associated with eccentric hypertrophy caused increased left
ventricular diastolic and systolic dimensions (as shown in Table
4) due to associated volume overload. This dilation of the left
ventricle is an important risk factor for subsequent progressive
reduction in left ventricular ejection fraction and heart fail-
ure. Those with eccentric hypertrophy also had the lowest left
ventricular ejection time in this study. This was possibly due to
ventricular chamber dilatation and consequently increased end-
diastolic volume. Hence, the left ventricular output decreases
and ultimately and progressively may lead to the development
of heart failure.
The aortic valve velocity–time interval is an echocardio-
graphic index of left ventricular output. It was lowest among
those in this study with eccentric hypertrophy. Diastolic dysfunc-
tion including LV relaxation abnormality, pseudonormalisation
(normal pulse wave of mitral valve inflow but with blunted or
reversed pulmonary venous flow indicating increased left atrial
pressure and restrictive filling) occurred in various LV geometric
patterns. They have been associated with an additive effect on
cardiovascular and all-cause mortality.
In this study, left atrial dimension was highest among subjects
with eccentric hypertrophy. This pattern is also associated with
other indices of diastolic dysfunction such as abnormal IVRT
and deceleration time. Left atrial dimension has been shown to
be a good index of left ventricular diastolic dysfunction.
32
Although, the mean e/a ratio and deceleration time across
the groups were not statistically different, the differing left atrial
dimension is a good index of the presence of diastolic dysfunc-
tion among the subjects. These findings suggest that abnormal
LV geometry (especially eccentric hypertrophy) was associated
with systolic and diastolic dysfunction among treated hyperten-
sive Nigerians. In regional left ventricular function studies such
as tissue Doppler studies, cardiac MRI may demonstrate more
significant evidence of left ventricular dysfunction.
It is important to note that LVH prevalence is still high, as
revealed among treated hypertensive subjects. Similar studies
from Ibadan, Nigeria also revealed a high prevalence of LVH
TABLE 3. ECHOCARDIOGRAPHIC PARAMETERS FOR THE LEFTVENTRICULAR GEOMETRIC PATTERNS
Variable
CH
CR
EH
N
p
EF
68.14
±
15.74
68.73
±
12.81
64.9
±
19.22
71.15
±
13.97
0.471
FS
34.8
±
9.07
33.0
±
8.95
31.74
±
13.01
37.92
±
12.04
0.106
AOD
31.46
±
4.5
31.0
±
4.8
30.93
±
4.51
29.62
±
5.3
0.478
LAD
36.4
±
6.06
33.36
±
5.79
37.42
±
9.92
33.6
±
4.9
0.001*
SV
76.5
±
29.23
45.16
±
20.29
99.3
±
36.1
71.87
±
34.9
0.000*
MERAT
1.24
±
1.65
0.94
±
0.29
1.12
±
0.57
1.13
±
1.11
0.508
DT
208.5
±
54.15
200.16
±
47.7
192.7
±
65.4
202.71
±
55.2
0.310
IVRT
107.27
±
28.3
100.4
±
30.94
163.7
±
29.61
102.47
±
28.5
0.287
AVV
max
1.21
±
0.31
1.19
±
0.39
1.17
±
0.25
1.18
±
0.31
0.737
AVVTI
26.8
±
25.2
20.89
±
5.87
19.84
±
4.39
23.06
±
16.3
0.188
AVPG
max
6.26
±
3.12
7.5
±
11.67
6.4
±
5.07
6.48
±
6.9
0.71
AVV
mean
0.78
±
0.19
0.73
±
0.18
0.73
±
0.15
0.75
±
0.17
0.371
LVET Dop
281.92
±
46.5
274.37
±
34.83
256.62
±
61.3
293.12
±
25.8
0.027*
LVPEP
97.25
±
46.7
87.24
±
29.5
102.7
±
33.9
88.9
±
20.6
0.234
LVSTI
0.34
±
0.12
0.33
±
0.12
0.40
±
0.15
1.4
±
0.46
0.140
LVDID
4.77
±
0.66
3.83
±
0.59
5.5
±
0.94
4.7
±
0.44
0.000*
LVISD
3.20
±
0.83
2.7
±
0.72
3.81
±
1.48
2.95
±
0.46
0.000*
IVSD
1.39
±
0.23
1.27
±
0.22
1.27
±
0.21
1.07
±
0.21
0.000*
PWTD
1.34
±
0.18
1.20
±
0.23
1.03
±
0.16
0.87
±
0.14
0.000*
LVM
269.25
±
74.4
164.8
±
38.6
264.94
±
75.9
160.84
±
36.0
0.000*
RWT
0.57
±
0.09
0.65
±
0.23
0.38
±
0.09
0.38
±
0.05
0.000*
LVMI
67.98
±
17.5
41.44
±
8.0
67.2
±
19.17
38.23
±
7.61
0.000*
CR: concentric remodelling, CH: concentric hypertrophy, EH: eccentric hypertrophy, N: normal geometry, BSA: body surface area (g/m
2
), SBP:
systolic blood pressure (mmHg), DBP: diastolic blood pressure (mmHg), EF: ejection fraction (%), FS: fractional shortening (%), AOD: aortic
root dimension (mm), LAD: left atrial dimension (mm), SV: stroke volume (ml), LVET (2D): left ventricular ejection time in 2-D echo (sec),
MERAT: mitral e/a ratio, DT: deceleration time (sec), PHT: pressure at half time (mmHg), IVRT: isovolumic relaxation time (seconds), AVV
max
:
maximum aortic valve pressure (mmHg), AVVTI: velocity time interval of aortic valve (mmHg), AVPG
max
: maximum aortic valve pressure gradi-
ent (mmHg), AVV
mean
: mean aortic valve pressure, LVET Dop: left ventricular ejection time with Doppler (sec), LVPEP: left ventricular pre-ejec-
tion pressure time (sec), LVSTI: left ventricular stroke–time interval gradient, LVIDD: left ventricular internal dimension in diastole (cm), LVISD:
left ventricular internal dimension in systole (cm), IVSd: interventricular dimension in diastole (cm), PWTD: posterior wall thickness in diastole
(cm), LVM: left ventricular mass (g), RWT: relative wall thickness, LVMI: left ventricular mass index (g/m
2.7
). *Statistically significant.
