CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 4, July/August 2010
AFRICA
187
Helsinki, on the ethical principles for medical research involving
human subjects.
8
The study was cross sectional in design and patients were
recruited serially from October 2008 to May 2009. After comput-
ing a minimum sample size using a validated formula,
9
applying
a prevalence of HHD in Kano of 56.7% (among patients referred
for echocardiography),
10
and a sample error of 10%, 186 patients
were eventually recruited to improve the power of the study.
Information obtained from all recruited patients included
relevant history, and findings from a physical examination,
echocardiogram and electrocardiogram (ECG). Additional infor-
mation obtained included recent (tested within the previous eight
weeks) serum levels of creatinine and urea, and packed-cell
volume (PCV) in venous blood.
Transthoracic echocardiography was performed using the
Aloka cardiac ultrasound system (model SSD 4000 PHD) in
AKTH, the Toshiba diagnostic ultrasound machine (model SSA
325A) in MMSH and the ATL Ultramark 9 ultrasound machine
at the private centre, with 3.75-MHz sector transducers. The
procedure was performed according to the recommendations of
the American Society of Echocardiography,
11,12
and by the same
person (KMK) in all cases to avoid inter-observer variability.
Patients were examined in the left lateral decubitus position.
Right ventricular long-axis function (TAPSE) was recorded
from the apical four-chamber view with the M-mode cursor
positioned at the free wall angle of the tricuspid valve annulus.
Right ventricular long-axis excursion amplitude (TAPSE) was
taken from end-systole to end-diastole.
13
Reduced TAPSE was defined as a value of
<
15 mm, which
has been found to be a strong predictor of death or emergency
heart transplantation among heart failure patients.
3
Normal RV
systolic function was therefore defined as TAPSE of
≥
15 mm
(patients categorised as group 1), while values below 15 mm
were considered abnormal (patients categorised as group 2).
Evidence of raised pulmonary vascular resistance, suggestive of
pulmonary hypertension, was defined as pulmonary valve (PV)
acceleration time of
<
100 ms.
Among the recruited hypertensive patients, a diagnosis of
hypertensive heart disease was made if an abnormality was detect-
ed on the echocardiogram, which was causally related to hyper-
tension and without an alternative explanation. These abnormali-
ties included any of the three abnormal LV geometric patterns of
HHD as defined by Ganau
et al
.,
14
increased left atrial (LA) size
and volume, and diastolic or systolic left ventricular dysfunctions.
Systemic hypertension was defined according to the recommen-
dation of the World Health Organisation/International Society
of Hypertension (WHO/ISH), using the cut-off values of systo-
lic/diastolic blood pressures (SBP/DBP) of
≥
140/90 mmHg.
15
Renal failure was simply defined as the presence of a serum
creatinine concentration of
≥
176
µ
mol/l (
≥
2 mg/dl).
15
Anaemia
was defined as packed-cell volume of
<
39% in men and
<
36% in
women. History of tobacco smoking was considered a risk factor
if smoking was daily, regardless of the dose. Excessive alcohol
intake was defined as a weekly intake of more than 21 units for
men and 14 units for women.
16
The diagnosis of diabetes mellitus
(DM) was based on WHO criteria.
17
Cardiac rhythm disturbances
were defined according to the recommendations of the American
College of Cardiology/American Heart Association task force on
clinical data standards.
18
Ischaemic heart disease was excluded
by the presence of all of the following: no history of angina,
no ECG changes suggestive of myocardial infarction,
18
and no
regional wall motion abnormalities on echocardiography.
Data were analysed with SPSS version 11.5. Means and stand-
ard deviations were computed and presented for quantitative
variables. The Student’s
t
-test, Wilcoxon rank-sum (
z
), Fisher’s
exact and Chi-square (
χ
2
) tests and measures of effect were used
for comparison between groups as appropriate, with
p
< 0.05
regarded as significant. Pearson’s correlation (
r
) coefficient and
the binary logistic regression model were used to analyse the
associations between TAPSE and a number of variables.
Results
A total of 186 patients were serially recruited and studied from
the three centres over seven months (October 2008 to May 2009),
comprising 89 males (47.85%) and 97 females (51.15%). The
mean age of all patients was 55.94
±
17.00 years.
Table 1 describes the baseline characteristics of the patients
and compares patients with normal RV systolic function (group
1) with those with abnormal function (group 2). The table shows
that compared with patients in group 2, group 1 patients were
significantly younger and tended to have a shorter duration of
hypertension. Group 1 patients also had a lower prevalence of
features of heart failure (dyspnoea and peripheral oedema) and
anaemia, and lower mean heart rate.
The mean TAPSE in all patients was 18.30
±
5.82 mm. Table
2 compares the echocardiographic features of the two groups.
Patients in group 2 had a significantly larger right ventricle, left
ventricle and left atrium, and lower mean TAPSE. Indices of
LV long-axis function (LV lateral and septal APSE) were also
significantly lower among group 2 patients.
Table 3 shows the findings in the resting ECG of the patients.
Atrial arrhythmias were more prevalent among group 2 patients,
and the most frequent were atrial fibrillation or flutter. Group 2
patients also had statistically significant shorter PR and longer
QT
c
intervals.
Table 4 describes the correlates of TAPSE. The strongest
correlates of TAPSE were its corresponding indices of long-axis
function of the left ventricle [lateral and septal annular-plane
systolic excursion (APSE)].
In the logistic regressionmodel controlling for other confound-
ing factors, independent predictors of reduced TAPSE were age
[odds ratio (OR)
=
1.035; confidence interval (CI)
=
1.012–1.058
years;
p
=
0.002], peripheral oedema (OR
=
2.921; CI
=
1.036–
8.239;
p
=
0.043), LA diameter (OR
=
1.061; CI
=
1.001–1.125
mm;
p
=
0.046), LV end-diastolic diameter (LVEDD) (OR
=
0.882; CI
=
0.811–0.959 mm;
p
=
0.003), LV end-systolic
diameter (LVESD) (OR
=
1.133; CI
=
1.058–1.214 mm;
p
<
0.001), LV out-flow tract (LVOT) diameter (OR
=
0.855; CI
=
0.754–0.970 mm;
p
=
0.015), and septal APSE (OR
=
0.777; CI
=
0.641–0.943 mm;
p
=
0.011).
Discussion
Although systemic hypertension is one of the most researched
subjects in medicine, the literature on right ventricular systolic
function among hypertensives is quite scanty,
6
especially among
Africans. This study showed that almost one-third of patients
with HHD (29.6%) on echocardiography in Kano had RV systolic
dysfunctionintheformofreducedRVlong-axisexcursion(TAPSE).
In a sample population of patients with heart failure of vari-
