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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018
340
AFRICA
For postoperative care, oral anticoagulants (warfarin sodium)
were administered routinely in addition to subcutaneous
low-molecular-weight heparin, starting from the first postoperative
day. Prothrombin time and INR values were maintained in a range
of 1.5–2.0 times the control values. Patients were re-evaluated
regarding clinical and echocardiographic findings in the sixth
month, and the first, third and fifth years.
Statistical analysis
Analysis of data was carried out using Statistical Package for
Social Sciences Program version 14.0 (SPSS Inc, Chicago, IL,
USA). Level of significance was set at
p
<
0.05. Clinical parameters
are expressed as mean
±
standard deviation. Comparison of
ratios between groups was assessed with chi-squared, Pearson’s
chi-squared and Fisher’s exact tests. The
t
-test andMann–Whitney
U
-test were performed for analysing average values of the groups.
Pre- and postoperative changes in the same group were evaluated
with the
t
-test and Wilcoxon signed rank test. Correlation between
variables was done with Spearman’s correlation test.
Results
When we compared baseline demographic data, patients that
received no 19 prosthetic valves were younger, thinner and had a
smaller body surface area than patients receiving nos 21, 23 and
25 valves. Gender, New York Heart Association score and other
demographic variables did not exhibit any significant difference
between the groups (Table 1).
Aortic valve area and mean diameter of the aortic annulus
was significantly lower in patients receiving no 19 valves. The four
groups did not seem to differ regarding left ventricular ejection
fraction, maximum and mean flow gradients, end-systolic and
end-diastolic left ventricular diameters, thicknesses of the
interventricular septum and posterior wall and left ventricular
mass index. Similarly, electrocardiography and telecardiography
measurements did not reveal any significant differences between
the groups (Tables 2, 3).
There were no significant differences between the four groups
with regard to surgical data such as duration of aortic cross-
clamp, cardiopulmonary bypass, and intensive care unit and
hospital stay (Table 2). In all groups postoperatively, the controls
did not yield any significant differences within each group and
between groups regarding heart rate, arterial tension and left
atrial diameter (
p
=
0.12).
Assessment of results within each group postoperatively
demonstrated that patients operated on using no 19 prosthetic
valves had improved ejection fraction and effort capacity.
Moreover, LVESD, LVEDD, PWT, IVST, PAG, MAG, LVM
and LVMI had decreased significantly. These changes were most
obvious for LVM and LVMI in all groups postoperatively (
p
=
0.001, for all postoperative periods) (Table 4).
For patients operated on with nos 21, 23 and 25 prosthetic
valves, both ejection fraction and effort capacity were increased
postoperatively. There were also significant reductions in MAG,
IVST, PWT, LVESD, LVEDD, LVM and LVMI. Interestingly,
reductions in LVM and LVMI were less obvious after the third
year postoperatively. The most dramatic changes in LVM and
LVMI occurred in the sixth month postoperatively; however, this
became less evident in the following years (Table 4).
When the patient groups operated on with different-sized
mechanical prosthetic valves were assessed together, the most
obvious reductions in LVM, LVMI, MGR, PGR, IVST, PWT,
LVESD and LVEDD were noted in patients who received nos 23
and 25 valves. The least obvious changes occurred in the group
operated on with no 19 valves. Similarly, the most noteworthy
improvements in ejection fraction and effort capacity were
observed in patients in whom nos 23 and 25 valves were inserted.
Table 1. Demographic and clinical data of the patient groups
Valve sizes
p
-value
Parameters
No 19 MP
(
n
=
8)
No 21 MP
(
n
=
38)
No 23 MP
(
n
=
40)
No 25 MP
(
n
=
6)
Age (years),
mean
±
SD
38.5
±
16.8* 51.5
±
9.8 55.2
±
6.8 58.1
±
6.4 0.001
Body surface area
(m
2
), mean
±
SD 1.56
±
0.1** 1.7
±
0.2 1.8
±
0.2 1.8
±
0.1 0.005
Gender
Female,
n
(%)
3 (37.5)
16 (42.1) 16 (40)
2 (33.3) 0.5
Male,
n
(%)
5 (62.5)
22 (57.3) 24 (60)
4 (66.6) 0.5
COPD,
n
(%)
1 (12.5)
6 (15.7)
7 (17.5)
1 (16.6) 0.5
Diabetes mellitus,
n
(%)
2 (25)
14 (36.8) 15 (37.5)
2 (33.3) 0.1
Hypertension,
n
(%)
4 (50)
24 (63.1) 25 (62.5)
4 (66.6) 0.1
Smoking,
n
(%)
3 (37.5)
18 (47.3) 18 (45)
3 (50)
0.1
MP
=
mechanical prosthesis; COPD
=
chronic obstructive pulmonary disease; SD
=
standard deviation.
*
p
=
0.001, statistically significant difference in terms of age between the group
with no 19 prosthesis and the other groups.
**
p
=
0.005, statistically significant difference in terms of body surface area
between the group with no 19 prosthesis and the other groups.
Table 2. Pre-operative, operative and postoperative
variables in the patient groups
Valve sizes
p
-value
Time periods
and variables
No 19 MP
(
n
=
8)
No 21 MP
(
n
=
38)
No 23 MP
(
n
=
40)
No 25 MP
(n
=
6)
Pre-operative
LVEF (%)
56.6
±
3.5 54.5
±
3.2 53.6
±
3.5 54.8
±
4.5 0.15
Aortic valve area
(cm
2
)
0.9
±
0.1* 1.0
±
0.1 1.1
±
0.1 1.1
±
0.2 0.001
Annulus diameter
(mm)
22.8
±
1.3** 24.2
±
1.1 25.7
±
0.7 27.2
±
0.9 0.001
PAG (mmHg)
78.6
±
5.5 80.3
±
5.2 83.5
±
4.5 85.2
±
4.7 0.2
MAG (mmHg)
38.8
±
4.5 49.7
±
5.0 47.8
±
6.0 48.5
±
5.8 0.18
LVEDD (mm)
54.2
±
4.6 55.8
±
5.2 56.5
±
6.3 57.8
±
6.0 0.08
LVESD (mm)
35.5
±
3.5 37.2
±
3.3 38.1
±
3.3 39.5
±
4.0 0.1
IVST (mm)
14.6
±
1.9 15.5
±
1.8 15.7
±
2.2 15.9
±
2.0 0.09
LVMI (g/m
2
)
216.0
±
24.4 224.7
±
36.4 226.1
±
45.3 235
±
53.6 0.5
Intra-operative
Cross-clamp
duration (min)
70.3
±
3.7
63
±
4.6
59.7
±
4.2 62.2
±
4.3 0.06
Cardiopulmonary
bypass duration
(min)
96.5
±
3.9 84.1
±
4.9 82.6
±
4.2 80.7
±
3.6 0.08
Post-operative
ICU stay (hours)
44
±
7.1 38.5
±
5.4 37.4
±
3.2 39.6
±
4.5 0.73
Duration of
hospitalisation
(days)
6.8
±
1.2 7.2
±
1.3 7.0
±
1.1 6.9
±
1.1 0.51
MP
=
mechanical prosthesis; LVEF
=
left ventricular ejection fraction; PAG
=
peak
aortic gradient; MAG
=
mean aortic gradient; LVESD
=
left ventricular end-systolic
diameter; LVEDD
=
left ventricular end-diastolic diameter; IVST
=
interventricular
septum thickness; LVMI
=
left ventricular mass index; ICU
=
intensive care unit.
*
p
=
0.001, statistically significant difference in terms of aortic valve area between
the group with no 19 prosthesis and the other groups.
**
p
=
0.001, statistically significant difference in terms of annulus diameter between
the group with no 19 prosthesis and the other groups.