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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 1, January/February 2015
18
AFRICA
the aorta, whereas group 2 patients (
n
=
23, 69.6% male, mean
age 65.78
±
9.29 years) were those undergoing CEA under
normothermic conditions before initiation of CPB.
According to our institution’s policy, patients scheduled for
CABG undergo duplex ultrasound scans for screening of CAS,
and those with
≥
70% stenosis and/or plaque ulceration in at
least one carotid artery undergo carotid angiography. It was the
surgeon’s discretion which procedure would be performed in any
given patient during the study period, but this decision was not
made on characteristics or certain risk factors that the patient
had.
Patients undergoing emergency operation, multiple
interventions including valve, ascending aorta and left atrial
size reduction were excluded. Patients with a history of recent
cerebral infarction, transient or permanent ischaemic stroke and/
or cerebral bleeding were also excluded.
Daily neurological assessment by physicians of patients
undergoing CEA has been the standard of care in this institution.
Daily chart notes were carefully inspected for records regarding
neurological status of the patients. Based on these observations,
the primary outcome of interest was considered occurrence
of any new neurological event, including seizures, coma and/
or ipsilateral or contralateral motor or sensorial involvement
during the postoperative period. Beginning on the day after the
operation, all patients were given subcutaneous low molecular
weight heparin and aspirin until discharge home.
All operations were performed under general anaesthesia.
In both groups, common, internal and external carotid arteries
were exposed first through a standard approach anterior to the
sternocleidomastoid muscle. In group 1, a median sternotomy
was made, the internal thoracic artery was harvested, 350 UI/
kg of systemic heparin was administered and cardiopulmonary
bypass was established in a standardised fashion.
The carotid arteries were clamped when the systemic
temperature had cooled down to moderate hypothermia. CEA
was performed, clamps were removed and the neck incision was
left open until heparin reversal by applying sponges over the
wound. The surgeon then cross clamped the aorta and proceeded
with the CABG procedure in a standardised fashion.
In group 2, systemic heparin was administered in similar
doses and CEA was performed before the sternotomy was made.
The clamps were removed and the neck incision was left open
by applying sponges. The surgeon proceeded with a median
sternotomy and the standardised CABG procedure thereafter.
In both groups, the arteriotomy was closed primarily in all
patients without using intraluminal shunts. Cardiac arrest was
established by antegrade normothermic blood cardioplegia and
proximal anastomoses were performed with an aortic side-biting
clamp.
Statistical analysis
Statistical analyses were performed using SPSS 19.0 packaged
software. Normal distribution of variables was tested using
visual histograms and the Kolmogorov–Smirnov test. Descriptive
statistics for continuous variables were reported as mean
±
SD and descriptive statistics for categorical variables were
reported as frequency and percentage. Categorical variables
were compared using the chi-square or Fisher’s exact tests,
where appropriate. Continuous variables were compared using
the independent samples
t
-test. Since new neurological events
occurred in very few patients, no additional tests (univariate or
multivariate analysis) were performed to identify independent
predictors of adverse outcomes. Study power was tested using
G-power software.
Results
Baseline patient characteristics were similar between the two
groups (Table 1). The mean time of CPB was shorter and mean
level of hypothermia was lower in group 1 patients than in those
in group 2. There was no difference between the two groups
regarding other operative values (Table 2). A total of 28 patients
(82.3%) in group 1 and 18 patients (78.2%) in group 2 were
asymptomatic for neurological complaints (
p
=
0.76).
Overall, early mortality occurred in one patient from each
group (
n
=
2, 3.7%,
p
=
0.86). Both patients died of low
cardiac output syndrome. Adverse neurological outcome with
permanent impairment occurred in one patient (2.9%) from
group 1. One patient from each group (2.9 and 4.3%) had
transient neurological events but they recovered completely on
the sixth and 11th postoperative days, respectively.
Table 1. Baseline characteristics
Variables
Group 1
n
(%)
Group 2
n
(%)
p
Men
30 (88.2)
16 (69.6)
0.09
Age
65.94
±
6.67 65.78
±
9.29 0.9
Previous MI
9 (26.5)
6 (26.0)
0.97
Unstable angina
3 (8.8)
1 (4.3)
0.64
Previous CVA
11 (32.3)
5 (21.7)
0.48
Stroke
4 (11.8)
1 (4.3)
0.63
Hypertension
29 (85.3)
18 (78.3)
0.50
Diabetes
17 (50)
12 (52.2)
0.87
Hyperlipidaemia
19 (55.9)
9 (39.1)
0.21
Renal failure
4 (11.8)
1 (4.3)
0.63
Smoking
27 (79.4)
14 (60.9)
0.12
PAD
13 (38.2)
7 (30.4)
0.54
MI; myocardial infarction, CVA: cerebrovascular accident, PAD;
peripheral arterial disease.
Table 2. Operative variables
Variables
Group 1
n
(%)
Group 2
n
(%)
p
Number of bypass grafts
2.9
±
0.6
2.9
±
0.8
0.91
CPB time (min)
72.3
±
21.9 59.6
±
20.8 0.03
Time of cross clamping (min) 32.6
±
9.4 31.2
±
6.9
0.78
Carotid clamping time (min)
9.8
±
2.7
9.7
±
3.1
0.91
Hypothermia
30.3
±
1.3 35.8
±
0.7
0.001
Left CEA,
n
(%)
17 (50)
14 (61)
0.41
CPB; cardiopulmonary bypass, CEA; carotid endarterectomy.
Table 3. Postoperative variables
Variables
Group 1
n
(%)
Group 2
n
(%)
p
Early neurological outcomes
2 (5.8)
1 (4.3)
0.12
Intensive care unit stay (day) 2.9
±
1.7 (1–9) 3.1
±
2.2 (1–11) 0.21
Hospital stay (day)
5.2
±
4.5 (4–8) 5.3
±
4.2 (4–9) 0.19