CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 2, March 2012
64
AFRICA
ular ejection fraction
>
50% were included in the study. In all
patients, there were severe, diffuse and multiple atherosclerotic
lesions on the right coronary artery. All the left anterior descend-
ing (LAD) lesions were located proximally.
Demographic data, including risk factors were recorded.
Presence of hypertension was defined as systolic blood pressure
>
140 mmHg and diastolic blood pressure
>
90 mmHg on two or
more occasions, or use of an antihypertensive drug. Patients who
were on antidiabetic medication (insulin or oral hypoglycaemic)
at the study entry or whose fasting blood glucose levels were
higher than 125 mg/dl were considered to have diabetes mellitus.
Hypercholesterolaemia was defined as total cholesterol level
>
200 mg/dl or any medication being used. Patients were classi-
fied as cigarette smokers if they had smoked within the last 10
years. None of the patients had acute coronary syndrome.
Exclusion criteria included a history of recent right-side
myocardial infarction, left ventricle systolic dysfunction (ejec-
tion fraction
<
50%), right ventricular ejection fraction
<
40%,
presence of atrial fibrillation, previous CABG, significant
valvular heart disease, pulmonary hypertension (
>
50 mmHg),
significant pulmonary disease, or left bundle branch block on
electrocardiogram.
All echocardiographic measurements were performed by a
single experienced investigator using an ultrasound imaging
system (Vingmed 5, General Electric, USA) with a 2.5-MHz
transducer equipped with pulsed-wave tissue Doppler. Heart
rate during the examination was kept at 60 to 100 beats/min.
Measurements were performed according to the recommen-
dations of the American Society of Echocardiography.
10
For
M-mode, two-dimentional and Doppler examination, a 2.5-mHz
transducer was used.
Pulmonary artery systolic pressure was calculated as the sum
of the pressure gradient measured from the tricuspid regurgita-
tion wave and estimated right atrial pressure.
11
After the conven-
tional echocardiographic examination, RV diastolic function was
determined on the apical four-chamber view using a 2.5-mHz
transducer.
With the subjects in the lateral supine position, tissue Doppler
recordings were obtained from the standard parasternal and
apical views. Three major velocities were recorded at the annular
sites: the peak major positive systolic velocity when the annulus
moved towards the apex, and two major negative velocities when
the annulus moved back towards the base (one during the early
phase of diastole and the other during the late phase of diastole).
The velocities were recorded online at a sweep speed of 50 mm/s.
A mean of five consecutive cycles was used for the calculations
of all echo-Doppler parameters. RV ejection fraction was deter-
mined using the ellipsoidal shell method. All measurements were
performed one month after the operation.
All operations were performed by the same surgeon who had
10 years of experience of coronary artery surgery. Complete
revascularisation was the ultimate goal in all patients. A median
sternotomy was performed in all patients. The
in situ
LIMA was
always the graft of choice for revascularisation of the LAD. The
LIMA was harvested with a pedicle and preserved in a sponge
with papaverine to avoid spasm. SVGs were used for revascu-
larisation of the remaining coronary vessels. The pericardium
was opened, followed by general heparinisation, and aortic and
venous cannulation using a double-stage atrial cannula, after
which cardiopulmonary bypass was initiated.
Cardiac arrest was maintained by warm blood cardioplegia
under moderate hypothermia. A sequential venous graft was
used for revascularisation of the RCA. The choice between
individual and sequential technique was based on the anatomical
position of the vessels and grafts. All coronary anastomoses were
performed using a double-armed 7-0 polypropylene suture with a
continuous suturing technique. Distal anastomosis was done end
to side. Side-to-side anastomoses were performed in a diamond
shape (graft axis perpendicular to coronary arteriotomy) and
end-to side anastomoses parallel to the native coronary vessel
axis (Fig. 1).
The length of the graft and the distance between segments to
be anastomosed were determined before the initiation of cross-
clamping while the size of the right ventricle was optimal, as an
‘empty’ right ventricle would lead to erroneous selection of an
over- or undersized graft. Proximal anastomoses were construct-
ed on the ascending aorta with continuous double-armed 6-0
polypropylene sutures using a side clamp during rewarming.
Complete revascularisation using the internal thoracic artery for
left anterior descending lesions and saphenous vein grafts for
other coronary arteries was the goal in all operations.
Statistical analysis
Statistical analysis was performed with SPSS software (SPSS
Inc, Chicago, IL, USA). Clinical data were expressed as
mean values
±
standard deviation and in percentages unless
stated otherwise. Categorical variables were assessed using the
Chi-square test. Continuous variables were compared using the
unpaired Student’s
t
-test or Mann-Whitney
U-
test. A
p
-value
<
0.05 was considered statistically significant in all comparisons.
Results
The basal clinical and echocardiographic parameters for the
patients is shown in Table 1. There were no significant differ-
ences between the two groups regarding demographic variables
and basal echocardiographic parameters. Mean age was 62.3
±
4.0 years in group A and 64.7
±
6.2 years in group B (
p
>
0.05).
Maximum pulmonary systolic pressures did not differ between
the two groups (34.3
±
13.3 vs 32.9
±
10.8 mmHg,
p
>
0.05).
There were no mortalities or complications noted in the postop-
Fig. 1. Intra-operative view of the right sequential bypass.
