Cardiovascular Journal of Africa: Vol 27 No 3 (May/June 2016)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 3, May/June 2016

144

AFRICA

no intimal tear was discovered over the aortic root or the arch,

simple reconstruction of the ascending aorta was done and the

patient was enrolled in our data set. In total there were 21 cases

of DeBakey type I and 30 of DeBakey type II (Table 1). Of these

51 cases, seven patients underwent concomitant re-suspension of

the aortic valve due to mild aortic regurgitation, noted during

pre-operative echocardiography.

The patients were divided into two groups based on their

arterial cannulation site. We collected the data retrospectively

and focused on mortality rate and short- and mid-term results

between the two cannulation groups. Operative mortality was

defined as death within 30 days after surgery. Of the survivors, we

compared ventilator-dependent days, intensive care unit (ICU)

stay, and hospital stay between the two subgroups. The patients

were scheduled for follow-up CT angiography every three months

in the first year and then every year for the next two years.

Demographics and pre-operative characteristics of all 51

patients (38 men and 13 women) are summarised in Table 1. The

mean age of the patients was 59.0

14.0 years (median: 60.5;

range: 33–87). All surgeries were performed on an emergency

basis within 12 hours of the onset of symptoms. Forty-two

patients (82%) had hypertension, 13 (25%) had congestive heart

failure, and seven (13%) had diabetes. With regard to clinical

presentations (Table 1), 12 patients (23%) were in shock (systolic

blood pressure

90 mmHg), 14 (27%) had haemopericardium,

and 11 (21%) had respiratory failure with ventilator support.

Two patients developed cerebral ischaemia (4%), six developed

visceral ischaemia (12%), 11 developed renal ischaemia (21%),

and four developed lower limb ischaemia (8%).

Surgical technique

Before 2005, our cannulation strategy for repairing AADA tended

towards more use of femoral artery cannulation. After 2005, the

strategy switched to more use of subclavian artery cannulation

because of developing familiarity with this technique. We

routinely used 8- or 10-mm T-grafts for cannulation to avoid

compromise of perfusion distally, and then performed median

sternotomy and dual-stage venous cannulation over the right

atrium.

Once cardiopulmonary bypass (CPB) was initiated, profound

hypothermia was induced until the bladder or oesophageal

temperature was less than 18°C. At the same time, protective

adjuncts, such as barbiturates, steroids, ice packed around the

head, and steep Trendelenburg positioning, were employed for

cerebral protection. Aortic clamping was abandoned to avoid

injury to the fragile intima. Once the temperature was below

18°C, hypothermic circulatory arrest without retrograde cerebral

perfusion was used in the femoral cannulation group, while

antegrade selective cerebral perfusion with arterial flow of 8–10

ml/kg/min was used in the subclavian cannulation subgroup.

Aortotomy approximately 3 cm above the sinus of Valsalva

was performed, and the aortic root and arch were carefully

inspected to determine the optimal procedure for each case. If

arch reconstruction, Bentall’s procedure or David’s procedure

was required, these patients were excluded from the study. St

Thomas cardioplegic solution was directly infused via both

coronary ostia for myocardial protection. Distal anastomosis

with a Hemashield graft and sandwich procedure with Teflon

felt strips for reinforcement of the diseased aorta was performed

first, after which the perfusion was converted through the

ascending graft and was initiated to minimise systemic ischaemic

time. Proximal anastomosis was subsequently performed,

followed by rewarming, adequate de-airing, and weaning of the

extracorporeal circulation.

The intra-operative variables are summarised in Table 1.

Overall, the mean CPB time was 184.9

57.1 min, the mean

heart ischaemic time was 95.9

33.6 min, and the mean

circulatory arrest time was 32.2

5.4 min. In the femoral group,

without selective antegrade cerebral perfusion, the mean brain

ischaemic time was 33.8

5.1 min.

Statistical analysis

All statistical analyses were performed using SPSS software

version 12 (SPSS, Chicago, IL, USA). Categorical variables are

expressed as percentages and were evaluated with the

test or

Fisher’s exact test. Continuous variables are expressed as mean

standard deviation and were evaluated using the Student’s

-test.

Stepwise logistic regression analysis was used to determine the

independent predictors of 30-day hospital mortality. Survival

was calculated by the Kaplan–Meier method.

Results

There were 11 (21%) deaths after surgery (Table 2), the causes of

which included cardiac failure in six, visceral ischaemia in three,

aortic re-dissection in one, and respiratory failure complicated by

adult respiratory distress syndrome (ARDS) in one. Five patients

(9%) had postoperative neurological complications, including

transient neurological dysfunctions in three and permanent

Table 1. Disease characteristics, clinical presentation

and intra-operative variables

Parameters

Total,

(%)

Femoral

group,

(%)

Subclavian

group,

(%)

value

Total number

26 (100)

25 (100)

DeBaykey type I

21 (41)

12 (46)

9 (36)

DeBaykey type II

30 (59)

14 (54)

16 (64)

Age (mean

SD)

59.0

14.0 60.9

13.7 57.0

14.4 0.33

Gender (male)

38 (74)

20 (77)

18 (72)

0.687

Cerebral vascular accident

1 (2)

1 (4)

0 (0)

1.00

Coronary artery disease

8 (15)

4 (15)

4 (16)

1.00

Diabetes

7 (13)

4 (15)

3 (12)

1.00

Hypertension

42 (82)

23 (88)

19 (76)

0.24

PAOD

1 (2)

0 (0)

1 (4)

0.98

Congestive heart failure

13 (25)

8 (30)

5 (20)

0.37

COPD

6 (11)

2 (7)

4 (16)

0.62

Shock

12 (23)

7 (27)

5 (20)

0.56

Haemopericardium

14 (27)

10 (38)

4 (16)

0.138

Aortic regurgitation

7 (13)

6 (23)

1 (4)

0.11

Cerebral ischaemia

2 (4)

2 (7)

0 (0)

0.48

Respiratory failure

11 (21)

6 (23)

5 (20)

0.78

Visceral ischaemia

6 (12)

3 (11)

3 (12)

0.95

Renal ischaemia

11 (21)

6 (23)

5 (20)

0.78

Limb ischaemia

4 (8)

2 (7)

2 (8)

0.96

Operation time (h)

7.13

1.60 7.53

1.72 6.72

1.39 0.07

Cardiopulmonary bypass

time (min)

184.9

57.1 177.9

62.1 192.2

51.6 0.37

Heart ischaemic time (min)

95.9

33.6 97.0

34.5 94.8

33.3 0.81

Circulatory arrest time (min) 32.2

5.4 33.8

5.1 30.6

5.3 0.03

Brain ischaemic time (min)

–

33.8

5.1

0.00

PAOD, peripheral arterial occlusion disease, COPD, chronic obstructive pulmo-

nary disease.