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

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

174

AFRICA

to death was found in 35% during the pre-operative phase by

Shannon

et al.

For the local study, a POCMA was not done. In practice, it

means an error in selection, an error in procedure or an error

in care. Hence co-morbidities and mortality risk factors are

part of the selection criteria. Determining those factors was

important for the surgeon, as every death or major complication

emphasises the surgeon’s feeling of responsibility or loneliness.

This is an emotional response, but it could progress to spiritual

reflection.

Some of the risk factors of the 1990s are even now important

contributors to the risk for death. In this particular study, female

gender was not a risk for mortality, although female patients

had a higher EuroSCORE than the males (4.7 vs 3.6). In fact,

male gender was almost a mortality hazard (

0.0801). In the

EuroSCORE II, female gender still contributes to death after

surgery, although this contribution is small.

Others claim that it

is not the gender per se, but rather the associated co-morbidities

associated with the female gender.

The finding that the referring cardiologist contributes to

the risk and therefore mortality rate was expected (Table 5);

however, it was not significant in the stepwise logistic regression.

Cardiologist B referred more patients with an additional

procedure (40.2% of the total of 122). Cardiologist C had only

one such patient, but then C presented 11.0% of patients with an

IABP, whereas C’s contribution to the total number of cases was

only 3.1%. In the EuroSCORE, IABP is a significant factor for

risk/mortality. It could be argued that Cardiologist B had a lower

threshold to refer patients with a higher risk for surgery in an

attempt to treat the patient. It could also mean that Cardiologist

B has a more aggressive interventional approach towards lower-

risk patients. It is hoped that this also attests to confidence in the

surgical team.

The significant risk factors from the

Tabula viva chirurgi

after

logistic regression differed from the original Working Group

Panel on the Cooperative CABG Database Project.

Only

re-operation and urgency remained as risk factors. Three of

the five theatre deaths were re-operations and the patient who

bled to death also had a second operation. The other deaths

among the re-operation group of patients had the same mixture

of reasons for death as the rest (Table 3). In a large series of

1 521 re-operations, the mortality rate was 9.7% (in the

Tabula

viva chirurgi

re-operations had a mortality rate of 9.2%).

Pre-operative renal impairment (CKD III in particular) and

an associated procedure were not investigated in the Working

Group during the 1990s.

If all the patients with one or more of these four significant

risk factors were excluded, the mortality rate would drop to

seven of 963 patients (0.73%), with an expected mortality

rate of 2.40% (EuroSCORE). Another way of confirming the

contribution of risk factors is to look at the observed mortality

rate of those patients with an expected mortality rate of 0% (i.e.

EuroSCORE 0). One individual of 237 patients died (0.42%). In

the recent EuroSCORE II, the lowest possible risk of mortality

is in any case 0.5%.

The impact of major morbidity on mortality is illustrated in

Table 8. Not all patients who bleed more than expected require

re-exploration, nevertheless excessive drainage is stressful to

the surgeon. To take patients back to theatre for bleeding/

tamponade puts severe strain on the surgeon. It is not only a

utilisation of resources (human and financial), but the bleeding,

re-opening of the chest and subsequent blood transfusion put

the patient at further risk. It is comforting to realise that a unit

such as Cleveland takes 3.0% of patients back to theatre.

A Swedish study reported on 2 000 CABG patients,

with a re-exploration rate of 4.9% and, interestingly enough,

10.0% (similar to the

Tabula viva chirurgi

) drained more than

1 000 ml, measured over 12 hours. In the

Tabula viva chirurgi

, the

measurement was done over 48 hours. Although 36 patients were

ventilated for longer than 48 hours, 15 patients were ventilated

for respiratory reasons and 21 because of a suppressed level of

consciousness.

Renal failure in particular needs to be addressed. As an

isolated complication, renal failure was found in 14 patients,

and another 15 had renal failure combined with mechanical

ventilation. Three patients had a third complication. Of these 32

(1.8%) patients, 25 required dialysis (seven patients died before

renal intervention). Prolonged mechanical ventilation with renal

failure (dialysis) is a lethal combination as 11 of 15 such patients

died. Only one of 10 patients who required postoperative dialysis

as an isolated major complication, died. Two-thirds of the

patients with renal failure were pre-operatively CKD III.

Both Cleveland Clinic

and the Japan Adult Cardiovascular

Surgery Database (JACVSD)

consider renal failure as new

dialysis. The prevalence of renal failure (new dialysis) in the

JACVSD was 3.18%. The STS defines renal failure as a critical

rise in serum creatinine.

21,22

In the

Tabula viva chirurgi

, 144 (8.2%)

patients increased their basal creatinine level by 50% or higher

postoperatively. This remains a sign of renal damage.

It is important to realise that three-quarters of patients

(

Tabula viva chirurgi

) are operated on in hospital directly

after their coronary angiogram and were therefore exposed to

contrast medium. The referring cardiologist is usually concerned

about unstable angina and critical coronary artery anatomy.

These patients are all at risk for renal injury and even more

so after the surgery that might follow.

Surgery within five

days of angiography has an odds ratio of 1.82 to lead to renal

impairment.

This is regardless of a pre-operative glomerular

filtration rate

60 ml/l/1.73 m

, and cardiopulmonary bypass

duration, which also affects renal performance.

Stroke is a shattering complication. Apart from it being a

blow to the patient and to those caring for him/her, a stroke

in particular contributes to this burden of liability surgeons

might experience, not only from a medico-legal perspective, but

also from a spiritual viewpoint. Stroke occurred in 20 patients

(1.1%), 11 as an isolated complication, but in another nine

as an associated major adverse event (Table 6). Four patients

died, therefore a mortality rate of 20%. This stroke rate is also

in accordance with the STS and JACVSD, 1.4% and 1.5%,

respectively, but both registries were for isolated CABG.

22,35

The

unit at Emory University reports a prevalence of 2.2% with an

almost similar mortality rate of 22.5%.

Deep sternal sepsis is another major complication of the

STS. The Centres for Disease Control and Prevention provide

criteria for the diagnosis of deep sternal sepsis.

In the local

series, dehiscence of the sternum was documented for deep

sternal sepsis. Ten patients were taken back to theatre for

rewiring during the initial hospital stay and another seven were

discharged, but were re-admitted within six weeks. Two of the

patients were also mechanically ventilated and one of them had