Materials and Methods
Approval for the study was granted by the local ethical committee, and
all participants provided signed written informed consent forms
(decision no. 15, session no. 2018/10, dated 16.05.2018).Thirty-nine
patients undergoing elective CABG surgery from June 2018 to February
2019 were randomly allocated to one of two groups (DNS being used in 17
patients and IWBC in 22)(Figure 1 ). Patients requiring
emergency surgery or any combined operations were excluded. Patients
undergoing reoperation for bleeding were alsoexcludedsince cardiac
enzyme values and myocardial damage cannot beevaluated objectively under
such circumstances. All procedures were carried out with CPB and under
general anesthesia. Midazolam (ZolamidR, Defarma, Tekirdağ, Turkey)(0.1
mg/kg via the intravenous (iv) route), fentanil (TalinatR, Vem,
Istanbul, Turkey) (5-8 μg/kg iv), and rocuronium bromide (MyocronR, Vem,
Istanbul, Turkey) (0.6 mg/kg iv) were used for anesthesia induction. A
Primus device (Drager, Lübeck, Germany) was used for maintenance of
general anesthesia,and Sevoflurane (SevoraneR, Abbvie, Istanbul, Turkey)
was employed as an intraoperative anesthetic agent.Rocuronium bromide
(0.6 mg/kg iv) was applied once every 30 min. In addition,320–400 IU/kg
unfractionated heparin was administered in order to maintain an
activated clotting time (ACT) exceeding 480 sec. The ascending aorta was
first cannulated, and venous drainage was provided by a single two-stage
atrial cannula or bicaval cannulation. A 1600 mL prime volume (1500ml
isolate S, 20% mannitol 100 cc, 5000IU heparin) was employed, and
2.0–2.5 L/min/m² flow rate, 200-250 mm Hg PaO2, and
35-45 mmHg PCO2were maintained. Blood specimens were
collected with the insertion of a retrograde cardioplegia cannula. DNS
and IWBC were applied in an antegrade manner. Our myocardial protection
routine involves the administration of an additional dose 60 min after
the first dose based on our clinical experienceof DNS. However, none of
our patients required a second dose. Following aortic clamping, 1000 mL
DNS was delivered once at +4°C. In case of patients receiving IWBC,
15ml/kg (maximum 1000 cc) blood cardioplegia was delivered at 32°C, and
an additional dose was administered every 20 min during the ischemic
period. Topical hypothermia was applied in all cases. A membrane
oxygenator and an arterial line filter were employed in all cases to
maintain a hematocrit (Hct) level>22% during CPB, while
mean arterial pressure was preserved at 60–80 mmHg.Serum glucose was
maintained between 110 and 200 mg/dL with insulin infusion if
required.Thıs was then cooled to 32°C (nasopharyngeal core body
temperature), and a-stat pH management was applied.IWBC and
DNScardioplegia contents are shown in Table 1.