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.