How Minimalized Extracorporeal Circulation Compares with the Off-Pump Technique in Coronary Artery Bypass Grafting

Prognostic indicators after cardiac surgery in children and their relationship with the oxidative stress response

OBJECTIVES

To analyse the trend in lipid peroxidation and antioxidant response as key markers of oxidative stress after paediatric cardiovascular surgery, and compare them with other internationally accepted clinical prognostic indicators.

PATIENTS AND METHODS

A prospective study was conducted on 30 children aged one month to 14 years, weight>5 kg, undergoing cardiopulmonary bypass surgery. Blood samples were taken just before the intervention, immediately after surgery, and after 18-20 h. Cell membrane lipid peroxidation was analysed by quantifying malondialdehyde, as well as measuring total glutathione (oxidized and reduced), as representatives of antioxidant response. An analysis was also performed on clinical variables for establishing a score for the systemic inflammatory response syndrome associated with cardiopulmonary bypass.

RESULTS

The study included 30 children with a mean age of 4.1 years old (interquartile range [IQR]: 2.7; 8.0). Of these, 62.1% were girls. The standard deviation of the median weight was -0.39 (IQR: -0.76; 0.24), the median height was -0.22 (IQR: -0.74; 0.27), and the median BMI was -0.43 (IQR: -1; 0.45). The final surgery times were divided into 2 parts: total time of extracorporeal circulation, with a mean of 79 min (IQR: 52.5; 125.5), and the clamping time, a measurement included in the previous figure with a mean value of 38.5 min (IQR: 22; 59). Malondialdehyde increased and glutathione decreased in postoperative time, with clear, statistically significant direct correlation between time of extracorporeal circulation and percentage decrease in total glutathione between preoperative and immediate postoperative time, and a decline between the preoperative and late postoperative. There was a statistical correlation between total glutathione levels at 18-20 h postoperatively and the duration of mechanical ventilation and inflammatory systemic response syndrome.

CONCLUSIONS

Surgery with extracorporeal circulation performed in children activates inflammatory mediators, being maximum after aortic clamping, and improving after the first 24h. The level of oxidative stress activation depends on surgical times. The development of systemic inflammatory response syndrome is associated with longer duration of mechanical ventilation, longer stay in intensive care, higher scores in the Aristotle model and longer surgical times. Those who do not meet criteria for inflammatory response have higher levels of glutathione in first 24h.

Haemostasis alterations in coronary artery bypass grafting: comparison between the off-pump technique and a closed coated cardiopulmonary bypass system

OBJECTIVES

To compare coagulation and fibrinolysis activation in off-pump coronary artery bypass operation and in patients in whom a closed phosphorylcholine-coated cardiopulmonary bypass system was applied. Cardiopulmonary bypass induces activation of coagulative and fibrinolytic systems, which together with intraoperative haemodilution augment the risk of postoperative bleeding and transfusion of blood products.

METHODS

Thirty-six off-pump coronary artery bypass and 36 coronary artery bypass grafting patients in whom a closed, phosphorylcholine-coated cardiopulmonary bypass system with a closed-collapsible venous reservoir (Physio group) was used were prospectively enrolled. Activation of coagulation and fibrinolytic systems was assessed evaluating the release of prothrombin fragment 1.2 and plasmin-antiplasmin complex preoperatively (T0), 30 min after heparin administration (T1), 15 min after protamine administration (T2), 3 h after protamin administration (T3) and on postoperative days 1 (T4) and 5 (T5). Platelet function was evaluated through Platelet Function Analyzer 100(®).

RESULTS

During the operation, prothrombin fragment 1.2 and plasmin-antiplasmin levels were slightly higher in the Physio group, the difference being not statistically significant. In the off-pump coronary artery bypass group, prothrombin fragment 1.2 was significantly higher at T3 (618.7 ± 282.7 vs 416.6 ± 250.2 pmol/l; P = 0.006), T4 (416.7 ± 278.8 vs 310.2 ± 394.6 pmol/l; P < 0.001) and T5 (629.3 ± 295.2 vs 408.4 ± 409.7 pmol/l; P = 0.002), and plasmin-antiplasmin was significantly higher at T4 (731.1 ± 790 vs 334 ± 300.8 ng/ml; P = 0.019) and T5 (1744.4 ± 820.7 vs 860.1 ± 488.4 ng/ml; P = 0.003). Platelet Function Analyzer 100® closure time values were significantly higher in the Physio group patients at T3 (131.3 ± 105.7 vs 215.6 ± 58.9 s; P = 0.002). The off-pump coronary artery bypass patients had greater chest tube drainage (874.3 ± 371.5 vs 629.1 ± 334.5 ml; P = 0.005). The mean priming volume was 1240 ± 215 ml in the Physio group. Much more Physio patients received red blood cell transfusions (14 vs 25 patient; P = 0.009), because of higher intraoperative transfusion rates (6 vs 15 patients; P = 0.016). Despite similar preoperative haemoglobin levels (13 ± 1.2 vs 12.6 ± 1.4 g/dl; P = 0.2), postoperative haemoglobin levels were significantly lower in the Physio group.

CONCLUSIONS

The Physio cardiopulmonary bypass approach does not significantly alter haemostasis during the operation compared with off-pump coronary artery bypass providing a reduced activation in the postoperative period reducing also chest tube drainage. However, further priming volume reduction is required to decrease intraoperative red blood cell transfusion.

Miniaturized extracorporeal circulation vs. off-pump coronary artery bypass grafting: What the evidence shows?

Recognition of the potentially deleterious effects of esxtracorporeal circulation led to off-pump coronary artery surgery (OPCAB) experiencing a surge in popularity in the initial decade after its conception. However, OPCAB has its own limitations and technical difficulties, such as coronary access, increased left ventricular size and reduced function, which may lead to the potential for suboptimal revascularization. As an alternative technique, miniaturized extracorporeal circulation (mECC) may provide a more controlled operative field in which the heart may be manipulated whilst minimizing the inflammatory, coagulopathic and haemodilutional effects of cardiopulmonary bypass. In this review, we outline the proposed benefits of the mECC system, discuss the pitfalls associated with mECC, and directly compare mECC to ‘off-pump’ coronary surgery for a variety of clinical and non-clinical outcomes.