Minimal Extracorporeal Circulation Group Research Articles

Effects on Cerebral Oxygen Balance in Coronary Artery Bypass Grafting: A Comparison of Conventional and Minimal Extracorporeal Circulation

Objective: To investigate the cerebral oxygen balance difference between minimal extracorporeal circulation (MECC) and conventional extracorporeal circulation (CECC) during coronary artery bypass grafting. Methods: 20 patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CPB) were divided into two groups, the CECC group (n=10) and the MECC group (n=10). Blood withdrawn from radial artery and right jugular vein were analyzed at the following timepoints: during the anesthesia induction (T1), before CPB (T2), the initiation of CPB (T3), aorta crossclamped (T4), after temperature decreased (T5), during stable hypothermia (T6), initiation of rewarming (T7), aorta unclamped (T8), after weaning of CPB (T9), end of the operation (T10).The artery oxygen content (CaO2 ) and cerebral oxygen extraction ratio (OER) were calculated. The mean artery pressure (MAP), hemoglobin (Hb), nasopharyngeal temperature (NPT), and pump perfusion flow were recorded during the operation. Results: (1) MAP and Hb of MECC group were significantly higher than those in the CECC group from T3 to T10 (P<0.05); perfusion flow in MECC group during CPB was significantly lower than those in CECC group (P<0.05); NPT in MECC group was significantly higher than those in CECC group (P<0.05). (2) During T3-T4 and T8-T9, jugular venous oxygen saturation in CECC group was significantly lower than those in MECC (P<0.05); OER in CECC group was significantly higher than those in MECC group (P<0.05). (3) The arterial lactic acid and venous lactic acid in these two groups were decreased gradually from T3 to T10. Thearteriovenous difference in lactic acid in CECC group were higher than those in MECC group during T3-T4 and T8-T9 (P<0.05). Conclusion: Patients undergoing coronary artery bypass grafting with MECC enjoy more stable blood pressure, less intense hemodilution and lighter temperature disturbance than those with CECC, which indicating a better cerebral oxygen balance in CABG.

Minimal extracorporeal circulation: An appraisal from a private practice

Introduction: The systemic inflammatory response associated with cardio-pulmonary bypass (CPB) is detrimental to organ function in varying degrees. Minimal extracorporeal circulation (MECC) assumes an attenuation of these deleterious effects. The aim of this study was to compare conventional CPB (CCPB) with MECC, in a population of patients who had their CABG done in a private practice in South Africa. Methods: Two historical cohort analytical studies were done on patients who had isolated CABG done by one surgeon in the Mediclinic Bloemfontein. Patients who had their CABG done using CCPB were compared statistically using logistic regression to those who had their CABG done with MECC. A propensity score matching was also used to compare the 2 groups. In a second follow-up study, a once-off lactate on arrival in the intensive care unit was compared. A qualitative assessment of the technique by the various role-players in theatre was added to the initial study. Results: The primary CCPB group had 1 572 patients. The MECC group comprised 367 patients. No statistically significant outcome difference was found in terms of mortality, major morbidity, post-operative blood loss or usage of homologous blood. Once the 2 groups were evenly matched, patients with MECC had a better serum creatinine postoperatively, but renal dialysis could not be avoided. Patients with MECC also had a statistically shorter hospital stay. The second study (CCPB n=63 and MECC n=100) confirmed the shorter hospital stay. There was no difference in the lactate value between the 2 groups. In general, there are varying levels of enthusiasm among the theatre specialists for a MECC strategy. Conclusions: MECC protects the kidneys, but not so much against renal dialysis. MECC patients could stay for a somewhat shorter time in hospital. Tissue perfusion based on a once-off lactate level was equal. MECC might be technically more demanding. This article is an important addition to the literature that adds a local perspective.

Minimal extracorporeal circulation (MECC) does not result in less hypertrophic scar formation as compared to conventional extracorporeal circulation (CECC) with dexamethasone

Cardiopulmonary bypass surgery is associated with a systemic inflammatory response through the interaction of air, blood and synthetic components in the bypass system and the physical trauma of surgery. An alternative cardiopulmonary bypass system, minimal extracorporeal circulation (MECC), has shown promising results in terms of reducing the inflammatory response. We hypothesized that this system may reduce pathological excessive scarring. To study this assumption, the effects of MECC and the effects of conventional extracorporeal circulation (CECC) with dexamethasone on skin scarring were compared in a standardized wound-healing model. Pre-sternal scars were evaluated prospectively at four and 12 months postoperatively. The height and width of the scars were measured, using a slide caliper and sonography. The scars were scored using the validated Patient and Observer Scar Assessment Scale. Additional risk factors for hypertrophic scar formation were identified by means of a questionnaire. During surgery, MECC was used in 45 patients and CECC/dexamethasone in 42 patients. Four months postoperatively, 22 patients of the MECC group (49%) and 18 patients in the CECC/dexamethasone group (43%) had developed hypertrophic scars. Twelve months postoperatively, the hypertrophic scars in four patients of the MECC group and in two patients of the CECC/dexamethasone group had become normotrophic. In 18 patients of the MECC group (38%) and 16 patients of the CECC group (41%) the scars remained hypertrophic at 12 months. These differences between the two groups were not statistically significant. MECC does not reduce hypertrophic scar formation compared with CECC with dexamethasone, but its use is more beneficial than the use of CECC/dexamethasone because of the circulatory and immunological advantages and because treatment with dexamethasone can be omitted.

Comparing microvascular alterations during minimal extracorporeal circulation and conventional cardiopulmonary bypass in coronary artery bypass graft surgery: A prospective, randomized study

Minimal extracorporeal circulation (MECC) has been introduced in coronary artery bypass graft (CABG) surgery, offering clinical benefits owing to reduced hemodilution and no blood-air interface. Yet, the effects of MECC on the intraoperative microvascular perfusion in comparison with conventional extracorporeal circulation (CECC) have not been studied so far. The current study aimed to analyze alterations in microvascular perfusion at 4 predefined time points (T1-T4) during on-pump CABG using orthogonal polarization spectral imaging. Forty patients were randomized for being operated on with either MECC or CECC. Changes in functional capillary density (FCD), blood flow velocity, and vessel diameter were analyzed by a blinded investigator. After start of extracorporeal circulation (ECC) and aortic crossclamping (T2), both groups showed a significant drop of FCD, with a significantly higher FCD in the MECC group (206.8 ± 33.6 cm/cm² in CECC group versus 217.8 ± 35.3 cm/cm² in MECC group; P = .034). In the late phase of the ECC (T3), FCD in the MECC group was already recovered, whereas FCD in the CECC group was still significantly depressed (223.1 ± 35.6 cm/cm² in MECC group; P = .100 vs T1; 211.1 ± 36.9 cm/cm² in CECC group; P = .017 vs T1). After termination of ECC (T4), FCD recovered in both groups to baseline. Blood flow velocity tended to be higher in the MECC group, with a significant intergroup difference after aortic crossclamping (T2). Orthogonal polarization spectral imaging data reveal an impairment of microvascular perfusion during on-pump CABG. Changes in FCD indicate a faster recovery of the microvascular perfusion in MECC during the reperfusion period. Beneficial recovery of microvascular organ perfusion could partly explain the perioperative advantages reported for MECC.

Minimized extracorporeal circulation system in coronary artery bypass surgery: a 10-year single-center experience with 2243 patients

Coronary artery bypass grafting (CABG) is the gold standard for the surgical therapy of multivessel coronary artery disease. To reduce the side effects, associated with standard extracorporeal circulation (ECC), a concept of minimal extracorporeal circulation (MECC) was devised in our center. We report on our 10-year experience with the MECC for coronary revascularization. From January 1998 to August 2009, 2243 patients underwent CABG with MECC in our center. In a retrospective observational study, we analyzed indication, preoperative patient co-morbidity, postoperative clinical course, and perioperative outcome of all patients operated on with MECC. Furthermore, the risk factors for mortality in the MECC group were assessed. Patients showed a mean logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) of 4.5±0.1%. The mean age of the patients was 66.8±9.1 years. The overall 30-day mortality after CABG with MECC was 2.3%, ranging from 1.1% for elective to 13.0% for emergent patients and was significantly better than standard ECC. Only 15.3% (n=344) of patients with MECC required intra-operative blood transfusion. Postoperative catecholamine support, red blood cell transfusion, need for hemodialysis, release of creatinine kinase, incidence of stroke, and postoperative delirium were low after MECC revascularization. Ejection fraction below 30% (odds ratio (OR): 5.1), emergent operation (OR: 9.4), and high-dose catecholamine therapy (OR: 2.6) were associated predictors for mortality. MECC until now is an established concept and has become an alternative for ECC in routine CABG in our center. The use of the MECC system is associated with low mortality and conversion rate. Excellent survival rates and low transfusion requirements in the perioperative course were achieved.

Minimal extracorporeal circulation and off-pump compared to conventional cardiopulmonary bypass in coronary surgery☆

Although minimal extracorporeal circulation (MECC) and off-pump surgery are equal or better alternatives to conventional cardiopulmonary bypass (CCPB) regarding perioperative morbidity, use of blood and blood products and completeness of revascularization, CCPB is still being used in the majority of coronary artery bypass grafting (CABG) operations. We investigated 1472 CABG operations in our center. A total of 1143 CABG operations were performed using CCPB, 220 using MECC and 109 were performed as off-pump coronary artery bypass (OPCAB). All patients were recorded prospectively. Perioperative follow-up was focused on the occurrence of arrhythmia, neurocognitive disorders and the need of blood and blood products. Operative mortality rates were comparable in all three groups. The mean number of distal anastomoses was 3.2+/-0.6 in the MECC group, 3.4+/-0.7 in the CCPB group and 1.9+/-0.8 in the OPCAB group (P=0.01). Arrhythmia occurred in 25% of the MECC group and in 35.6% of the CCPB group (P=0.05). Arrhythmia occurred in 21.7% of the OPCAB group. Seven patients (3%) of the MECC group suffered neurocognitive disorders perioperatively compared to 74 (7%) patients of the CCPB group (P=0.05) and three patients of the OPCAB group (3%). The median number of blood transfusions per patient was 0.8 in the MECC group, 1.8 in the CCPB group and 0.8 in the OPCAB group (P<0.0001). Perioperative morbidity of MECC and OPCAB is comparable to or even less in comparison to CCPB. MECC allows CABG surgery in cardiac arrest so that completeness of revascularization is being warranted and longer patency rates can be guaranteed. Furthermore, the use of blood and blood products is significantly less in MECC surgery so that MECC should be considered first choice in CABG surgery over CCPB and OPCAB.

Myocardial Revascularization by Left Ventricular Assisted Beating Heart Is Associated With Reduced Systemic Inflammatory Response

The present study was designed to investigate whether use of left ventricular assisted technique (LVA) in beating-heart myocardial revascularization would exert less impact on patients' inflammatory response, as compared with minimal extracorporeal circulation (MECC). Seventy-three consecutive high-risk patients undergoing myocardial revascularization were randomly assigned either to LVA (group A) or to MECC (group B). Monocyte count and plasma concentration of C-reactive protein, inflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha, and polymorphonuclear elastase were measured at baseline and at various time points postoperatively. Preoperative clinical and demographic data did not differ between the two groups. The two groups also were similar with respect to mortality, number of grafts performed, duration of extracorporeal circulation, and need for inotropes. However, LVA was associated with significantly less inflammatory response postoperatively compared with MECC, as indicated by a significant difference in interleukin-6 (p = 0.002), C-reactive protein (p = 0.002), monocyte percentage (p = 0.006), tumor necrosis factor-alpha (p = 0.002), and polymorphonuclear elastase (p = 0.001). High-risk patients undergoing beating-heart myocardial revascularization with LVA show reduced inflammatory response compared with patients treated with the MECC.

Analysis in primary clinic outcomes of minimal extracorporeal circulation in the coronary artery bypass grafting

To analysis comparatively the primary clinic outcomes between minimal extracorporeal circulation (MECC) and conventional extracorporeal circulation (cECC). Forty cases accepted coronary artery bypass grafting from August to October at 2006 were divided into MECC group and cECC group at random, 20 cases for each group. Record and analysis of the general information, clinic data perioperatively, and complications postoperatively for each group were performed. There were no deference between groups in gender, anamnesis and preoperative cardiac function, while age (P < 0.05), standard EuroSCORE and logistic EuroSCORE were much more higher in MECC group than in cECC group (P < 0.01). Similarly, there were no deference in operative time, bypass time, ischemic time and graft number between two groups. Contrasted with cECC group, the values of cTNI were lower in MECC group at 2 h, 6 h and 12 h post-ECC (P < 0.01), oxygen index were higher post-operatively and there was a statistic deference at 12 h post-ECC (P < 0.05). The valves of ALT and TBIL in cECC group were higher abnormally at early post-ECC, and significant higher than in MECC group at 2 h, 6 h post-ECC of ALT (P < 0.05), and at termination, 2 h post-ECC of TBIL (P < 0.05). The values of activated partial thromboplastin time were almost at physiological status in MECC group, but were significantly prolonged in cECC group at early post-ECC, and were statistically longer than in MECC group at 2 h, 6 h, 12 h post-ECC (P < 0.05). The concentration of free hemoglobin in cECC group were higher than in MECC group peri-operative, and there was a statistic deference at 2 h post-ECC (P < 0.05). There were no deference between the two group in Cr, PLT and WBC. Compared with cECC, MECC carries more biocompatibility, more safe and credible. MECC system can alleviate the organ injury postoperatively and decrease the incidence of complications, especially in high-risk patients.

Minimal Extracorporeal Circulation is a Promising Technique for Coronary Artery Bypass Grafting

Minimal extracorporeal circulation (MECC) is a promising perfusion technology, taking the advantage of an ECC while having a significantly reduced priming volume. We analyzed the actual possible benefits of using MECC in patients undergoing CABG procedures and compared the results with conventional extracorporeal circulation (CECC). One thousand fifty-three consecutive patients underwent CABG surgery using the MECC perfusion technique. Subgroup analyses focused on perioperative myocardial markers (cardiac troponin I [cTnI]), incidence of atrial fibrillation (AF), and perioperative evaluation of inflammatory markers and data were compared with those of patients who underwent CABG using CECC. A propensity score analysis was performed. Patient characteristics and distribution of EuroSCORE risk were similar in both groups. Severity of coronary artery disease and extent of revascularization were also comparable in both groups (number of distal anastomoses: 3.2 +/- 1.1 in CECC vs 3.2 +/- 0.9 in MECC; p = not significant [ns]). The cTnI was significantly lower in the MECC group (11.0 +/- 10.8 microg/L in MECC vs 24.7 +/- 25.3 microg/L in CECC; p < 0.05). Incidence of AF was 11.1% in MECC and 39.0% in CECC (p < 0.05). Inflammatory markers (interleukin-6, SC5b-9) were lower in MECC patients (p < 0.05). Propensity score analysis confirmed faster recovery in MECC patients and lower incidence of AF. Minimal extracorporeal circulation is a safe perfusion technique for CABG and may therefore concurrence OPCAB and traditional CABG under CECC.

Vorteile des minimalen extrakorporellen Kreislaufs in der Koronarchirurgie

Summary Objective: Minimal extracorporeal circulation (MECC) is a new perfusion technology, which includes a centrifugal pump and an optoelectrical suction system. The main advantage consists in a significant reduction of the priming volume. Aim of the present study was to analyse if MECC has a positive effect in term of reduction of the activation of inflammatory markers and on the incidence of postoperative atrial fibrillation (AF) in comparison to conventional cardiopulmonary bypass (CPB). Methods: Two collectives have been studied: 30 patients scheduled for isolated coronary artery bypass graft (CABG) surgery were randomised to either receive MECC or CPB. Activation of inflammatory markers (IL-6, SC5-b9, Human Lactoferrin) was analysed. In a second collective 86 patients were analysed to evaluate the incidence of AF: 41 patients (47.7%) with CPB and 45 patients (52.3%) with MECC. Patients’ characteristics were similar in both groups. In-hospital outcome was assessed. Results: Inflammatory markers were significant lower in the MECC-group early post operative. AF was documented in 16 patients (39.0%) of the CPB and in 5 patients (11.1%) of the MECC group (p <0.05). Postoperative the increase of weight was less pronounced in the MECC group (2.9 ± 2.4% vs 4.4 ± 2.6%; p <0.05). Antiarrhythmic medication was similar in both groups and administered in 95.1% of the patients in the CPB and in 93.3% in the MECC group (p = ns). No differences were found in serum potassium between the two groups (p = ns). Conclusion: MECC is an established and safe perfusion technique. Activation of inflammatory markers is less pronounced in MECC than in CPB patients. The reduction of the priming volume leads to a less pronounced volume shift in the early postoperative period and reduces the incidence of postoperative AF, compared to patients operated with CPB.

Circulating endothelial cells demonstrate an attenuation of endothelial damage by minimizing the extracorporeal circulation

Detachment of endothelial cells may represent serious injury of the endothelium after cardiopulmonary bypass. We investigated whether the extent of endothelial injury is related to the type of cardiopulmonary bypass system used (conventional or minimized) and determined circulating endothelial cells as well as von Willebrand factor and soluble thrombomodulin. Twenty patients scheduled for elective coronary bypass grafting were randomly assigned to either the minimal extracorporeal circulation system or the standard cardiopulmonary bypass. Ten healthy volunteers served as controls. Circulating endothelial cells per milliliter of full blood were perioperatively determined by immunomagnetic cell separation technique. Endothelial plasma markers were measured by enzyme-linked immunosorbent assay. Preoperative circulating endothelial cell numbers did not differ between the experimental groups, but were significantly higher than in the healthy controls (18.6 +/- 5.6 vs 7.2 +/- 3.8, P < .001). At 6 hours, circulating endothelial cell numbers increased significantly compared with baseline in both experimental groups and peaked at 12 hours after cardiopulmonary bypass initiation, each time with significantly lower values in the minimal extracorporeal circulation group (6 hours: 44.0 +/- 9.9 vs 29.6 +/- 9.8, P = .007; 12 hours: 48.1 +/- 6.8 vs 31.8 +/- 7.1, P < .001). Likewise, von Willebrand factor and soluble thrombomodulin postoperatively increased in both groups with a tendency toward lower levels in the minimal extracorporeal circulation group. Although circulating endothelial cells gradually declined, continually with lower numbers in the minimal extracorporeal circulation group, the endothelial plasma markers remained elevated during observation time. Circulating endothelial cells represent a novel marker of the intrinsic endothelial damage caused by cardiopulmonary bypass. Its analysis facilitates the evaluation of cardiopulmonary bypass modifications as the minimal extracorporeal circulation system could be proven to be less injurious to endothelium and myocardium.