Less invasive coronary artery revascularization with a minimized extracorporeal circulation system: preliminary results of a comparative study with off-pump-procedures

Mini-extracorporeal circulation surgery produces less inflammation than off-pump coronary surgery

OBJECTIVES

Both off-pump coronary artery bypass grafting surgery (OPCABG) and mini-extracorporeal circulation (MECC) have been associated with lower morbidity and mortality and less inflammation than conventional cardiopulmonary bypass. However, studies comparing the 2 techniques are scarce and the results are controversial. We compared the clinical outcomes and inflammatory response of low-risk patients undergoing coronary bypass grafting with MECC versus OPCABG.

METHODS

We conducted a prospective, randomized study in patients undergoing coronary heart surgery. Two hundred and thirty consecutive low-risk patients were randomly assigned to either receive OPCABG (n = 117) or MECC (n = 113). Clinical outcomes and postoperative biochemical results were analysed in both groups. We also analysed 19 circulating inflammatory markers in a subgroup of 40 patients at 4 perioperative time points. The area under the curve for each marker was calculated to monitor differences in the inflammatory response.

RESULTS

No significant differences were found between groups regarding perioperative clinical complications and no deaths occurred during the trial. Plasma levels in 9 of the 19 inflammatory markers were undetectable or showed no temporal variation, 3 were higher in the MECC group [interleukin (IL)-10, macrophage inflammatory protein-1β and epidermal growth factor] and 7 were higher in the OPCABG group (growth regulator oncogene, IL-6, IL-8, soluble CD40 ligand, monocyte chemoattractant protein-1, monocyte chemoattractant protein-3 and tumour necrosis factor-α). Differences in 2 proinflammatory cytokines, IL-6 and monocyte chemoattractant protein 1, between the 2 surgical procedures were statistically significant.

CONCLUSIONS

No clinical differences were observed between in low-risk patients undergoing MECC or OPCABG surgery, but OPCABG was associated with an increased release of proinflammatory cytokines compared with MECC. Studies in larger cohorts and in patients at higher risk are needed to confirm these findings.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02118025.

The effect of using the minimized cardio-pulmonary bypass Systems for Coronary Artery Bypass Grafting in diabetic patients

Introduction

Multiple studies have shown a decrease in the inflammatory response with minimized bypass circuits leading to less complications and mortality rate. On the other hand, some other studies showed that there is no difference in post-operative outcomes. So, the aim of this study is to investigate the clinical benefits of using the Minimized cardiopulmonary Bypass system in Coronary Artery Bypass Grafting and its effect on postoperative morbidity and mortality in diabetic patients as one of the high-risk groups that may benefit from these systems.

Methods

This is a retrospective study that included 114 diabetic patients who underwent Coronary artery bypass grafting (67 patients with conventional cardiopulmonary bypass system and 47 with Minimized cardiopulmonary bypass system). The patients’ demographics, intra-operative characteristics and postoperative complications were compared between the two groups.

Results

Coronary artery bypass grafting was done on a beating heart less commonly in the conventional cardiopulmonary bypass group (44.78% vs. 63.83%, p = 0.045). There was no difference between the two groups in blood loss or transfusion requirements. Four patients in the conventional cardiopulmonary bypass group suffered perioperative myocardial infarction while no one had perioperative myocardial infarction in the Minimized cardiopulmonary bypass group. On the other hand, less patients in the conventional group had postoperative Atrial Fibrillation (4.55% vs. 27.5%, p = 0.001). The requirements for Adrenaline and Nor-Adrenaline infusions were more common the conventional group than the Minimized group.

Conclusion

The use of conventional cardiopulmonary bypass for Coronary Artery Bypass Grafting in diabetic patients was associated with higher use of postoperative vasogenic and inotropic support. However, that did not translate into higher complications rate or mortality.

From less invasive to minimal invasive extracorporeal circulation

Development of minimally invasive cardiac surgery (MICS) served the purpose of performing surgery while avoiding the surgical stress triggered by a full median sternotomy. Minimizing surgical trauma is associated with improved cosmesis and enhanced recovery leading to reduced morbidity. However, it has to be primarily appreciated that the extracorporeal circulation (ECC) stands for the basis of nearly all MICS procedures. With some fundamental modification and advancement in perfusion techniques, the use of ECC has become the enabling technology for the development of MICS. Less invasive cardiopulmonary bypass (CPB) techniques are based on remote cannulation and optimization of perfusion techniques with assisted venous drainage and use of centrifugal pump, so as to facilitate the demanding surgical maneuvers, rather than minimizing the invasiveness of the CPB. This is reflected in the increased duration of CPB required for MICS procedures. Minimal invasive Extracorporeal Circulation (MiECC) represents a major breakthrough in perfusion. It integrates all contemporary technological advancements that facilitate best applying cardiovascular physiology to intraoperative perfusion. Consequently, MiECC use translates to improved end-organ protection and clinical outcome, as evidenced in multiple clinical trials and meta-analyses. MICS performed with MiECC provides the basis for developing a multidisciplinary intraoperative strategy towards a "more physiologic" cardiac surgery by combining small surgical trauma with minimum body's physiology derangement. Integration of MiECC can advance MICS from non-full sternotomy for selected patients to a "more physiologic" surgery, which represents the real face of modern cardiac surgery in the transcatheter era.

Effects of Minimal Extracorporeal Circulation on the Systemic Inflammatory Response and the Need for Transfusion after Coronary Bypass Grafting Surgery

Objectives

The aim of this study is to compare the effects of the minimal extracorporeal circulation (MiECT) on postoperative systemic inflammatory response and the need for transfusion in patients undergoing open heart surgery with cardiopulmonary bypass.

Methods

Patients were divided into two groups; Group M (n=31) included the patients operated via using the MiECT system and Group C (n=27) included the patients operated via using conventional cardiopulmonary bypass (CPB). Perioperative markers of inflammation after cardiopulmonary bypass in both groups were tested by measuring the levels via chemiluminescent immunometric assay. Blood samples were taken consecutively after anesthesia induction, 30^th minute of CPB, on the 6^th, 24^th, and 48^th hours after cardiopulmonary bypass.

Results

The mean amount of priming solution was significantly lower in Group M when compared to Group C (802.60 ± 48.26 and 1603.71 ± 49.85 ml). The mean hematocrit (Hct) value taken immediately after cardiopulmonary bypass was found to be significantly higher in the MiECT patients with respect to the other group (% 32.71 ± 3.98 and % 28.82 ± 4.39). The transfused amounts of erythrocyte suspension and fresh frozen plasma were found to be significantly lower in patients in Group M when compared to those in Group C. Postoperative mediastinal drainage was also significantly lower in patients in Group M with respect to the other group. There was no significant difference between markers of inflammation.

Conclusion

Our results show that MiECT seems to be more advantageous in terms of priming volume, perioperative hematocrit levels, need for blood and blood product transfusion, and mediastinal drainage with respect to the conventional approach after coronary artery bypass grafting.

Minimally Circulatory-Assisted On-Pump Beating Coronary Artery Bypass Grafting for Patients With Complex Conditions for Off-Pump Surgery

Off-pump coronary artery bypass grafting (OPCAB) in patients with acute myocardial infarction (AMI) is difficult because of circulatory deterioration during displacement of the heart. At our institution, we performed minimally circulatory-assisted on-pump beating coronary artery bypass grafting (MICAB) in these patients. During MICAB, support flow was controlled at a minimal level to maintain a systemic blood pressure of approximately 100 mm Hg and a pulmonary arterial systolic pressure of <30 mm Hg, providing optimal pulsatile circulation for end-organ perfusion and prevention of heart congestion. From September 2006 to March 2012, MICAB was performed in 37 patients. Either emergent or urgent MICAB was performed in 27 patients following AMI because of hemodynamic instability during reconstruction. Elective MICAB was performed in the remaining 10 patients because of dilated left ventricle (LV) or small target coronary arteries. The details of bypass grafts, perioperative renal function, and early and mid-term morbidity and mortality were compared between the patients who received MICAB and the 37 consecutive patients who underwent OPCAB during the study period at our hospital. The assist flow indices (actual support flow/body surface area) during anastomosis to the left anterior descending artery, left circumflex artery, and right coronary artery were 0.95 ± 0.48 L/min/m² , 1.32 ± 0.53 L/min/m² , and 1.15 ± 0.47 L/min/m² , respectively, in the emergent and urgent patients following AMI, and 0.44 ± 0.39 L/min/m² , 1.25 ± 0.39 L/min/m² , and 1.14 ± 0.43 L/min/m² , respectively, in the elective patients with either dilated LVs or small target vessels. The lowest mixed venous oxygen saturation during pump support in the MICAB group was significantly higher than that in the OPCAB group (83.8 ± 10.8%, 71.6 ± 7.5%, P < 0.001). Comparing MICAB and OPCAB, the median number of distal bypass grafts for both groups was 4 (25th, 75th percentile: 3, 4) (P = 0.558); the complete revascularization rates were 94.6 and 97.3%, respectively (not significant [NS]); the acute patency rates were 98.9 and 99.2%, respectively (NS); and the 30-day mortality rates were 2.7 and 0%, respectively (NS). No instances of either cerebrovascular complications or newly occurring postoperative renal failure were noted in either group. There were no statistically significant differences between the groups with respect to early and mid-term results (freedom from all-cause death: 82.9 vs. 86.5%, respectively, and freedom from cardiac events at 3 years: 96.4 vs. 96.4%, respectively). MICAB is a safe alternative to OPCAB, particularly in patients with AMI and dilated LV. MICAB is associated with high rates of complete revascularization and acute graft patency, adequate preservation of end-organ function, and early and mid-term results comparable with those observed following OPCAB.

Minimally Invasive Extracorporeal Circulation Circuit Is Not Inferior to Off-Pump Coronary Artery Bypass Grafting: Meta-Analysis Using the Bayesian Method

The pathophysiologic side effects of cardiopulmonary bypass have already been identified. Minimally invasive extracorporeal circulation technologies (MiECT) and off-pump coronary artery bypass graft surgery (OPCABG) aim to reduce these problems. This meta-analysis provides a comparison of MiECT and OPCABG in randomized and observational studies. A fully probabilistic, Bayesian approach of primary and secondary endpoints was conducted. MiECT does not give inferior results when compared with OPCABG. However, there is a trend to borderline significantly higher blood loss in this group in randomized controlled trials. The question whether MiECT is equivalent to OPCABG can be answered with the affirmative, but long-term follow-up data are needed to detect any advantage over time.

Outcomes after different non-sternotomy approaches to left single-vessel revascularization: a comparative study with up to 10-year follow-up

OBJECTIVES

Various non-sternotomy approaches have been used for left internal mammary artery (LIMA) grafting in left single-vessel revascularization. The aim of this study was to evaluate the impact of three different non-sternotomy techniques on long-term outcomes after left single-vessel revascularization.

METHODS

A total of 502 patients having single-vessel LAD disease treated from April 2003 to May 2013 by minimally invasive direct coronary artery bypass grafting (MIDCAB), endoscopically assisted coronary artery bypass grafting (EACAB) or robotically assisted direct coronary artery bypass grafting (RADCAB) were reviewed. In all cases, distal anastomoses were performed through anterolateral minithoracotomy incisions. In-hospital and long-term (10-year) outcomes were compared using standard and propensity score-adjusted analyses.

RESULTS

One hundred and eighty-nine patients had MIDCAB, 76 had EACAB and 236 had RADCAB. After propensity score matching, RADCAB patients had significantly longer operative duration (P < 0.001), whereas MIDCAB and RADCAB patients had significantly higher incidence of postoperative angina over the follow-up (P = 0.034). The groups were comparable regarding in-hospital mortality and reintervention rate as well as incidence of myocardial infarction, reoperations, reinterventions and cardiac death. All groups showed comparable long-term survival (P = 0.943).

CONCLUSIONS

MIDCAB, EACAB and RADCAB are associated with similar long-term survival and incidence of major adverse cardiac events (MACEs) in single-vessel surgical revascularization. However, the endoscopic approach was found to be free from the disadvantages of longer operating duration observed in RADCAB or higher incidence of angina and shorter freedom from MACEs observed in both MIDCAB and RADCAB groups.