Type II Minimal-Invasive Extracorporeal Circuit for Aortic Valve Replacement: A Randomized Controlled Trial

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

Effects of interventions targeting the systemic inflammatory response to cardiac surgery on clinical outcomes in adults

BACKGROUND

Organ injury is a common and severe complication of cardiac surgery that contributes to the majority of deaths. There are no effective treatment or prevention strategies. It has been suggested that innate immune system activation may have a causal role in organ injury. A wide range of organ protection interventions targeting the innate immune response have been evaluated in randomised controlled trials (RCTs) in adult cardiac surgery patients, with inconsistent results in terms of effectiveness.

OBJECTIVES

The aim of the review was to summarise the results of RCTs of organ protection interventions targeting the innate immune response in adult cardiac surgery. The review considered whether the interventions had a treatment effect on inflammation, important clinical outcomes, or both.

SEARCH METHODS

CENTRAL, MEDLINE, Embase, conference proceedings and two trial registers were searched on October 2022 together with reference checking to identify additional studies.

SELECTION CRITERIA

RCTs comparing organ protection interventions targeting the innate immune response versus placebo or no treatment in adult patients undergoing cardiac surgery where the treatment effect on innate immune activation and on clinical outcomes of interest were reported.

DATA COLLECTION AND ANALYSIS

Searches, study selection, quality assessment, and data extractions were performed independently by pairs of authors. The primary inflammation outcomes were peak IL-6 and IL-8 concentrations in blood post-surgery. The primary clinical outcome was in-hospital or 30-day mortality. Treatment effects were expressed as risk ratios (RR) and standardised mean difference (SMD) with 95% confidence intervals (CI). Meta-analyses were performed using random effects models, and heterogeneity was assessed using I2.

MAIN RESULTS

A total of 40,255 participants from 328 RCTs were included in the synthesis. The effects of treatments on IL-6 (SMD -0.77, 95% CI -0.97 to -0.58, I2 = 92%) and IL-8 (SMD -0.92, 95% CI -1.20 to -0.65, I2 = 91%) were unclear due to heterogeneity. Heterogeneity for inflammation outcomes persisted across multiple sensitivity and moderator analyses. The pooled treatment effect for in-hospital or 30-day mortality was RR 0.78, 95% CI 0.68 to 0.91, I2 = 0%, suggesting a significant clinical benefit. There was little or no treatment effect on mortality when analyses were restricted to studies at low risk of bias. Post hoc analyses failed to demonstrate consistent treatment effects on inflammation and clinical outcomes. Levels of certainty for pooled treatment effects on the primary outcomes were very low.

AUTHORS' CONCLUSIONS

A systematic review of RCTs of organ protection interventions targeting innate immune system activation did not resolve uncertainty as to the effectiveness of these treatments, or the role of innate immunity in organ injury following cardiac surgery.

2021 MiECTiS focused update on the 2016 position paper for the use of minimal invasive extracorporeal circulation in cardiac surgery

The landmark 2016 Minimal Invasive Extracorporeal Technologies International Society (MiECTiS) position paper promoted the creation of a common language between cardiac surgeons, anesthesiologists and perfusionists which led to the development of a stable framework that paved the way for the advancement of minimal invasive perfusion and related technologies. The current expert consensus document offers an update in areas for which new evidence has emerged. In the light of published literature, modular minimal invasive extracorporeal circulation (MiECC) has been established as a safe and effective perfusion technique that increases biocompatibility and ultimately ensures perfusion safety in all adult cardiac surgical procedures, including re-operations, aortic arch and emergency surgery. Moreover, it was recognized that incorporation of MiECC strategies advances minimal invasive cardiac surgery (MICS) by combining reduced surgical trauma with minimal physiologic derangements. Minimal Invasive Extracorporeal Technologies International Society considers MiECC as a physiologically-based multidisciplinary strategy for performing cardiac surgery that is associated with significant evidence-based clinical benefit that has accrued over the years. Widespread adoption of this technology is thus strongly advocated to obtain additional healthcare benefit while advancing patient care.

Minimized Extracorporeal Circulation Is Associated with Reduced Plasma Levels of Free-Circulating Mitochondrial DNA Compared to Conventional Cardiopulmonary Bypass: A Secondary Analysis of an Exploratory, Prospective, Interventional Study

The use of minimized extracorporeal circulation (MiECC) during cardiac surgery is associated with a reduced inflammatory reaction compared to conventional cardiopulmonary bypass (cCPB). Since it is unknown if MiECC also reduces the amount of free-circulating mitochondrial DNA (mtDNA), this study aims to compare MiECC-induced mtDNA release to that of cCPB as well as to identify potential relations between the plasma levels of mtDNA and an adverse outcome. Overall, 45 patients undergoing cardiac surgery with either cCPB or MiECC were included in the study. MtDNA encoding for NADH dehydrogenase 1 was quantified with quantitative polymerase chain reaction. The plasma amount of mtDNA was significantly lower in patients undergoing cardiac surgery with MiECC compared to cCPB (MiECC: 161.8 (65.5−501.9); cCPB 190.8 (82−705.7); p < 0.001). Plasma levels of mtDNA showed comparable kinetics independently of the study group and peaked during CPB (MiECC preoperative: 68.2 (26.5−104.9); MiECC 60 min after start of CPB: 536.5 (215.7−919.6); cCPB preoperative: 152.5 (80.9−207.6); cCPB 60 min after start of CPB: 1818.0 (844.2−3932.2); all p < 0.001). Patients offering an mtDNA blood concentration of >650 copies/µL after the commencement of CPB had a 5-fold higher risk for postoperative atrial fibrillation independently of the type of cardiopulmonary bypass. An amount of mtDNA being higher than 650 copies/µL showed moderate predictive power (AUROC 0.71 (0.53−071)) for the identification of postoperative atrial fibrillation. In conclusion, plasma levels of mtDNA were lower in patients undergoing cardiac surgery with MiECC compared to cCPB. The amount of mtDNA at the beginning of the CPB was associated with postoperative atrial fibrillation independent of the type of cardiopulmonary bypass.

Conventional versus miniaturized cardiopulmonary bypass: A systematic review and meta-analysis

Objective

A meta-analysis of randomized controlled trials was performed to compare the effects of miniaturized extracorporeal circulation (MECC) and conventional extracorporeal circulation (CECC) on morbidity and mortality rates after cardiac surgery.

Methods

A comprehensive literature search was conducted using Ovid, PubMed, Medline, EMBASE, and the Cochrane databases. Randomized controlled trials from the year 2000 with n > 40 patients were considered. Key search terms included variations of "mini," "cardiopulmonary," "bypass," "extracorporeal," "perfusion," and "circuit." Studies were assessed for bias using the Cochrane Risk of Bias tool. The primary outcomes were postoperative mortality and stroke. Secondary outcomes included arrhythmia, myocardial infarction, renal failure, blood loss, and a composite outcome comprised of mortality, stroke, myocardial infarction and renal failure. Duration of intensive care unit, and hospital stay was also recorded.

Results

The 42 studies eligible for this study included a total of 2154 patients who underwent CECC and 2196 patients who underwent MECC. There were no significant differences in any preoperative or demographic characteristics. Compared with CECC, MECC did not reduce the incidence of mortality, stroke, myocardial infarction, and renal failure but did significantly decrease the composite of these outcomes (odds ratio, 0.64; 95% confidence interval [CI], 0.50-0.81; P = .0002). MECC was also associated with reductions in arrhythmia (odds ratio, 0.67; 95% CI, 0.54-0.83; P = .0003), blood loss (mean difference [MD], -96.37 mL; 95% CI, -152.70 to -40.05 mL; P = .0008), hospital stay (MD, -0.70 days; 95% CI, -1.21 to -0.20 days; P = .006), and intensive care unit stay (MD, -2.27 hours; 95% CI, -3.03 to -1.50 hours; P < .001).

Conclusions

MECC demonstrates clinical benefits compared with CECC. Further studies are required to perform a cost-utility analysis and to assess the long-term outcomes of MECC. These should use standardized definitions of endpoints such as mortality and renal failure to reduce inconsistency in outcome reporting.

Minimized extracorporeal circulation in non-coronary surgery

Minimally invasive extracorporeal circulation (MiECC) technology is characterized by improved biocompatibility due to closed-loop design, minimized priming, and markedly reduced artificial surface. Despite well-evidenced clinical advantages in coronary surgery, MiECC penetration in complex open-heart surgery is low. Concerns have been raised by surgeons and perfusionist regarding safety of perfusion in situations when the heart is opened and air is entering the closed system. Moreover, issues of blood and volume management are deemed impractical without having a reservoir. In the evolution of MiECC safety aspects as well as means of air and volume management have been addressed. The integration of active air removal devices, and the possibility of venting and volume buffering made MiECC suitable for valvular or even more complex surgery. However, typical clinical benefits found with MiECC in coronary artery bypass grafting (CABG) surgery, in particular blood sparing effects, were not reproducible. Air handling and blood management remain the main issues of MiECC in non-coronary surgery. With the introduction of modular (type IV) MiECC systems containing a second, accessory circuit for immediate conversion to open cardiopulmonary bypass (CPB), the last obstacles seem to be cleared away. The first reports using this latest development in MiECC technology sound promising. It is now up to the cardiac surgical community to adopt this technology and produce data helping to answer the question whether MiECC is the best perfusion strategy for all comer's cardiac surgery.

Inflammation and coagulation following minimally invasive extracorporeal circulation technologies

Minimally invasive extracorporeal perfusion technologies are based on the use of a minimally invasive extracorporeal circulation (MiECC) system. This includes a closed CPB circuit; biologically inert blood contact surfaces; reduced priming volume; a centrifugal pump; a membrane oxygenator; a heat exchanger; a cardioplegia system; a venous bubble trap/venous air removing device; and a shed blood management system. Some of these items, alone or in combination, are able to modify the blood activation usually elicited by cardiopulmonary bypass (CPB). The hemostatic system activation is less activated and lower degrees of thrombin generation and platelet activation have been found in numerous studies. Additionally, the reduced level of hemodilution plays an important role in preserving clot firmness after CPB with MiECC. These biochemical changes are reflected by a blood loss containment, a reduced need for allogeneic blood transfusions, and, in some studies, by a lower thromboembolic complications rate. The activation of the inflammatory cascade is in turn limited by MiECC, both directly (through a blunting of the contact-phase activation) and indirectly (through a limited thrombin generation, platelet activation, and consequent lower release of pro-inflammatory cytokines). The clinical consequences of this are mainly demonstrated by a lower rate of postoperative atrial fibrillation; other inflammation-derived outcomes appear favorably affected by MiECC (lung function, acute kidney injury) but the multi-factorial nature of these complications makes difficult to clearly attribute this pattern to a lower degree of inflammation. Overall, the existing body of evidence is in favor of MiECC with respect to standard CPB.

Artificial Organs 2018: A Year in Review

In this Editor's Review, articles published in 2018 are organized by category and summarized. We provide a brief reflection of the research and progress in artificial organs intended to advance and better human life while providing insight for continued application of these technologies and methods. Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level." Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ Replacement, Recovery, and Regeneration from all over the world. Peer-reviewed special issues this year included contributions from the 13th International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion edited by Dr. Akif Undar, and the 25th Congress of the International Society for Mechanical Circulatory Support edited by Dr. Marvin Slepian. Additionally, many editorials highlighted the worldwide survival differences in hemodialysis and perspectives on mechanical circulatory support and stem cell therapies for cardiac support. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers the quality expected from such a journal could not be possible. We also express our special thanks to our Publisher, John Wiley & Sons for their expert attention and support in the production and marketing of Artificial Organs. We look forward to reporting further advances in the coming years.

Aortic valve replacement with or without myocardial revascularization in octogenarians. Can minimally invasive extracorporeal circuits improve the outcome?

OBJECTIVE

The positive impact of minimally invasive extracorporeal circuits (MiECC) on patient outcome is expected to be most evident in patients with limited physiologic reserves. Nevertheless, most studies have limited their use to low-risk patients undergoing myocardial revascularization. As such, there is little evidence to their benefit outside this patient population. We, therefore, set out to explore their potential benefit in octogenarians undergoing aortic valve replacement (AVR) with or without concomitant myocardial revascularization.

METHODS

Based on the type of the utilized ECC, we performed a retrospective propensity score-matched comparison among all octogenarians (n = 218) who received a primary AVR with or without concomitant coronary artery bypass grafting in our institution between 2003 and 2010.

RESULTS

A MiECC was utilized in 32% of the patients. The propensity score matching yielded 52 matched pairs. The 30-day postoperative mortality (2% vs. 10%; p=0.2), the incidence of low cardiac output (0% vs. 6%; p=0.2) and the Intensive Care Unit (ICU) stay (2.5 ± 2.6 vs. 3.8 ± 4.7 days; p=0.06) were all in favour of the MiECC group, but failed to reach statistical significance while the 90-day postoperative mortality did (2% vs. 16%; p=0.02).

CONCLUSION

MiECCs have a positive influence on the outcome of octogenarians undergoing AVR with or without concomitant coronary artery bypass grafting. Their use should, therefore, be extended beyond isolated coronary artery bypass graft (CABG) surgery.