Changes in mesenteric vascular reactivity and inflammatory response after cardiopulmonary bypass in a rat model

Promising results of a clinical feasibility study: CIRBP as a potential biomarker in pediatric cardiac surgery

Objective

Cold-inducible RNA binding Protein (CIRBP) has been shown to be a potent inflammatory mediator and could serve as a novel biomarker for inflammation. Systemic inflammatory response syndrome (SIRS) and capillary leak syndrome (CLS) are frequent complications after pediatric cardiac surgery increasing morbidity, therefore early diagnosis and therapy is crucial. As CIRBP serum levels have not been analyzed in a pediatric population, we conducted a clinical feasibility establishing a customized magnetic bead panel analyzing CIRBP in pediatric patients undergoing cardiac surgery.

Methods

A prospective hypothesis generating observational clinical study was conducted at the German Heart Center Berlin during a period of 9 months starting in May 2020 (DRKS00020885, https://drks.de/search/de/trial/DRKS00020885). Serum samples were obtained before the cardiac operation, upon arrival at the pediatric intensive care unit, 6 and 24 h after the operation in patients up to 18 years of age with congenital heart disease (CHD). Customized multiplex magnetic bead-based immunoassay panels were developed to analyze CIRBP, Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Monocyte chemotactic protein 1 (MCP-1), Syndecan-1 (SDC-1), Thrombomodulin (TM), Vascular endothelial growth factor (VEGF-A), Angiopoietin-2 (Ang-2), and Fibroblast growth factor 23 (FGF-23) in 25 µl serum using the Luminex MagPix® system.

Results

19 patients representing a broad range of CHD (10 male patients, median age 2 years, 9 female patients, median age 3 years) were included in the feasibility study. CIRBP was detectable in the whole patient cohort. Relative to individual baseline values, CIRBP concentrations increased 6 h after operation and returned to baseline levels over time. IL-6, IL-8, IL-10, and MCP-1 concentrations were significantly increased after operation and except for MCP-1 concentrations stayed upregulated over time. SDC-1, TM, Ang-2, as well as FGF-23 concentrations were also significantly increased, whereas VEGF-A concentration was significantly decreased after surgery.

Discussion

Using customized magnetic bead panels, we were able to detect CIRBP in a minimal serum volume (25 µl) in all enrolled patients. To our knowledge this is the first clinical study to assess CIRBP serum concentrations in a pediatric population.

Organ damage evaluation in a temperature-controlled circulatory arrest rat model

BACKGROUND

Deep hypothermic circulatory arrest (DHCA) is commonly used in adult aortic surgery and pediatric complex congenital heart disease, and is associated with pathophysiological changes and postoperative complications. Here, a temperature-controlled circulatory arrest model in rats was established to study the suitable temperature of circulatory arrest by investigating the damage to body organs under different temperatures.

METHODS

Thirty Sprague‒Dawley rats were randomly divided into 5 equal groups for DHCA experiments: I (15-20 °C), II (20-25 °C), III (25-30 °C), IV (normothermic cardiopulmonary bypass), and V (sham operation group). Blood gas analysis, homodynamic parameters, and intervals of cardiac recovery were measured at different time points in all groups. Morphological changes in intestinal tissue were observed under light and electron microscopes. Oxidative stress was measured by MPO activity, MDA, and SOD content. Tissue damage was confirmed by serum detection of ALT, AST, BUN, Cr, and LDH. To examine the inflammatory response, cytokines, including IL-1, IL-4, IL-10, IFN-γ, and TNF-α, were detected.

RESULTS

The extracorporeal circulation technique caused damage to the body; the degree of the damage caused by the circulatory arrest technique may be related to circulating temperature, with the least amount of damage occurring at 20-25 °C compared to 15-20 °C and 25-30 °C. Ischemia and hypoxia can cause intestinal tissue damage, which manifests primarily as a loss of the intestinal mucosal barrier. Ischemic intestinal damage caused by DHCA was not associated with inflammation.

CONCLUSION

The study provides new insights into the pathophysiologic mechanisms of DHCA.

Priming of Cardiopulmonary Bypass with Human Albumin Decreases Endothelial Dysfunction after Pulmonary Ischemia-Reperfusion in an Animal Model

The routine use of mechanical circulatory support during lung transplantation (LTx) is still controversial. The use of prophylactic human albumin (HA) or hypertonic sodium lactate (HSL) prime in mechanical circulatory support during LTx could prevent ischemia−reperfusion (IR) injuries and pulmonary endothelial dysfunction and thus prevent the development of pulmonary graft dysfunction. The objective was to investigate the impact of cardiopulmonary bypass (CPB) priming with HA and HSL compared to a CPB prime with Gelofusine (GF) on pulmonary endothelial dysfunction in a lung IR rat model. Rats were assigned to four groups: IR-CPB-GF group, IR-CPB-HA group, IR-CPB-HSL group and a sham group. The study of pulmonary vascular reactivity by wire myograph was the primary outcome. Glycocalyx degradation (syndecan-1 and heparan) was also assessed by ELISA and electron microscopy, systemic and pulmonary inflammation by ELISA (IL-1β, IL-10, and TNF-α) and immunohistochemistry. Clinical parameters were evaluated. We employed a CPB model with three different primings, permitting femoral−femoral assistance with left pulmonary hilum ischemia for IR. Pulmonary endothelium-dependent relaxation to acetylcholine was significantly decreased in the IR-CPB-GF group (11.9 ± 6.2%) compared to the IR-CPB-HA group (52.8 ± 5.2%, p < 0.0001), the IR-CPB-HSL group (57.7 ± 6.3%, p < 0.0001) and the sham group (80.8 ± 6.5%, p < 0.0001). We did not observe any difference between the groups concerning glycocalyx degradation, and systemic or tissular inflammation. The IR-CPB-HSL group needed more vascular filling and developed significantly more pulmonary edema than the IR-CPB-GF group and the IR-CPB-HA group. Using HA as a prime in CPB during Ltx could decrease pulmonary endothelial dysfunction’s IR-mediated effects. No effects of HA were found on inflammation.

Cardiopulmonary bypass increases endothelial dysfunction after pulmonary ischaemia-reperfusion in an animal model

OBJECTIVES

Endothelial dysfunction during ischaemia-reperfusion (IR) is a major cause of primary graft dysfunction during lung transplantation. The routine use of cardiopulmonary bypass (CPB) during lung transplantation remains controversial. However, the contribution of CPB to pulmonary endothelial dysfunction remains unclear. The objective was to investigate the impact of CPB on endothelial dysfunction in a lung IR rat model.

METHODS

Rats were allocated to 4 groups: (i) Sham, (ii) IR, (iii) CPB and (iv) IR-CPB. The primary outcome was the study of pulmonary vascular reactivity by wire myograph. We also assessed glycocalyx degradation by enzyme-linked immunosorbent assay and electron microscopy and both systemic and pulmonary inflammation by enzyme-linked immunosorbent assay and immunohistochemistry. Rats were exposed to 45 min of CPB and IR. We used a CPB model allowing femoro-femoral support with left pulmonary hilum ischaemia for IR.

RESULTS

Pulmonary endothelium-dependent relaxation to acetylcholine was markedly reduced in the IR-CPB group (10.7 ± 9.1%) compared to the IR group (50.5 ± 5.2%, P < 0.001), the CPB group (54.1 ± 4.7%, P < 0.001) and the sham group (80.8 ± 6.7%, P < 0.001), suggesting that the association of pulmonary IR and CPB increases endothelial dysfunction. In IR-CPB, IR and CPB groups, vasorelaxation was completely abolished when inhibiting nitric oxide synthase, suggesting that this relaxation process was mainly mediated by nitric oxide. We observed higher syndecan-1 plasma levels in the IR-CPB group in comparison with the other groups, reflecting an increased degradation of glycocalyx. We also observed higher systemic inflammation in the IR-CPB group as shown by the increased plasma levels of IL-1β, IL-10.

CONCLUSIONS

CPB significantly increased the IR-mediated effects on pulmonary endothelial dysfunction. Therefore, the use of CPB during lung transplantation could be deleterious, by increasing endothelial dysfunction.

Hemodynamic Influences on Mesenteric Blood Flow in Shock Conditions

The gastrointestinal (GI) system, is most vulnerable to hypoperfusion among the splanchnic organs. Disturbed perfusion of the mesenteric area may lead to GI dysfunction, cause further injury to the patients and even vital outcomes. However, due to the limitation of detection methods, the hemodynamic influences on mesenteric blood flow in clinical practice are not fully understood. By elucidating the underlying mechanisms, we may be able to recognize disturbed GI perfusion and eventually GI dysfunction at an early phase. Thus, in this review, we will focus on situations where mesenteric blood flow is disturbed due to hemodynamic causes in shock conditions, and the present research status will be discussed. English language articles published before 2020 were identified through a computerized PubMed search using the terms "mesenteric, gastrointestinal, intestinal, splanchnic, blood flow, perfusion" and the cofactors. Relevant publications were retrieved and scanned for additional sources. There were few clinical trials focusing on mesenteric blood flow in shock patients. Most were animal experiments. Based on the best current evidence from these sources, we described the major influences on mesenteric blood flow in the context of physiologic accommodation, disease-related effects and the consequences of medical interventions related to shock conditions. During circulatory shock, sepsis, and medical interventions related to shock treatment, mesenteric blood flow changes and shows different features. We need to carefully consider these issues when making medical decisions, and more work needs to be done on early detection of GI hypoperfusion and its accurate correlation with GI dysfunction.

The correlation between bowel complications and cardiac surgery

Although advances in knowledge and technology have improved outcomes in surgical cardiac patients over the last decade, complications following cardiac operations still remain to be potentially fatal. Gastrointestinal complications, in particular, tend to have high rates of reintervention and mortality following cardiac surgery, with ischemia and hemorrhage being two of the commonest underlying causes. The intention of this review is to identify which risk factors play important roles in predisposing patients to such complications and to gain better insight into the pathogenesis of the sequelae. Furthermore, strategies for prevention have been discussed to educate and increase awareness of how adverse cardiac surgical outcomes can be minimized.

Cardiopulmonary bypass and internal thoracic artery: Can roller or centrifugal pumps change vascular reactivity of the graft? The IPITA study: A randomized controlled clinical trial

Background

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response (SIRS) and affects the organ vascular bed. Experimentally, the lack of pulsatility alters myogenic tone of resistance arteries and increases the parietal inflammatory response. The purpose of this study was to compare the vascular reactivity of the internal thoracic arteries (ITAs) due to the inflammatory response between patients undergoing coronary artery bypass grafting (CABG) under CPB with a roller pump or with a centrifugal pump.

Methods

Eighty elective male patients undergoing CABG were selected using one or two internal thoracic arteries under CPB with a roller pump (RP group) or centrifugal pump (CFP group). ITA samples were collected before starting CPB (Time 1) and before the last coronary anastomosis during aortic cross clamping (Time 2). The primary endpoint was the endothelium-dependent relaxation of ITAs investigated using wire-myography. The secondary endpoint was the parietal inflammatory response of arteries defined by the measurements of superoxide levels, leukocytes and lymphocytes rate and gene expression of inflammatory proteins using. Terminal complement complex activation (SC5b-9) and neutrophil activation (elastase) analysis were performed on arterial blood at the same times.

Results

Exposure time of ITAs to the pump flow was respectively 43.3 minutes in the RP group and 45.7 minutes in the CFP group. Acetylcholine-dependent relaxation was conserved in the two groups whatever the time. Gene expression of C3 and C4a in the artery wall decreased from Time 1 to Time 2. No oxidative stress was observed in the graft. There was no difference between the groups concerning the leukocytes and lymphocytes rate. SC5b-9 and elastase increased between Time 1 and Time 2.

Conclusion

Endothelium-dependent relaxation of the internal thoracic arteries was preserved during CPB whatever the type of pump used. The inflammatory response observed in the blood was not found in the graft wall within this time frame.

Trial registration

Name of trial study protocol: IPITA

Registration number (ClinicalTrials.gov): NCT04168853.

Effect of ulinastatin on post-operative blood loss and allogeneic transfusion in patients receiving cardiac surgery with cardiopulmonary bypass: a prospective randomized controlled study with 10-year follow-up

BACKGROUND

Major bleeding and allogeneic transfusion leads to negative outcomes in patients receiving cardiac surgery with cardiopulmonary bypass (CPB). Ulinastatin, a urine trypsin inhibitor, relieves systemic inflammation and improves coagulation profiles with however sparse evidence of its effects on blood loss and allogeneic transfusion in this specific population.

METHODS

In this prospective randomized controlled trial, 426 consecutive patients receiving open heart surgery with CPB were randomly assigned into three groups to receive ulinastatin (group U, n = 142), tranexamic acid (group T, n = 143) or normal saline (group C, n = 141). The primary outcome was the total volume of post-operative bleeding and the secondary outcome included the volume and exposure of allogeneic transfusion, the incidence of stroke, post-operative myocardial infarction, renal failure, respiratory failure and all-cause mortality. A ten-year follow-up was carried on to evaluate long-term safety.

RESULTS

Compared with placebo, ulinastatin significantly reduced the volume of post-operative blood loss within 24 h (688.39 ± 393.55 ml vs 854.33 ± 434.03 ml MD - 165.95 ml, 95%CI - 262.88 ml to - 69.01 ml, p < 0.001) and the volume of allogeneic erythrocyte transfusion (2.57 ± 3.15 unit vs 3.73 ± 4.21 unit, MD-1.16 unit, 95%CI - 2.06 units to - 0.26 units, p = 0.002). The bleeding and transfusion outcomes were comparable between the ulinastatin group and the tranexamic acid group. In-hospital outcomes and 10-year follow-up showed no statistical difference in mortality and major morbidity among groups.

CONCLUSIONS

Ulinastatin reduced post-operative blood loss and allogeneic erythrocyte transfusion in heart surgery with CPB. The mortality and major morbidity was comparable among the groups shown by the 10-year follow-up.

TRIAL REGISTRATION

The trial was retrospectively registered on February 2, 2010.

TRIAL REGISTRATION NUMBER

https://www.clinicaltrials.gov Identifier: NCT01060189.

κ-opioid receptor agonists may alleviate intestinal damage in cardiopulmonary bypass rats by inhibiting the NF-κB/HIF-1α pathway

The aims of the present study were to investigate the protective effect of a κ-opioid receptor (KOR) agonist on intestinal barrier dysfunction in rats during cardiopulmonary bypass (CPB), as well as to examine the role of NF-κB and the transcription factor hypoxia-inducible factor-1α (HIF-1α) signaling pathway in the regulatory mechanism. A total of 50 rats were randomly divided into five groups, with 10 rats in each group: Sham surgery group (group Sham), CPB surgery group (group CPB), KOR agonist + CPB (group K), KOR agonist + specific KOR antagonist + CBP (group NK) and KOR agonist + NF-κB pathway specific inhibitor + CPB (group NF). Intestinal microcirculation was evaluated to determine intestinal barrier dysfunction in rats following CPB surgery. Hematoxylin and eosin (H&E) staining was used to observe intestinal tissue injury in the rats. ELISA was used to detect the inflammatory factors interleukin (IL)-1β, IL-6, IL10 and tumor necrosis factor-α, and the oxidative stress factors superoxidase dismutase, malondialdehyde and nitric oxide in serum. In addition, ELISA was used to investigate the serum levels of the intestinal damage markers D-lactic acid, diamine oxidase and intestinal fatty acid-binding protein. Western blotting was used to investigate the protein expression levels of tight junction proteins zonula occludens-1 and claudin-1. Furthermore, immunohistochemistry was used to examine intestinal injuries and western blotting was used to detect expression levels of NF-κB/HIF-1α signaling pathway-related proteins. H&E staining results suggested that the KOR agonist alleviated intestinal damage in the CPB model rats. This effect was reversed by the addition of a KOR antagonist. Further investigation of inflammatory and oxidative stress factors using ELISA revealed that the KOR agonist reduced the inflammatory and oxidative stress responses in the intestinal tissues of the CPB model rats. The ELISA results of intestinal damage markers and western blotting results of tight junction protein expression suggested that KOR agonist treatment may alleviate intestinal injury in CPB model rats. In addition, the western blotting and immunohistochemistry results suggested that KOR agonists may decrease the expression levels of NF-κB, p65 and HIF-1α in CPB. Collectively, the present results suggested that KOR agonists are able to ameliorate the intestinal barrier dysfunction in rats undergoing CPB by inhibiting the expression levels of NF-κB/HIF-1α signaling pathway-related proteins.

A 30-Minute Supraceliac Aortic Clamping in the Rat Causes Death Due to an Inflammatory Response and Pulmonary Lesions

BACKGROUND

The treatment of thoracoabdominal aortic aneurysms through an open approach has general and pulmonary consequences of multiple etiologies. Our assumption was that the supraceliac aortic clamping needed for this operation causes a systemic inflammatory response associated with a pulmonary attack.

METHODS

We developed a model of 30-min supraceliac aortic clamping in Wistar rats weighing 300 g. After 90 min of reperfusion, the rats were sacrificed. The effects on the digestive tract wall were analyzed by measurement of the mucosal thickness/total thickness ratio. The effects on the mesenteric endothelial function were determined by an ex situ measurement of the arterial pressure/volume curves (third branch). The systemic consequences of the procedure were analyzed by dosing tumor necrosis factor alpha (TNFα), interleukin (IL)1β, and IL10 in the blood. The pulmonary consequences were analyzed by the measurement of macrophages, polymorphonuclear neutrophils (PNs), T lymphocyte infiltration, pulmonary apoptosis (TUNEL) and active caspase 3. The experimental scheme included 20 rats with ischemia-reperfusion (IR) and 20 control rats. An analysis of survival was carried out on 20 other rats (10 IR and 10 controls).

RESULTS

The results were expressed as average ± standard error of the mean. The statistical tests were Student's t-test and Mann-Whitney test. This visceral IR model decreased the ratio of the thickness of the intestinal mucosa compared with that of the control rats (0.77 ± 0.008 vs. 0.82 ± 0.009 [P < 0.001]). This local effect was not accompanied by any mesenteric endothelial dysfunction (P = 0.91). On a systemic level, IR increased TNFα (37.9 ± 1.5 vs. 28.2 ± 0.6 pg/mL; P < 0.0001), IL1β (67.1 ± 9.8 vs. 22.5 ± 5.6 pg/mL; P < 0.001), and IL10 (753.3 ± 96 vs. 3.7 ± 1.7 pg/mL; P < 0.0001). As regards the lungs, IR increased the parenchymal cellular infiltration by macrophages (6.8 ± 0.8 vs. 4.5 ± 0.4 cells per field; P < 0.05) and PNs (7.4 ± 0.5 vs. 6.2 ± 03 cells per field; P < 0.05). There was no increase in the pulmonary cellular apoptosis measured by TUNEL (P = 0.77) or in the caspase 3 activity (P = 0.59). The mortality of the visceral IR rats was 100% at 36 hr vs. 0% in the animals without IR.

CONCLUSIONS

This work showed that the inflammatory response to visceral IR had systemic and pulmonary effects which always results in the death in the rat.

Risk factor analysis for nonocclusive mesenteric ischemia following cardiac surgery: A case-control study

Although rare, postcardiac surgery nonocclusive mesenteric ischemia (NOMI) is a life-threatening condition. Identifying the risk factors for NOMI during immediate postoperative period may help early detection and intervention, which leads to improved clinical outcomes. The objective of this study was to identify the clinical features and risk factors of NOMI for prognosis identification after cardiac surgery, focusing on immediate postoperative parameters.Among 9445 patients who underwent cardiac surgery over a span of 9 years, 40 NOMI cases (0.4%) requiring surgical interventions were reviewed. Suspected NOMI was diagnosed by sigmoidoscopy or computed tomography. To identify the risk factors, a control group (case: control = 1:3 ratio) was randomly selected and compared using logistic regression models.NOMI was diagnosed after a mean of 8.1 ± 9.6 days following cardiac surgery. Age (odds ratio: 1.16, 95% confidence interval: 1.08-1.25, P < .001), total vasoactive-inotropic score (VIS), and the maximal lactate level at postoperative day 0 (1.003, [1.001-1.005], P = .012), (1.23, [1.04-1.44], P = .011) were shown as risk factors. NOMI cases showed persistent hyperlactatemia without washout during the first 48 hours (P = .04). Thirty-four cases underwent exploratory laparotomy within a median of 10 (2-356) hours after the diagnosis, but only 17 patients (42.5%) survived. Compared with survivors, nonsurvivors showed higher total VIS at diagnosis, higher lactate levels during the first 24 hours postoperatively, and more frequently required extensive bowel resection (P < .05).Old age, postoperative high-dose vasoactive-inotropic use, and persistent high lactate level during the first 24 hours postsurgery were identified as risk factors for NOMI. Lactic acidosis and necrotic-bowel extent at surgical exploration were associated with poor survival.

Cardiopulmonary Bypass-Induced Inflammatory Response: Pathophysiology and Treatment

OBJECTIVES

The objectives of this review are to discuss the pathophysiology of the pro-inflammatory response to the cardiopulmonary bypass circuit, the impact of ischemia reperfusion injury on post-operative organ function, the compensatory anti-inflammatory response and the evidence for immune-modulatory strategies and their impact on outcomes.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSION

Innovations such as the development of more biocompatible surfaces and miniaturized circuits, as well as the increasing expertise of surgeons, anesthesiologists and perfusionists has transformed cardiac surgery and the use of cardiopulmonary bypass into a relatively routine procedure with favorable outcomes. Despite these refinements, the attendant inflammatory response to bypass, ischemia reperfusion injury and the compensatory anti-inflammatory response contribute to post-operative morbidity and mortality. Additional studies are needed to further delineate the impact of immunomodulatory strategies on outcomes.

Long-term prognosis and a prediction model for acute bowel ischaemia following cardiac surgery

OBJECTIVES

Bowel ischaemia following cardiac surgery is associated with a high postoperative mortality. No scoring system exists as yet to predict this complication following surgery. In addition, the long-term survival is not known. We sought to evaluate in-hospital outcomes and long-term outcomes in bowel ischaemia following cardiac surgery. We also sought to devise a simple risk prediction model for this catastrophic entity.

METHODS

This was a retrospective study of data entered prospectively into our cardiac surgical database between July 1999 and May 2014. We compared the short- and long-term outcomes of patients who developed bowel ischaemia following cardiac surgery with those who did not develop bowel ischaemia using propensity-matched analysis. We developed a prediction model for bowel ischaemia from logistic regression.

RESULTS

In total, 13 853 patients underwent cardiac surgery. Of these, 85 had confirmed bowel ischaemia following surgery. The in-hospital mortality rate for those with bowel ischaemia was 60%, while in those without bowel ischaemia, the mortality rate was 3% (P < 0.0001). In those bowel ischaemia patients who had a laparotomy for corrective surgery, the in-hospital mortality was significantly less compared with those who did not have a laparotomy (39.2 vs 91.2%, P < 0.0001). The long-term survival for bowel ischaemia at 2, 6 and 10 years was 35% (±5), 31% (±5) and 26% (+/6), respectively. Multivariable analysis revealed that advanced age at surgery, peripheral vascular disease, intra-aortic balloon pump usage, NYHA IV and postoperative atrial fibrillation were the significant (P < 0.005) determinants of developing postoperative bowel ischaemia. We developed a model to predict bowel ischaemia and validated it within our population (c-index = 0.781).

CONCLUSIONS

We have shown that whilst bowel ischaemia carries a higher short-term mortality, the long-term mortality is not significantly greater for those few who survive to discharge. We have developed a simple prediction model to identify those at high risk of developing bowel ischaemia following cardiac surgery in order to optimize perioperative strategies in future.

Oxygenator Is the Main Responsible for Leukocyte Activation in Experimental Model of Extracorporeal Circulation: A Cautionary Tale

In order to assess mechanisms underlying inflammatory activation during extracorporeal circulation (ECC), several small animal models of ECC have been proposed recently. The majority of them are based on home-made, nonstandardized, and hardly reproducible oxygenators. The present study has generated fundamental information on the role of oxygenator of ECC in activating inflammatory signaling pathways on leukocytes, leading to systemic inflammatory response, and organ dysfunction. The present results suggest that experimental animal models of ECC used in translational research on inflammatory response should be based on standardized, reproducible oxygenators with clinical characteristics.

Managing the inflammatory response after cardiopulmonary bypass: review of the studies in animal models

Objective

To review studies performed in animal models that evaluated therapeutic interventions to inflammatory response and microcirculatory changes after cardiopulmonary bypass.

Methods

It was used the search strategy ("Cardiopulmonary Bypass" ^(MeSH)) and ("Microcirculation" ^(MeSH) or "Inflammation" ^(MeSH) or "Inflammation Mediators" ^(MeSH)). Repeated results, human studies, non-English language articles, reviews and studies without control were excluded.

Results

Blood filters, system miniaturization, specific primers regional perfusion, adequate flow and temperature and pharmacological therapies with anticoagulants, vasoactive drugs and anti-inflammatories reduced changes in microcirculation and inflammatory response.

Conclusion

Demonstrated efficacy in animal models establishes a perspective for evaluating these interventions in clinical practice.

Is there a role of TNFR1 in acute lung injury cases associated with extracorporeal circulation?

The signaling pathway for tumor necrosis factor-α (TNF-α) and its receptors is up-regulated during extracorporeal circulation (ECC), and recruits blood neutrophil into the lung tissue, which results in acute lung injury (ALI). In this study, we evaluated the role of tumor necrosis factor receptor 1 (TNFR1) in ECC-induced ALI by blocking TNF-α binding to TNFR1 with CAY10500. Anesthetized Sprague-Dawley (SD) rats were pretreated intravenously with phosphate buffered saline (PBS) or vehicle (0.3 ml ethanol IV) or CAY10500, and then underwent ECC for 2 h. The oxygenation index (OI) and pulmonary inflammation were assessed after ECC. OI was significantly decreased, while TNF-α and neutrophil in bronchoalveolar lavage fluid (BALF) and plasma TNF-α increased after ECC. Pretreatment of CAY10500 decreased plasma TNF-α level, but did not decrease TNF-α levels and neutrophil counts in BALF or improve OI. Lung histopathology showed significant alveolar congestion, infiltration of the leukocytes in the airspace, and increased thickness of the alveolar wall in all ECC-treated groups. CAY10500 pretreatment slightly reduced leukocyte infiltration in lungs, but did not change the wet/dry ratio in the lung tissue. Blocking TNF-α binding to TNFR1 by CAY10500 intravenously slightly mitigates pulmonary inflammation, but cannot improve the pulmonary function, indicating the limited role of TNFR1 pathway in circulating inflammatory cell in ECC-induced ALI.

S1P1 receptor modulation preserves vascular function in mesenteric and coronary arteries after CPB in the rat independent of depletion of lymphocytes

Background

Cardiopulmonary bypass (CPB) may induce systemic inflammation and vascular dysfunction. Sphingosine 1-phosphate (S1P) modulates various vascular and immune responses. Here we explored whether agonists of the S1P receptors, FTY720 and SEW2871 improve vascular reactivity after CPB in the rat.

Methods

Experiments were done in male Wistar rats (total n = 127). Anesthesia was induced by isoflurane (2.5–3%) and maintained by fentanyl and midazolam during CPB. After catheterization of the left femoral artery, carotid artery and the right atrium, normothermic extracorporeal circulation was instituted for 60 minutes. In the first part of the study animals were euthanized after either 1 hour, 1 day, 2 or 5 days of the recovery period. In second part of the study animals were euthanized after 1 day of postoperative period. We evaluated the contractile response to phenylephrine (mesenteric arteries) or to serotonin (coronary artery) and vasodilatory response to acethylcholine (both arteries).

Results

Contractile responses to phenylephrine were reduced at 1 day recovery after CPB and Sham as compared to healthy control animals (Emax, mN: 7.9±1.9, 6.5±1.5, and 11.3±1.3, respectively). Mainly FTY720, but not SEW2871, caused lymphopenia in both Sham and CPB groups. In coronary and mesenteric arteries, both FTY720 and SEW2871 normalized serotonin and phenylephrine-mediated vascular reactivity after CPB (p<0.05) and FTY720 increased relaxation to acetylcholine as compared with untreated rats that underwent CPB.

Conclusion

Pretreatment with FTY720 or SEW2871 preserves vascular function in mesenteric and coronary artery after CPB. Therefore, pharmacological activation of S1P₁ receptors may provide a promising therapeutic intervention to prevent CPB-related vascular dysfunction in patients.

Acute bowel ischemia after heart operations

Acute bowel ischemia is a perioperative complication that is frequently unrecognized as a cause of death after cardiac surgical procedures, with an in-hospital mortality of 50% to 100%. In recent years, controversy regarding the most appropriate approach to resolve clinical or laboratory suspicion and the limited therapeutic options have led to very little improvement in patient prognosis. This article reviews the related literature examining the actual prevalence, pathophysiologic mechanisms, predisposing factors, diagnostic tests, and therapeutic approaches providing a glance at new promising tools in diagnostic workup.

Mesenteric endothelial dysfunction in a cardiopulmonary bypass rat model: the effect of diabetes

BACKGROUND

Diabetes is a risk factor for perioperative complications after cardiac surgery. We studied its effects on mesenteric endothelial function in a cardiopulmonary bypass (CPB) model.

METHODS

Forty Wistar rats were divided into four groups: sham (D-CPB-), cardiopulmonary bypass (D-CPB+), diabetic (D+CPB-) and diabetic that have undergone CPB (D+CPB+). Two samples of mesenteric artery were used for nitric oxide synthase (NOS) Western blot analysis, and two others for assessing contractile response and endothelium relaxations. Nitrite products and tumour necrosis factor-alpha (TNF-α) were assessed as markers of inflammatory response.

RESULTS

We observed an enhanced contractile response to the α-adrenergic agonist associated with impairment of mesenteric vasorelaxation in D+CPB+ rats. Western immunoblot analysis of D+CPB+ highlighted an additive effect of hyper-expression of inducible NOS. A significantly increased inflammatory response was observed after CPB in diabetic animals.

CONCLUSIONS

This work confirms the potential deleterious impact of diabetes on the mesenteric endothelium during CPB in cardiac surgery.

Albumin limits mesenteric endothelial dysfunction and inflammatory response in cardiopulmonary bypass

The aim of this study was to investigate the potential anti-inflammatory and endothelial protective properties of albumin during cardiopulmonary bypass (CPB) in an experimental porcine model. Two groups underwent CPB for 90 min (n = 7 in each group), and a baseline (BL) control group did not undergo CPB (n = 7). Priming consisted of a gelatin solution (4% gelofusine, CPBG group) or colloid solution (5% albumin, CPBA group). Mesenteric arterial segments were isolated and exposed in vitro to phenylephrine (with or without nitric oxide synthase inhibition) to assess contractility, and exposed to acetylcholine and sodium nitroprusside to assess relaxation. Plasma tumor necrosis factor (TNF)-α levels, intestinal and pulmonary TNF-α and heme oxygenase (HO)-1 mRNA expression, and organ injury were studied. Upon sacrifice, TNF-α levels were significantly higher in the CPBG group than in the CPBA and BL groups. The contractile response was significantly higher in the CPBG group, whereas the response to acetylcholine was significantly lower in the CPBG group than in the other groups. HO-1 mRNA expression was significantly higher in intestine samples in the CPBA group than in the CPBG and BL groups. HO-1 mRNA expression was significantly higher in lung samples in the CPBA group than in the CPBG group. Leukocyte infiltration was significantly higher in intestine and lung samples in the CPBG group than in the CPBA and BL groups. Albumin priming reduced CPB-induced mesenteric vascular dysfunction and prevented the development of a systemic inflammatory response by modeling HO-1 expression in target organs.

Cardiopulmonary bypass model in the rat: a new minimal invasive model with a low flow volume

Numerous cardiopulmonary bypass (CPB) models in the rat have already been described, but these models often have an important mortality and differ a lot from human clinical conditions thus making them hardly usable. The CPB model in the rat we describe allows a femoro-femoral support CPB with a low priming volume, minimal surgical approach and excellent peroperative survival. This CPB model in the rat allows evaluating extracorporeal circulation effects.

The effect of ulinastatin on postoperative blood loss in patients undergoing open heart surgery with cardiopulmonary bypass

This prospective, randomized, double-blind study evaluated the effect of ulinastatin on postoperative blood loss and transfusion requirements of patients undergoing open-heart surgery with cardiopulmonary bypass (CPB) and aortic cross-clamping (ACC). CPB and ACC produce variable systemic inflammatory reactions that are associated with multiorgan dysfunction via leucocytes, especially polymorphonuclear neutrophils (PMNs). PMNs increase blood loss and transfusion requirements. Ulinastatin, a urinary trypsin inhibitor, inhibits PMN activity and reduces the systemic inflammatory response. Patients received either 5000 U/kg ulinastatin or the equivalent volume of normal saline (control group) before ACC. Postoperative blood loss and transfusion requirements were recorded. Duration of intubation and length of stay in the intensive care unit (ICU) were also noted. There were no statistically significant between-group differences in postoperative blood loss and transfusion requirements. Ulinastatin caused a non-significant decrease in duration of intubation. Patients who received ulinastatin had significantly shorter ICU stays than control patients.

Minimized and conventional cardiopulmonary bypass damage intestinal mucosal integrity

OBJECTIVES

Previous studies have suggested that gastrointestinal integrity is compromised after cardiopulmonary bypass (CPB). We compared the effects of prolonged minimized (MCPB) and conventional CPB (CCPB) on intestinal mucosal integrity by determining mucosal damage, epithelial cell proliferation rate and distribution of tight junction proteins in a porcine model.

DESIGN

Fourteen animals were randomly assigned to undergo 240 minutes of mild hypothermic MCPB or CCPB. Ileal and colonic biopsies were obtained prior and at the end of CPB. Mucosal damage was determined under light microscopic evaluation. Immunohistochemistry was used to investigate epithelial expression of Ki-67 as a measure of cell proliferation rate and claudin-1, 2, 3, 4, 5, and 7 as elements of tight junctions.

RESULTS

In colonic biopsies, independent of the circuit type used, moderate mucosal damage was observed as indicated by focal epithelial damage, increased epithelial cell proliferation and decreased expression of tight junction protein claudin-4.

CONCLUSIONS

Colonic mucosal damage was observed similarly in MCPB and CCPB. Based on these results, the effects of MCPB on intestinal mucosal stability are similar to those of CCPB.

Case control study of gastrointestinal complications after cardiopulmonary bypass heart surgery

Background: Gastrointestinal complications (GIC) after cardiopulmonary bypass (CPB) surgery are rare, but, nevertheless, extremely dangerous.The identification of risks for GIC may be helpful in planning appropriate perioperative management strategies. The aim of the present study was to analyze perioperative factors of GIC in patients undergoing CPB surgery. Methods: We retrospectively analysed 206 patients who underwent GIC after cardiopulmonary bypass surgery from 2000 to 2007 and compared them with 206 matched control patients (matched for surgery, temperature, hemodilution and date). Univariate analysis and multiple logistic regression analysis were performed on 12 risk factors. Result: Sex and types of cardioplegia perfusate did not significantly influence the GIC after CPB surgery. Multiple logistic regression revealed that CPB time, preoperative serum creatinine (PSC) ≥ 179 mg/dL, emergency surgery, perfusion pressure ≤40mmHg, low cardiac output syndrome (LCOS), age ≥ 61, mechanical ventilation ≥96 h, New York Heart Association (NYHA) class III and IV were predictors of the occurrence of GIC after CPB surgery. Perfusion pressure and aprotinin administration were protective factors. Conclusion: Gastrointestinal complications after CPB surgery could be predictive in the presence of the above risk factors. This study suggests that GIC can be reduced by maintenance of higher perfusion pressure and shortening the time on CPB and ventilation.

Vasopressin as adjunct vasopressor for vasodilatory shock due to non-occlusive mesenteric ischemia

We present the case of an 83-year-old patient who underwent cardiac surgery and developed postoperative non-occlusive mesenteric ischemia (NOMI), which was treated with a local intra-arterial papaverine and prostaglandin E1 infusion. After successful mesenteric reperfusion, a multiple organ dysfunction syndrome with severe cardiovascular failure developed. High norepinephrine dosages (1.09 microg/kg body weight/min) and catecholamine-related complications (tachycardiac atrial fibrillation) required initiation of supplementary argininevasopressin (AVP) infusion (4 U/h). AVP stabilized vasodilatory shock, ensured adequate gut perfusion pressure and had no adverse clinical or angiographic effects on restitution of gut integrity. In conclusion, after reperfusion of NOMI in this patient, adjunct AVP therapy combined with local vasodilator infusion was beneficial as a potentially life-saving vasopressor.

Acute mesenteric ischemia after cardio-pulmonary bypass surgery

Acute mesenteric ischemia (AMI) is a highly-lethal surgical emergency. Several pathophysiologic events (arterial obstruction, venous thrombosis and diffuse vasospasm) lead to a sudden decrease in mesenteric blood flow. Ischemia/reperfusion syndrome of the intestine is responsible for systemic abnormalities, leading to multi-organ failure and death. Early diagnosis is difficult because the clinical presentation is subtle, and the biological and radiological diagnostic tools lack sensitivity and specificity. Therapeutic options vary from conservative resuscitation, medical treatment, endovascular techniques and surgical resection and revascularization. A high index of suspicion is required for diagnosis, and prompt treatment is the only hope of reducing the mortality rate. Studies are in progress to provide more accurate diagnostic tools for early diagnosis. AMI can complicate the post-operative course of patients following cardio-pulmonary bypass (CPB). Several factors contribute to the systemic hypo-perfusion state, which is the most frequent pathophysiologic event. In this particular setting, the clinical presentation of AMI can be misleading, while the laboratory and radiological diagnostic tests often produce inconclusive results. The management strategies are controversial, but early treatment is critical for saving lives. Based on the experience of our team, we consider prompt exploratory laparotomy, irrespective of the results of the diagnostic tests, is the only way to provide objective assessment and adequate treatment, leading to dramatic reduction in the mortality rate.

Influence of physical preconditioning on the responsiveness of rat pulmonary artery after pulmonary ischemia/reperfusion

The aim of this work was to evaluate the effect of physical preconditioning in the responsiveness of rat pulmonary rings submitted to lung ischemia/reperfusion (IR). Wistar rats were divided into three groups: Sedentary sham-operated (SD/SHAM); sedentary submitted to ischemia/reperfusion (SD/IR) and trained submitted to ischemia/reperfusion (TR/IR) animals. Exercise training consisted in sessions of 60 min/day running sessions, 5 days/week for 8 weeks. Left pulmonary IR was performed by occluding for 90 min and reperfusing for 120 min. After that, pulmonary arteries were isolated and concentration-response curves to acetylcholine (ACh), histamine (HIST), sodium nitroprusside (SNP), phenylephrine and U46619 were obtained. Neither potency (-log EC(50)) nor maximal responses (E(max)) were modified for ACh and HIST in all groups. On the other hand, the potency for SNP was significantly increased in TR/IR group (8.23+/-0.06) compared to SD/IR group (7.85+/-0.04). Contractile responses mediated by a-adrenergic receptor were markedly decreased in IR groups (SD/IR: 6.75+/-0.06 and TR/IR: 6.62+/-0.04) compared to SD/SHAM (7.33+/-0.05). No changes were seen for the U46619 in all groups. In conclusion, the present study shows that exercise training has no protective actions in the local blood vessel where the IR process takes place.

Differential effects on the mesenteric microcirculatory response to vasopressin and phenylephrine after cardiopulmonary bypass

OBJECTIVE

Mesenteric ischemia is a rare but potentially devastating complication of cardiac surgery with cardiopulmonary bypass. We hypothesized that alterations in mitogen-activated protein kinase pathways contribute to mesenteric microcirculatory dysfunction resulting from cardiopulmonary bypass.

METHODS

Pigs underwent cardiopulmonary bypass (n = 6) for 90 minutes and postbypass reperfusion for 180 minutes. Sham operations (n = 6) were performed on controls. Mesenteric tissue was harvested before bypass and after postbypass reperfusion. Microvascular contraction to phenylephrine and vasopressin was examined by videomicroscopy. Contractile responses with inhibition of the extracellular regulated kinase 1/2 (ERK1/2) pathway by PD98059 (30 micromol/L) and p38 kinase inhibition by SB203580 (1 micromol/L) also were determined. Activated forms of ERK1/2 and p38 kinase were measured by Western blot. ERK1/2 and p38 activity were localized in mesenteric tissue by immunohistochemistry.

RESULTS

Contractile responses to phenylephrine were increased at 180 minutes after cardiopulmonary bypass (+49.7% +/- 5.5%, P < .01), whereas contraction to vasopressin was unchanged. ERK1/2 pathway inhibition reduced contractile responses to phenylephrine at baseline and 180 minutes after bypass (both P < .01) but had no effect on contraction to vasopressin. p38 Kinase inhibition decreased the contractile responses to vasopressin at baseline and 180 minutes after bypass (both P < .01) but did not alter the contractile response to phenylephrine. Activated ERK1/2 levels were increased by more than 40% at 180 minutes after bypass (P < .01). Protein levels of activated p38 kinase were not changed. The increased ERK1/2 activity was associated with mesenteric arterioles by immunohistochemistry.

CONCLUSIONS

A differential pattern of mesenteric vasomotor regulation exists after cardiopulmonary bypass that may contribute to the risk of mesenteric ischemia after cardiac surgery.

Gastrointestinal dysfunction following cardiac surgery

Cardiac surgery is associated with a low incidence of GI complications, but with a disproportionate mortality. A number of risk factors have become established which identify patients at risk. CPB is associated with profound reductions in mucosal blood flow. Mesenteric perfusion is altered by primary endothelial dysfunction, which may further be exacerbated by the use of vasoconstrictors during CPB; inflammatory mediators can 'prime' the mesenteric vasculature. Cardiac surgery with or without CPB is associated with increased tissue oxygen demands, particularly by the splanchnic bed. The disparity in general and regional oxygen supply and demand results in the development of mucosal hypoxia and this cannot be attributed to CPB alone. This injury is measurable by reductions in both absorptive and barrier functions of the gut. Protection may be conferred by modulating the perfusion protocol during bypass and pharmacological interventions which modify the inflammatory response to surgery.

Changes in Cerebral Vascular Reactivity Occur Early During Cardiopulmonary Bypass in the Rat

BACKGROUND

Cardiopulmonary bypass (CPB) is known to cause cerebrovascular dysfunction. The etiology of these complications is complex, but disruption of normal cerebral endothelial function as a consequence of inflammatory or hypoperfusion phenomena have been implicated. The aim of this study was to investigate the effect of CPB time on cerebrovascular reactivity and to investigate the correlation of these findings with measured inflammatory markers.

METHODS

Cardiopulmonary bypass was carried out for 30 or 60 minutes on two groups of rats. Sham groups underwent the same surgical procedure without CPB. The middle cerebral artery was harvested and prepared for assessment of induced endothelial and vascular smooth muscle cell responses. Systemic inflammation was evaluated by measuring tumor necrosis factor-alpha and immunohistochemical staining for intercellular adhesion molecule-1.

RESULTS

Acetylcholine caused a dose-dependent vasodilation in the control groups that was absent in animals undergoing CPB (21.3% +/- 1.3% increase in diameter at 30 minutes in the sham group compared with 5.4% +/- 1.1% in the corresponding CPB group, p < 0.001). Significantly, this was apparent after only 30 minutes of CPB. Cardiopulmonary bypass did not alter the response to sodium nitroprusside (45.3% +/- 8.6% after 30 minutes in the sham group compared with 57.8% +/- 8.0% in the corresponding CPB group, p < 0.2). Furthermore, the contractile response to serotonin remained intact in all groups (32.9 +/- 4.6 and 27.6 +/- 2.6 at 30 and 60 minutes, respectively, in the sham groups compared with 23.1 +/- 1.6 and 28.0 +/- 4.4 in the corresponding CPB groups, p < 0.2). Cardiopulmonary bypass also led to an early and marked increase in tumor necrosis factor-alpha and overexpression of intercellular adhesion molecule-1.

CONCLUSIONS

Cerebrovascular impairment appears early after the onset of CPB. The specific loss of acetylcholine-induced vasodilation suggests endothelial cell dysfunction rather than impaired vascular smooth muscle response to nitric oxide. This loss of endothelium-dependent regulatory factors after CPB may enhance vasoconstriction, impair cerebrovascular function, and contribute to neurologic injury after CPB.

Endothelial Ca2+ signal transduction is altered by postoperative serum from patients undergoing coronary surgery with cardiopulmonary bypass

Endothelial dysfunction after surgery may be caused by alterations in the intracellular signaling properties of endothelial cells. Functional alterations are believed to be systemic and dependent on the amount of invasiveness. This led us to assume that there would be a mediator in the blood. Therefore, we investigated the influence of perioperative serum obtained from patients undergoing highly invasive surgical interventions (cardiac surgery [CS] with cardiopulmonary bypass) and less invasiveness (total joint arthroplasty [TJA]) on endothelial single cell Ca2+ responses. Aortic endothelial cells were incubated with preoperative and postoperative serum samples from 26 patients undergoing CS and from 15 patients undergoing TJA. Adenosine triphosphate (100 microM)-induced alterations in FURA-2 fluorescence was used to measure intracellular Ca2+ in single cells. In CS samples the induced [Ca2+]i signals were enhanced by postoperative serum (peak levels: 96 +/- 41 FU versus 116 +/- 45 FU; P < 0.05). These postoperative enhancements were absent in TJA patients serum. Preincubation of CS samples with nifedipine to block voltage gated Ca2+ channels did not alter this effect, but the absence of extracellular Ca2+ abolished the increased response from postoperative CS serum exposure. Ca2+ entry probed with Mn2+ quenching was increased in endothelial cells exposed with postoperative CS serum and Ca2+ entry correlated with postoperative circulating interleukin-6 levels (P < 0.007). Endothelial functional alterations after CS with cardiopulmonary bypass are attributable, in part, to systemic factors present in serum that lead to specific endothelial enhanced Ca2+-signaling. This enhancement can be separated in vitro as an increased Ca2+ entry not present in serum from patients recovering from TJA.

Hemodynamic effects of cardiotomy suction blood

OBJECTIVE

Cardiac surgery induces a systemic inflammatory activation, which in severe cases is associated with peripheral vasodilation and hypotension. Cardiotomy suction blood contains high levels of inflammatory mediators, but the effect of cardiotomy suction blood on the vasculture is unknown. We investigated the effect of cardiotomy suction blood on systemic vascular resistance in vivo and whether cell-saver processing of suction blood affects the vascular response.

METHODS

Twenty-five patients undergoing coronary surgery (mean age, 68 +/- 2 years; 80% men) were included in a prospective randomized study. The patients were randomized to retransfusion of cell-saver processed (n = 13) or cell-saver unprocessed (n = 12) suction blood during full cardiopulmonary bypass. Mean arterial blood pressure was continuously registered during retransfusion, and systemic vascular resistance was calculated. Plasma concentrations of tumor necrosis factor alpha, interleukin 6, and complement factor C3a were measured in suction blood.

RESULTS

Retransfusion of cardiotomy suction blood induced a transient reduction in systemic vascular resistance in all patients. The peak reduction was significantly less pronounced in the group receiving cell-saver processed blood (-12% +/- 2% vs -28% +/- 3%, P = .001). There was a significant correlation between tumor necrosis factor alpha concentration in retransfused cardiotomy suction blood and peak reduction of systemic vascular resistance (r = 0.60, P = .002).

CONCLUSIONS

The results suggest cardiotomy suction blood is vasoactive and might influence vascular resistance and blood pressure during cardiac surgery. The observed vasodilation is proportional to the inflammatory activation of suction blood and can be reduced by processing suction blood with a cell-saving device before retransfusion.

Gastric intramucosal perfusion during descending aortic repair under femoro-femoral bypass

The changes in gastric mucosal perfusion during distal aortic perfusion with femoro-femoral bypass (F-F bypass) were assessed by air-automated gastric tonometry. A prospective study was performed in six patients who underwent descending aortic surgery for aortic aneurysm under F-F bypass with mild hypothermia (34 degrees C). Gastric intramucosal pH (pHi) and PaCO2-PgCO2 gap (PCO2 gap) were measured. Data are presented as means and standard deviations and analyzed by using one-way analysis of variance followed by Scheffe test. Perioperative variables of hepatorenal functions are also evaluated. The PCO2 gap significantly increased during F-F bypass (3.0 +/- 2.1 mm Hg at control, 14.2 +/- 5.5 mm Hg during F-F bypass; p = 0.004), indicating abnormal gastric mucosal perfusion during F-F bypass. Significantly low pHi was found at weaning from F-F bypass (7.35 +/- 0.05 at control, 7.21 +/- 0.10 at weaning; p = 0.009), which might be related to progressing systemic metabolic acidosis. No impairment of hepatorenal functions was observed after the surgery. Distal perfusion with F-F bypass during descending aortic surgery could impair the gastric mucosal perfusion, but may have little effect on postoperative visceral dysfunction.

Gastrointestinal complications in patients undergoing heart operation: an analysis of 8709 consecutive cardiac surgical patients

INTRODUCTION

Gastrointestinal (GI) complications following heart operation may be life-threatening. Systematic analysis of risk factors to allow early identification of patients at risk for GI complication may lead to the development of strategies to mitigate this complication as well as to optimize management after its occurrence.

METHODS

Of 8709 consecutive patients undergoing heart operation during 7 years (1997-2003), 46 (0.53%) developed GI complications requiring surgical consultation. Preoperative, intraoperative, and postoperative predictors of complication and death were identified and compared with a control group.

RESULTS

Significant (P < 0.05) preoperative predictors of complication were prior cerebrovascular accident (CVA), chronic obstructive pulmonary disease (COPD), type II heparin-induced thrombocytopenia, atrial fibrillation, prior myocardial infarction, renal insufficiency, hypertension, and need for intra-aortic balloon counter-pulsation. The most frequent serious GI complication was mesenteric ischemia, which developed in 31 (67%) patients. Twenty-two (71%) of these patients were explored, and 14 (64%) died within 2 days of heart operation. Of the 9 patients with mesenteric ischemia who were not explored, 7 (78%) died within 3 days of heart operation. Other complications included diverticulitis (5), pancreatitis (4), peptic ulcer disease (4), and cholecystitis (2). The mortality rate in this group of other diagnoses was lower (40%), and death occurred later (32 days) after heart operation (P = 0.03 compared with mesenteric ischemia). Predictors of death from GI complication included New York Heart Association (NYHA) class III and IV heart failure, smoking, chronic obstructive pulmonary disease, history of syncope, aspartate aminotransferase (AST) >600 U/L, direct bilirubin >2.4 mg/dL, pH < 7.30, and the need for >2 pressors.

CONCLUSIONS

The most common catastrophic GI complication after cardiac surgery is mesenteric ischemia, which is frequently fatal. This complication may be a result of atheroembolization, heparin-induced thrombocytopenia, or hypoperfusion. Techniques to reduce the occurrence of and/or preemptively diagnosis postcardiotomy mesenteric ischemia are necessary to decrease its associated mortality.

MESENTERIC VASCULAR DYSFUNCTION AFTER CARDIOPULMONARY BYPASS WITH CARDIAC ARREST IS AGGRAVATED BY COEXISTENT HEART FAILURE

Although patients suffering from heart failure (HF) have an increased incidence of nonocclusive mesenteric ischemia after opened heart surgery, the impact of cardiopulmonary bypass with cardiac arrest (CPB) on mesenteric vascular circulation in such situation remains unexplored. Therefore, the present study investigates the effects of CPB on mesenteric vascular reactivity, regional metabolism, and oxidative stress in an experimental model of HF. Volume-overload HF was induced in six dogs by bilateral femoral arteriovenous fistula. Six sham-operated dogs were used as controls. Eight weeks later, the short-term effects of 90 min of CPB were assessed in vivo during acute experiments. The significant increase in left ventricular end-diastolic volume in HF animals did not influence the vasodilator response of the superior mesenteric artery to acetylcholine (ACH) and nitroprusside (SNP) under baseline conditions. However, reduced mesenteric oxygen delivery, increased oxygen extraction, and lactate release were found during CPB in the HF group. In addition, an increased free radical production was assessed in the HF group during (89 +/- 23 x 10 relative light units [RLU]) and after CPB (93 +/- 15 x 10 RLU) compared with controls (45 +/- 15 and 49 +/- 7 x 10 RLU, respectively). Finally, 90 min of CPB led to a more pronounced decrease of ACH- (-22% +/- 5% vs. -42% +/- 9%, P < 0.05) and SNP- (-14% +/- 4% vs. -50% +/- 7%, P < 0.002) induced mesenteric vasodilations in the HF group compared with controls. We conclude that coexistent HF significantly enhances the pathological effects of CPB on the mesenteric vascular circulation by additionally altering endothelial and smooth muscle vascular function consequent to augmented oxidative stress.

Gut permeability in paediatric cardiac surgery

BACKGROUND

Intestinal mucosal ischaemia can occur in infants and children during and after cardiac surgery. Severe decreases in mucosal perfusion may cause complications such as necrotizing enterocolitis and postoperative mortality. We investigated gut permeability in paediatric patients undergoing cardiac surgery using the dual sugar permeability test and absorption of two other saccharides.

METHODS

Thirty-four patients undergoing palliative or corrective surgical procedures with and without cardiopulmonary bypass were investigated. Intestinal permeability was measured using 3-O-methyl-D-glucose, D-xylose, L-rhamnose and lactulose, given orally after induction of anaesthesia and 12 and 24 h later.

RESULTS

Lactulose/rhamnose ratios were raised from the outset [median 0.39 (confidence interval 0.07-1.8 for patients undergoing operations without cardiopulmonary bypass and 0.30 (0.02-2.6) with cardiopulmonary bypass]. The highest lactulose/rhamnose ratios were recorded 12 h after surgery 0.32 (0.07-6.9), when cardiopulmonary bypass was used. This is approximately seven times the value expected in healthy children. There was an improvement in patients not undergoing cardiopulmonary bypass: 0.22 (0.03-0.85) 12 h and 0.11 (0-0.48) 24 h after induction of anaesthesia. Patients undergoing repair of aortic coarctation showed the fastest recovery: 0.09 (0.03-0.31) 12 h and 0.07 (0.04-0.35) 24 h after induction of anaesthesia.

CONCLUSIONS

Patients with congenital heart defects have abnormal gut permeability when compared with healthy children of similar age. Cardiopulmonary bypass seems to affect the intestinal barrier morphologically (lactulose and rhamnose absorption) and functionally (3-O-methyl-D-glucose and D-xylose absorption).