Coagulation and fibrinolytic protein kinetics in cardiopulmonary bypass

Protracted fibrinolysis resistance following cardiac surgery with cardiopulmonary bypass: A prospective observational study of clinical associations and patient outcomes

BACKGROUND

Surgery on cardiopulmonary bypass (CPB) elicits a pleiomorphic systemic host response which, when severe, requires prolonged intensive care support. Given the substantial cross-talk between inflammation, coagulation, and fibrinolysis, the aim of this hypothesis-generating observational study was to document the kinetics of fibrinolysis recovery post-CPB using ClotPro® point-of-care viscoelastometry. Tissue plasminogen activator-induced clot lysis time (TPA LT, s) was correlated with surgical risk, disease severity, organ dysfunction and intensive care length of stay (ICU LOS).

RESULTS

In 52 patients following CPB, TPA LT measured on the first post-operative day (D1) correlated with surgical risk (EuroScore II, Spearman's rho .39, p < .01), time on CPB (rho = .35, p = .04), disease severity (APACHE II, rho = .52, p < .001) and organ dysfunction (SOFA, rho = .51, p < .001) scores, duration of invasive ventilation (rho = .46, p < .01), and renal function (eGFR, rho = -.65, p < .001). In a generalized linear regression model containing TPA LT, CPB run time and markers of organ function, only TPA LT was independently associated with the ICU LOS (odds ratio 1.03 [95% CI 1.01-1.05], p = .01). In a latent variables analysis, the association between TPA LT and the ICU LOS was not mediated by renal function and thus, by inference, variation in the clearance of intraoperative tranexamic acid.

CONCLUSIONS

This observational hypothesis-generating study in patients undergoing cardiac surgery with cardiopulmonary bypass demonstrated an association between the severity of fibrinolysis resistance, measured on the first post-operative day, and the need for extended postoperative ICU level support. Further examination of the role of persistent fibrinolysis resistance on the clinical outcomes in this patient cohort is warranted through large-scale, well-designed clinical studies.

Which strategy is better for lung transplantation: Cardiopulmonary bypass or extracorporeal membrane oxygenation?

Background: In lung transplantation surgery, extracorporeal life support (ECLS) is essential for safety. Various support methods, including cardiopulmonary bypass (CPB) and off-pump techniques, are used, with extracorporeal membrane oxygenation (ECMO) gaining prominence. However, consensus on the best support strategy is lacking.Purpose: This article reviews risks, benefits, and outcomes of different support strategies in lung transplantation. By consolidating knowledge, it aims to clarify selecting the most appropriate ECLS modality.Research Design: A comprehensive literature review examined CPB, off-pump techniques, and ECMO outcomes in lung transplantation, including surgical results and complications.Study Sample: Studies, including clinical trials and observational research, focused on ECLS in lung transplantation, both retrospective and prospective, providing a broad evidence base.Data Collection and/or Analysis: Selected studies were analyzed for surgical outcomes, complications, and survival rates associated with CPB, off-pump techniques, and ECMO to assess safety and effectiveness.Results: Off-pump techniques are preferred, with ECMO increasingly vital as a bridge to transplant, overshadowing CPB. However, ECMO entails hidden risks and higher costs. While safer than CPB, optimizing ECMO postoperative use and monitoring is crucial for success.Conclusions: Off-pump techniques are standard, but ECMO's role is expanding. Despite advantages, careful ECMO management is crucial due to hidden risks and costs. Future research should focus on refining ECMO use and monitoring to improve outcomes, emphasizing individualized approaches for LT recipients.

Intraoperative Extracorporeal Support during Lung Transplantation: Not Just for the High-Risk Patient

The use of intraoperative mechanical support during lung transplantation has traditionally been a controversial topic. Trends for intraoperative mechanical support strategies swing like a pendulum. Historically, cardiopulmonary bypass (CPB) was the modality of choice during transplantation. It provides full hemodynamic support including oxygenation and decarboxylation. Surgical exposure is improved by permitting the drainage of the heart and provides more permissive retraction. CPBs contain drainage reservoirs with hand-held pump suction catheters promoting blood conservation through collection and re-circulation. But CPB has its disadvantages. It is known to cause systemic inflammation and coagulopathy. CPB requires high doses of heparinization, which increases bleeding risks. As transplantation progressed, off-pump transplantation began to trend as a preferable option. ECMO, however, has many of the benefits of CPB with less of the risk. Outcomes were improved with ECMO compared to CPB. CPB has a higher blood transfusion requirement, a higher need for post-operative ECMO support, a higher re-intubation rate, high rates of kidney injury and need for hemodialysis, longer ICU stays, higher incidences of PGD grade 3, as well as overall in-hospital mortality when compared with ECMO use. The focus now shifts to using intraoperative mechanical support to protect the graft, helping to reduce ischemia-reperfusion injury and allowing for lung protective ventilator settings. Studies show that the routine use of ECMO during transplantation decreases the rate of primary graft dysfunction and many adverse outcomes including ventilator time, need for tracheostomy, renal failure, post-operative ECMO requirements, and others. As intraoperative planned ECMO is considered a safe and effective approach, with improved survival and better overall outcomes compared to both unplanned ECMO implementation and off-pump transplantation, its routine use should be taken into consideration as standard protocol.

Coagulation Tests and Bleeding Classification After Cardiopulmonary Bypass: A Prospective Study

OBJECTIVE

No recent prospective studies have analyzed the accuracy of standard coagulation tests and thromboelastography (TEG) to identify patients with excessive microvascular bleeding following cardiopulmonary bypass (CPB). The aim of this study was to assess the value of coagulation profile tests, as well as TEG, for the classification of microvascular bleeding after CPB.

DESIGN

A prospective observational study.

SETTING

At a single-center academic hospital.

PARTICIPANTS

Patients ≥18 years of age undergoing elective cardiac surgery.

INTERVENTIONS

Qualitative assessment of microvascular bleeding post-CPB (surgeon and anesthesiologist consensus) and the association with coagulation profile tests and TEG values.

MEASUREMENTS AND MAIN RESULTS

A total of 816 patients were included in the study-358 (44%) bleeders and 458 (56%) nonbleeders. Accuracy, sensitivity, and specificity for the coagulation profile tests and TEG values ranged from 45% to 72%. The predictive utility was similar across tests, with prothrombin time (PT) (62% accuracy, 51% sensitivity, 70% specificity), international normalized ratio (INR) (62% accuracy, 48% sensitivity, 72% specificity), and platelet count (62% accuracy, 62% sensitivity, 61% specificity) displaying the highest performance. Secondary outcomes were worse in bleeders versus nonbleeders, including higher chest tube drainage, total blood loss, transfusion of red blood cells, reoperation rates (p < 0.001, respectively), readmission within 30 days (p = 0.007), and hospital mortality (p = 0.021).

CONCLUSIONS

Standard coagulation tests and individual components of TEG in isolation agree poorly with the visual classification of microvascular bleeding after CPB. The PT-INR and platelet count performed best but had low accuracy. Further work is warranted to identify better testing strategies to guide perioperative transfusion decisions in cardiac surgical patients.

Intraoperative Cell Savage, Infection and Organ Failure in Infective Endocarditis Patients-A Retrospective Single Center Evaluation

Surgery is indicated in about 50% of infective endocarditis patients, and bleeding or the transfusion of blood a common finding. The intraoperative use of cell salvage may reduce the perioperative transfusion requirement, but its use is limited in the underlying disease. In this retrospective study, we therefore evaluated n = 335 patients fulfilling the modified Duke criteria for infective endocarditis characterized by the use of intraoperative cell salvage with autologous blood retransfusion. Inflammation markers and organ dysfunction, including catecholamine dependency, were evaluated by using linear regression analysis. Between 2015 and 2020, 335 patients underwent surgery for left-sided heart valve endocarditis. Intraoperative cell salvage was used in 40.3% of the cases, especially in complex scenarios and reoperation. Intraoperative cell salvage significantly altered the white blood cell count after surgery. On average, leucocytes were 3.0 Gpt/L higher in patients with intraoperative cell salvage compared to patients without after adjustment for confounders (95% CI: 0.39-5.54). Although the difference in WBC was statistically significant, i.e., higher in the ICS group compared to the no-ICS group, this difference may be clinically unimportant. Organ dysfunction, including hemodynamic instability and lactate values, were comparable between groups. In conclusion, intraoperative cell salvage enhanced the re-transfusion of autologous blood, with minor effects on the postoperative course of inflammatory markers, but was not associated with increased hemodynamic instability or organ dysfunction in general. The restriction of intraoperative cell salvage in surgery for infective endocarditis should be re-evaluated, and more prospective data in this topic are needed.

Comparison of mechanical cardiopulmonary support strategies during lung transplantation

INTRODUCTION

Lung transplantation outcomes are influenced by the intraoperative mechanical cardiopulmonary support strategy used. This surgery was historically done either on cardiopulmonary bypass (CPB) or off pump. Recently, there has been increased interest in intraoperative support with veno-arterial (VA) or veno-venous (VV) extracorporeal membrane oxygenation (ECMO). However, there is a lack of consensus on the relative risks, benefits and indications for each intraoperative support strategy.

AREAS COVERED

This review includes information from cohort studies, case-control studies, and case series that compare morbidity and/or mortality of two or more intraoperative cardiopulmonary support strategies during lung transplantation.

EXPERT OPINION

The optimal strategy for intraoperative cardiopulmonary support during lung transplantation remains an area of debate. Current data suggest that off pump is associated with better outcomes and could be considered whenever feasible. ECMO is generally associated with preferable outcomes to CPB, but the data supporting this association is not robust. Interestingly, whether CPB is unplanned or prolonged might influence outcomes more than the use of CPB itself. These observations can help guide surgical teams in their approach for intraoperative mechanical support strategy during lung transplantation and should serve as the basis for further investigations.

Application of a Modified Extracorporeal Circulation Perfusion Method During Surgery for Acute Stanford Type A Aortic Dissection

AIM

The aim of this study was to investigate the effect of the modified extracorporeal circulation perfusion method during surgery for acute Stanford type A aortic dissection in patients who underwent stented elephant trunk implantation and arch replacement.

METHOD

A total of 69 patients with acute Stanford type A aortic dissection who underwent stented elephant trunk implantation and arch replacement were retrospectively analysed from 2017 to 2018. According to the perfusion method of extracorporeal circulation, patients were divided into a routine perfusion (RP) group and a modified perfusion (MP) group. Clinical data were collected, including the time of extracorporeal circulation and deep hypothermic circulatory arrest, incidence of acute kidney injury and neurological complications, and comparisons between the two groups were conducted by using independent sample t-tests for normally distributed qualitative data, the Mann-Whitney U-test for skewed qualitative data, and the chi square test or Fisher's exact test for categorical data.

RESULTS

There were 55 (80%) males and 14 (20%) females in the entire cohort, and the mean ± standard deviation age was 50.4±9.0 years. A total of 53 (77%) patients were included in the RP group, and 16 (23%) were included in the MP group. Patients in the MP group were older (55.5±7.8 vs 48.8±8.9 years), and the difference was significant (p=0.008). Compared with the RP group, the time of extracorporeal circulation (218.0 [44.7] vs 246.0 [58.0] min; p=0.005) and deep hypothermic circulatory arrest (4.0 [2.0] vs 25.0 [10.0] min; p<0.001) was shorter, and the incidence of postoperative acute kidney injury (n=6 [37.5%] vs n=36 [67.9%]; p=0.029) was lower in the MP group; the differences were significant. Six (6) patients died in the RP group; no patients died in the MP group. The total in-hospital mortality rate was 8.7%.

CONCLUSIONS

The modified extracorporeal circulation perfusion method is feasible, with satisfactory results.

LncRNA CAIF was downregulated in end-stage cardiomyopathy and is a promising diagnostic and prognostic marker for this disease

Cardiac autophagy inhibitory factor (CAIF) is a novel lncRNA with protective effects on myocardial infarction. We explored the involvement of CAIF in end-stage cardiomyopathy. Patients with end-stage cardiomyopathy and healthy volunteers were included in this study. Myocardial tissues and serum were collected. CAIF was detected by RT-qPCR. ROC curve was used for diagnostic analysis. Prognostic value of CAIF expression for end-stage cardiomyopathy was evaluated by survival curve analysis. Correlations between CAIF expression and clinicopathological data of patients with end-stage cardiomyopathy were analysed by chi-square test. Downregulated CAIF was observed in end-stage cardiomyopathy patients than in healthy controls. CAIF expression distinguished end-stage cardiomyopathy patients from healthy controls and predict the survival of patients. LncRNA CAIF was downregulated in end-stage cardiomyopathy and may serve as a promising prognostic and diagnostic marker for this disease.

Comparison of two point of care whole blood coagulation analysis devices and conventional coagulation tests as a predicting tool of perioperative bleeding in adult cardiac surgery-a pilot prospective observational study in Japan

BACKGROUND

It is widely accepted that Point-of Care Test (PoCT) devices are useful in the detection of coagulopathies in situations of massive bleeding such as major cardiac surgery. These devices contribute to the reduction of blood transfusion. However, their implementation remains limited in Japan because of their cost and lack of health insurance support.

STUDY DESIGN AND METHODS

Conventional coagulation tests and thromboelastography (TEG)/Sonoclot values were measured in 50 consecutive cardiac surgery cases. Clinical background information such as operative procedures was obtained from electronic medical records, and the theoretical perioperative total blood loss was calculated by measuring the hemoglobin content and total red blood cell transfusion volume. The correlation between perioperative total blood loss and the measured laboratory values or clinical parameters was evaluated by a multivariate linear regression analysis. The risk factors of the total amount of platelet transfusion and postoperative drain bleeding volume were similarly evaluated.

RESULTS

No significant association between the estimated perioperative total blood loss (eTBL) and the laboratory measurements including conventional coagulation tests, TEG and Sonoclot was observed. On the other hand, postoperative drain bleeding volume was significantly associated with postoperative Sonoclot CR (p = 0.039) as well as preoperative use of oral anticoagulants and cell saver treated blood volume. Platelet transfusion amount was significantly associated with post-CBP PF and time to peak value of Sonoclot (p = 0.014 and 0.001, respectively).

CONCLUSION

Sonoclot measurements may be useful to estimate the risks of postoperative bleeding and platelet transfusion in cardiac surgeries in Japan.

Feasibility and acceptability of continuous postoperative pericardial flushing for blood loss reduction in patients undergoing coronary artery bypass grafting

INTRODUCTION

Postoperative bleeding requires blood transfusion and surgical re-exploration that can affect the short- and long-term postoperative outcomes. Interventions that can be used in the postoperative period to reduce blood loss should be developed. Continuous postoperative pericardial flushing (CPPF) with an irrigation solution may reduce blood loss by preventing the accumulation of clots. This study examined the feasibility and acceptability of CPPF for reducing bleeding after coronary artery bypass surgery.

METHODS

This pilot study adopted a prospective and group comparison design. Between January and April 2018, 42 patients who underwent isolated coronary artery bypass surgery received CPPF from sternal closure up to 8 h postoperative. The mean actual blood loss in the CPPF group was compared to the mean of retrospectively group (n = 58). In the CPPF group, an extra infusion catheter was inserted through one of the tube incision holes and an irrigation solution (0.9% NaCl at 38 °C) was delivered to the pericardial cavity by using a volumetric pump. Safety aspects, feasibility issues, and complications were documented. The primary outcome was blood loss, and it was assessed 18 h after the surgery.

RESULTS

CPPF was successfully completed in 40 patients (95.24%). Method-related complications were not observed. Feasibility was good in this experimental setting. Blood loss was lower in the CPPF group (257.24 mL) than non-CPPF group (p < 0.001).

CONCLUSIONS

CPPF after coronary artery bypass grafting surgery is safe, effective, feasible, and acceptable. However, standardized randomized clinical trials are necessary to draw definitive conclusions.

The association of preoperative atrial fibrillation with post-cardiopulmonary bypass hyperfibrinolysis in rheumatic valvular heart disease patients

OBJECTIVE

The purpose of this study was to assess the fibrinolytic status after cardiopulmonary bypass in rheumatic valvular heart disease patients, and detect the associated factors of post-cardiopulmonary bypass hyperfibrinolysis.

METHODS

According to the fibrinolytic status after cardiopulmonary bypass, 203 rheumatic valvular heart disease patients were divided into two groups: hyperfibrinolysis group (H group, n = 78) and non-hyperfibrinolysis group (NH group, n = 125). The demographic characteristics, operative variables, and postoperative follow-ups were compared between these two groups.

RESULTS

The incidence of hyperfibrinolysis was 38.4% after cardiopulmonary bypass. Patients in the H group had a significant higher incidence of preoperative atrial fibrillation than patients in the NH group (92.3% vs. 55.2%, P < 0.01). Furthermore, postoperative daily drainage (655.3 ± 131.5 ml vs. 535.4 ± 161.4 ml, P < 0.01), transfusion volume of fresh frozen plasma (621.8 ± 220.2 ml vs. 455.2 ± 208.5 ml, P < 0.01), and red blood cells (5.9 ± 2.2 u vs. 4.7 ± 2.8 u, P < 0.01) was greater in the H group than in the NH group. Moreover, the logistic regression analysis revealed that preoperative atrial fibrillation was associated with post-cardiopulmonary bypass hyperfibrinolysis (OR = 19.691, 95% CI = 6.849-56.612; P < 0.05).

CONCLUSION

Preoperative artial fibrillation is associated with post-cardiopulmonary bypass hyperfibrinolysis in rheumatic valvular heart disease patients.

Deep Hypothermic Circulatory Arrest Does Not Show Better Protection for Vital Organs Compared with Moderate Hypothermic Circulatory Arrest in Pig Model

Background

Continued debates exist regarding the optimal temperature during hypothermic circulatory arrest in aortic arch repair for patients with type A aortic dissection. This study seeks to examine whether the use of moderate hypothermic circulatory arrest in a pig model provides comparable vital organ protection outcomes to the use of deep hypothermic circulatory arrest.

Methods

Thirteen pigs were randomly assigned to 30 minutes of hypothermic circulatory arrest without cerebral perfusion at 15°C (n = 5), 25°C (n = 5), and a control group (n = 3). The changes in standard laboratory tests and capacity for protection against apoptosis in different vital organs were monitored with different temperatures of hypothermic circulatory arrest management in pig model to determine which temperature was optimal for hypothermic circulatory arrest.

Results

There were no significant differences in the capacity for protection against apoptosis in vital organs between 2 groups (p > 0.05, respectively). Compared with the moderate hypothermic circulatory arrest group, the deep hypothermic circulatory arrest group had no significant advantages in terms of the biologic parameters of any other organs (p > 0.05).

Conclusions

Compared with deep hypothermic circulatory arrest, moderate hypothermic circulatory arrest is a moderate technique that has similar advantages with regard to the levels of biomarkers of injury and capacity for protection against apoptosis in vital organs.

Hemorrhagic disorders of fibrinolysis: a clinical review

Hyperfibrinolytic bleeding can be caused by a deficiency of one of the inhibitors of fibrinolysis (plasminogen activator inhibitor type 1 [PAI-1] or α2-antiplasmin [α2-AP]), or an excess of one of the activators of fibrinolysis: tissue-type plasminogen activator or urokinase-type plasminogen activator. This review focuses on the clinical implications of these disorders. The bleeding phenotype of fibrinolytic disorders is characterized by delayed bleeding after trauma, surgery and dental procedures. Bleeding in areas of high fibrinolytic activity is also common, such as menorrhagia and epistaxis. Patients with α2-AP deficiency present with the most severe bleeding episodes. Recently, it was discovered that hyperfibrinolytic disorders are associated with a high rate of obstetric complications such as miscarriage and preterm birth, especially in PAI-1 deficient patients. Hyperfibrinolytic disorders are probably underdiagnosed because of lack of knowledge and lack of accurate diagnostic tests. A substantial part of the large group of patients diagnosed as 'bleeding of unknown origin' could actually have a hyperfibrinolytic disorder. In the case of a high index of suspicion (i.e. because of a positive family history, recurrent bleeding or uncommon type of bleeding such as an intramedullary hematoma), further testing should not be withheld because of normal results of standard hemostatic screening assays. Timely diagnosis is important because these disorders can generally be treated well with antifibrinolytic agents.

Validation of a modified thromboelastometry approach to detect changes in fibrinolytic activity

Background

Thus far, validated whole blood assays used in in vitro fibrinolysis experiments using thromboelastometry (ROTEM) are lacking or have yet to be tested in humans.

The objective was first, to establish a standardized modified ROTEM approach to detect both hypo- and hyperfibrinolysis. And second, to perform a technical and clinical validation of the assay.

Methods

Blood was used of healthy volunteers, patients with sepsis, patients after cardiothoracic surgery, pregnant women, and cirrhotic liver disease patients. A whole blood tissue factor (TF) activated ROTEM assay with and without the addition of recombinant tissue plasminogen activator (rTPA) was developed. Plasma fibrinolysis determinants were measured in all volunteers and patients.

Results

Thirty five pM TF and additions of 125 and 175 ng/ml rTPA resulted in full lysis within 60 min in healthy volunteers. Coefficients of variation were below 10 % without and below 20 % with rTPA addition. In sepsis the hypofibrinolytic ROTEM profiles with 175 ng/ml rTPA were in line with the plasma determinants (high PAI-1, high fibrinogen, low tPA activity, and high d-dimers). After cardiothoracic surgery, reduced fibrinogen and platelet levels accounted for the reduced maximum clot firmness. The hypofibrinolytic profile is attributed to tranexamic acid use and elevated PAI-1 levels. The lowest rTPA concentration in cirrhosis resulted in hyperfibrinolysis in only few of the patients. In pregnancy normal profiles were found.

Discussion

Our high rTPA concentration demonstrates hypofibrinolytic profiles adequately in sepsis and after cardiothoracic surgery. Our low rTPA concentration of 125 ng/ml seems too high for demonstrating hyperfibrinolysis in cirrhotic liver disease.

Conclusions

We were able to present a validated whole blood ROTEM approach to fibrinolysis testing using added rTPA, which can be of added value next to classical plasma based fibrinolysis assays.

Polymorphisms on PAI-1 and ACE genes in association with fibrinolytic bleeding after on-pump cardiac surgery

Background

Carriers of plasminogen activator inhibitor -1 (PAI-1) -675 genotype 5G/5G may be associated with lower preoperative PAI-1 plasma levels and higher blood loss after heart surgery using cardiopulmonary bypass (CPB). We speculate if polymorphisms of PAI-1 -844 A/G and angiotensin converting enzyme (ACE) intron 16 I/D also might promote fibrinolysis and increase postoperative bleeding.

Methods

We assessed PAI-1 -844 A/G, and ACE intron 16 I/D polymorphisms by polymerase chain reaction technique and direct sequencing of genomic DNA from 83 open heart surgery patients that we have presented earlier. As primary outcome, accumulated chest tube drainage (CTD) at 4 and 24 h were analyzed for association with genetic polymorphisms. As secondary outcome, differences in plasma levels of PAI-1, t-PA/PAI-1 complex and D-dimer were determined for each polymorphism. SPSS® was used for statistical evaluation.

Results

The lowest preoperative PAI-1 plasma levels were associated with PAI-1 -844 genotype G/G, and higher CTD, as compared with genotype A/A at 4 and 24 h after surgery. Correspondingly, 4 h after the surgery CTD was higher in carriers of ACE intron 16 genotype I/I, as compared with genotype D/D. PAI-1 plasma levels and t-PA/PAI-1 complex reached nadir in carriers of ACE intron 16 genotype I/I, in whom we also noticed the highest D-dimer levels immediately after surgery. Notably, carriers of PAI-1 -844 genotype G/G displayed higher D-dimer levels at 24 h after surgery as compared with those of genotype A/G.

Conclusions

Increased postoperative blood loss secondary to enhanced fibrinolysis was associated with carriers of PAI-1 -844 G/G and ACE Intron 16 I/I, suggesting that these genotypes might predict increased postoperative blood loss after cardiac surgery using CPB.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-015-0101-1) contains supplementary material, which is available to authorized users.

Addressing the Global Burden of Trauma in Major Surgery

Despite a technically perfect procedure, surgical stress can determine the success or failure of an operation. Surgical trauma is often referred to as the "neglected step-child" of global health in terms of patient numbers, mortality, morbidity, and costs. A staggering 234 million major surgeries are performed every year, and depending upon country and institution, up to 4% of patients will die before leaving hospital, up to 15% will have serious post-operative morbidity, and 5-15% will be readmitted within 30 days. These percentages equate to around 1000 deaths and 4000 major complications every hour, and it has been estimated that 50% may be preventable. New frontline drugs are urgently required to make major surgery safer for the patient and more predictable for the surgeon. We review the basic physiology of the stress response from neuroendocrine to genomic systems, and discuss the paucity of clinical data supporting the use of statins, beta-adrenergic blockers and calcium-channel blockers. Since cardiac-related complications are the most common, particularly in the elderly, a key strategy would be to improve ventricular-arterial coupling to safeguard the endothelium and maintain tissue oxygenation. Reduced O2 supply is associated with glycocalyx shedding, decreased endothelial barrier function, fluid leakage, inflammation, and coagulopathy. A healthy endothelium may prevent these "secondary hit" complications, including possibly immunosuppression. Thus, the four pillars of whole body resynchronization during surgical trauma, and targets for new therapies, are: (1) the CNS, (2) the heart, (3) arterial supply and venous return functions, and (4) the endothelium. This is termed the Central-Cardio-Vascular-Endothelium (CCVE) coupling hypothesis. Since similar sterile injury cascades exist in critical illness, accidental trauma, hemorrhage, cardiac arrest, infection and burns, new drugs that improve CCVE coupling may find wide utility in civilian and military medicine.

Continuous Postoperative Pericardial Flushing: A Pilot Study on Safety, Feasibility, and Effect on Blood Loss

BACKGROUND

Prolonged or excessive blood loss is a common complication after cardiac surgery. Blood remnants and clots, remaining in the pericardial space in spite of chest tube drainage, induce high fibrinolytic activity that may contribute to bleeding complications. Continuous postoperative pericardial flushing (CPPF) with an irrigation solution may reduce blood loss by preventing the accumulation of clots. In this pilot study, the safety and feasibility of CPPF were evaluated and the effect on blood loss and other related complications was investigated.

METHODS

Between November 2011 and April 2012 twenty-one adult patients undergoing surgery for congenital heart disease (CHD) received CPPF from sternal closure up to 12 h postoperative. With an inflow Redivac drain that was inserted through one of the chest tube incision holes, an irrigation solution (NaCl 0.9% at 38 °C) was delivered to the pericardial cavity using a volume controlled flushing system. Safety aspects, feasibility issues and complications were registered. The mean actual blood loss in the CPPF group was compared to the mean of a retrospective group (n = 126).

RESULTS

CPPF was successfully completed in 20 (95.2%) patients, and no method related complications were observed. Feasibility was good in this experimental setting. Patients receiving CPPF showed a 30% (P = 0.038) decrease in mean actual blood loss 12 h postoperatively.

CONCLUSIONS

CPPF after cardiac surgery was found to be safe and feasible in this experimental setting. The clinically relevant effect on blood loss needs to be confirmed in a randomized clinical trial.

Genetic variation influences the risk of bleeding after cardiac surgery: novel associations and validation of previous findings

BACKGROUND

Severe post-operative bleeding in cardiac surgery is associated with increased morbidity and mortality. We hypothesized that variation in genetic susceptibility contributes to post-operative bleeding in addition to clinical factors.

METHODS

We included 1036 adults undergoing cardiac surgery with cardiopulmonary bypass. Two different endpoints for excessive post-operative bleeding were used, either defined as blood loss exceeding 2 ml/kg/h the first 4 h post-operatively or a composite including bleeding, transfusions, and reoperations. Twenty-two single nucleotide polymorphisms (SNPs) central in the coagulation and fibrinolysis systems or in platelet membrane receptors were genotyped, focusing on replication of earlier non-replicated findings and exploration of potential novel associations. Using logistic regression, significant SNPs were added to a model with only clinical variables to evaluate whether the genetic variables provided additional information.

RESULTS

Univariate tests identified rs1799809 (located in the promoter region of the PROC gene), rs27646 and rs1062535 (in the ITGA2 gene), rs630014 (in the ABO gene), and rs6048 (in the F9 gene) as significantly associated with excessive post-operative bleeding (P < 0.05, P-values confirmed by permutation). The SNPs were significant also after adjustment with clinical variables, showing almost unchanged odds ratios except for rs1799809 (P = 0.06). Addition of the genetic covariates to a logistic regression model with clinical variables significantly improved the model (P < 0.01).

CONCLUSION

We identified five SNPs associated with post-operative bleeding after cardiac surgery, of which two validated previously published associations. Addition of genetic information to models with only clinical variables improved the models. Our results indicate that common genetic variations significantly influence post-operative bleeding after cardiac surgery.

Comparison of three point-of-care testing devices to detect hemostatic changes in adult elective cardiac surgery: a prospective observational study

Background

Bleeding complications in cardiac surgery may lead to increased morbidity and mortality. Traditional blood coagulation tests are not always suitable to detect rapid changes in the patient's coagulation status. Point-of-care instruments such as the TEG (thromboelastograph) and RoTEM (thromboelastometer) have been shown to be useful as a guide for the clinician in the choice of blood products and they may lead to a reduction in the need for blood transfusion, contributing to better patient blood management.

Methods

The purpose of this study was to evaluate the ability of the TEG, RoTEM and Sonoclot instruments to detect changes in hemostasis in elective cardiac surgery with cardiopulmonary bypass and to investigate possible correlations between variables from these three instruments and routine hematological coagulation tests. Blood samples from thirty-five adult patients were drawn before and after surgery and analyzed in TEG, RoTEM, Sonoclot and routine coagulation tests. Data were compared using repeated measures analysis of variance and Pearson's test for linear correlation.

Results

We found significant changes for all TEG variables after surgery, for three of the RoTEM variables, and for one variable from the Sonoclot. There were significant correlations postoperatively between plasma fibrinogen levels and variables from the three instruments.

Conclusions

TEG and RoTEM may be used to detect changes in hemostasis following cardiac surgery with CPB. Sonoclot seems to be less suitable to detect such changes. Variables from the three instruments correlated with plasma fibrinogen and could be used to monitor treatment with fibrinogen concentrate.

Effect of cardiopulmonary bypass on thrombin generation and protein C pathway

OBJECTIVE

The purpose of this study was to evaluate the mechanisms of cardiopulmonary bypass (CPB)-induced dysregulation between thrombin and its regulatory anticoagulant activated protein C (APC).

DESIGN

A prospective observational cohort study.

SETTING

A tertiary care university hospital and associated research laboratory.

PATIENTS

Twenty patients undergoing elective coronary artery bypass surgery with (n = 10) or without CPB (n = 10).

INTERVENTIONS

Blood samples were collected at 7 time points: preinduction; after heparin; 1 hour after the institution of CPB (or the completion of distal anastomoses in off-CPB group); after protamine; and at 0, 4, and 18 hours in the Intensive care unit (ICU). Samples were analyzed for prothrombin fragments (F1+2), thrombin-antithrombin complexes, protein C (PC), APC, soluble thrombomodulin (sTM), and soluble endothelial protein C receptor (sEPCR).

MEASUREMENTS AND MAIN RESULTS

F1+2 levels increased significantly 1 hour after the initiation of CPB in comparison with baseline (2.7 ± 0.5 v 0.5 ± 0.2 nmol/L, p < 0.001) (mean ± standard deviation) and remained elevated until 4 hours after ICU admission (p < 0.001). In contrast, APC levels did not show any significant changes over time in either group. sEPCR, sTM, and PC levels did not change during CPB although sEPCR decreased significantly after the termination of CPB compared with baseline in the CPB group.

CONCLUSIONS

Exposure to CPB is associated with a distinct thrombin surge that continues postoperatively for 4 hours. The impaired ability to generate APC reflects a complex process that is not associated with increased levels of sEPCR and thrombomodulin during CPB. Further studies are required to evaluate the regulation of the host APC response in cardiac surgery.

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

Despite surgical proficiency and innovation driving low mortality rates in cardiac surgery, the disease severity, comorbidity rate, and operative procedural difficulty have increased. Today's cardiac surgery patient is older, has a "sicker" heart and often presents with multiple comorbidities; a scenario that was relatively rare 20 years ago. The global challenge has been to find new ways to make surgery safer for the patient and more predictable for the surgeon. A confounding factor that may influence clinical outcome is high K(+) cardioplegia. For over 40 years, potassium depolarization has been linked to transmembrane ionic imbalances, arrhythmias and conduction disturbances, vasoconstriction, coronary spasm, contractile stunning, and low output syndrome. Other than inducing rapid electrochemical arrest, high K(+) cardioplegia offers little or no inherent protection to adult or pediatric patients. This review provides a brief history of high K(+) cardioplegia, five areas of increasing concern with prolonged membrane K(+) depolarization, and the basic science and clinical data underpinning a new normokalemic, "polarizing" cardioplegia comprising adenosine and lidocaine (AL) with magnesium (Mg(2+)) (ALM™). We argue that improved cardioprotection, better outcomes, faster recoveries and lower healthcare costs are achievable and, despite the early predictions from the stent industry and cardiology, the "cath lab" may not be the place where the new wave of high-risk morbid patients are best served.

The effect of surface contact activation and temperature on plasma coagulation with an RNA aptamer directed against factor IXa

The anticoagulant properties of a novel RNA aptamer that binds FIXa depend collectively on the intensity of surface contact activation of human blood plasma, aptamer concentration, and its binding affinity for FIXa. Accordingly, anticoagulation efficiency of plasma containing any particular aptamer concentration is low when coagulation is strongly activated by hydrophilic surfaces compared to the anticoagulation efficiency in plasma that is weakly activated by hydrophobic surfaces. Anticoagulation efficiency is lower at hypothermic temperatures possibly because aptamer-FIXa binding decreases with decreasing temperatures. Experimental results demonstrating these trends are qualitatively interpreted in the context of a previously established model of anticoagulation efficiency of thrombin-binding DNA aptamers that exhibit anticoagulation properties similar to the FIXa aptamer. In principle, FIXa aptamer anticoagulants should be more efficient and therefore more clinically useful than thrombin-binding aptamers because aptamer binding to FIXa competes only with FX that is at much lower blood concentration than fibrinogen (FI) that competes with thrombin-binding aptamers. Our findings may have translatable relevance in the application of aptamer anticoagulants for clinical conditions in which blood is in direct contact with non-biological surfaces such as those encountered in cardiopulmonary bypass circuits.

PAI-1 and t-PA/PAI-1 complex potential markers of fibrinolytic bleeding after cardiac surgery employing cardiopulmonary bypass

Background

Enhanced bleeding remains a serious problem after cardiac surgery, and fibrinolysis is often involved. We speculate that lower plasma concentrations of plasminogen activator inhibitor – 1 (PAI-1) preoperatively and tissue plasminogen activator/PAI-1 (t-PA/PAI-1) complex postoperatively might predispose for enhanced fibrinolysis and increased postoperative bleeding.

Methods

Totally 88 adult patients (mean age 66 ± 10 years) scheduled for cardiac surgery, were enrolled into a prospective study. Blood samples were collected pre-operatively, on admission to the recovery and at 6 and 24 hours postoperatively. Patients with a surgical bleeding that was diagnosed during reoperation were discarded from the study. The patients were allocated to two groups depending on the 24-hour postoperative chest tube drainage (CTD): Group I > 500ml, Group II ≤ 500ml. Associations between CTD, PAI-1, t-PA/PAI-1 complex and D-dimer were analyzed with SPSS.

Results

Nine patients were excluded because of surgical bleeding. Of the 79 remaining patients, 38 were allocated to Group I and 41 to Group II. The CTD volumes correlated with the preoperative plasma levels of PAI-1 (r = − 0.3, P = 0.009). Plasma concentrations of preoperative PAI-1 and postoperative t-PA/PAI-1 complex differed significantly between the groups (P < 0.001 and P = 0.012, respectively). Group I displayed significantly lower plasma concentrations of fibrinogen and higher levels of D-dimer from immediately after the operation and throughout the first 24 hours postoperatively.

Conclusions

Lower plasma concentrations of PAI-1 preoperatively and t-PA/PAI-1 complex postoperatively leads to higher plasma levels of D-dimer in association with more postoperative bleeding after cardiac surgery.

Comparison of two platelet activation markers using flow cytometry after in vitro shear stress exposure of whole human blood

Platelet activation is the initiating step to thromboembolic complications in blood-contacting medical devices. Currently, there are no widely accepted testing protocols or relevant metrics to assess platelet activation during the in vitro evaluation of new medical devices. In this article, two commonly used platelet activation marker antibodies, CD62P (platelet surface P-selectin) and PAC1 (activated GP IIb/IIIa), were evaluated using flow cytometry. Anticoagulant citrate dextrose solution A (ACDA) and heparin anticoagulated human blood from healthy donors were separately exposed to shear stresses of 0, 10, 15, and 20 Pa for 120 s using a cone-plate rheometer model, and immediately mixed with the platelet marker antibodies for analysis. To monitor for changes in platelet reactivity between donors and over time, blood samples were also evaluated after exposure to 0, 2, and 20 µM of adenosine diphosphate (ADP). Following ADP stimulation, the percentage of both CD62P and PAC1 positive platelets increased in a dose dependent fashion, even 8 h after the blood was collected. After shear stress stimulation, both CD62P and PAC1 positive platelets increased significantly at shear stress levels of 15 and 20 Pa when ACDA was used as the anticoagulant. However, for heparinized blood, the PAC1 positive platelets decreased with increasing shear stress, while the CD62P positive platelets increased. Besides the anticoagulant effect, the platelet staining buffer also impacted PAC1 response, but had little effect on CD62P positive platelets. These data suggest that CD62P is a more reliable marker compared with PAC1 for measuring shear-dependent platelet activation and it has the potential for use during in vitro medical device testing.

Prophylactic Fibrinogen Infusion in Cardiac Surgery Patients: Effects on Biomarkers of Coagulation, Fibrinolysis, and Platelet Function

Objective: We have recently reported that prophylactic fibrinogen infusion reduces bleeding after coronary artery bypass grafting (CABG) surgery. Because fibrinogen for the first time was administered to patients without hereditary fibrinogen deficiency or ongoing bleeding, a detailed analysis of the effects of fibrinogen concentrate on biomarkers of coagulation, fibrinolysis, and platelet function was performed. Methods: Twenty CABG patients with preoperative plasma fibrinogen levels <3.8 g/L were included in a prospective study. Patients were randomized to preoperative infusion of 2 g fibrinogen concentrate (fibrinogen group) or no infusion (control group). Activated partial thromboplastin time (aPTT), prothrombin time, activated clotting time, and plasma concentrations of fibrinogen, antithrombin, thrombin-antithrombin complex, prothrombin fragment 1.2, and D-dimer, thromboelastometry, platelet count, and platelet aggregometry were analyzed before and 15 minutes after infusion, and 2 and 24 hours after surgery. Results: Fifteen minutes after infusion of fibrinogen concentrate, fibrinogen plasma levels increased by 0.6 ± 0.2 g/L (P < .001 between groups), and induced minimal changes in aPTT and plasma levels of antithrombin, while remaining variables remained unchanged. After surgery, fibrinogen levels no longer differed between groups. D-dimer was significantly higher after surgery in the fibrinogen group (P = .03), while none of the other markers were statistically different between groups. Conclusions: Infusion of 2 g fibrinogen to cardiac surgery patients, without hereditary or acquired fibrinogen deficiency or ongoing bleeding, results in no or minimal changes in biomarkers reflecting coagulation and platelet function. An increased release of fibrin degradation products was detected after surgery in fibrinogen-treated patients.