Clues of incomplete reversal of heparin in cardiac surgery.

OBJECTIVES: In our center, an unusual rate of patients had abnormalities of hemostasis in immediate postoperative period of cardiac surgery. Our objectives were to identify the cause of these sudden hemostasis abnormalities and to evaluate the performances of point of care coagulation testing. METHODS: In this prospective and descriptive study, we included 33 consecutive patients undergoing elective cardiac surgery for 1 month. Heparin-induced anticoagulation and calculation of the protamine dose were tested by the Hemostasis Management System Plus device (Medtronic, Minneapolis, MN, USA). Fifteen minutes after the end of the protamine infusion, activated clotting time (ACT), activated partial thromboplastin time and anti Xa activity were measured. In case of unusual clinical bleeding, a Quantra analysis (Stago, HemoSonics LLC, Charlottesville, VA) was added. RESULTS: Residual antiXa activity >0.2 IU/mL after neutralization was present in 44% of patients. Our investigation concluded incomplete heparin reversal. There was no association between cellular reinfusate and the presence of heparin. The unusual rate of hemostasis abnormalities was explained by a less efficient protamine reversal of heparin. ACT and Clot Time Ratio (CTR, Quantra system) correlated with AntiXa with Spearman's coefficients of 0.85 (p < .0001) and 0.95 (p = .0012), respectively. About ACT, a threshold of 150 seconds had a sensitivity of 85% [58-97] and a specificity of 85% [58-97%] for detection of AntiXa>0.2. For CTR, a threshold of 1.4 had a sensitivity of 67% [30-94] and a specificity of 100% [18-100]. CONCLUSION: The use of point of care coagulation testing is effective in detecting incomplete reversal of heparin.

Fate of aortic bioprostheses: An 18-year experience.

OBJECTIVE: To report our experience in aortic valve replacement with the Mitroflow (Sorin, Vancouver, Canada) aortic bioprosthesis. METHODS: We retrospectively reviewed all patients who underwent aortic valve replacement with a Mitroflow bioprosthesis at our institution from January 1994 to December 2011. No exclusion criteria were retained. Patients were followed yearly. Echocardiography follow-up was performed systematically before the hospital discharge and annually by patients' cardiologists. RESULTS: Seven hundred twenty-eight patients (mean age, 76 ± 6 years; range, 33-91 years) underwent aortic valve replacement with Mitroflow 12A or LX model and were included in this analysis. 30-day mortality for nonemergent isolated aortic valve replacement was 5.5%. Eight patients (1%) underwent reoperation for structural valve deterioration (SVD) and 30 patients (5.8%) presented echocardiographic signs of SVD. Actuarial freedom from reoperation for SVD was 99% ± 0.5% and 95% ± 5% at 10 and 15 years. Actuarial freedom from echocardiographic signs of SVD was 77% ± 5% and 56% ± 11% at 10 and 15 years, respectively. At the univariate analysis, only the mean gradient at discharge (P = .0200), the prevalence of size 19 (P = .0273), and severe patient-prosthesis mismatch (P = .0384) were significantly different in patients developing SVD at follow-up. Freedom from echocardiographic signs of SVD at 8 years were 88% ± 4% and 64% ± 13% in patients with a Mitroflow > 19 and Mitroflow 19, respectively (log-rank test, P = .0056; Wilcoxon test, P = .0589). CONCLUSIONS: Overall outcomes were satisfactory. However the risk of early SVD seems higher for the Mitroflow size 19. This size should be reserved for applications when annulus enlargement is risky or there is an anatomic contraindication to sutureless or stentless valve.

Anaphylactic shock to fresh-frozen plasma inactivated with methylene blue.

BACKGROUND: Methylene blue allergy is a well-known entity associated with food or lymph node location. Inactivation of viruses by methylene blue in fresh-frozen plasma (FFP-MB) has been recently introduced in France after many years of use in other parts of Europe. CASE REPORT: We describe here two anaphylactic shock reactions occurring during FFP-MB infusion in patients after cardiac surgery. The follow-up was favorable using epinephrine infusion in one patient and extracorporeal circulatory assistance in the other. RESULTS: The allergy was suspected based on the following arguments: chronology of the event, absence of other allergen infused to patients, and an associated symptom (generalized rash). Methylene blue allergy was documented by prick tests and/or intradermal reactions with methylene blue and patent blue. Additional allergic tests with basophil activation tests confirm the role of the dye in the anaphylactic reaction. CONCLUSION: These two cases questioned the safety of FFP-MB.

Usefulness of postoperative heart rate as an independent predictor of mortality after coronary bypass grafting.

Heart rate (HR) predicts mortality and cardiovascular events in the general population and in patients with coronary artery disease. However, little evidence is available for patients after coronary revascularization. The aim of this study was to assess the prognostic value of ambulatory postoperative HR after coronary artery bypass grafting. Data from a prospective cohort study enrolling patients who underwent nonurgent coronary artery bypass grafting from 1998 to 2002 were analyzed. Baseline postoperative HR was measured 2 months after surgery, and patients were followed annually thereafter. The primary outcome was all-cause mortality. The secondary outcome combined any of the following events: death, nonfatal acute coronary syndromes, stroke or transient ischemic attack, secondary coronary revascularization, or vascular surgery. Seven hundred ninety-four patients (mean age 65.8 ± 9.3 years) were eligible for follow-up, predominantly men (84.1%). The mean follow-up duration was 3.2 ± 1.3 years, during which 40 patients (5.0%) died. In the univariate analysis, HR >90 beats/min was significantly associated with all outcomes. After adjustments for major confounding factors and the use of ß blockers, postoperative HR >90 beats/min remained significantly associated with the secondary outcome (hazard ratio 2.26, 95% confidence interval 1.04 to 4.91, p = 0.04). Association of postoperative HR >90 beats/min with all-cause mortality was only borderline in the multivariate analysis (hazard ratio 3.57, 95% confidence interval 0.90 to 14.17, p = 0.07), because of the limited sample population size. In conclusion, postoperative HR >90 beats/min may be associated with poor prognoses in patients with coronary artery disease, even after surgical revascularization.

Alterations in plasma soluble vascular endothelial growth factor receptor-1 (sFlt-1) concentrations during coronary artery bypass graft surgery: relationships with post-operative complications.

BACKGROUND: Plasma concentrations of sFlt-1, the soluble form of the vascular endothelial growth factor receptor (VEGF), markedly increase during coronary artery bypass graft (CABG) surgery with extracorporeal circulation (ECC). We investigated if plasma sFlt-1 values might be related to the occurrence of surgical complications after CABG. METHODS: Plasma samples were collected from the radial artery catheter before vascular cannulation and after opening the chest, at the end of ECC just before clamp release, after cross release, after weaning from ECC, at the 6th and 24th post-operative hour. Thirty one patients were investigated. The presence of cardiovascular, haematological and respiratory dysfunctions was prospectively assessed. Plasma sFlt-1 levels were measured with commercially ELISA kits. RESULTS: Among the 31 investigated patients, 15 had uneventful surgery. Patients with and without complications had similar pre-operative plasma sFlt-1 levels. Lowered plasma sFlt-1 levels were observed at the end of ECC in patients with haematological (p = 0.001, ANOVA) or cardiovascular (p = 0.006) impairments, but not with respiratory ones (p = 0.053), as compared to patients with uneventful surgery. CONCLUSION: These results identify an association between specific post-CABG complication and the lower release of sFlt-1 during ECC. sFlt-1-induced VEGF neutralisation might, thus, be beneficial to reduce the development of post-operative adverse effects after CABG.

Release of soluble vascular endothelial growth factor receptor-1 (sFlt-1) during coronary artery bypass surgery.

BACKGROUND: This study was conducted to follow plasma concentrations of sFlt-1 and sKDR, two soluble forms of the vascular endothelial growth factor (VEGF) receptor in patients undergoing coronary artery bypass graft (CABG) surgery with extracorporeal circulation (ECC). METHODS: Plasma samples were obtained before, during and after surgery in 15 patients scheduled to undergo CABG. Levels of sFlt-1 and KDR levels were investigated using specific ELISA. RESULTS: A 75-fold increase of sFlt-1 was found during cardiac surgery, sFlt-1 levels returning to pre-operative values at the 6th post-operative hour. In contrast sKDR levels did not change during surgery. The ECC-derived sFlt-1 was functional as judge by its inhibitory effect on the VEGF mitogenic response in human umbilical vein endothelial cells (HUVECs). Kinetic experiments revealed sFlt-1 release immediately after the beginning of ECC suggesting a proteolysis of its membrane form (mFlt-1) rather than an elevated transcription/translation process. Flow cytometry analysis highlighted no effect of ECC on the shedding of mFlt-1 on platelets and leukocytes suggesting vascular endothelial cell as a putative cell source for the ECC-derived sFlt-1. CONCLUSION: sFlt-1 is released during CABG with ECC. It might be suggested that sFlt-1 production, by neutralizing VEGF and/or by inactivating membrane-bound Flt-1 and KDR receptors, might play a role in the occurrence of post-CABG complication.