Tam Hoang Minh

Plasma fibrinogen level on admission to the intensive care unit is a powerful predictor of postoperative bleeding after cardiac surgery with cardiopulmonary bypass

INTRODUCTION Evidence regarding the behavior of fibrinogen levels and the relation between fibrinogen levels and postoperative bleeding is limited in cardiac surgery under cardiopulmonary bypass (CPB). To evaluate perioperative fibrinogen levels as a predictor of postoperative bleeding in patients undergoing cardiac surgery with CPB. MATERIALS AND METHODS In this prospective, single-center, observational cohort study of 1956 patients following cardiac surgery with CPB, fibrinogen level was measured perioperatively. Excessive bleeding group was defined as patients with a 24-h chest tube output (CTO) exceeded the 90th percentile of distribution. RESULTS The median 24-h CTO was 728.6±431.1ml. A total of 189 patients (9.7%) were identified as having excessive bleeding. At admission to the intensive care (Day 0), the fibrinogen levels were 2.5±0.8g/l and 2.1±0.8g/l in the control and excessive bleeding groups, respectively (P<0.0001). The fibrinogen level on Day 0 was significantly correlated with the 24-h CTO (rho=-0.237; P<0.0001). Multivariate analysis demonstrated that the fibrinogen level at Day 0 was the best perioperative standard laboratory test to predict excessive bleeding (P=0.0001; odds ratio, 0.5), whereas preoperative fibrinogen level was not a predictor. Using receiver operating characteristics curve analyses, the best Day 0 fibrinogen level cutoff to predict postoperative bleeding was 2.2g/l. CONCLUSIONS In this large prospective study, the fibrinogen level upon admission to the intensive care unit after CPB predicted the risk of postoperative bleeding. Our data add to the concern regarding the fibrinogen level threshold that might require fibrinogen concentrate infusion to reduce postoperative blood loss.

Pressure overload-induced mild cardiac hypertrophy reduces left ventricular transmural differences in mitochondrial respiratory chain activity and increases oxidative stress.

Objective: Increased mechanical stress and contractility characterizes normal left ventricular (LV) subendocardium (Endo) but whether Endo mitochondrial respiratory chain complex activities is reduced as compared to subepicardium (Epi) and whether pressure overload-induced LV hypertrophy (LVH) might modulate transmural gradients through increased reactive oxygen species (ROS) production is unknown. Methods: LVH was induced by 6 weeks abdominal aortic banding and cardiac structure and function were determined with echocardiography and catheterization in sham-operated and LVH rats (n = 10 for each group). Mitochondrial respiration rates, coupling, content and ROS production were measured in LV Endo and Epi, using saponin-permeabilized fibers, Amplex Red fluorescence and citrate synthase activity. Results: In sham, a transmural respiratory gradient was observed with decreases in endo maximal oxidative capacity (−36.7%, P < 0.01) and complex IV activity (−57.4%, P < 0.05). Mitochondrial hydrogen peroxide (H2O2) production was similar in both LV layers. Aortic banding induced mild LVH (+31.7% LV mass), associated with normal LV fractional shortening and end diastolic pressure. LVH reduced maximal oxidative capacity (−23.6 and −33.3%), increased mitochondrial H2O2 production (+86.9 and +73.1%), free radical leak (+27.2% and +36.3%) and citrate synthase activity (+27.2% and +36.3%) in Endo and Epi, respectively. Transmural mitochondrial respiratory chain complex IV activity was reduced in LVH (−57.4 vs. −12.2%; P = 0.02). Conclusions: Endo mitochondrial respiratory chain complexes activities are reduced compared to LV Epi. Mild LVH impairs mitochondrial oxidative capacity, increases oxidative stress and reduces transmural complex IV activity. Further studies will be helpful to determine whether reduced LV transmural gradient in mitochondrial respiration might be a new marker of a transition from uncomplicated toward complicated LVH.

The prothrombotic paradox of severe obesity after cardiac surgery under cardiopulmonary bypass

BACKGROUND Obesity is suggested to reduce postoperative bleeding in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) but perioperative hemostasis variations have not been studied. Therefore, we investigated the effects of severe obesity (body mass index [BMI] ≥35kg/m(2)) on chest tube output (CTO) and hemostasis in patients undergoing cardiac surgery with CPB. MATERIALS AND METHODS We prospectively investigated 2799 consecutive patients who underwent coronary and/or valve surgery using CPB between 2008 and 2012. 204 patients (7.3%) presented a severe obesity. RESULTS In the severe obesity group, the 6-h and 24-h CTO were significantly reduced by -21.8% and -14.8% respectively (P<0.0001) compared with the control group. A significant reduction of the mean number of red blood cell units transfused at 24h was observed in the severe obesity groups (P=0.01). On admission to the intensive care unit, a significant increase of platelet count (+9.2%; P<0.0001), fibrinogen level (+12.2%; P<0.0001) and prothrombin time (+4.1%; P<0.01) and a significant decrease of the activated partial thromboplastin time (-4.2%; P<0.01) were observed in the severe obesity group compared with the control group. In multivariate analysis, severe obesity was significantly associated to a decreased risk of excessive bleeding (24-h CTO >90th percentile; Odds ratio: 0.37, 95% CI: 0.17 to 0.82). No significant differences were observed regarding postoperative thromboembolic events between the two groups. CONCLUSIONS Severe obesity is associated with a prothrombotic postoperative state that leads to a reduction of postoperative blood loss in patients undergoing cardiac surgery with CPB.

Exclusive Low-Molecular-Weight Heparin as Bridging Anticoagulant After Mechanical Valve Replacement

BACKGROUND Unfractionated heparin has been the standard anticoagulant used immediately after mechanical heart valve replacement (MHVR). The purpose of this study was to assess a postoperative anticoagulation protocol with low-molecular-weight heparin (LMWH) immediately after MHVR without the use of unfractionated heparin or anti-factor Xa monitoring. METHODS We performed a prospective, single-center, observational study of 1,063 consecutive patients undergoing elective MHVR with postoperative LMWH anticoagulation treatment. The exclusion criteria were as follows: renal failure, intraaortic balloon counterpulsation, critical perioperative state, or a recent neurologic event. The postoperative anticoagulation protocol used subcutaneous enoxaparin as a bridging anticoagulant treatment beginning on the first postoperative day and continuing until vitamin K antagonist treatment was fully effective. Patients were followed for 6 weeks. The primary endpoints were the incidence of thromboembolic or major bleeding events. RESULTS Eleven (1%) thromboembolic events occurred. Ten of these events were transient or permanent strokes. Major bleeding events occurred in 44 patients (4.1%), 7 of which were observed before the enoxaparin treatment period. At the time of discharge, 570 patients (53.6%) were no longer receiving LMWH treatment due to achieving the target international normalized ratio. The mean length of hospital stay was 8.5 ± 2.9 days. There were no deaths during the 6-week follow-up period. CONCLUSIONS In our highly selected population, after MHVR, postoperative anticoagulation using LMWH is associated with a low rate of thromboembolic and major bleeding events. This large observational study demonstrates that the use of LMWH as an anticoagulant is effective and safe after MHVR.

Concomitant repair of tetralogy of Fallot and an aortic root aneurysm in an adult

We reported the case of a 56‐year‐old male with tetralogy of Fallot associated with an aneurysm of the aortic root and severe aortic insufficiency. Repair of the aortic aneurysm along with a complete tetralogy repair was performed.

Trends in isolated coronary artery bypass grafting over the last decade

OBJECTIVES The purpose of this study was to assess the impact on hospital mortality and morbidity of extensive myocardial revascularization, using arterial grafts in patients undergoing isolated coronary artery bypass grafting (CABG). METHODS Our prospective perioperative database was used to define two groups of patients who underwent isolated CABG with cardiopulmonary bypass, based on the years in which the operation was performed: Group A (2000-2003; 898 patients) and Group B (2009-2012; 1249 patients). The baseline and operative characteristics and outcomes were compared. RESULTS Several significant changes in perioperative variables were observed. Group B included higher percentages of patients aged over 80 years (+58.1%), with diabetes (+32.0%) and with a history of percutaneous coronary intervention (+24.9%). The mean EuroSCORE II was significantly increased from 2.5 ± 4.4% in Group A to 3.2 ± 5.7% in Group B (P= 0.001). The mean number of distal anastomoses was significantly increased over time (total: 2.6 ± 0.8 vs 3.1 ± 1.0, P< 0.0001 and with arterial grafts: 1.6 ± 0.8 vs 2.6 ± 0.9, P< 0.0001). In-hospital mortality was low and did not significantly differ between Groups A and B (1.3 vs 2.4%; P= 0.08). Significant increases of new-onset atrial fibrillation (11.7 vs 21.9%, P= 0.017) and deep sternal infection (0.2 vs 1.1%, P= 0.017) were observed in Group B, compared with Group A. In multivariate analysis, extensive use of arterial grafts was not a risk factor of hospital mortality or sternal morbidity. CONCLUSIONS Despite the increasing risk profiles of patients undergoing CABG, extensive myocardial revascularization using arterial grafts is associated with good early results.

Left Ventricular Transmural Gradient in Mitochondrial Respiration Is Associated with Increased Sub-Endocardium Nitric Oxide and Reactive Oxygen Species Productions.

Objective: Left ventricle (LV) transmural gradient in mitochondrial respiration has been recently reported. However, to date, the physiological mechanisms involved in the lower endocardium mitochondrial respiration chain capacity still remain to be determined. Since, nitric oxide (NO) synthase expression in the heart has spatial heterogeneity and might impair mitochondrial function, we investigated a potential association between LV transmural NO and mitochondrial function gradient. Methods: Maximal oxidative capacity (VMax) and relative contributions of the respiratory chain complexes II, III, IV (VSucc) and IV (VTMPD), mitochondrial content (citrate synthase activity), coupling, NO (electron paramagnetic resonance), and reactive oxygen species (ROS) production (H2O2 and dihydroethidium (DHE) staining) were determined in rat sub-endocardium (Endo) and sub-epicardium (Epi). Further, the effect of a direct NO donor (MAHMA NONOate) on maximal mitochondrial respiratory rates (Vmax) was determined. Results: Mitochondrial respiratory chain activities were reduced in the Endo compared with the Epi (−16.92%; P = 0.04 for Vmax and –18.73%; P = 0.02, for Vsucc, respectively). NO production was two-fold higher in the Endo compared with the Epi (P = 0.002) and interestingly, increasing NO concentration reduced Vmax. Mitochondrial H2O2 and LV ROS productions were significantly increased in Endo compared to Epi, citrate synthase activity and mitochondrial coupling being similar in the two layers. Conclusions: LV mitochondrial respiration transmural gradient is likely related to NO and possibly ROS increased production in the sub-endocardium.

CT-ADP Point-of-Care Assay Predicts 30-Day Paravalvular Aortic Regurgitation and Bleeding Events following Transcatheter Aortic Valve Replacement

BACKGROUND Paravalvular aortic regurgitation (PVAR) remains a frequent postprocedural concern following transcatheter aortic valve replacement (TAVR). Persistence of flow turbulence results in the cleavage of high-molecular-weight von Willebrand multimers, primary haemostasis dysfunction and may favour bleedings. Recent data have emphasized the value of a point-of-care measure of von Willebrand factor-dependent platelet function (closure time [CT] adenosine diphosphate [ADP]) in the monitoring of immediate PVAR. This study examined whether CT-ADP could detect PVAR at 30 days and bleeding complications following TAVR. METHODS CT-ADP was assessed at baseline and the day after the procedure. At 30 days, significant PVAR was defined as a circumferential extent of regurgitation more than 10% by transthoracic echocardiography. Events at follow-up were assessed according to the Valve Academic Research Consortium-2 consensus classification. RESULTS Significant PVAR was diagnosed in 44 out of 219 patients (20.1%). Important reduction of CT-ADP could be found in patients without PVAR, contrasting with the lack of CT-ADP improvement in significant PVAR patients. By multivariate analysis, CT-ADP > 180 seconds (hazard ratio [HR]: 5.1, 95% confidence interval [CI]: 2.5-10.6; p < 0.001) and a self-expandable valve were the sole independent predictors of 30-day PVAR. At follow-up, postprocedural CT-ADP >180 seconds was identified as an independent predictor of major/life-threatening bleeding (HR: 1.7, 95% CI [1.0-3.1]; p = 0.049). Major/life-threatening bleedings were at their highest levels in patients with postprocedural CT-ADP > 180 seconds (35.2 vs. 18.8%; p = 0.013). CONCLUSION Postprocedural CT-ADP > 180 seconds is an independent predictor of significant PVAR 30 days after TAVR and may independently contribute to major/life-threatening bleedings.

Impact of prosthesis-patient mismatch on early haemodynamic status after aortic valve replacement.

OBJECTIVES Prosthesis-patient mismatch (PPM) has been reported to impact early haemodynamic status and early mortality after prosthetic aortic valve replacement (AVR) in patients with aortic stenosis (AS). The aim of this study was to assess the impact of PMM on early haemodynamic status after AVR using vasoactive-inotropic dependency index (VDI), postoperative pressures and end-organ perfusion. METHODS A total of 183 patients with AS were included in this prospective cohort study, and underwent elective AVR with or without combined coronary artery bypass graft surgery. PPM was defined as a projected indexed effective orifice area of ≤0.85 cm2/m2, and was present in 27.9% of the patients. The primary end-point was the VDI [VDI = vasoactive-inotropic score/mean arterial pressure] measured upon admission to the intensive care unit (POD0) and on the morning of the first postoperative day (POD1). The secondary end-points were the following: mean left atrial pressure, mean central venous pressure, fluid balance, brain natriuretic peptide, troponin I, glomerular filtration rate and lactate levels on POD0 and POD1. RESULTS No significant differences in VDI were observed between the no PPM and PPM groups on POD0 (0.08 ± 0.48 vs 0.05 ± 0.13, respectively, P = 0.622) or on POD1 (0.09 ± 0.40 vs 0.06 ± 0.13, respectively; P = 0.583). The mean arterial pressure, mean left atrial pressure, central venous pressure, troponin I, glomerular filtration rate and lactate levels did not differ between the two groups on POD0 and POD1, as well as fluid balance and brain natriuretic peptide on POD1. CONCLUSIONS PPM is not associated with early haemodynamic status impairment and end-organ perfusion after AVR. CLINICAL TRIAL NUMBER ClinicalTrials.gov number, NCT00699673.