Thromboembolic events after major bleeding events in patients with mechanical heart valves: a 13-year analysis.

Anticoagulation in patients with mechanical heart valves (MHV) is associated with a risk of major bleeding episodes (MBE). In case of MBE, anticoagulant interruption is advocated. However, there is lack of data regarding the thrombo-embolic events (TE) risk associated with anticoagulant interruption. The main objective of the study was to evaluate the rate and risk factors of 6-months of TEs in patients with MHV experiencing MBE. This observational study was conducted over a 13-year period. Adult patients with a MHV presenting with a MBE were included. The main study endpoint was 6-month TEs, defined by clinical TEs or an echocardiographic documented thrombosis, occurring during an ICU stay or within 6-months. Thromboembolic events were recorded at ICU discharge, and 6 months after discharge. Seventy-nine MBEs were analysed, the rate of TEs at 6-months was 19% CI [11-29%]. The only difference of presentation and management between 6-month TEs and free-TE patients was the time without effective anticoagulation (TWA). The Receiver Operator Characteristic curve identified the value of 122 h of TWA as a cut-off. The multivariate analysis identified early bleeding recurrences (OR 3.62, 95% CI [1.07-12.25], p = 0.039), and TWA longer than 122 h (OR 4.24, 95% CI [1.24-14.5], p = 0.021), as independent risk factors for 6-month TEs. A higher rate of TE was associated with anticoagulation interruption longer than 5 days and early bleeding recurrences. However, the management should still be personalized and discussed for each case given the heterogeneity of causes of MBE and possibilities of haemostatic procedures.

A decade of experience in over 300 surgically treated spine patients with long-term oral anticoagulation: a propensity score matched cohort study.

PURPOSE: The aim of this study was to investigate the risks and outcomes of patients with long-term oral anticoagulation (OAC) undergoing spine surgery. METHODS: All patients on long-term OAC who underwent spine surgery between 01/2005 and 06/2015 were included. Data were prospectively collected within our in-house Spine Surgery registry and retrospectively supplemented with patient chart and administrative database information. A 1:1 propensity score-matched group of patients without OAC from the same time interval served as control. Primary outcomes were post-operative bleeding, wound complications and thromboembolic events up to 90 days post-surgery. Secondary outcomes included intraoperative blood loss, length of hospital stay, death and 3-month post-operative patient-rated outcomes. RESULTS: In comparison with the control group, patients with OAC (n = 332) had a 3.4-fold (95%CI 1.3-9.0) higher risk for post-operative bleeding, whereas the risks for wound complications and thromboembolic events were comparable between groups. The higher bleeding risk was driven by a higher rate of extraspinal haematomas (3.3% vs. 0.6%; p = 0.001), while there was no difference in epidural haematomas and haematoma evacuations. Risk factors for adverse events among patients with OAC were mechanical heart valves, posterior neck surgery, blood loss > 1000 mL, age, female sex, BMI > 30 kg/m2 and post-operative PTT levels. At 3-month follow-up, most patients reported favourable outcomes with no difference between groups. CONCLUSION: Although OAC patients have a higher risk for complications after spine surgery, the risk for major events is low and patients benefit similarly from surgery.

Frequency of prothrombin time-international normalized ratio monitoring and the long-term prognosis in patients with mechanical valve replacement.

BACKGROUND: The study aimed to assess the correlation between the monitoring frequency of PT-INR and the long-term prognosis in patients with mechanical heart valve (MHV) replacement after discharge. METHODS: This single-center, observational study enrolled patients who underwent MHV replacement and discharged from June 2015 to May 2018. Patients or their corresponding family members were followed with a telephone questionnaire survey in July-October 2020. Based on monitoring intervals, patients were divided into frequent monitoring (FM) group (≤ 1 month) and less frequent monitoring (LFM) group (> 1 month). The primary endpoint was the composite of thromboembolic event, major bleeding or all-cause death. The secondary endpoints were thromboembolic event, major bleeding or all-cause death, respectively. RESULTS: A total of 188 patients were included in the final analysis. The median follow-up duration was 3.6 years (Interquartile range: 2.6 to 4.4 years). 104 (55.3%) patients and 84 (44.7%) patients were classified into the FM group and the LFM group, respectively. The FM group had a significantly lower incidence of the primary endpoint than the LFM group (3.74 vs. 1.16 per 100 patient-years, adjusted HR: 3.31 [95% CI 1.05-10.42, P = 0.041]). Secondary analysis revealed that the risk of thromboembolic events and all-cause death were also reduced in the FM group. CONCLUSIONS: The management of warfarin treatment in patients after MHV replacement remains challenging. Patients with less frequent monitoring of PT-INR might have worse clinical prognosis than those with frequent PT-INR monitoring.

Outcomes of leadless pacemaker implantation in patients with mechanical heart valves.

INTRODUCTION: Device infections constitute a major complication of transvenous pacemakers. Mechanical heart valves (MHV) increase the risk of infective endocarditis (IE) and pacemaker infection, requiring lifelong vitamin K-antagonists (VKA), which may affect patient management. Leadless pacemakers (LP) are associated with low infection rates, posing an attractive option in MHV patients requiring permanent pacing. This study describes outcomes following LP implantation in patients with MHV. METHODS: This is a multicenter, observational, retrospective study including consecutive patients implanted with an LP at 5 centers between June 2015 and January 2020. Procedural outcomes, antithrombotic management, complications, performance during follow-up and episodes of bacteremia and IE were compared between patients with and without an MHV (MHV and non-MHV groups). RESULTS: Four hundred fifty-nine patients were included (74 in the MHV group, 16.1%, and 385 in the non-MHV group, 83.9%). Procedural outcomes and acute electrical performance were comparable between groups. Vascular complications and cardiac perforation occurred in 2.7 versus 2.3% (p = 1) and 0% versus 0.8% (p = 1) in the MHV group and non-MHV group. One case of IE occurred in the MHV group and 2 in the non-MHV group. In MHV patients, uninterrupted VKA was used in 83.8%, whereas 16.2% were heparin-bridged. Vascular complication or tamponade occurred in 1 (8.3%) MHV heparin-bridged patient versus 1 (1.6%) MHV uninterrupted VKA patient (p = .3). CONCLUSION: LP implantation outcomes in MHV patients are comparable to the general LP population. Device-related infections are rare following LP implantation, including in patients with MHV. In the MHV group, periprocedural anticoagulation management was not associated with significantly different rates of tamponade or vascular complication.

Cohort study: "Outcomes of kidney transplantation in patients with prosthetic heart valves".

The number of kidney transplant candidates with prosthetic heart valves (PHVs) is increasing. Yet, outcomes of kidney transplantation in these patients are still unclear. This is the first report of post-transplant outcomes in patients with PHVs at time of kidney transplantation. We conducted a matched cohort study among recipients from the multicentric and prospective DIVAT cohort to compare the outcomes in patients with left-sided PHVs at time of transplantation and a group of recipients without PHV matched according to age, dialysis time, initial disease, pretransplant DSA, diabetes, and cardiovascular events. Of 23 018 patients, 92 patients with PHVs were included and compared to 276 patients without PHV. Delayed graft function and postoperative bleeding occurred more frequently in patients with PHVs. Kidney graft survival was similar between groups. 5-year overall survival was 68.5% in patients with PHV vs. 87.9% in patients without PHV [HR, 2.72 (1.57-4.70), P = 0.0004]. Deaths from infection, endocarditis, and bleeding were more frequent in patients with PHV. Mechanical valves, but not bioprosthetic valves, were independent risk factors for mortality [HR, 2.89 (1.68-4.97), P = 0.0001]. Patients with PHV have high mortality rates after kidney transplantation. These data suggest that mechanical valves, but not biological valves, increase risks of post-transplant mortality.

TGF-ß1 polymorphism increases the risk of bleeding complications in patients on oral anticoagulant after cardiac valve replacement.

Although an elevated INR is highly associated with an increased risk of warfarin-associated bleeding, it has been reported that some patients also experience bleeding complications at therapeutic INRs. TGF-ß1 polymorphisms has been reported to cause vascular malformations, resulting in bleeding complications, but there are few published genetic studies regarding bleeding complications in patients on warfarin therapy. This study aimed to determine if there is an association between transforming growth factor beta-1 (TGF-ß1) polymorphisms and bleeding complications in patients who maintain international normalized ratios (INRs) of 2.0-3.0 with warfarin therapy after cardiac valve replacement. Eleven single nucleotide polymorphis (SNPs) of TGF-ß1 (rs1800469, rs2241718, rs4803455, rs2241717, rs2241716, rs2241715, rs2241714, rs11083616, rs2317130, rs747857, and rs1982073) were analyzed. Univariate and multivariable analyses were conducted to evaluate the associations between genetic polymorphisms and bleeding risk. Attributable risk and the number needed to genotype (NNG) were calculated to identify the potential clinical value of genotyping. A discrimination of model was assessed via an analysis of the area under the receiver operating curve (AUROC). To test the model's goodness of fit, a Hosmer-Lemeshow test was performed. Of 142 patients, 21 experienced bleeding complications. Among analyzed single nucleotide polymorphis (SNPs) of TGF-ß1 (rs1800469, rs2241718, rs4803455, rs2241717, rs2241716, rs2241715, rs2241714, rs11083616, rs2317130, rs747857, and rs1982073), AA genotype carriers in rs2241718 had about 5.5 times more bleeding complications than those with the G allele after adjusting for other confounders. The attributable risk and NNG for rs2241718 were 81.9% and 57.8, respectively. The presence of atrial fibrillation and myocardial infarction increased bleeding complications 3.9- and 9.8-fold, compared with those without atrial fibrillation and myocardial infarction, respectively. Bleeding complications during warfarin therapy in patients with mechanical heart valves were associated with TGF-ß1 polymorphisms as well as atrial fibrillation and myocardial infarction.

Mechanical heart valve thrombosis during pregnancy under non-warfarin anticoagulation therapy: Two-case report and literature review. / å¦Šå¨ æœŸæœºæ¢°å¿ƒè„ç“£è†œç½®æ¢éžåŽæ³•æž—æŠ—å‡æ‚£è€ å‡ºçŽ°è¡€æ “å¡ç“£2ä¾‹å¹¶æ–‡çŒ®å¤ä¹ .

Anticoagulation drugs should be used for patients with mechanical heart valve (MHV) in case of potential risk of thrombosis. Pregnant women with MHV have to change therapies due to teratogenic effect of some anti-coagulation drugs. European Society of Cardiology clinical guidelines for the management of cardiovascular diseases during pregnancy gives specific suggestions for anticoagulation therapy.We have treated 2 patients with mechanical heart valve thrombosis (MVT) during pregnancy: One received low molecular weight heparin (LMWH) throughout the pregnancy and developed MVT at the third trimester of pregnancy; one developed MVT at the first trimester when replacing vitamin K antagonists (VKA) with LMWH. These patients raised secondary reflection on the balance between clinical guideline and personalized medicine. During LMWH therapy, we should dynamically monitor patients' anti-activated factor X (anti-Xa) level to evaluate coagulation function during pregnancy. When a pregnant woman with MHV develops symptoms of acute heart failure, stuck mechanical valve should be paid attention to and surgery should be promptly performed if necessary.

Determinants of low-quality warfarin anticoagulation in patients with mechanical prosthetic heart valves. The nationwide PLECTRUM study.

Quality of warfarin therapy in patients with a mechanical prosthetic heart valve (MPHV) has been barely investigated. We analysed determinants of low time in the therapeutic range (TiTR <60%) in 2111 patients with MPHVs from the nationwide PLECTRUM study by the Italian Federation of Anticoagulation Clinics. Overall, 48·5% of patients had a TiTR of < 60%. At logistic regression analysis, arterial hypertension (odds ratio [OR] 1·502, P < 0·001), diabetes (OR 1·732, P < 0·001), heart failure (OR 1·484, P = 0·004), mitral site (vs. aortic) (OR 1·399, P = 0·006), international normalised ratio (INR) ranges of 2·5-3·5 (OR 2·575, P < 0·001) and 3·0-4·0 (OR 8·215, P < 0·001) associated with TiTR < 60%. TiTR is substantially suboptimal in MPHV patients, particularly in higher INR ranges.

Numerical investigation on the effect of bileaflet mechanical heart valve's implantation tilting angle and aortic root geometry on intermittent regurgitation and platelet activation.

Platelet activation induced by shear stresses and non-physiological flow field generated by bileaflet mechanical heart valves (BMHVs) leads to thromboembolism, which can cause fatal consequences. One of the causes of platelet activation could be intermittent regurgitation, which arises due to asynchronous movement and rebound of BMHV leaflets during the valve closing phase. In this numerical study, the effect of intermittent regurgitation on the platelet activation potential of BMHVs was quantified by modeling a BMHV in the straight and anatomic aorta at implantation tilt angles 0°, 5°, 10°, and 20°. A fully implicit Arbitrary Lagrangian-Eulerian-based Fluid-Structure Interaction formulation was adopted with blood modeled as a multiphase, non-Newtonian fluid. Results showed that the intermittent regurgitation and consequently the platelet activation level increases with the increasing implantation tilt of BMHV. For the straight aorta, the leaflet of the 20° tilted BMHV underwent a rebound of approximately 20° after initially closing, whereas the leaflet of the 10°, 5°, and 0° tilted BMHVs underwent a rebound of 8.5°, 3°, and 0°, respectively. For the anatomic aorta, the leaflet of the 20° tilted BMHV underwent a rebound of approximately 24° after initially closing, whereas the leaflet of the 10°, 5°, and 0° tilted BMHVs underwent a rebound of 14°, 10°, and 7°, respectively. For all the implantation orientations of BMHVs, intermittent regurgitation and platelet activation were always higher in the anatomic aorta than in the straight aorta. The study concludes that the pivot axis of BMHV must be implanted parallel to the aortic root's curvature to minimize intermittent regurgitation and platelet activation.

[Comparison on efficacy and safety of different bridging anticoagulation therapies in patients undergoing mechanical heart valve replacement surgery].

Objective: To evaluate the efficacy and safety of different bridging anticoagulant therapies in patients undergoing mechanical heart valve replacement (MHVR) surgery. Methods: Consecutive patients undergoing MHVR surgery from January 2018 to December 2018 in First Hospital of Lanzhou University were prospectively enrolled in this study. Patients were divided into unfractionated heparin (UFH) group and low molecular weight heparin (LMWH) group according to the postoperative bridging anticoagulation methods. Preoperative clinical data and postoperative related time and cost parameters, including drainage time, duration of stay in intensive care unit (ICU), postoperative time (interval from end of operation to discharge) and INR stabilization time (interval from start of bridge anticoagulation to INR value reaching the standard for 2 consecutive days) of all enrolled patients were collected, and all patients were followed up for 4 weeks and thromboembolic or bleeding events were analyzed. Multivariate logistic regression was used to determine the independent prognostic factors of thromboembolic or bleeding events after MHVR receiving various bridging anticoagulant therapies. Results: A total of 217 patients were included in the study, including 120 patients in the UFH group and 97 patients in the LMWH group. Stroke occurred in two patients in the UFH group, while no stroke event occurred in the LMWH group. The incidence of bleeding events was significantly higher (9.28%(9/97) vs. 1.67%(2/120), P=0.02), while the drainage time, duration of stay in ICU, postoperative time, INR stabilization time were all significantly shorter in LMWH group than in UFH group (all P<0.05). Multivariate logistic regression analysis showed that bridging anticoagulation therapies (OR=0.18, 95%CI 0.04-0.86, P=0.03), fibrinogen level (OR=1.99, 95%CI 1.16-3.41, P=0.01) and creatinine level (OR=1.05, 95%CI 1.01-1.08, P=0.04) were independent prognostic factors for bleeding events. Conclusion: LMWH use is associated with increased risk of bleeding events, but can significantly reduce the drainage time, duration of stay in ICU, postoperative time, INR stabilization time in patients post MHVR surgery.

Thromboembolism and bleeding in patients with cancer and mechanical heart valves.

Mechanical heart valves (MHV) require life-long anticoagulation with vitamin K antagonists (VKA), but anticoagulation management is complex in patients with cancer due to a high risk of thrombosis and bleeding. This is a retrospective, single-center study to assess anticoagulation management and thrombotic (stroke/valve thrombosis) and bleeding events in patients with active cancer and MHV. The incidence of thrombotic complications was compared to a control group (matched 1:1) of patients with MHV but without cancer. We included 48 patients, 60% of whom had aortic prostheses, 23% mitral prostheses and 17% both types. All patients received VKA as anticoagulant. With a median follow-up of 5.12 years, we observed two arterial thrombotic events (two strokes and no heart valve thrombosis). The 5-year incidence (95% confidence interval [CI]) of stroke/valve thrombosis was 5.7% (0.9-17.9%). The control group had a similar incidence of stroke/valve thrombosis (5-year incidence 7.9% [95%CI 2-19.8], p = 0.16). There were also 15 major bleeding episodes in the cancer group, 11 of which were related to a surgical procedure. The 5-year incidence (95% CI) of major bleeding was 32.9% (18.5-48%), and that of major bleeding unrelated to any procedure was 10.3% (3-23%). We found a low incidence of thrombotic events in this series of patients with active cancer and MHV who were anticoagulated with VKA. However, the incidence of bleeding was high, particularly in relation to invasive procedures.

Experimental investigation of the flow downstream of a dysfunctional bileaflet mechanical aortic valve.

Mechanical heart valve replacement is the preferred alternative in younger patients with severe symptomatic aortic valve disease. However, thrombus and pannus formations are common complications associated with bileaflet mechanical heart valves. This leads to risks of valve leaflet dysfunction, a life-threatening event. In this experimental study, we investigate, using time-resolved planar particle image velocimetry, the flow characteristics in the ascending aorta in the presence of a dysfunctional bileaflet mechanical heart valve. Several configurations of leaflet dysfunction are investigated and the induced flow disturbances in terms of velocity fields, viscous energy dissipation, wall shear stress, and accumulation of viscous shear stresses are evaluated. We also explore the ability of a new set of parameters, solely based on the analysis of the normalized axial velocity profiles in the ascending aorta, to detect bileaflet mechanical heart valve dysfunction and differentiate between the different configurations tested in this study. Our results show that a bileaflet mechanical heart valve dysfunction leads to a complex spectrum of flow disturbances with each flow characteristic evaluated having its own worst case scenario in terms of dysfunction configuration. We also show that the suggested approach based on the analysis of the normalized axial velocity profiles in the ascending aorta has the potential to clearly discriminate not only between normal and dysfunctional bilealfet heart valves but also between the different leaflet dysfunction configurations. This approach could be easily implemented using phase-contrast MRI to follow up patients with bileaflet mechanical heart valves.

The scalographic pattern of Morlet continuous wavelet transform can differentiate bileaflet valve function.

The authors have discussed the significance of the Morlet continuous wavelet transform of bileaflet mechanical heart valve (BLMHV) sound for detecting its malfunction: consecutive single patterns on the scalogram alway suggested its malfunction, whereas the tandem pattern with two steepled figures was demonstrated in both normal and malfunctioning valves. Therefore, authors have tried to distinguish this pattern between them by manually calculated multiple scalographic parameters. Although only the sum of wavelet coefficients (SWC) is supposed to be closer to valve sound property than other parameters, its calculation was not available in the original wavelet application. Therefore, the application was customized in the current study to semi-automatically calculate the SWC ratio between two figures for classifying the scalographic pattern of malfunctioning valves, and its efficacy to distinguish valve function was compared to other parameters. Among 155 BLMHVs, 6 valves with consecutive single patterns (type-I) and other 6 with two similar needle-like narrow figures (type-II) were confirmed to be a malfunction by fluoroscopic examination, whereas 14 malfunctioning valves with the tandem pattern which showed a great difference between two figure sizes (type-III) were distinguished from 129 normal valves by the cutoff point of the SWC ratio < 0.482 with the highest AUC (0.960) compared to other parameters by the ROC analysis.

[Application of Biological Heart Valves (BHV) and Mechanical Heart Valves (MHV) in the Female Patients of Childbearing Age: a Matched Paired Study].

OBJECTIVE: To observe the efficacy and safety of biological heart valves (BHV) and mechanical heart valves (MHV) in childbearing age women (CAW) during the perinatal and short-moderate term postoperative (SMTP) periods. METHODS: There were 33 patients [(25.2±7.1) yr.] undergoing BHV replacement from September 2009 to December 2014 had completely followed-up,whose data were retrospectively collected. A 1∶4 matching study was conducted,therefore there were 132 patients undergoing MHV were included. The collected date included the clinical outcomes in the perioperative, perinatal,and SMTP period event-free survival (EFS) was determined using the Kaplan-Meier method and compared using the log-rank test. RESULTS: The average follow-up time was (5.8±3.6) years,and the two groups had similar baseline . The clinical outcomes difference of perinatal and SMTP between the two groups were not significant. There were 17 patients in BHV group and 60 in MHV group with pregnancy and birth experiences (PBE),which also showed no significant difference for adverse events both in the maternity and in the fetus. The rates of valve-related adverse events of BHV replacement patients with and without PBE were 5.9% and 0% at 3 years after the operation, and 11.8% and 5.9% after 5 years. PBE was not identified as an adverse prognostic factor for EFS (P=0.43). CONCLUSION: Either artificial BHV or MHV replacement can achieve ideal SMTP effect in CAW. BHV seems not superior to MHV. Pregnancy and birth experience will not increase the risk of BHV relevant adverse events.

Phonographic detection of mechanical heart valve thrombosis.

The formation of thrombotic deposits affects the functionality of mechanical prosthetic heart valves; as a consequence, mechanical valves thrombosis needs early diagnosis to prevent thromboembolic events. This paper compares the acoustic signals produced by two commercial bileaflet mechanical heart valves in the closing phase to detect the presence of thrombi. The closing sounds were recorded in vitro by means of a phonocardiographic device under different hydrodynamic conditions. Thrombotic deposits of different weight and shape were applied onto the valve leaflet and the annular housing, until the movement of one leaflet was completely blocked. From the acoustic signals, the corresponding spectra were calculated and four diagnostic frequency bands were identified: their comparison allowed detecting malfunctioning valves because of the presence of thrombotic formations.

Are the Current Doppler Echocardiography Criteria Able to Discriminate Mitral Bileaflet Mechanical Heart Valve Malfunction? An In Vitro Study.

Malfunction of bileaflet mechanical heart valves in the mitral position could either be due to patient-prosthesis mismatch (PPM) or leaflet obstruction. The aim of this article is to investigate the validity of current echocardiographic criteria used for diagnosis of mitral prosthesis malfunction, namely maximum velocity, mean transvalvular pressure gradient, effective orifice area, and Doppler velocity index. In vitro testing was performed on a double activation left heart duplicator. Both PPM and leaflet obstruction were investigated on a St. Jude Medical Master. PPM was studied by varying the St. Jude prosthesis size (21, 25, and 29 mm) and stroke volume (70 and 90 mL). Prosthesis leaflet obstruction was studied by partially or totally blocking the movement of one valve leaflet. Mitral flow conditions were altered in terms of E/A ratios (0.5, 1.0, and 1.5) to simulate physiologic panel of diastolic function. Maximum velocity, effective orifice area, and Doppler velocity index are shown to be insufficient to distinguish normal from malfunctioning St. Jude prostheses. Doppler velocity index and effective orifice area were 1.3 ± 0.49 and 1.83 ± 0.43 cm(2) for testing conditions with no malfunction below the 2.2 and 2 cm(2) thresholds (1.19 cm(2) for severe PPM and 1.23 cm(2) for fully blocked leaflet). The mean pressure gradient reached 5 mm Hg thresholds for several conditions of severe PPM only (6.9 mm Hg and mean maximum velocity value: 183.4 cm/s) whereas such value was never attained in the case of leaflet obstruction. In the case of leaflet obstruction, the maximum velocity averaged over the nine pulsed-wave Doppler locations increased by 38% for partial leaflet obstruction and 75% for a fully blocked leaflet when compared with normal conditions. Current echocardiographic criteria might be suboptimal for the detection of bileaflet mechanical heart valve malfunction. Further developments and investigations are required in order to further improve current guidelines.

Non-Newtonian Blood Flow Simulation of Diastolic Phase in Bileaflet Mechanical Heart Valve Implanted in a Realistic Aortic Root Containing Coronary Arteries.

Coronary arteries, which are branched from the sinuses, have tangible effects on the hemodynamic performance of the bileaflet mechanical heart valve (BMHV), especially in the diastolic phase. To better understand this issue, a computer model of ascending aorta including realistic sinus shapes and coronary arteries has been generated in this study in order to investigate the BMHV performance during diastole. Three-dimensional transient numerical analysis is conducted to simulate the diastolic blood flow through the hinges and in coronary arteries under the assumption of non-Newtonian behavior. Results indicate that as blood flows to the coronary arteries mainly during diastole, leakage flow from the hinge and other gaps will change considering the influence of coronary arteries. In addition, BMHV in the case of aortic replacement will increase blood flow rate into the coronary arteries about 100% as the mechanical valve resistance is higher than a native heart valve. Also, it will change the wall shear stress (WSS) distribution and increase coronary artery disease (CAD) potential. It is found out that although less leakage flow reduces the velocity magnitudes through the gaps, the shear stress acting on blood elements with non-Newtonian assumption will be detrimental in the hinge corner at the ventricular side. High WSS of 1800 Pa is observed at beginning of diastole at this region.

Ultrananocrystalline Diamond Integration with Pyrolytic Carbon Components of Mechanical Heart Valves.

In this report, an idea of integrating ultrananocrystalline diamond (UNCD) with pyrolytic carbon (PyC) -based mechanical heart valves, has been demonstrated. The report addresses the strategies to avoid graphitization and film delamination during the diamond coating. Raman and scratch tests showed that a UNCD film with high purity could adhere to the PyC substrate strongly. A thrombin generation study demonstrated an excellent biocompatibility of UNCD towards fresh human platelets. These results suggest that UNCD could be a good candidate of surface material for next generation heart valves and other implantable devices.

Anticoagulant management of pregnant women with mechanical heart valve replacement during perioperative period.

OBJECTIVE: To investigate the morbidity of complications and pregnancy outcomes in women with mechanical heart valve replacement who received low-dose oral anticoagulation treatment with warfarin throughout the pregnancy, compare the prognosis and complications of patients who were treated with single oral warfarin treatment or the "bridging" therapy treatment, investigate the influence of using vitamin K1 before emergency cesarean section delivery on postoperative warfarin anticoagulant effect and to explore an appropriate anticoagulant regimen during perioperative period for pregnant women with mechanical heart valve replacement. METHOD: 46 pregnant women with mechanical heart valve replacement who received low-dose oral anticoagulation treatment from October 2008 to October 2014 treated at West China Women's and Children's Hospital were retrospectively reviewed. Eight patients received emergency cesarean section (CS), while 38 patients received selective CS, in which 17 patients received single oral warfarin and 21 patients received "bridging" anticoagulation treatment during postoperative period. Morbidity of complications and the time to achieve the target INR after operation were compared. RESULTS: The mechanical valves were at the mitral position in 35 (76.09 %) patients, at the aortic position in 2 (4.35 %) patient and at both the mitral and aortic position in 9 (19.57 %) patients. 46 full-term healthy babies were delivered and no maternal thromboembolic was observed during pregnancy. There was no significant difference of the amount of uterine bleeding between single oral warfarin group and "bridging" treatment group during postpartum period. In single oral warfarin group, one valve thrombosis was observed and led to sudden death. No periphery thrombosis, hematoma, general hemorrhage or other sign of over-anticoagulation was observed. The INR increased more slowly in the group who received emergency CS with preoperative application of vitamin K1 than other two groups. CONCLUSION: The use of vitamin K1 preoperatively might result in warfarin resistance and discontinuation of warfarin therapy before selective CS might be more appropriate than application of vitamin K1. The "bridging" anticoagulation treatment which combines oral warfarin and subcutaneous LMWH might be more effective and safer than single oral warfarin therapy for patients with mechanical heart valve replacement during postoperative period, no matter selective or emergency CS. The safety of low-dose oral warfarin therapy throughout pregnancy is still under controversy.