We inserted the 0.6 mm caliber graft-heparin (in inner wall) conduits into the tailarteries of 14 mice. The results showed that the graft conduit could be used repeatedly with no blood oozing out in the wound, no massive internal hemorrhage, and no additional coagulative reagent given during the whole experiment. On the other hand, the graft-heparin conduits of variant caliber were inserted into the femur arteries of 4 rabbits and 4 dogs for blood pressure experiment and femur arterio-venous bypass tests. The results showed that the anticoagulative effect of these conduits was markedly improved, but there was a strip of thrombus. There was no thrombus track in the wall of the conduit. The strip of thrombus was formed first in the cone of conduit where caliber changed. The results indicate that the blood flow resistance is in inverse proportion to 4 power of the conduit radius. So the thinner the conduit is, the more sensitive to conduit radius variation the conduit resistance will be. In studying and making the arfificial conduit, one must take notice of the conduit caliber, which should be equal to the caliber of the blood vessel.
Animals ; Anticoagulants ; administration & dosage ; Blood Vessel Prosthesis ; Dogs ; Heparin ; administration & dosage ; Mice ; Rabbits ; Regional Blood Flow

INTRODUCTIONNovel oral anticoagulants (NOACs) have at least equivalent efficacy compared to standard anticoagulants with similar bleeding risk. Optimal management strategies for bleeding complications associated with NOACs are currently unestablished.

MATERIALS AND METHODSA working group comprising haematologists and vascular medicine specialists representing the major institutions in Singapore was convened to produce this consensus recommendation. A Medline and EMBASE search was conducted for articles related to the 3 available NOACs (dabigatran, rivaroxaban, apixaban), bleeding and its management. Additional information was obtained from the product monographs and bibliographic search of articles identified.

RESULTSThe NOACs still has substantial interactions with a number of drugs for which concomitant administration should best be avoided. As they are renally excreted, albeit to different degrees, NOACs should not be prescribed to patients with creatinine clearance of <30 mLs/min. Meticulous consideration of risk versus benefits should be exercised before starting a patient on a NOAC. In patients presenting with bleeding, risk stratification of the severity of bleeding as well as identification of the source of bleeding should be performed. In life-threatening bleeds, recombinant activated factor VIIa and prothrombin complex may be considered although their effectiveness is currently unsupported by firm clinical evidence. The NOACs have varying effect on the prothrombin time and activated partial thromboplastin time which has to be interpreted with caution. Routine monitoring of drug level is not usually required.

CONCLUSIONNOACs are an important advancement in antithrombotic management and careful patient selection and monitoring will permit optimisation of their potential and limit bleeding events.

Administration, Oral ; Anticoagulants ; therapeutic use ; Benzimidazoles ; Consensus ; Dabigatran ; Hemorrhage ; prevention & control ; Humans ; Singapore ; Thiophenes

Administration, Oral ; Anticoagulants ; adverse effects ; Aspirin ; adverse effects ; Epistaxis ; chemically induced ; Humans

Oral anticoagulants play an important role in the prevention and treatment of thromboembolic diseases.Warfarin,a traditional oral anticoagulant,is limited in clinical use due to its limitations such as narrow therapeutic window and requirements on frequent monitoring and dose adjustment.Direct oral anticoagulants(DOACs)such as dabigatran,rivaroxaban,apixaban,and edoxaban are increasingly used to prevent and treat venous thrombosis or thrombus formation.However,recent studies have documented inter-individual variability in plasma drug levels of DOACs.This article summarizes the recent advances in the pharmacogenomics of DOACs.
Administration, Oral ; Anticoagulants ; therapeutic use ; Atrial Fibrillation ; drug therapy ; Dabigatran ; Pharmacogenetics ; Rivaroxaban

Administration, Oral ; Anticoagulants/adverse effects* ; Atrial Fibrillation/drug therapy* ; Humans ; Stroke ; Vascular Calcification/drug therapy* ; Warfarin

BACKGROUNDNon-valvular atrial fibrillation is associated with an increased risk of ischemic stroke; however, the appropriate intensity of anticoagulation therapy for Chinese patients has not been determined. The purpose of this study was to compare the safety and the efficacy of standard-intensity warfarin therapy, low-intensity warfarin therapy, and aspirin therapy for the prevention of ischemic events in Chinese patients with non-valvular atrial fibrillation (NVAF).

METHODSA total of 786 patients from 75 Chinese hospitals were enrolled in this study and randomized into three therapy groups: standard-intensity warfarin (international normalized ratio (INR) 2.1 to 2.5) group, low-intensity warfarin (INR 1.6 to 2.0) group and aspirin (200 mg per day) group. All patients were evaluated by physicians at 1, 3, 6, 9, 12, 15, 18, 21 and 24 months after randomization to obtain a patient questionnaire, physical examination and related laboratory tests.

RESULTSThe annual event rates of ischemic stroke, transient ischemic attack (TIA) or systemic thromboembolism were 2.6%, 3.1% and 6.9% in the standard-intensity warfarin, low-intensity warfarin and aspirin groups, respectively (P = 0.027). Thromboembolic event rates in both warfarin groups were significantly lower than that in the aspirin group (P = 0.018, P = 0.044), and there was no significant difference between the two warfarin groups. Severe hemorrhagic events occurred in 15 patients, 7 (2.6%) in the standard-intensity warfarin group, 7 (2.4%) in the low-intensity warfarin group and 1 (0.4%) in the aspirin group. The severe hemorrhagic event rates in the warfarin groups were higher than that in the aspirin group, but the difference did not reach statistical significance (P = 0.101). The mild hemorrhagic and total hemorrhagic event rates in the warfarin groups (whether in the standard-intensity warfarin group or low-intensity warfarin group) were much higher than that in the aspirin group with the annual event rates of total hemorrhages of 10.2%, 7.6% and 2.2%, respectively, in the 3 groups (P = 0.001). Furthermore, there was no significant difference in all cause mortality among the three study groups.

CONCLUSIONIn Chinese patients with NVAF, the warfarin therapy (INR 1.6 - 2.5) for the prevention of thromboembolic events was superior to aspirin.

Aged ; Aged, 80 and over ; Anticoagulants ; administration & dosage ; therapeutic use ; Aspirin ; administration & dosage ; therapeutic use ; Atrial Fibrillation ; drug therapy ; Female ; Humans ; Male ; Middle Aged ; Warfarin ; administration & dosage ; therapeutic use

Anticoagulation therapy is effective in preventing primary and secondary thromboembolic events due to atrial fibrillation. Warfarin, which was approved by the United States in 1954, was the only long-term oral anticoagulation therapy till the approval of dabigatran in 2010, and of rivaroxaban and other direct factor Xa inhibitors from 2011, forming a group known as novel oral anticoagulants (NOAC). NOAC have fewer food and drug interactions compared to warfarin; hence, the patient will require fewer clinic visits. However, the short half-life of NOAC means that twice-a-day dosing is needed and there is higher risk of a prothrombotic state when doses are missed. Other disadvantages are the lack of long-term data on NOAC, their high cost and the current lack of locally available antidotes.
Administration, Oral ; Anticoagulants ; administration & dosage ; Atrial Fibrillation ; drug therapy ; Cardiology ; methods ; Dabigatran ; administration & dosage ; Family ; Humans ; Professional-Patient Relations ; Rivaroxaban ; administration & dosage ; Stroke ; prevention & control ; Thromboembolism ; prevention & control ; Warfarin ; administration & dosage

BACKGROUNDWhether an addition of OAC to double antiplatelet therapy for patients with an indication of chronic oral anticoagulation undergoing PCI-S may improve clinical outcomes is still debated. This meta-analysis aimed to update and re-compare the benefits and risks of triple antithrombotic therapy (TT) with double anti-platelet therapy (DAPT) after in patients who requiring oral anticoagulation after percutaneous coronary interventions with stenting (PCI-s).

METHODSTen reports of observational retrospective or prospective studies were retrieved, including a total of 6296 patients, follow-up period ranging from 1 year to 2 years.

RESULTSBaseline characteristics were similar in both groups. The main finding of this study is the overall incidence of major adverse cardiovascular events (MACE), myocardial infarction (MI) and stent thrombosis was comparable between two groups. Patients with TT was associated with significant reduction in ischemic stroke (OR: 0.27; 95%CI: 0.13 - 0.57; P = 0.0006) as compared to DAPT. We reaffirmed triple therapy significantly increased the risk of major bleeding (OR: 1.47; 95%CI: 1.22 - 1.78; P < 0.0001) and minor bleeding (OR: 1.55; 95%CI: 1.07 - 2.24; P = 0.02).

CONCLUSIONSTriple therapy is more efficacious in reducing the occurrence of ischemic stroke in PCI-s patients with an indication of chronic oral anticoagulation (OAC), compared with DAPT. However, it significantly increased major and minor risk of bleeding. It is imperative that further prospective randomized controlled trials are required to defne the best therapeutic strategy for patients with an indication of chronic OAC undergoing PCI-s.

Aged ; Anticoagulants ; therapeutic use ; Drug Therapy, Combination ; Female ; Fibrinolytic Agents ; administration & dosage ; Humans ; Male ; Middle Aged ; Percutaneous Coronary Intervention ; Platelet Aggregation Inhibitors ; administration & dosage ; Publication Bias ; Stents

OBJECTIVETo investigate the clinical application of anticoagulation treatment with warfarin after prosthetic heart valve replacement and compare the effect and safety of different anticoagulant intensities.

METHODSA total of 845 Chinese patients receiving oral warfarin for anticoagulant treatment after prosthetic heart valve replacement in Guangdong General Hospital between 2000 and 2008 were enrolled in this survey. The general data, clinical data, medications, international normalized ratio (INR) and results of echocardiogram of these patients were followed up to observe the incidence of complication of thrombo-embolism and such adverse effect as hemorrhage.

RESULTSAll the patients were of Han nationality, and Cantonese accounted for 88.04%. The daily mean maintenance dose of warfarin was 2.92∓0.88 mg in these patients with a median INR of 2.09∓0.39. Of these patients, 44.62% received low-intensity anticoagulant treatment with warfarin with the INR maintained between 1.5 and 2.0, and 56.45% had standard anticoagulant intensity with the INR maintained between 2.0 and 3.0. The total incidence of thrombo-embolism was 4.14%. Severe hemorrhage occurred in 14 cases (1.66%), most frequently in the alimentary tract. The events of hemorrhage were correlated to the type of prosthetic heart valve replacement, occurring more frequently in patients with mechanical prosthetic heart valve replacement than in those with biological ones. No significant difference was found in the incidence of thrombo-embolism and server hemorrhage between the two groups receiving low and standard intensity therapy anticoagulant.

CONCLUSIONThe effect and safety of low-intensity anticoagulant treatment are comparable to that of standard intensity treatment in Chinese Han patients, and anticoagulation treatment with warfarin is effective and safe to maintain the INR between 1.8-3.0.

Adult ; Anticoagulants ; administration & dosage ; therapeutic use ; Female ; Heart Valve Prosthesis Implantation ; methods ; Humans ; Male ; Middle Aged ; Postoperative Period ; Warfarin ; administration & dosage ; therapeutic use

OBJECTIVETo study the therapeutic effects of early administration of low-dose heparin in patients with severe sepsis.

METHODSTwenty-two patients were randomly divided into experimental group and control group. In addition to the routine treatment, the patients in experimental group were given low-dose heparin, while those in control group were not. Prothrombin time (PT), activated partial thromboplastin time (APTT), platelet count, APACHE II score, ICU days, hospital days, cure rate, and 28-day survival rate were investigated in the two groups.

RESULTSAfter the treatment, PT and APTT recovered normal in the experimental group, but remained abnormal in the control group. There was no significant difference in platelet count between the two groups. ICU days in experimental group was shorter than that in control group (P < 0.01). Cure rate in experimental group was 81.8%, which was significantly higher than that in control group (54.5%). There was no significant difference in hospital days and 28-day survival rate between the two groups.

CONCLUSIONSEarly administration of low-dose heparin therapy can improve coagulative function in patients with severe sepsis, however, the survival rate was not improved.

Aged ; Anticoagulants ; administration & dosage ; Combined Modality Therapy ; Female ; Heparin ; administration & dosage ; Humans ; Injections, Intravenous ; Male ; Middle Aged ; Sepsis ; drug therapy ; mortality ; therapy ; Survival Rate ; Treatment Outcome