View clinical trials related to Unfractionated Heparin.
Filter by:Unfractionated heparin (UFH) is an anticoagulant to prevent thrombus formation or worsening of an existing thrombus. It is indicated for patients with deep vein thrombosis/pulmonary embolism (DVT/PE) or acute coronary syndrome (ACS). Unfractionated heparin treatment consists of an initial bolus followed by a continuous infusion that is adjusted based on the patient's subsequent partial thromboplastin time (PTT) levels
This study is to understand the changes occurring in a blood clotting protein, von Willebrand factor (VWF), in patients undergoing cardiac surgery who receive the blood thinner called Heparin. These patients are given Heparin through their veins, to prevent blood clot formation as it passes through the heart bypass machine. At the end of the operation, the effect of Heparin is reversed by another drug, Protamine Sulphate. Heparin prevents blood clots forming mainly by inactivating thrombin, a crucial protein needed for blood clotting. This effect of Heparin is monitored through blood tests called the 'Anti Factor-Xa' and the 'APTT'. Heparin has another effect on clotting: it can block the attachment of special blood cell fragments called platelets to damaged blood vessels, but this effect is not usually measured. Following blood vessel injury, the large VWF sticks to the damaged surface and captures platelets to form a 'plug' which stops bleeding. The platelet plug is then stabilised by other clotting proteins. This stops blood loss and allows vessel repair underneath. Heparin blocks the ability of VWF to capture platelets at the site of blood vessel injury. The higher the dose of Heparin, the greater this blocking effect is. This secondary effect of Heparin cannot be readily monitored and may explain why bleeding complications occur in patients receiving Heparin despite the monitoring with blood tests used. This study will look at the blood levels of Heparin, VWF and platelets before, during and after surgery and how well VWF functions in the presence of heparin, including its ability to attach to platelets. The investigators will determine if all of the heparin related changes in blood clotting can be detected using a method that looks at all of the different steps in forming a blood clot.