Evaluation of the Accuracy of the INRatio Prothrombin Time (PT) Monitoring System With a New Test Strip for the Oral Anticoagulation Therapy Patient in the Presence of Heparin and Low Molecular Weight Heparin (e.g., Enoxaparin or Dalteparin)

Inclusion Criteria: * Adults (18 years of age or older). * Willing and able to provide written informed consent and comply with study procedures. * Receiving warfarin/heparin bridge therapy. * Therapy with both warfarin and one of the heparins listed below must have been initiated for at least 12 hours before the first study specimens are obtained. * UH (last known aPTT prior to enrollment (if available†) must confirm heparin has been administered) * Dalteparin (last known anti-factor Xa prior to enrollment (if available†) must confirm heparin has been administered) * Enoxaparin (last known anti-factor Xa prior to enrollment (if available†) must confirm heparin has been administered) † If a pre-study aPTT or anti-factor Xa is not available, subsequent testing of the study phlebotomy or a phlebotomy as a part of routine medical care taken before or during the time of the study phlebotomy must confirm the presence of heparin (unfractionated or low molecular weight) in order for that data point to be included in the analysis. Exclusion Criteria * Known or suspected hematocrit less than 25 or greater than 55%; * Auto-immune disorders known to interfere with INR measurements, such as lupus or anti-phospholipid syndrome (APS) * Already participated in this specific study