In the past 2 years, Mr. L., a 56-year-old architect, has experienced three episodes of deep vein thrombosis. All occurred without complications, and all were treated successfully with anticoagulant therapy and bed rest. He now arrives at the urgent care center because of increased pain and swelling in is left calf that has lasted for the past 3 days. On admission to the hospital for anticoagulant therapy, Mr. L. receives a bolus of 5000 units of heparin and is started on a continuous heparin infusion.
What patient findings would indicate a therapeutic response to the heparin therapy?