James E. Wilson

Heparin Therapy in Venous Thromboembolism

Patients with pulmonary embolism or deep venous thrombosis were randomly assigned to receive either intermittent or continuous intravenous heparin therapy. In patients with an enhanced risk of bleeding, major bleeding was significantly more common during the intermittent use of heparin; in patients without these risk factors, hemorrhage occurred with equal frequency during intermittent and continuous heparin therapy. Recurrent thromboembolism was seen significantly more often in patients receiving continuous heparin therapy. Controlling the dose of heparin with coagulation tests resulted in the administration of significantly larger daily doses of heparin with intermittent injections than with continuous infusion. Therefore, the bleeding complications of intermittent heparin therapy could have been due to the higher dose, and the recurrences associated with continuous heparin therapy may have resulted from lower doses rather than from differences in the method of administration. In a small trial, arbitrary lower doses of heparin given intermittently similar to the doses of heparin given continuously resulted in fewer bleeding complications and more recurrences. In patients without risk factors for bleeding, the intermittent administration of heparin in the higher dose is preferable because of fewer recurrences and no increase in hemorrhagic complications. In patients with a high risk of bleeding, conventional doses of heparin given continuously can reduce the rate of hemorrhagic complications but will result in more recurrences.

Low-dose heparin therapy in the long-term management of venous thromboembolism

The efficacy of a six-month course of low-dose heparin therapy was compared to a conventional warfarin regimen by a prospective, controlled trial in 48 patients with pulmonary embolism or deep venous thrombosis of the legs. All subjects had complicated medical illnesses and a high risk of recurrent thromboembolism. Bleeding complications were virtually negligible during heparin therapy and occurred significantly more frequently in patients receiving warfarin. Heparin was as effective as warfarin in the prevention of recurrent thromboembolism. Patient compliance with the two treatment regimens was comparable. Self-administered, low-dose heparin therapy is a useful alternative to warfarin in the long-term management of complicated thromboembolic disorders.

Noninvasive Diagnosis of Deep Venous Thrombosis by Phleborheography

Phleborheography, a recently described noninvasive test for deep venous thrombosis, was compared with leg venography in 75 patients. Acute deep venous thrombosis was accurately diagnosed by phleborheography in 24 patients, with no false-positive diagnoses. External venous compression without thrombosis was diagnosed correctly in two patients. The remaining patients appeared normal or had chronic venous disease by phleborheography; however, 11 of these had acute deep venous thrombosis by venography, for a false-negative rate of 31%. Most undetected thrombi were in small calf veins. The specificity of phleborheography is thus 100%, but the sensitivity is only 69%. Similarly, its positive predictive value is 100% and the negative predictive value is 78%. When phleborheography shows acute deep venous thrombosis, this diagnosis may be accepted with confidence and therapy chosen accordingly, without venographic confirmation. Venography may still be required to withhold anticoagulation when phleborheography is negative.

Radiographic techniques for balloon-occlusion pulmonary angiography.

Pulmonary angiography was performed in 125 patients with suspected pulmonary embolism. Standard angiographic techniques were combined with balloon occlusion of pulmonary arterial branches using a double lumen catheter and contrast material injection distal to the occlusion. Vessel opacification was fluoroscopically monitored and images obtained with either a conventional cut-film camera, a spot-film camera, or cineangiography. Balloon-occlusion angiography improved image quality and contributed substantially to the radiographic diagnosis of pulmonary embolism in most patients. The technique is useful in patients too ill to undergo conventional angiography and may be performed at the bedside.