Calf Vein Thrombosis Research Articles

Prophylaxis Against Deep-Vein Thrombosis

To the Editor. —We were distressed by a recent article about deep-vein thrombosis (DVT) by Oster et al. 1 In this drug company-sponsored analysis of the risks and cost-effectiveness of prophylaxis against DVT, the authors conclude that all patients undergoing major orthopedic surgery require one of their recommended prophylactic regimens. This conclusion is unsupportable with the data that the authors have chosen to include or exclude in their analysis. To begin with, the authors assume that all DVTs are associated with pulmonary embolism (PE). They mention that calf-vein thromboses are relatively insignificant and that they do not represent a major risk to patients. However, despite this comment, they base their data on articles that measure the effectiveness of prophylaxis against calf DVT. Second, they quote statistics on the clinical incidence of PE that are out-of-date. It now is appreciated that approximately 1% of patients undergoing total hip or total knee

Popliteal cyst rupture and the pseudothrombophlebitis syndrome

Fifteen patients presented during a four-year period with a pseudothrombophlebitis syndrome, subsequently confirmed arthrographically as being due to popliteal cyst rupture. Initially the majority of patients (73%) were erroneously diagnosed as having calf vein thrombosis, and were anticoagulated for periods of three to ten days. Clinical differentiation from venous thrombosis was usually impossible. Contrast arthrography was the definitive diagnostic investigation, revealing popliteal cysts in all patients, and an active synovial leak into the calf in 13 cases (87%). The mean delay in performing arthrography was 5.3 days, the procedure usually being performed after normal contrast venography. Doppler and isotope venography yielded misleading or equivocal results (42%) delaying diagnosis, and prolonging periods of potentially dangerous anticoagulation. We suggest that the marked overlap in the emergency presentation of popliteal cyst rupture and calf vein thrombosis mandates the aggressive use of arthrography combined with venography in all patients presenting with a painful swollen leg.

Vascular complications in renal transplantation: The Johannesburg experience

The aim of this retrospective study, involving 909 renal transplants in 773 patients, was to determine the incidence of vascular complications. Four patients had isolated calf vein thrombosis (0.4%), 13 had ileofemoral thrombosis (1.4%), 3 had superficial vein thrombosis (0.3%), 10 developed pulmonary emboli (1.1%), 6 had renal vein thrombosis (0.66%), 3 had renal artery thrombosis (0.3%), 3 had renal artery stenosis, 2 patients developed anastomotic aneurysms and a further patient ruptured his arterial anastomosis. Cyclosporine has not increased the incidence of thrombosis since its introduction to the unit.

Diagnosis of Recurrent Deep Venous Thrombosis Using B-Mode Ultrasonic Imaging

Accurate diagnosis of recurrent deep venous thrombosis (DVT) in patients with postphlebitic syndrome or a history of previous DVT can be extremely difficult. Real-time B-mode ultrasonic imaging (UI) was compared to ascending contrast venography (ACV) in a prospective study of 38 limbs with suspected recurrent DVT to determine if UI could reliably detect recurrent thrombosis. Six limbs had normal deep veins and 32 had evidence of previous DVT by both techniques. Acute thrombus was diagnosed by both UI and ACV in 9 limbs and by UI alone in an additional three limbs. New thrombus was found in 13 popliteal-proximal and 10 calf veins by UI; while ACV detected 12 popliteal-proximal and five new calf vein thromboses. UI is comparable to ACV in detecting recurrent thrombosis and may be particularly useful in assessing the calf veins.

Clinical features and diagnosis of venous thrombosis

The clinical diagnosis of venous thrombosis is inaccurate because the clinical findings are both insensitive and nonspecific. The sensitivity of clinical diagnosis is low because many potentially dangerous venous thrombi are clinically silent. The specificity of clinical diagnosis is low because the symptoms or signs of venous thrombosis all can be caused by nonthrombotic disorders. For these reasons, a practical approach for the diagnosis of venous thrombosis is important. A current approach to the diagnosis of clinically suspected venous thrombosis favors the use of impedance plethysmography over Doppler ultrasonography as the main test for this disorder. This is because impedance plethysmography is precise and objective, whereas the interpretation of Doppler ultrasonography is subjective and requires considerable skill and experience to form reliable diagnoses. The use of serial impedance plethysmography has been evaluated recently in a prospective study. The rationale of repeated impedance plethysmography evaluation is based on the premise that calf vein thrombi are only clinically important when they extend into the proximal veins, at which point detection with impedance plethysmography is possible. Therefore, by performing repeated examinations with impedance plethysmography in patients with clinically suspected venous thrombosis, it is possible to identify patients with extending calf vein thrombosis who can be treated appropriately. Impedance plethysmography is performed immediately on referral; if it is positive in the absence of clinical conditions that are known to produce falsely positive results, the diagnosis of venous thrombosis is established, and the patient is treated accordingly. If the result of the initial impedance plethysmography evaluation is negative, anticoagulant therapy is withheld, and impedance plethysmography is repeated the following day, again on day 5 to 7 and on day 10 to 14. If impedance plethysmography becomes positive during this time, a diagnosis of venous thrombosis is made and anticoagulant therapy is commenced. Positive impedance plethysmography in the presence of conditions known to produce a false positive result (for example, congestive cardiac failure) should be confirmed by venography. If noninvasive tests for the diagnosis of venous thrombosis are not available, a clinical suspicion of venous thrombosis should be objectively confirmed or excluded by performing ascending venography.

Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis: Lagerstedt CI, Fagher BO, Olsson CG, et al. Lancet 1985;1:515-8

Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis: Lagerstedt CI, Fagher BO, Olsson CG, et al. Lancet 1985;1:515-8

NEED FOR LONG-TERM ANTICOAGULANT TREATMENT IN SYMPTOMATIC CALF-VEIN THROMBOSIS

The need for oral anticoagulation in patients with calf-vein thrombosis was examined in a randomised study of 51 patients, of whom 23 received warfarin for 3 months and 28 did not. Both groups received an initial course of heparin and all wore compression stockings. Progress was monitored by the use of serial isotope tests and physical examination. Phlebography was repeated if recurrence was suspected. During the first 3 months, 8 patients in the non-warfarin group (29%) had recurrences compared with none in the warfarin group (p<0·01). 5 patients had recurrence with proximal extension and 1 patient had a pulmonary embolus. After 1 year, 22 out of 23 patients in the warfarin group had not had a recurrence, compared with 19 out of 28 (p<0·02). The findings indicate that oral anticoagulants should be given to all patients with thrombi that produce symptoms. Treatment for 3 months seems to be sufficient.

Venous function five to eight years after clinically suspected deep venous thrombosis.

One hundred and fifty-four patients, who had been subjected to phlebography 5-8 years previously because of clinical suspicion of deep venous thrombosis (DVT), were investigated to evaluate the frequency of deep venous insufficiency (DVI). The evaluation included clinical examination, registration of subjective complaints and objective measurements with plethysmography, venous pressure and Doppler ultrasound. DVT had been present in 75 legs. There were no statistically significant differences between legs with and without earlier DVT apart from more venous outflow obstruction in the former. DVI was as common after calf vein thrombosis as after more proximal DVT. DVI was more frequent in elderly patients and in patients with a history of previous DVI or DVT. The sufficiency of the popliteal vein seemed to be of great importance in the development of DVI. More than one third of legs without DVT had developed DVI at follow-up.

STUDIES ON THE MEDICAL TREATMENT OF DEEP VEIN THROMBOSIS

The aim of these studies was to investigate different regimens of thrombolytic therapy and oral anticoagulation, and to evaluate the effects of streptokinase (SK), heparin and warfarin in the treatment of deep vein thrombosis (DVT). Low-dose SK, although controlled according to the fibrinogen levels, did not provide improved thrombolysis compared to conventional high-dose SK, and more postthrombotic changes were registered after an average of 3 years. Furthermore, serious hemorrhagic side-effects occurred, which makes this regimen inexpedient. Various regimens of local venous infusion of SK were tried, and with a dose of 4,000 IU/h for 72 h in combination with heparin a thrombolytic effect was achieved, albeit not greater than usually observed with conventional SK. Systemic hypofibrinogenemia and hemorrhage were not avoided. A hitherto not described side-effect with bullous dermatitis was reported. Venographic severity of calf vein thrombosis displayed a statistically significant correlation to long-term hemodynamic changes, as assessed with foot volumetry, after an average of 5 years. This correlation was stronger for the size of the thrombus after initial treatment than for the size at diagnosis. Thus it seems important to treat calf vein thrombosis with heparin in order to limit the extent of the thrombus, thereby reducing long-term sequelae. During heparin treatment, an average reduction of the thrombi of 17% was observed. This reduction was significantly correlated to a short duration of symptoms but not to parameters of heparin therapy or fibrinolytic components. However, patients with substantial thrombolysis had high plasmin-alpha 2-antiplasmin (PAP) levels, and those with high tissue plasminogen activator (t-PA) inhibitor levels and remarkably also those with high t-PA antigen levels had no lysis. The concentration of t-PA antigen showed a significant increase during heparin infusion, whereas that of PAP and t-PA inhibitor was not influenced. By applying more intensive initial oral anticoagulation, stable therapeutic prothrombin time (PT)-levels were achieved one day earlier and the duration of heparin infusion could be equally reduced compared to the conventional regimen (4.4-5 days vs 5.4-6 days). The activity of coagulation factors II, VII, IX and X had dropped to the same level with both regimens the day heparin was discontinued, observed. The effectiveness of oral anticoagulation after DVT was studied in 596 patients treated for a total of 4450 months.(ABSTRACT TRUNCATED AT 400 WORDS)

Radionuclide plethysmography and Tc-99m red blood cell venography in venous thrombosis: comparison with contrast venography.

Radionuclide plethysmography (RPG) is a new technique that uses Tc-99m labelled red blood cells to ascertain changes in venous volumes by detecting the change in counts in response to the inflation and deflation of proximal thigh cuffs. Diagnosis of ileofemoral venous occlusion is possible using this technique, which also provides kinetic data of venous outflow. A range of normal values was defined in 19 subjects for per cent change in venous capacitance and venous outflow. Twenty-one patients with suspected deep venous thrombosis were studied prospectively using RPG, radionuclide venography (RV), and contrast venography (CV) to establish the usefulness of RPG alone and in combination with RV in the diagnosis of deep venous thrombosis. RPG proved to be a reliable technique for the diagnosis of ileofemoral venous thrombosis (sensitivity, 91%; specificity, 100%). RV was less sensitive (73%) and less specific (93%) in diagnosing that condition. When RPG is used as the criterion for the detection of ileofemoral vein thrombosis and RV is used as the criterion for the detection of calf vein thrombosis, the combined techniques show improved sensitivity (92%) and specificity (93%) for the detection of all deep venous thromboses.

Venous thrombosis in diabetes mellitus.

The incidence over 7 days of isotopically-detected calf and popliteal vein thrombosis was determined in a group of 60 diabetic patients admitted to hospital with myocardial infarction, heart failure or stroke, or for abdominal surgery. The result was compared with the incidence in 60 control subjects matched for age, sex and presenting diagnosis. Twenty-one diabetic patients developed positive 125I-fibrinogen scans, compared with 19 control subjects; this difference is not significant. We conclude that diabetes is not associated with an enhanced risk of thrombosis in veins. It is therefore possible that the arterial and capillary abnormalities found in diabetes may arise from mechanisms other than a generalised thrombotic tendency.

Venous thromboembolism prophylaxis in gynecologic oncology: A prospective, controlled trial of low-dose heparin

One hundred eighty-five patients undergoing operation-for gynecologic malignancy participated in a randomized controlled trial of low-dose heparin prophylaxis. Prospective surveillance for deep venous thrombosis was performed with daily fibrinogen 125I counting in the legs and impedance plethysmography. Twelve of 97 (12.4%) patients in the control group and 13 of 88 (14.8%) patients in the low-dose heparin group developed a venous thromboembolic complication. There was no statistical difference in the incidence of proximal deep vein thrombosis, calf vein thrombosis, or pulmonary emboli between the control and low-dose heparin groups. Low-dose heparin does not afford any prophylactic benefit to patients undergoing major pelvic operative procedures for gynecologic malignancy.

Deep Venous Thrombophlebitis Following Aortoiliac Reconstructive Surgery

One hundred patients undergoing elective aortic surgery were scanned prospectively for development of deep venous thrombosis (DVT). The incidence of DVT in this population was 13%. Eleven patients showed only calf vein thrombosis on venography, whereas two had occlusive iliofemoral thrombus. The correlation between venous Doppler ultrasound and venography was 80%. More importantly, Doppler examination correctly identified both patients with occlusive thrombus. Fibrinogen scanning was associated with a false-positive rate of 31%. Only one patient suffered a nonfatal pulmonary embolus. Fibrinogen scanning has an unacceptably high false-positive rate; however, Doppler ultrasound will identify significant occlusive thrombus without a high false-positive rate. The low incidence of pulmonary emboli does not warrant such definitive measures as prophylactic vena caval interruption.

A Clinical and Phlebographie Study of Postoperative Deep Vein Thrombosis Following Knee Meniscus Extirpation

To evaluate the risk of deep vein thrombosis, a clinical and phlebographic examination was performed 7 to 16 days after a bloodless knee meniscus operation in 37 male patients aged 20 to 35 years. Anticoagulant prophylaxis was not administered. Phlebography revealed asymptomatic calf vein thrombosis in three patients and these were not treated. In two of these phlebography was repeated after six weeks, and complete regression of the thrombi was noted. The present study may underestimate the frequency of postoperative venous thrombosis, as some thrombi may already have lysed at the time of phlebography. However, our results indicate a low incidence of thrombosis after knee meniscus extirpation.

Home-Diagnosis of Deep Venous Thrombosis with Impedance Plethysmography

In order to assess the value of I.P.G. for the diagnosis of D.V.T. in general practice, an I.P.G. was carried out by a skilled technician in 255 consecutive patients with suspected D.V.T. at home. Ascending venography was carried out in 185 of these patients. In addition, blood for assay of AT III, platelet count, fibrinogen, a2-antiplasmin, ethanol gelation test and spontaneous platelet aggregation was collected at the time the I.P.G. was performed. In 61 patients (33%) venography showed the presence of D.V.T., and was negative in the remaining 124 patients. I.P.G. was positive in 51 of the 61 patients with D.V.T., a sensitivity of 84%. I.P.G. was normal in 115 of the 124 patients with a negative venogram, a specificity of 93%. The sensitivity of the I.P.G. for proximal vein thrombosis was 92% and for calf vein thrombosis 68%. Mean a2-antiplasmin concentration was significant (p less than 0.05) lower (101 +/- 15%, mean +/- SD) in patients with D.V.T. compared with patients with a normal venogram (107 +/- 11%, mean +/- SD). No differences between the two groups were observed in the other coagulation parameters assayed, and none was of diagnostic value, either alone or in combination with I.P.G. This study shows that I.P.G. is of potential value for the home diagnosis of D.V.T., in particular proximal vein thrombosis. This is potentially clinically useful, because these thrombi are thought to carry a high risk for pulmonary embolism.

Intermittent Calf Compression: A Randomized Trial In Elective Hip Replacement

We have evaluated venous thrombosis prevention with intermittent calf compression in 78 patients aged over 50 years having elective hip replacement. 38 patients were randomly allotted to intermittent calf compression with a “BOC-Roberts Venous Flow Stimulator”, begun at the start of surgery and continued for 7 days, while 40 patients had no prophylaxis. Age, weight, length of surgery, and other risk factors were similar in the two groups. All patients had ascending venography of the operated leg on the seventh day, or bilateral venography if routine 125I fibrinogen legscanning and impedance plethysmography suggested thrombosis on the unoperated side.Venography showed thrombosis in 12/38 patients treated with intermittent calf compression (32%) and 21/40 untreated patients (53%). The difference is not statistically significant, but further analysis showed some interesting treatment effects: (a) calf vein thrombosis was found in 13% of treated and 35% of untreated patients (p &lt;0.05), (b) femoral or popliteal vein thrombosis developed in 24% of treated and 38% of untreated patients, while isolated femoral vein thrombosis (without calf vein thrombosis) developed in 18% of treated and untreated patients, but (c) the femoral vein thrombi were smaller in treated patients - 8% of treated and 30% of untreated patients had femoral vein thrombi with an estimated length above 5 cm (p &lt;0.05).This suggests that intermittent calf compression prevents calf vein thrombosis and prevents extension of femoral vein thrombi after elective hip replacement, although it cannot prevent the initiation of femoral vein thrombi which is presumably due largely to local vein trauma. This limited effect may be clinically valuable, allowing delay in starting anticoagulant prophylaxis until this is safe.

Transfemoral temporary pacing and deep vein thrombosis

The incidence of deep vein thrombosis following transfemoral temporary pacing was prospectively assessed in 20 consecutive patients using serial 125I-fibrinogen scanning, impedance plethysmography, and measurements of fibrin degradation products. Four patients underwent venography. Of the twenty patients, five (25%) had definite evidence of deep vein thrombosis, six demonstrated equivocal abnormalities, and nine had no evidence of thrombosis. Thrombosis was found only in the legs used for pacing. Of the five with deep vein thrombosis, one had positive findings in all the noninvasive tests. Venography confirmed the diagnosis in the other four; one had thrombosis of the femoral vein, one had thrombosis of several calf veins, and one had thrombosis of both the thigh and calf veins; the fourth patient had thrombosis of the entire deep venous system of the leg. This latter patient was the only one who had clinical evidence of venous thrombosis. The patients with deep vein thrombosis did not differ in clinical characteristics from those without thrombosis. There was no relationship between the occurrence of deep vein thrombosis and the number of venepunctures, the state of the electrode, the presence of the introducer sheath in the femoral vein, or the duration of pacing. In conclusion, deep vein thrombosis is a common complication of transfemoral temporary pacing and the high incidence of its occurrence should be considered before deciding upon the site of entry for a temporary pacemaker.

Pneumatic calf compression, fibrinolysis, and the prevention of deep venous thrombosis.

In a previous pilot study that did not reach statistical significance, intermittent single-leg pneumatic compression appeared effective in reducing the incidence of calf vein thrombosis not only in the pumped calf but also in the unpumped leg in 37 patients, using the 125I-fibrinogen (Abbott Laboratories) technique. The present study was undertaken to investigate mechanical induction of local and systemic fibrinolysis. The euglobulin lysis time in the arm venous effluent was determined in five volunteers before and after unilateral arm compression for 1/2 hour. Shortening averaged 19% (not significant). The experiment was repeated using bilateral calf-length boots with femoral vein sampling. Euglobulin lysis decreased 22% (P < 0.001). To uncover possible systemic effects, the protocol was altered using calf boots with sampling from the arm. The euglobulin lysis diminished 6% in 57 volunteers (P < 0.001). In 27 others the effects of thigh-length and calf-length boots were compared. In half, pumping with a short boot was undertaken first, and in the remainder, the long boot was applied initially. One-half hour of pumping was followed by 1/2 hour of rest. Immediately afterward the second period of pumping took place and continued for 1/2 hour. A total of four arm vein samples were obtained, one before and after each pumping period. Although, in retrospect, the 1/2-hour rest period was inadequate to permit the subjects to return to basal conditions, statistically significant decreases in euglobin lysis time (P = 0.05) occurred with the long boots. This study shows intermittent calf compression increases fibrinolytic potential locally and this effect can be demonstrated systemically. The greater the volume of tissue compressed, the greater the response. The efficacy of intermittent venous compression in reducing the incidence of deep venous thrombosis may be due, in part, to localized induction of fibrinolysis.

An objective study of alternative methods of heparin administration

The efficacy and safety of two methods of heparin administration was investigated; 100 patients with calf vein thrombosis were randomly allocated to receive either subcutaneous (SC) or intravenous (IV) heparin for seven days. Venography was performed in each patient to confirm the exact size and site of thrombus and was repeated at the end of heparin treatment. IV heparin was administered using a constant infusion pump. The dose of heparin to be administered was determined by daily estimation of KCCT. In SC group, thrombi increased in size in 2%, remained unchanged in 50% and decreased in 48%. In the IV group, they increased in size in 20%, were unchanged in 62% and decreased in 18%. The difference in decreases in size was significant (p<0.01). Pretreatment lung scans confirmed the presence of emboli in 10 patients in SC and II in IV group; post-treatment scan showed improvement in 60% in SC compared to 91% in IV group. The mean daily heparin requirement (± SD) was 36,998 ± 7.121 IU in the SC group and 36,814 ± 6.63 IU in the IV group. The average KCCT fluctuation index in the SC group was 59.08 sees compared to 64.6 seconds in the IV group. Major bleeding complications occurred in 2 patients on SC heparin and in 4 treated with IV heparin. Subcutaneous injection appears to be a suitable method for administering doses of heparin for treating patients suffering from calf vein thrombosis.

Reliability of Doppler ultrasound in the diagnosis of acute venous thrombosis both above and below the knee

We have found the Doppler examination to be accurate in 92 per cent of limbs with suspected iliofemoral thrombosis and in 86 per cent of limbs with suspected calf vein thrombosis. Above the knee, the sensitivity was 94 per cent and the specificity, 90 per cent. Below the knee, the sensitivity was 91 per cent and the specificity, 84 per cent. In the hands of a skilled examiner, Doppler ultrasound is a reliable noninvasive technique for evaluating patients with suspected deep venous thrombosis and one on which therapy can safely be based.