Epidemiologic characteristics, management, and outcome of deep venous thrombosis in a tertiary-care hospital: the Brigham and Women's Hospital DVT registry

The Effect of Venous Thromboembolism on Survival of Cancer Patients and its Relationship with Serum Levels of Factor VIII and Vascular Endothelial Growth Factor: A Prospective Matched-Paired Study

Background

Venous thromboembolism (VT) increases mortality and morbidity in cancer patients. The primary aim of this study was to evaluate the effect of VT on the survival of cancer patients and its relationship with serum vascular endothelial growth factor (VEGF) and plasma factor VIII levels.

Patients and methods

Eighty-two patients with locally advanced or metastatic cancer were included in this study between September 2001 and March 2004, and 31 of them had VT. Fifty-one matched-paired cancer patients without VT were prospectively selected as a control group in the same period. Criteria for the selection of control group patients were having the same malignancy, stage, metastatic site, performance status and age (±5 years) as patients in the VT group.

Results

Plasma factor VIII and serum D-dimer levels in the VT group were significantly higher than those in the control group (p=0.030 and p=0.016, respectively). However, mean serum VEGF levels were similar in both groups (p=0.199). In the VT group, the median survival of patients who had higher serum VEGF levels (>150 pg/mL) was significantly shorter than that of patients in the same group with lower serum VEGF levels (p=0.005). The median survival of the VT group was 14 months, whereas it was 25 months in the control group (p=0.199).

Conclusion

There was a worse prognostic trend for cancer patients with VT. Nevertheless, the difference in survival was not statistically significant between the groups. Plasma factor VIII and serum D-dimer levels might have prognostic value in cancer patients with VT. Cancer patients with VT and higher serum VEGF levels had a significantly poorer prognosis.

Evidence-Based Therapies for Pharmacologic Prevention and Treatment of Acute Deep Vein Thrombosis and Pulmonary Embolism

Venous thromboembolism (VTE) remains a significant mortal and morbid disease. The major risks have not changed and many patients present with unprovoked VTE disease. Prevention of VTE in hospitalized patients depends on comprehensive risk factor assessment, with an individual risk score. Proper and timely prophylaxis with mechanical, pharmacologic, or both is then effective. Treatment of VTE with parenteral anticoagulation followed by either a direct oral anticoagulant or warfarin is standard to reduce risk of VTE recurrence and death. Selected cases of iliofemoral deep vein thrombosis may be treated by pharmacomechanical thrombolysis, but more data are needed before this is standard of care.

Management and adherence to VTE treatment guidelines in a national prospective cohort study in the Canadian outpatient setting

Documenting patterns and outcomes of venous thromboembolism (VTE) management and degree of adherence by clinicians to treatment guidelines could help identify remediable gaps in patient care. Prospective, clinical practice-based data from Canadian outpatient settings on management of VTE, degree of adherence with treatment guidelines and frequency of recurrent VTE and bleeding during follow-up was obtained in a multicentre, prospective observational study. From 12 Canadian centres, we assessed 868 outpatients with acute symptomatic VTE who received the low-molecular-weight heparin (LMWH) enoxaparin alone or with vitamin K antagonists (VKA), at baseline and at six months (or at the end of treatment, whichever came first). Index VTE was limb deep venous thrombosis (DVT) in 583 (67.2%) patients, pulmonary embolism (PE) with or without DVT in 262 (30.2%) patients, and unusual site DVT in 23 (2.6%) patients. VTE was unprovoked in 399 (46.0%) patients, associated with cancer in 74 (8.5%) patients, transient risk factors in 327 (37.7%) patients and hormonal factors in 68 (7.8%) patients. With regard to guideline adherence, 58 (7.3%) patients received <5 days LMWH and 114 (14.5%) had overlap <1 day. Among patients with cancer-related VTE, 59.5% were prescribed LMWH monotherapy and 43.2% received such treatment for >3 months. Only 38.1% of patients with transient VTE risk factors had received thromboprophylaxis. Our study provides useful information on clinical presentation, management and related outcomes in Canadian outpatients with VTE. Our results suggest there may be important gaps in use of thromboprophylaxis to prevent VTE and use of LMWH mono-therapy to treat cancer-related VTE.

Note: Part of this study was presented as an Oral Abstract Presentation at the American Society of Hematology meeting, Dec. 4–7, 2010, Orlando, FL, USA.

Natural history of nonimmune-mediated thrombocytopenia and acute kidney injury in pediatric open-heart surgery

OBJECTIVE

Thrombocytopenia and acute kidney injury (AKI) are common following pediatric cardiac surgery with cardiopulmonary bypass (CPB). However, the relationship between postoperative nadir platelet counts and AKI has not been investigated in the pediatric population. Our objective was to investigate this relationship and examine independent predictors of AKI.

DESIGN

After IRB approval, we performed a retrospective review of the institution's medical records and database.

SETTING

This study was performed at a single institution over a 5-year period.

PATIENTS

We included patients <21 years of age undergoing cardiac surgery with CPB.

INTERVENTIONS

Demographics, laboratory, and surgical characteristics were captured, and clinical event rates were recorded.

MEASUREMENTS

Descriptive statistics were used to evaluate platelet and creatinine distributions. T-tests and chi-squared tests were used to compare characteristics among Acute Kidney Injury Network groups. Multivariable logistic and ordinal logistic regression models were used to determine the association of our predictor of interest, postoperative nadir platelet count and AKI.

RESULTS

Eight hundred and fourteen patients (23% infants and 23% neonates) were included in the analysis. Postoperative platelet counts decreased 48% from baseline reaching a mean nadir value of 150 × 10⁹ ·l^-1 on postoperative day 3. AKI occurred in 37% of patients including 13%, 17%, and 6% with Acute Kidney Injury Network stages 1, 2, and 3, respectively. The magnitude of nadir platelet counts correlated with the severity of AKI. Independent predictors of severity of AKI include nadir platelet counts, CPB time, Aristotle score, patient weight, intra-operative packed red blood cell transfusion, and having a heart transplant procedure.

CONCLUSIONS

In pediatric open-heart surgery, thrombocytopenia and AKI occur commonly following CPB. Our findings show a strong association between nadir platelet counts and the severity of AKI.

Incidence of and mortality from venous thromboembolism in a real-world population: the Q-VTE Study Cohort

BACKGROUND

The public health burden of venous thromboembolism, which includes deep vein thrombosis and pulmonary embolism, is not fully known, and contemporary incidence and mortality estimates are needed. We determined the incidence and case fatality of venous thromboembolism in a general population.

METHODS

Using the administrative health care databases of the Canadian province of Québec, we identified all incident cases of deep vein thrombosis or pulmonary embolism between 2000 and 2009 and classified them as definite or probable venous thromboembolism. We formed 2 patient cohorts, one with definite cases and the other including cases with definite or probable venous thromboembolism that were followed until December 31, 2009.

RESULTS

We identified 67,354 definite and 35,123 probable cases of venous thromboembolism. The age- and sex-adjusted incidence rates of definite or probable venous thromboembolism, deep vein thrombosis, and pulmonary embolism were 1.22 (95% confidence interval [CI], 1.22-1.23), 0.78 (95% CI, 0.77-0.79), and 0.45 (95% CI, 0.44-0.45) per 1000 person-years, respectively, while for definite venous thromboembolism it was 0.90 (95% CI, 0.89-0.90) per 1000 person-years. The 30-day and 1-year case-fatality rates after definite or probable venous thromboembolism were 10.6% (95% CI, 10.4-10.8) and 23.0% (95% CI, 22.8-23.3), respectively, and were slightly higher among definite cases. The 1-year survival rate was 0.47 (95% CI, 0.46-0.48) for cases with definite or probable venous thromboembolism and cancer, 0.93 (95% CI, 0.93-0.94) for cases with unprovoked venous thromboembolism, and 0.84 (95% CI, 0.83-0.84) for cases with venous thromboembolism secondary to a major risk factor. Similar survival rates were seen for cases with definite venous thromboembolism.

CONCLUSION

The risk of venous thromboembolism in the general population remains high, and mortality, especially in cancer patients with venous thromboembolism, is substantial.

Venous thromboembolism in patients with cancer and its relationship to the coagulation cascade and vascular endothelial growth factor

Venous thromboembolism (VTE) is a well-recognized problem in malignancy. Patients with cancer who have VTE have a worse prognosis than other patients with cancer. Hypercoagulability in patients with cancer is related to malignancy itself and its treatment. These patients have multiple risk factors for thromboembolism, such as being immobilized, having central venous catheters, and receiving chemoradiation therapy. Cancer procoagulant, tissue factor, factor VIII, and thrombin have important roles in causing cancer-associated thromboembolism. Tumors require neovascularization for delivering oxygen and other nutrients. Therefore, angiogenesis facilitates tumor growth, invasion, and metastasis. New blood vessels formed by angiogenesis are thrombogenic. Hypercoagulability and tumor growth are closely related. Vascular endothelial growth factor (VEGF) is a proangiogenic factor that may also cause VTE in patients with cancer. The relationship between cancer, angiogenesis, VEGF, and thrombosis is reviewed herein. Studies are ongoing to enhance our understanding of this complex interaction.

Current status of the Korean venous thromboembolism registry

The Korean venous thromboembolism (VTE) registry, which was initiated by the Working Parties of Korean Society on Thrombosis and Hemostasis, and the Korean Society of Hematology, is a web-based multicenter registry (http://kdvt.chamc.co.kr) for recruiting consecutive VTE patients. The aim of the registry is to prospectively collect data on the epidemiology and clinical outcomes of VTE from a large, unselected cohort of patients, and to provide data on the true incidence and management of VTE in the real-world. By the end of 2007, the starting year of the registry, 840 patients were registered. By the end of 2008, 1,121 were registered, with 1,289 by the end of 2009, and 1,463 by April 2010 from 11 hospitals. The first report on the epidemiologic characteristics of 596 consecutive VTE patients was released in October 2007.

A study of hospital discharges for venous thromboembolism in the south of Spain. An analysis of 19,170 cases from a regional database from 1998 to 2001

BACKGROUND

Our objective was to learn about the incidence of hospitalization for venous thromboembolism (VTE) in the public health care system in Andalusia and to define the profile of the patients, with special reference to the Department of Internal Medicine.

METHODS

We analyzed the discharged data set of 32 hospitals in the Andalusian Health Care Service between 1998 and 2001, identifying the cases in whom the diagnosis was VTE. The age, sex, length of stay, outcome, number of diagnoses, diagnosis-related group (DRG), and coded procedures were studied.

RESULTS

During the period studied, there were 2,228,894 discharges, 19,170 of which involved VTE. In 8494 of these, VTE was the cause of the admission. Some 3961 patients (46.6%) were admitted for pulmonary embolism (PE); 45% were discharged from internal medicine, 41% from pneumology, and 14% from other departments. The average patient age was 65, the length of stay 13.8 days, and the global in-hospital mortality rate 13%. Some 4533 cases (53.4%) were admitted due to deep vein thrombosis (DVT): 38.5% to internal medicine, 21.30% to general surgery, 12.35% to angiology, and the remainder to other departments. The length of stay was 10.6 days with an in-hospital mortality rate of 2.20%. In 7721 cases, VTE was the secondary diagnosis (after excluding 2955 cases of superficial thrombophlebitis of the upper limbs); 74% was associated with a medical DRG.

CONCLUSIONS

VTE is a frequent pathology in our hospitals. It shows a great variability in clinical practice although there are differences between patients treated by different specialists. VTE as secondary diagnosis was more frequent in medical inpatients.

Deep vein thrombosis and pulmonary embolism in two cohorts: the longitudinal investigation of thromboembolism etiology

PURPOSE

To determine the incidence of deep vein thrombosis and pulmonary embolism in two cohorts representing regions of the United States.

METHODS

The sample comprised 21,680 participants of the Atherosclerosis Risk in Communities study and the Cardiovascular Health Study. Subjects were aged >/=45 years, resided in six communities, and were followed for 7.6 years. All hospitalizations were identified and thromboses were validated by chart review.

RESULTS

The age-standardized incidence of first-time venous thromboembolism was 1.92 per 1000 person-years. Rates were higher in men than women, and increased with age in both sexes. There was no antecedent trauma, surgery, immobilization, or diagnosis of cancer for 48% (175/366) of events. The 28-day case-fatality rate was 11% (29/265) after a first venous thromboembolism and 25% (17/67) for cancer-associated thrombosis. The recurrence rate 2 years after a first venous thromboembolism was 7.7% per year (95% confidence interval [CI]: 4.5% to 10.9% per year). Cancer was the only factor independently associated with 28-day fatality (relative risk [RR] = 5.2; 95% CI: 1.4 to 19.9) or recurrent thrombosis (RR = 9.2; 95% CI: 2.0 to 41.7).

CONCLUSION

The incidence of venous thromboembolism in this cohort of middle- and older-aged subjects was similar to that observed in more geographically homogeneous samples. Half of cases were idiopathic. Short-term mortality and 2-year recurrence rates were appreciable, especially among subjects with cancer. Based on this study we estimate that 187,000 cases of first-time venous thromboembolism are diagnosed yearly in the United States among those aged 45 years or older.

A prospective registry of 5,451 patients with ultrasound-confirmed deep vein thrombosis

We enrolled 5,451 patients with ultrasound-confirmed deep vein thrombosis (DVT), including 2,892 women and 2,559 men, from 183 United States sites in our prospective registry. The 5 most frequent co-morbidities were hypertension (50%), surgery within 3 months (38%), immobility within 30 days (34%), cancer (32%), and obesity (27%). Of the 2,726 patients who had their DVT diagnosed while in the hospital, only 1,147 (42%) received prophylaxis within 30 days before diagnosis.

Inferior Vena Cava Filter is a New Additional Therapeutic Option to Reduce Mortality From Acute Pulmonary Embolism

BACKGROUND

There are few reports that examine the current imaging and management techniques according to the severity of acute pulmonary embolism (APE) or that clarify whether the management strategy ameliorated the mortality from APE.

METHODS AND RESULTS

The study group were 456 patients with APE who were clinically diagnosed before their death. The severity at diagnosis, and the imaging and management techniques were analyzed. Mortality from APE was 0.8% in patients without shock nor right ventricular overload, 2.7% in patients with right ventricular overload without shock, 15.6% in patients with shock, and 52.4% in patients with cardiopulmonary arrest (p<0.0001). In the more severe cases, pulmonary angiography and trans-thoracic echocardiography were used more frequently, whereas both ventilation and perfusion lung scans were used less frequently. Computed tomography was used widely, regardless of the severity. Thrombolytic therapy and catheter therapy were used more frequently in the more severe cases, but an inferior vena cava filter was the only management strategy that reduced the mortality from APE.

CONCLUSIONS

The severity of APE at diagnosis affected the selection of both the diagnostic techniques and the type of management. Implantation of inferior vena cava filters reduced the mortality from APE.

The management and outcome of acute venous thromboembolism: a prospective registry including 4011 patients

OBJECTIVE

To obtain a realistic overview of management and clinical outcomes of patients with venous thromboembolism (VTE) in Spain on the basis of data from a national multicenter registry.

METHODS

A prospective registry was initiated in Spain in March 2001. Data were collected from patients with objectively confirmed deep vein thrombosis (DVT) and/or pulmonary embolism (PE) and entered into the online registry by physicians who were responsible for the management of these patients.

RESULTS

As of August 2002, 4011 patients with confirmed VTE were included in the registry: 60% with DVT, 23% with PE, and 17% with both DVT and PE. Diagnostic methods for VTE included compression ultrasonography (86%), venography (10%), V/Q lung scans (42%), computed tomography scan (28%), and pulmonary angiography (0.9%). D-dimer testing was performed in 61% of cases and was positive in 92% of patients with confirmed VTE. The majority of DVT (95%) were located in the lower extremities (82% proximal and 4% bilateral), while 4.8% were located in the upper extremities or neck veins. Most patients (90.5%) were admitted to hospital. In the acute phase, treatment consisted of low molecular weight heparin (LMWH) in 88%, unfractionated heparin (UFH) in 11%, and fibrinolysis in 0.8%. Cava filters were inserted in 2% of patients, mainly because of active bleeding (13%), increased hemorrhagic risk (38%), or recurrent VTE (29%). Absolute bed rest was recommended to 63% of patients. Secondary prevention of VTE included oral anticoagulants (75%) and LMWH (24.5%). Therapeutic compression stockings were prescribed to 53% of patients at the time of hospital discharge. Regarding the main clinical outcomes during an average (+/-SD) follow-up period of 156 +/- 95 days, 19% had adverse events: 12.5% of patients died, 5.5% had clinically confirmed VTE recurrence, and 9.8% suffered bleeding complications (44% with major bleeding).

CONCLUSIONS

This prospective observational multicenter registry provides a large database reflecting the actual day-to-day clinical practice regarding VTE management in a European country. The most important findings were the increasing use of spiral computed tomography for PE diagnosis, the unexpectedly high proportion of patients admitted to hospital despite the use of LMWH in almost 90% of cases in the acute phase, and the utilization of LMWH for secondary prevention in almost 25% of cases. On the other hand, this large-scale prospective registry permits on-line consultation of high-risk situations to assess how difficult cases were treated and what their outcomes were. This will provide a most useful tool for the practicing physician responsible for the management of VTE patients.

Venous thromboembolism guidebook

This venous thromboembolism guidebook incorporates evolving contemporary concepts in diagnosis and management of pulmonary embolism (PE) and deep venous thrombosis (DVT) into a user-friendly menu. The purpose of this document is to provide a literature-based review of the current clinical approach to venous thromboembolism and up-to-date references for further study in this important topic.

Epidemiology of venous thromboembolic disease

From the information presented in this article, it can be concluded that clinical suspicion of VTE should be increased in patients with a history of VTE, recent surgery, spinal cord injury, trauma, or malignancy. A variety of medical illnesses also increase the risk of venous thrombosis, including congestive heart failure, myocardial infarction, stroke with paresis, nephrotic syndrome, cigarette smoking, and obesity. Hypercoagulable states, such as antithrombin III deficiency, protein C deficiency, protein S deficiency, or factor V Leiden mutation should be considered in those patients who develop VTE in the absence of known risk factors. Additionally, the presence of vena caval filters does not exclude the possibility of PE or recurrent DVT. With a careful assessment of risk, physicians can hope to increase the diagnostic yield of VTE and decrease the significant morbidity and mortality of caused by this disease.

Alteration of haemostasis in non-metastatic gastric cancer

BACKGROUND

Cancer is one of the most common acquired causes of venous thromboembolism.

AIM

To evaluate haemostasis disorders in patients with non-metastatic gastric cancer.

PATIENTS AND METHODS

We studied 11 patients with non-metastatic gastric cancer (9 males and 2 females, median age 54 years) and 20 healthy subjects (15 males and 5 females, median age 48 years) control. We measured prothrombin time, activated partial thromboplastin time, coagulation time, clot lysis time, fibrinogen, clotting factors (II, VII, VIII, IX, X), C protein, S protein, AT III, activated protein C resistance, prothrombin 1+2 fragment, tissue plasminogen activator and D-Dimer in all subjects.

RESULTS

Fibrinogen plasma levels were significantly higher in patients with non-metastatic gastric cancer than in control group (505+/-24 mg/dl vs 336+/-30 mg/dl, p<0.001). We also found a significant increase in prothrombin 1+2 fragment plasma concentration compared with controls (3.8+/-0.6 nM vs 0.83+/-0.09 nM, p<0.001). Plasma D-dimer levels were 20-fold higher in patients with non-metastatic gastric cancer compared with controls (9.57+/-0.4 ng/dl vs 0.4+/-0.05 ng/dl, p<0.001). Also tissue plasminogen activator was significantly higher in gastric cancer patients than in controls (20.8+/-2.32 ng/ml vs 9.1+/-1.37 ng/ml, p<0.01). Finally clot lysis time was significantly accelerated in gastric cancer patients compared with control subjects (81+/-37 min vs 233+/-74 min, p<0.01).

CONCLUSIONS

Patients with non-metastatic gastric cancer are at risk for thrombotic events due to the combined increase in fibrinogen plasma levels and thrombin formation.

D-dimer testing: the role of the clinical laboratory in the diagnosis of pulmonary embolism

Pulmonary embolism is a common, yet often unsuspected and unrecognised disease associated with a high mortality. New, objective, "user friendly" and cost effective diagnostic strategies are being explored. D-dimers, the fibrinolytic degradation products of crosslinked fibrin, have emerged as the most useful of the procoagulant activity and ongoing fibrinolysis markers. D-dimer measurements are very sensitive in excluding a diagnosis of pulmonary embolism in the setting of normal values, a low clinical suspicion, and non-diagnostic lung scans. Several assays have been developed and are reviewed.

Does the location of thrombosis determine the risk of disease recurrence in patients with proximal deep vein thrombosis?

PURPOSE

To determine if the location of deep vein thrombosis is a predictor of recurrent venous thromboembolism during the initial 3 months of anticoagulant therapy.

METHODS

The study population consisted of 1,149 consecutive patients with symptomatic proximal deep vein thrombosis. In all patients, deep vein thrombosis was confirmed by Duplex ultrasound or venography and was classified as popliteal, femoral, or iliofemoral. Patients received initial treatment with unfractionated heparin, enoxaparin, or reviparin for least 4 days, as well as a coumarin derivative, with a target international normalized ratio of 2.0 to 3.0, starting on the 1st or 2nd day of treatment. All patients were followed for 3 months, and all episodes of recurrent venous thromboembolism were confirmed with objective diagnostic tests.

RESULTS

The overall rate of recurrent venous thromboembolism during the initial 3 months of anticoagulant therapy was 5.5% (63/1,149). The rate of recurrence in patients with popliteal vein thrombosis was 5.1% (23/453); in patients with femoral vein thrombosis, it was 5.3% (34/645); and in patients with iliofemoral vein thrombosis, it was 11.8% (6/51). Two clinical risk factors were associated with an increased risk of recurrent venous thromboembolism: iliofemoral vein thrombosis (odds ratio [OR] = 2.4; 95% confidence interval [CI]: 0.95, 5.9), and cancer (OR = 2.6; 95% CI: 1.5, 4.4).

CONCLUSIONS

Patients with extensive iliofemoral vein thrombosis who receive conventional anticoagulant therapy have a greater than twofold higher risk of developing recurrent venous thromboembolism than patients without iliac vein involvement (i.e., 11.8% vs. 5.2%). Prospective studies are needed to determine whether alternative antithrombotic strategies are warranted in such patients.

Diagnosis of deep venous thrombosis

Although deep venous thrombosis (DVT) is often considered an elusive disease that is difficult to recognize clinically, important clinical clues and properly ordered imaging tests can reliably detect or exclude this condition. This article will provide a practical approach to recognizing clinical settings in which DVT should be suspected, suggesting a focused history and physical examination and outlining optimal strategies for test ordering. This information will help ensure that patients with DVT are identified rapidly and, conversely, that those without DVT will receive reassurance or specific treatment for the medical problem that mimics it. Once DVT is suspected, a workup can proceed rapidly and accurately to resolve the diagnostic issue.

The anatomy of deep venous thrombosis of the lower extremity

BACKGROUND

The diagnosis, treatment, and long-term sequelae of lower extremity deep venous thrombosis (DVT) depend on the anatomic location and extent of the process, yet a lack of such fundamental knowledge has limited the development of effective protocols for managing patients with DVT.

METHODS

Venograms with evidence of acute DVT were evaluated, and the extent of the thrombotic process was recorded and correlated with the clinical presentation. Thrombi were classified according to the venous segments involved and to the thrombus' isolation to one segment or multiple segments. The left-to-right ratio of the DVT was assessed for various etiologic subgroups.

RESULTS

Among 2762 venograms performed in 2541 patients over a 10-year period, there were 885 cases (34.8%) of DVT documented. Of these cases, 344 cases (39%) were idiopathic, 307 cases (35%) were postoperative, 84 cases (10%) occurred in the setting of malignancy, and 70 cases (8%) occurred as the result of trauma. Distal thrombi were more common than proximal thrombi, with calf involvement in 734 patients (83%), femoropopliteal involvement in 470 patients (53%), and iliac involvement in 75 patients (9%). The most common site of thrombus was the peroneal vein, which was involved in 595 patients (67%). The ratio of left-to-right-sided DVT was 1.32:1 overall but was greater for proximal thrombi, with a ratio of 2.4:1 for iliac DVT versus 1.3:1 for infrainguinal DVT. The preponderance of left-sided DVT appeared to be related to the high-frequency, left common iliac vein involvement; the left-to-right ratio was much closer to equality (1.09:1) for isolated infrainguinal DVT. The anatomic configuration of the DVT was correlated with the etiologic subgroup; postoperative DVTs were more often distal, whereas DVT developing in the setting of malignancy was more frequently proximal and often right sided. Proximal, left-sided DVTs were common in the idiopathic subgroup, presumably as a result of undiagnosed left iliac vein webs.

CONCLUSIONS

The frequency of distal vein involvement greatly exceeds that of proximal involvement in patients with DVTs. Proximal DVTs are more frequently left sided, whereas distal DVTs occur with a more equal left-to-right distribution. The anatomic extent of DVTs appears to depend on the etiology of the process. These observations may shed light on the pathophysiology of venous thrombosis. The findings are of value in planning therapeutic interventions directed at venous recanalization.

[Fibrinolytic therapy of deep vein thrombosis]

BACKGROUND

The most important complications of deep vein thrombosis are pulmonary embolism and postthrombotic syndrome. While the medicine of lethal pulmonary embolism is reduced to less than 2% by conventional anticoagulation, fibrinolytic therapy aims at a reduction of the greater than 50% incidence of postthrombotic syndrome. The optimal therapeutic regimen concerning risks and effect has not been established yet.

RESULTS

A review of 26 studies involving ultrahigh-dose streptokinase (UHSK), urokinase (UK), and tissue-type plasminogen activator (rt-PA) shows the highest success rate for UHSK (45% complete and 40% parital patency), whereas there are lower rates for UK (25% and 40%) and low-dose locoregionally applied rt-PA (22% and 44%). The studies were not directly comparative, however. Published data concerning complications range from 1.7% mortality for UHSK to 0.9% for UK and 0.0% for rt-PA. Success criteria, however, are varying and not well defined. The influence of fibrinolytic therapy on the incidence of postthrombotic syndrome has not been established prospectively, but a reduction by 40 to 50% can be assumed. Calf vein thromboses are not indication for lytic therapy. In patients with iliacal vein thromboses there is an increased risk of pulmonary embolism using UHSK.

CONCLUSIONS

UHSK can be regarded the standard concerning success rate in deep vein thromboses. DATA involving locoregional therapy with rt-PA are inconsistent and worse, but bleeding complications might be less frequent. Large prospective studies evaluating the impact on incidence and severity of the postthrombotic syndromes, which involve a controlled application of compression therapy are needed.