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PubMed1997

The Varying Behavior of Stent Thrombosis in Native Coronary Arteries Versus Aorto-Coronary Saphenous Vein Bypass Grafts.

Out-of-lab closure due to stent thrombosis is a major limitation of stent implantation. In this report, the incidence of stent thrombosis in native coronary arteries is compared to saphenous vein bypass grafts. Elective stent placement was performed in 1,782 patients. Overall, stent thrombosis occurred in 64 (3.6%) of patients. There was a significantly higher incidence of stent thrombosis in native coronary arteries (56/1153, 4.9%) compared with venous bypass grafts (8/629, 1.3%), (p < 0.0001). Multivariate analysis demonstrated vessel size to be the most important predictor of stent thrombosis. We conclude that stent thrombosis occurs less frequently in vein bypass grafts and that the risk in the native circulation is inversely related to vessel size.

Journal Article↗
PubMed2002

Diagnosing deep vein thrombosis in the lower extremity: correlation of clinical and duplex scan findings.

OBJECTIVE: To identify factors that predict a positive duplex scan examination result in patients with suspected deep vein thrombosis of the lower extremity. DESIGN: Retrospective study. SETTING: Vascular laboratory in a university teaching hospital. PATIENTS AND METHODS: The results of 345 lower extremity duplex venous scans performed between August 1994 and November 1998 were reviewed. All patients were in-patients referred from different specialties due to clinical suspicion of lower extremity deep vein thrombosis. Positive duplex scans were correlated with patients' demographic data (sex, age), medical history (history of malignancy, deep vein thrombosis, and pulmonary embolism) and clinical features (leg swelling, venous insufficiency, calf pain, and leg ulcer). Univariate analysis was performed using the Chi squared test. RESULTS: A total of 345 scans were performed for 313 patients. The mean age was 55 years (range, 19-92 years). Sixty-three patients (49 male, 14 female) had a positive scan, giving a yield of 18.3%. Four factors had a significant association with a positive scan: male sex (P=0.0102), history of malignancy (P=0.0040), history of deep vein thrombosis (P=0.0001), and history of pulmonary embolism (P=0.0265). CONCLUSIONS: Common presenting clinical features do not predict the result of ultrasonographic investigation for deep vein thrombosis. The chance of having a positive scan is significantly higher in male patients and those with a history of malignancy, deep vein thrombosis, or pulmonary embolism.

Adult↗
PubMed1992

Importance of platelets in experimental venous thrombosis in the rat.

Venous thrombosis was induced by ligature of the inferior vena cava in rats whose blood was made hypercoagulable by intravenous (IV) administration of tissue thromboplastin. From a dose-response showing that the administration of increasing doses of tissue thromboplastin resulted in a subsequent progressive increase of thrombus weight, two concentrations of tissue thromboplastin were chosen: a high dose (550 microL/kg, IV) where thrombus formation was optimal and a concentration (7 microL/kg, IV) where tissue thromboplastin-hypercoagulability was intermediate. In both experimental conditions, leukopenia provoked by a myelotoxic drug did not influence the development of venous thrombosis. However, after thrombocytopenia induced by an antiplatelet antiserum, a dramatic decrease in thrombus formation was observed in animals that had been pre-challenged with the lower dose of tissue thromboplastin, whereas decrease in platelet count did not affect venous thrombosis under high thrombogenic challenge. When administered orally 2 hours before thrombosis induction, the ticlopidine analogue clopidogrel showed dose-dependent inhibition of thrombus formation in animals that were pre-challenged with a low dose of tissue thromboplastin (ED50 = 7.9 +/- 1.5 mg/kg, orally) but remained ineffective against high tissue thromboplastin-induced venous thrombosis. We further determined the effect of heparin and hirudin, and showed that both of these drugs exhibited a more potent antithrombotic activity after injection of the lower dose of tissue thromboplastin than after injection of a high dose of tissue thromboplastin. Therefore, using our model of stasis and hypercoagulability, platelet activation played a major role in the development of venous thrombosis when the thrombogenitic stimulus was mild.

Animals↗
PubMedDate not supplied

Colour duplex scanning and phlebography in deep vein thrombosis.

Clinical evaluation of deep venous thrombosis is often unreliable. Recently it has been shown that deep venous thrombosis may be detected with colour duplex scanning which is safer than phlebography. However it is not clear how colour duplex correlates with phlebography. One hundred and twenty consecutive patients with suspected deep vein thrombosis were studied by colour duplex scanning and phlebography to compare the two methods. Both tests were positive in 102 limbs and negative in 16 limbs. In two cases of below-knee thrombosis colour duplex was negative while phlebography showed small localised thrombosis. The sensitivity of colour duplex was 98%, its specificity and positive predictive value 100% and its negative predictive value 88.8%. In conclusion colour duplex appears to be as effective as phlebography in detecting deep venous thrombosis above knee.

Adult↗
PubMedDate not supplied

Atraumatic subclavian vein thrombosis in a collegiate baseball player: a case report.

OBJECTIVE: To introduce the case of a collegiate baseball player who suffered an atraumatic subclavian vein thrombosis. This case presents an opportunity to discuss the diagnosis and treatment of a 22-year-old male with a thrombosis of his right subclavian vein. BACKGROUND: Upper extremity deep venous thrombosis is an uncommon vascular problem, occurring primarily in young, healthy, active people. Although the history and symptoms are often unremarkable, the condition can lead to complications if not correctly recognized and appropriately treated. In this case, the athlete reported tightness in his right biceps muscle and upper back after sleeping on his shoulder. The patient denied substance abuse or illegal anabolic steroid use, and these possibilities were ruled out as factors in the diagnosis and treatment. DIFFERENTIAL DIAGNOSIS: Shoulder tendinitis, thoracic outlet syndrome, primary upper extremity thrombosis of the right subclavian vein. TREATMENT: After diagnosis, the patient was placed on blood thinners to dissolve the clot and referred to a vascular surgeon. The patient underwent a balloon angioplasty and later had the first rib removed. A second clot formed, and a stent was placed in the vein after the clot was removed by medication and another angioplasty procedure. He developed a pulmonary embolism during the stent procedure and was sent postoperatively to the intensive care unit, where he underwent therapeutic anticoagulation. After 10 weeks of therapy, the patient stopped all anticoagulant medication and returned to school to play baseball. UNIQUENESS: We present the atraumatic pathogenesis of a subclavian venous thrombosis in a young, active, and otherwise healthy college athlete with unremarkable predisposing factors. Within 24 hours after rib resection, the subclavian vein rethrombosed. The patient was thought to have experienced a small pulmonary embolus. CONCLUSIONS: Individuals who participate in athletics can develop atraumatic upper extremity deep venous thrombosis. Therefore, it is important that team physicians and certified athletic trainers be prepared to recognize the signs and symptoms of this condition to institute prompt, appropriate treatment.

Journal Article↗
PubMed1990

Prevention of venous thrombosis after total knee arthroplasty. Comparison of antithrombin III and low-dose heparin with dextran.

In a prospective, randomized trial, we compared the efficacy of a combination of antithrombin III and heparin with that of dextran 40 as prophylaxis against venous thrombosis after total knee arthroplasty. Ascending venography identified thrombosis in about one-third of the patients who received the combination of antithrombin III and heparin, compared with about four-fifths of those who received dextran (p less than 0.001). In both groups, the patients who had venous thrombosis had a significantly lower concentration of antithrombin III postoperatively than those who did not have thrombosis. Venous thrombosis occurred in all patients in whom the concentration of antithrombin III was less than 65 per cent postoperatively. These findings demonstrated that, after total knee replacement, the combination of antithrombin III and heparin effectively reduces the incidence of postoperative venous thrombosis and is significantly better than dextran. Furthermore, the findings suggested a relationship between postoperative deficiency of antithrombin III and the occurrence of thrombotic complications.

Adult↗
PubMed1991

Deep vein thrombosis and fibrinolysis. Defective urokinase type plasminogen activator release.

In the present study 57 consecutive patients with a first episode of venographically proven deep vein thrombosis were investigated to evaluate the release of tissue-type plasminogen activator (t-PA) and of urokinase-type plasminogen activator (u-PA) in response to DDAVP stimulation as well as the resting plasminogen activator inhibitor (PAI) concentration, comparing this to the results obtained in 66 similar patients with a clinical suspicion of thrombosis but with a normal venogram. All assays were performed without knowledge of the patient's status. Four patients in the deep vein thrombosis-group (7%) had an absent u-PA antigen response upon DDAVP infusion, while a normal response was observed in all control subjects. Patients and controls showed similar increases in t-PA antigen level upon DDAVP. High resting PAI antigen levels were encountered in 5 patients in the deep vein thrombosis-group (9%) and in 6 subjects in the control group (9%). The results from this controlled study indicate that a defective release of u-PA may occur in patients with deep vein thrombosis and may have pathogenetic significance. Furthermore it is concluded that elevation of PAI levels cannot be considered as a specific risk factor for venous thrombosis.

Antigens↗
PubMed1991

A new computerized impedance plethysmograph: accuracy in the detection of proximal deep-vein thrombosis in symptomatic outpatients.

Because of the lack of specificity of the clinical diagnosis it is appropriate in patients with clinically suspected deep-vein thrombosis to apply an objective test before starting anticoagulant treatment. Impedance plethysmography is a highly accurate technique for the detection of proximal-vein thrombosis with a reported sensitivity and specificity of 93 and 97%, respectively. In all previous reported evaluations of impedance plethysmography an apparatus which was developed in 1971 was used. A new computerized impedance plethysmography, using a novel device to measure impedance, was blindly compared against venography in 443 consecutive outpatients with clinically suspected deep-vein thrombosis. In the first phase of the study the computerized impedance plethysmography test results of 242 symptomatic patients were used to develop a discriminant line. Subsequently, this discriminant line was validated in the second phase of the study in another 201 symptomatic patients. The combined sensitivity and specificity of these two phases for proximal-vein thrombosis was 91% [95% confidence interval (CI), 86 to 94%] and 94% and (95% CI, 90 to 96%), respectively, which compares favourably with impedance plethysmography. It is concluded that computerized impedance plethysmography is a simple, portable, non-invasive technique with a high accuracy for the detection of proximal vein thrombosis. However, before computerized impedance plethysmography can be used as the only test in the diagnosis of deep-vein thrombosis, the safety of withholding anticoagulant treatment to patients with repeated normal computerized test results should be assessed during long-term follow-up studies.

Adolescent↗
PubMed1991

Failure of computerized impedance plethysmography in the diagnostic management of patients with clinically suspected deep-vein thrombosis.

Before a new diagnostic modality can be introduced in clinical medicine, the validity of both a normal and abnormal test result have to be assessed prospectively in an appropriate patient group. We have evaluated the clinical validity of a new computerized impedance plethysmography (CIP) in the diagnostic management of 381 consecutive patients with clinically suspected venous thrombosis. In patients with serially normal CIP results, the diagnosis of venous thrombosis was refuted and, consequently, they were not treated with anticoagulant therapy and all were followed up for a period of 6 months to estimate the occurrence of symptomatic venous thromboembolism. The study was prematurely terminated by the safety monitoring committee because of an unacceptably high incidence of confirmed venous thromboembolism (10 patients, 3.2%; 95% confidence interval: 1.6% to 6%), including 4 episodes of fatal pulmonary embolism. In a subsequent explanatory study using ultrasonography in 29 other symptomatic patients who had at least 2 repeated normal CIP test results, the failure of CIP to detect proximal vein thrombosis was confirmed in 4 patients (14%). The reasons for this failure are probably related to the use of a modified device to measure impedance in the CIP apparatus, resulting in a lower ability to separate patients without venous thrombosis from those with the disease. We concluded that CIP is insensitive for the detection of proximal vein thrombosis and, therefore, not clinically useful in the diagnostic management of patients with suspected venous thrombosis.

Adolescent↗
PubMed1990

Compression ultrasonography as a reliable imaging monitor in deep venous thrombosis.

Our experience at Hippokration Athens Hospital with high-resolution real-time ultrasonography of the deep veins of the lower extremities is described, drawn from the results of a prospective comparative study of 65 patients. We used a combination of sonography and contrast venography for the detection of deep venous thrombosis (DVT). Of the study group, 33 had clinically suspected DVT, 20 were asymptomatic high-risk patients, while 12 with varicosities of the leg and scheduled for saphenectomy were examined preoperatively for deep venous patency confirmation. For all patients, venography, the reference method, was performed within 12 hours of the ultrasound scan. Since 29 of the examinations were bilateral, the total number of extremities studied was 94. The sonographic criteria analyzed were the intraluminal echogenicity and the venous compressibility with the ultrasound transducer probe. In addition, the response of the common femoral vein to the Valsalva maneuver was studied. Among these three criteria, compressibility was by far the most accurate. Noncompressible abnormal veins were noted in all of the 24 extremities with proximal thrombosis and in six of the 12 with thrombosis limited to the calf veins. Thus, the sensitivity of the compressibility criterion was 100 per cent for proximal and 50 per cent for isolated calf venous thrombosis (83 per cent). All venographically patent veins were fully compressible (specificity, 100 per cent). Abnormal intraluminal echoes were found in 18 of the 36 extremities with thrombosis but not in those with negative findings on venography. Sensitivity of intraluminal echogenicity was, therefore, 50 per cent and specificity, 100 per cent. For the Valsalva criterion, the standard lower normal limit of 10 per cent was applied, leading to 40 per cent sensitivity and 93 per cent specificity rates. In comparison with venography, ultrasonography underestimated the extent of thrombosis in 60 per cent of the true-positive examinations, although never to a clinically significant degree. In conclusion, compression ultrasonography, a technique based upon the unique criterion of venous compressibility, is a highly accurate and objective noninvasive diagnostic method, and is also suitable as a screening test. We urge clinicians to support their therapeutic decisions concerning the management of DVT with it.

Adult↗
PubMedDate not supplied

[Unreliability of the clinical diagnosis in deep venous thrombosis of the lower limbs].

277 patients subjected to phlebography for clinically suspect acute deep venous thrombosis of the lower extremities have been examined. Instrumental examination evidenced the presence of thrombosis in 140 of them (50.5%) while in the remaining 137 (49.5%) in whom venography proved negative, it was possible to define the pathologies responsible for the clinical picture in 89% of cases. In out-patients, the incidence of thrombosis proved lower (46%, 65/141 patients) than that presented by patients already hospitalised for other pathologies (55%, 75/136 patients). No significant differences were observed in the incidence of clinical symptoms and signs between patients with thrombosis and patients without at phlebography, while as regards the distribution of risk factors, there was a greater incidence of the following: age over-65, cancers, recent surgery and fractures of the lower extremities in the group of patients suffering from thrombosis. Personal experience would therefore appear to point to the total fallibility of the clinical diagnosis of deep venous thrombosis of the lower extremities and the consequent need for a constant objective instrumental diagnostic approach to this type of pathology.

Acute Disease↗
PubMed1985

Prediction of deep vein thrombosis after extensive abdominal operations by the quotient between plasmin-alpha 2-antiplasmin complex and fibrinogen concentration in plasma.

In 97 patients over 49 years of age who underwent extensive abdominal operations, post-operative deep vein thrombosis was prospectively diagnosed by the 125I-fibrinogen test. Blood was sampled preoperatively for analysis of the plasma levels of PAP (by a radioimmunoassay) and fibrinogen. The development of postoperative deep vein thrombosis was correlated to the quotient between the preoperative plasma concentration of PAP and fibrinogen. The quotient was significantly lower in the 30 patients who had thrombosis develop postoperatively as compared with the patients who did not. A simple linear discrimination analysis showed that, in the 31 patients with a quotient of more than 0.48, only two patients (6 per cent) had deep vein thrombosis. The results emphasize the importance of the preoperative fibrinolytic status in the development of postoperative deep vein thrombosis. The results of the study indicate that the quotient between PAP and fibrinogen concentration in plasma might be used for the prediction of patients with a high risk for having deep vein thrombosis develop after undergoing extensive abdominal operations.

Adult↗
PubMed1985

The prevention of postoperative venous thrombosis.

Postoperative thrombosis can be effectively prevented by low doses of heparin (5,000 units 2-3 times daily), by dextran (initially 1,500 ml, subsequently 500 ml twice weekly) and by coumarin and indanedione derivatives (prothrombin time 20%). The prophylactic measures substantially reduce the incidence of postoperative thrombosis--which otherwise affects 20-50% of patients subjected to intermediate or major operations--by a factor of 2-10. As every thrombosis is potentially life-threatening, surgeons have a duty to protect all patients from postoperative thrombosis by means of heparin or dextran or, in special circumstances, coumarins. This applies particularly to abdominal and chest surgery, but also to orthopedic surgery and urology. It applies to all gynecological interventions--laparotomies, vaginoplasty, Caesarean section, and every type of sterilization. Finally, the use of drugs to prevent thrombosis has become established, subject to certain conditions, in traumatology, ophthalmology, and even in brain surgery. To reiterate: omission of the prophylactic administration of anticoagulants may constitute a technical error. Without preventive measures, 20-50% of postoperative patients are at risk from potentially life-threatening thrombosis, and 1% are likely to die. Prophylactic measures have reduced this to hardly more than 1/10, i.e., 2-5% of postoperative patients develop thromboses, and one patient per thousand dies of an embolism.

Anticoagulants↗
PubMed1989

Prevention of venous thrombosis after total hip arthroplasty. Antithrombin III and low-dose heparin compared with dextran 40.

The anticoagulant action of heparin is mediated through antithrombin III, and the postoperative decrease in the plasma concentration of antithrombin III may contribute to the relative ineffectiveness of prophylaxis with low-dose heparin in preventing venous thrombosis after total hip arthroplasty. We conducted a prospective, randomized trial to compare the effectiveness of a regimen of antithrombin III, given intravenously once daily, and low-dose heparin with a regimen of dextran 40, given intravenously, in preventing venographically documented venous thrombosis after total hip arthroplasty. The results demonstrated an incidence of venous thrombosis of 4.9 per cent in patients who received antithrombin III and heparin; this was significantly lower than the incidence (28.6 per cent) in patients who received dextran 40 (p less than 0.005). Venous thrombosis occurred only in patients who had total hip arthroplasty with a cemented prosthesis (fourteen of fifty-seven patients, or 24.6 per cent); none of the twenty-six patients in whom a non-cemented prosthesis was used had venous thrombosis (p less than 0.01). Of the patients in whom a cemented prosthesis had been inserted, the incidence of venous thrombosis was lower in those who were treated with antithrombin III and heparin (7.4 per cent) than in those who were treated with dextran 40 (40 per cent) (p less than 0.005). Postoperative levels of antithrombin III were maintained at more than 90 per cent of the baseline level in patients who received it; this was significantly higher than in patients who received dextran 40.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1989

Doppler ultrasound evaluation for lower extremity deep venous thrombosis in a community hospital.

The accuracy of Doppler examination for lower extremity deep venous thrombosis in a community hospital vascular laboratory was determined by comparing the Doppler results with venograms of 97 limbs in 90 patients. There were 47 limbs with a normal Doppler study, 46 abnormal (consistent with deep venous thrombosis) and 4 with an equivocal study. The overall accuracy was 95%. Both the sensitivity and specificity were 94% when equivocal studies were considered abnormal. Based on these results, we recommend venography or repeat Doppler examination for patients with a normal Doppler study only if the clinical findings are strongly suggestive of deep venous thrombosis. Patients with an abnormal Doppler examination and clinical findings consistent with deep venous thrombosis can be treated for deep venous thrombosis, with a high degree of confidence in the diagnosis, without venography. Patients with equivocal Doppler examinations are advised to have a venogram. While our results are equal to the best reports from research-oriented university vascular laboratories it should not be assumed that they can be readily reproduced in other settings. The technologists performing these studies should be highly skilled, experienced and preferably board certified. Internal quality control of any testing facility is necessary to assure accurate and reliable Doppler ultrasonic results prior to recommending treatment of deep venous thrombosis based on Doppler ultrasound without venography.

Hospitals, Community↗
PubMed1989

[Pathogenesis and laboratory diagnosis of venous thrombosis].

UNLABELLED: Due to the increasing number of elderly as well as chronically-ill patients, venous thrombosis assumes an increasing role as a typical complication of many courses of disease. Postoperatively, in patients without anticoagulation, fibrinogen tests show venous thrombosis in the lower extremities in up to 50% but not all were clinically relevant. Prophylactic treatment has markedly lowered the manifestation of deep venous thrombosis. Nevertheless, in current epidemiologic studies, the prevalence of thrombotic disease is three-fold higher (1:7,500) than that of bleeding diseases (1:20,000). PATHOGENESIS: Congenital deficiency or congenital dysfunction of inhibitors of activated clotting factors have provided insight into the functional principles of limited proteolysis. Unequivocal causes of recurrent thrombosis are deficiency or dysfunction of AT III, protein C, protein S or plasminogen (Figure 1). Dysfibrinogenemia, in about 10% of the patients, leads to a tendency to thrombosis. Unclarified remains the relevance of lowered values for factor XII, heparin-cofactor II (HC II) and histidine-rich glycoprotein (HRG) (Table 1). Congenital disorders usually manifest themselves in the early adulthood. For the clinical manifestation of venous thrombosis, imbalance between pro-coagulatory and inhibitor factors are of importance, therefore the compensatory capabilities of other protease inhibitors, for example, alpha-2-macroglobulin should be taken into consideration. In acquired lowering of hemostasis factors, the balance in the plasma protein cascade should be assessed (Figure 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Tests↗
PubMed1988

Low incidence of deep-vein thrombosis after cementless total hip replacement.

The incidence of deep-vein thrombosis was studied in 146 consecutive Korean patients who had a cementless total hip replacement with a porous-coated anatomic prosthesis. All of the patients had discontinued taking aspirin, aspirin-containing compounds, or other antiplatelet medications fourteen days before admission to the hospital for the operation. Deep-vein thrombosis was diagnosed by roentgenographic venography, and pulmonary embolism, by perfusion lung-scanning. There was an unusually low incidence (10 per cent) of deep-vein thrombosis in this series. In contrast to other reports, we did not identify a relationship between deep-vein thrombosis and so-called risk factors such as advanced age, number of venous valves (more than five) in the lower extremity, abnormal coagulation-assay data, certain diseases, or preoperative limitation of mobility. In addition, hypertension, blood group, surgical approach, and choice of cemented or cementless total hip replacement did not seem to affect the incidence of deep-vein thrombosis. There was a low incidence of deep-vein thrombosis in patients in whom obesity, prolonged immobilization postoperatively, varicose veins, and hyperlipemia were not factors.

Aged↗
PubMed1987

Platelet structural physiology: the ultrastructure of adhesion, secretion, and aggregation in arterial thrombosis.

The leading cause of mortality in industrialized societies is sudden cardiac death. Almost half a million people die each year in the United States from myocardial ischemia and infarction leading to ventricular fibrillation. These phenomena result from severe coronary artery disease due to atherosclerosis with acute mural thrombosis causing occlusion, which serves as the terminal event. Various studies have found evidence of fresh coronary artery mural thrombosis in 74 to 94 percent of patients undergoing autopsies shortly after death due to acute myocardial infarction. Not all thrombi are occlusive, but vasospasm associated with fresh injury to the diseased vessel may be sufficient with developing new thrombus to block blood flow. Because platelets are a major constituent of newly formed thrombi and contribute significantly to vaso-occlusive disease, it is important to understand basic aspects of their function. Such studies may lead to measures that prevent vascular disease and thrombosis. This chapter has described ultrastructural features of platelet-vessel wall interaction. Adhesion, spreading, secretion, and aggregate or thrombus formation have been emphasized. The findings of current studies indicate strong similarities between platelet-vessel wall interactions and the response of platelets to other surfaces. Also, platelet transformations observed during aggregate formation in suspension are identical to physical changes in thrombi on damaged vessels. The similarities are much more impressive than the differences. Therefore, the role of platelets in arterial thrombosis can be understood best as an extension of their hemostatic function. An advantage of this observation is that understanding basic mechanisms of platelet function in hemostasis can lead to solution of the problems presented by platelet involvement in thrombosis. The disadvantage is that agents used to prevent thrombosis can place the hemostatic mechanism in jeopardy. Finding the answer to this paradox will occupy our attention for years to come.

Animals↗