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Impedance plethysmography. A screening procedure to detect deep-vein thrombosis.

Impedance plethysmography has great potential in the non-invasive detection of dangerous iliofemoral thrombosis. It was used to examine 198 patients undergoing total hip replacement for evidence of proximal venous segment thrombosis. There were 13 abnormal results, and subsequent venography in 12 of these revealed a false-positive rate of 4.0%; there was one false-negative result giving a sensitivity of 85.7%. A venographic study of 46 other patients clinically suspected of having a proximal deep-vein thrombosis confirmed this sensitivity. The iliofemoral thrombosis rate was 3.9% after total hip replacement and this rate increased significantly in the group of patients over 70 kg in weight. Impedance plethysmography was found to be a useful non-invasive screening procedure for potentially fatal proximal venous thrombosis.

Adult↗

Deep-vein thrombosis in high-energy skeletal trauma despite thromboprophylaxis.

We report the incidence and location of deep-vein thrombosis in 312 patients who had sustained high-energy, skeletal trauma. They were investigated using magnetic resonance venography and Duplex ultrasound. Despite thromboprophylaxis, 36 (11.5%) developed venous thromboembolic disease with an incidence of 10% in those with non-pelvic trauma and 12.2% in the group with pelvic trauma. Of patients who developed deep-vein thrombosis, 13 of 27 in the pelvic group (48%) and only one of nine in the non-pelvic group (11%) had a definite pelvic deep-vein thrombosis. When compared with magnetic resonance venography, ultrasound had a false-negative rate of 77% in diagnosing pelvic deep-vein thrombosis. Its value in the pelvis was limited, although it was more accurate than magnetic resonance venography in diagnosing clots in the lower limbs. Additional screening may be needed to detect pelvic deep-vein thrombosis in patients with pelvic or acetabular fractures.

Acetabulum↗

Anti-beta 2-glycoprotein I and antiphosphatidylserine antibodies are predictors of arterial thrombosis in patients with antiphospholipid syndrome.

The predictive value (PV) and association of 4 antiphospholipid antibodies with clinical manifestations of the antiphospholipid syndrome (APS) were evaluated in 90 patients with systemic lupus erythematosus (SLE) and 100 with APS. Patients with APS were classified into arterial thrombosis, venous thrombosis, and pregnancy morbidity subgroups. IgG, IgM, and IgA anticardiolipin (aCL), antiphosphatidylserine (aPS), anti-beta 2-glycoprotein I (anti-B2GPI), and antiprothrombin (aPT) antibodies were determined by enzyme-linked immunosorbent assay. Individually, anti-B2GPI and aPS antibodies had the strongest PV for APS (86.4%-94.1%; P < .001) in patients with SLE. The PV for APS reached 100% when 2 or more antibodies were present. Similarly, anti-B2GPI and aPS antibodies had a stronger PV and association for arterial thrombosis (87%-95%; P < .001) compared with venous thrombosis (80%-92%; P = .01). Weak PV and association with pregnancy morbidity were seen with all antibodies. These results suggest an important pathogenic role of anti-B2GPI antibodies in arterial thrombosis. In addition, anti-B2GPI and aPS antibodies seem to provide the best diagnostic value for the laboratory assessment of APS.

Abortion, Spontaneous↗

Bleeding and thrombosis in high-risk renal transplantation candidates using heparin.

BACKGROUND: Heparin can reduce the risk of renal artery/vein thrombosis in renal transplant patients with hypercoagulable states (HCS), but is associated with a high bleeding risk. Little is known about risk factors for this bleeding risk or the optimal anticoagulation target. OBJECTIVE: To determine factors associated with this bleeding risk and determine the optimal partial thromboplastin time (PTT) ratio. METHODS: We retrospectively reviewed medical records of consecutive adult renal transplant recipients administered heparin for perioperative renal thrombosis prevention (1998-2002). RESULTS: Twenty-eight (3.86%) of 725 consecutive renal transplant recipients received heparin to prevent renal thrombosis. Eighteen patients (64.3%) had clinically important bleeding (14 major bleeding). Patients with and without bleeding were similar in baseline demographic characteristics and overall mean PTT. Bleeding occurred at a mean PTT ratio of 2.5 +/- 1, higher than the overall mean in bleeders and nonbleeders (p = 0.001). Among postoperative characteristics, higher maximum PTT (p = 0.052) and prolonged surgical antibiotic prophylaxis (p = 0.053), particularly with cefotetan (p = 0.091), trended toward a significant association with bleeding. Two renal thrombotic episodes occurred, both at PTT ratios <1.5. A PTT ratio of 1.5-1.9 resulted in no thrombosis and < or = 4.2% bleeding. CONCLUSIONS: The benefits and risks of therapeutic heparin anticoagulation in renal transplant patients with HCSs were confirmed. Higher PTTs and cefotetan antibiotic surgical prophylaxis could contribute to bleeding. The optimal PTT ratio appeared to be 1.5-1.9 to prevent thrombosis and limit bleeding risk.

Adult↗

Thrombolytic therapy of left-sided prosthetic valve thrombosis.

Thrombosis of left-sided prosthetic valves is an uncommon yet potentially serious complication. Thrombolytic therapy has been proposed as an alternative to surgical methods in treating this condition. We sought to determine from a review of the literature what outcomes may be expected subsequent to thrombolytic administration and what groups may be at risk or benefit from this approach. We searched for studies including two or more patients treated with thrombolytic agents. Ten studies were reviewed. We describe and include two patients with valve thrombosis treated at our institution. A total of 182 episodes of prosthetic valve thrombosis in 162 patients were examined. Clinical success was achieved in 72.0% of cases and there was a mortality risk of 9.9%. Clinical success from thrombolysis was significantly related to the degree of heart failure at presentation and aortic valve position. Clinical success was not related to the duration of symptoms, time from valve replacement to obstruction, or valve type. Rethrombosis of successfully treated valve occurred subsequently in 19.5% of cases. Repeated thrombolytic administration in these patients was associated with similar rates of success as those treated for their initial episode of prosthetic valve thrombosis. Candidates for thrombolytic therapy include patients with obstructive valve thrombosis with or without congestive heart failure who are hemodynamically stable. Duration of time since valve replacement or symptom onset does not limit successful outcome. Close observation and aggressive maintenance of anticoagulation after therapy is suggested.

Aged↗

Risk factors and management of patients with upper limb deep vein thrombosis.

STUDY OBJECTIVES: To determine the prevalence of endogenous and exogenous risk factors for venous thrombosis in patients with upper limb deep vein thrombosis (DVT), and to evaluate the risk of clinically detectable pulmonary embolus, recurrent DVT, and postphlebitic symptoms in these patients. DESIGN: A combined prospective and retrospective descriptive analysis of a cohort of patients with upper limb DVT compared with age- and sex-matched patients with lower limb DVT. SETTING: Internal medicine departments, and hematology and vascular surgery outpatient clinics at a tertiary-care university hospital. PATIENTS: Consecutive patients with "spontaneous" upper limb DVT diagnosed between 1989 and 1997 were studied. Twenty age- and sex-matched patients with lower limb DVT admitted to the hospital via the emergency department served as control patients. RESULTS: Eighteen patients with upper limb DVT were studied. An endogenous risk factor (thrombophilia) was present in 11 of 18 patients vs 8 of 20 control patients (p = not significant). In the upper limb group, nine patients had activated protein C resistance, four patients had anticardiolipin antibodies, and two patients had both forms of thrombophilia. Furthermore, 14 of the upper limb DVT patients were found to have an exogenous risk factor for thrombosis compared with 7 of the patients with lower limb DVT (p = 0.01), and 66.6% of patients with upper limb DVT had both an exogenous and an endogenous risk factor for thrombosis vs 15% of patients with lower limb DVT (p < 0.002). No clinically detectable pulmonary emboli occurred among the upper limb DVT patients. Three patients have minor postphlebitic symptoms. Two patients experienced recurrent DVT. CONCLUSION: In the majority of patients with upper limb DVT that we studied in this relatively small study, exogenous (environmental) or endogenous risk factors for venous thrombosis, or a combination of both, were found. Furthermore, in our patients, these thromboses had a low propensity to cause clinically significant pulmonary embolus and did not cause significant postphlebitic symptoms. Finally, we suggest that anticoagulant therapy for these thromboses may be adequate and that thrombolytic agents and surgical intervention are not routinely indicated.

Activated Protein C Resistance↗

The incidence of clinical postoperative thrombosis after gastric surgery for obesity during 16 years.

BACKGROUND: Suggested risk factors for postoperative thrombosis such as high fatty acid levels, hypercholesterolemia and diabetes are common in obese patients. METHODS: In a retrospective study, the case records of 328 patients operated for obesity by gastric procedure from September 1977 until December 1993 were analyzed: 253 women and 75 men with a mean age of 38 years and a mean body mass index (BMI) of 44 kg/m2. The operation time, use of epidural anesthesia, and the occurrence of risk factors; fatty acid levels, hypercholesterolemia and diabetes were recorded. Symptomatic thromboses were verified by phlebography or phlethysmography and pulmonary embolism with ventilation/perfusion scintigraphy or autopsy. RESULTS: The mean operating time was 128 minutes, 77% had epidural anesthesia and the mean hospital stay was 12.3 days. The long hospital stay was due to the fact that most patients took part in different scientific studies perioperatively. The incidence of thromboembolism was 2.4%. Four patients had pulmonary embolism, in one of them this was fatal. Three patients had deep leg vein thrombosis and one patient had arm thrombosis secondary to a central venous catheter. None of these patients had high fatty acids, diabetes or high cholesterol. Of the patients, 298 were given dextran-70 (Macrodex, Pharmacia) as prophylaxis, seven were given heparin and 23 were given no prophylaxis. In the patient group without diagnosed thrombosis, 31% had high fatty acid levels, 2% had high cholesterol levels and 9% had diabetes. CONCLUSIONS: Obese patients seem to have a moderate risk of developing postoperative thrombosis when an effective prophylaxis is used. High free fatty acids, hypercholesterolemia and diabetes are not obvious extra risk factors in obese patients. Thromboprophylaxis should be given to all operated obesity patients regardless of age. The surgeons must be aware and investigate promptly any symptoms suggestive of thromboembolism.

Adult↗

Plasma total homocysteine and hemodialysis access thrombosis: a prospective study.

Mild hyperhomocysteinemia, a putative risk factor for atherothrombotic cardiovascular disease morbidity and mortality, may contribute to the excess incidence of atherothrombotic outcomes in the dialysis-dependent end-stage renal disease population. Hemodialysis access (fistula or graft) thrombosis is an unfortunately common and costly morbidity in this patient population. In this study, using a prospective design, the potential relationship between baseline nonfasting, predialysis plasma total homocysteine (tHcy) levels and vascular access-related morbidity was examined in a cohort of 84 hemodialysis patients with a fistula or prosthetic graft as their primary hemodialysis access. Vascular access thrombotic episodes were recorded over a subsequent 18-mo follow-up period. Forty-seven patients (56% of the total) had at least one access thrombosis during the 18-mo follow-up period (median follow-up, 13 mo; rate, 0.6 events per patient-year of follow-up). Proportional hazards modeling revealed that each 1 microM/L increase in the tHcy level was associated with a 4.0% increase in the risk of access thrombosis (95% confidence interval, 1.0 to 6.0%, P = 0.008). This association persisted after adjustment for type of access (fistula versus graft), age, gender, time on dialysis, diabetes, smoking, hypertension, nutritional status, urea reduction ratio, dyslipidemia, and the presence of previous vascular disease. Elevated tHcy levels appear to confer a graded, independent increased risk for hemodialysis access thrombosis. A randomized, controlled trial examining the effect of tHcy-lowering intervention on hemodialysis access thrombosis appears to be justified.

Aged↗

Prophylaxis of hemodialysis graft thrombosis with fish oil: double-blind, randomized, prospective trial.

Diets enriched with fish oil may favorably affect the vascular perturbations underlying synthetic graft thrombosis. Therefore, these studies were designed to test the hypothesis that diets enriched with fish oil would decrease the incidence of thrombosis in newly constructed polytetrafluorethylene grafts. A double-blind, randomized trial was conducted. Twenty-four patients were randomized to receive 4000 mg of fish oil or 4000 mg of control oil. Both preparations were enriched with antioxidants and deodorized with peppermint. Patients began therapy within 2 wk after graft placement and were monitored for 12 mo or until thrombosis developed. With a permuted-block randomization schedule, 12 patients received fish oil and 12 patients received control oil. The primary patency rates at 365 d were 14.9% for the control group and 75.6% for the fish oil-treated group. Survival analysis revealed a significant difference between fish oil-treated and untreated patients (P < 0.03, Mantel-Cox test), with a power of 90%. Moreover, analysis of covariables, including age of > or =50 yr, gender, race, body weight, diabetes mellitus, bleeding times, and lipid profiles, indicated that this effect occurred principally as a result of fish oil administration. Importantly, fish oil treatment also decreased venous outflow resistance and systemic BP, compared with control values. Fish oils possess unique biologic properties that favorably affect the incidence of polytetrafluorethylene graft thrombosis, and they thus represent a potential treatment strategy for the prevention of access thrombosis.

Administration, Oral↗

Probability of thrombosis of vascular access among hemodialysis patients treated with recombinant human erythropoietin.

The objective was to evaluate the effect of the treatment of anemia with recombinant human erythropoietin (EPO) on thrombosis of the vascular access used for hemodialysis. The research design was a prospective cohort study comparing EPO-treated hemodialysis patients with a comparison group matched for type of vascular access, clinical center, and age. All patients commencing hemodialysis in the study centers between March 1988 and July 1991 were eligible if either a graft or fistula had been used as a first permanent vascular access. There were 64 matched fistula pairs and 38 matched graft pairs. There were more patients with a history of cardiovascular disease in the EPO group than in the comparison group for both fistulae and grafts, 34 versus 14% for the former and 37 versus 5% for the latter. There was no difference between EPO and comparison groups with respect to time to first thrombosis of fistula, 11.3 versus 10.6%, respectively, by thrombosis of grafts among those treated with EPO--33.6 versus 11.2% (P = 0.02). EPO treatment does not increase the probability of fistula thrombosis, but there is an association with an increased probability of graft thrombosis.

Actuarial Analysis↗

Recurrent vascular thrombosis in an adolescent transplant recipient.

Vascular thrombosis is one of the more difficult problems of pediatric renal transplantation; its etiology in multifactorial and, in most cases, it is irreversible. Vascular thrombosis accounts for 12.9% of graft failures in primary transplants in children and for 20% of graft failures in repeat transplants. Although it is seen most often in very young recipients and in recipients of kidneys from young donors, it can manifest in older children and adolescents as well. The peak incidence is seen in the first 48 h after transplantation; however, the event may be delayed until after the first week. When thrombosis occurs in an adolescent patients late in the course of transplantation, the pathogenesis is undetermined and immunosuppressive therapy is frequently implicated. This article describes a 19-yr-old patient with a three-antigen-matched cadaveric kidney who received cyclosporine and anti-thymocyte globulin for induction. Vascular thrombosis occurred after 7 d of initial good function. Eventually the graft was removed after attempts to re-establish vascularization failed. The patient received a second graft and despite an optimal six-antigen-match and different immunosuppression with tacrolimus, thrombosis recurred by the fifth postoperative day. The discussion that follows reviews the incidence and the factors implicated in the pathogenesis of this entity.

Adult↗

Prophylaxis against fat and bone-marrow embolism during total hip arthroplasty reduces the incidence of postoperative deep-vein thrombosis: a controlled, randomized clinical trial.

BACKGROUND: Clinical and experimental studies have suggested that the maximum risk of thrombogenesis occurs during, rather than after, total hip arthroplasty. With use of conventional cementing techniques, insertion of a femoral component results in marrow embolization of tissue thromboplastin into the veins of the proximal part of the femur, leading to activation of the clotting cascade and thrombogenesis. We hypothesized that an operative technique designed for the prevention of fat and bone-marrow embolism can also reduce the incidence of postoperative deep-vein thrombosis and pulmonary embolism. METHODS: A total of 130 consecutive patients with osteoarthritis who were to have a primary total hip arthroplasty were randomly assigned to one of two groups. One group consisted of sixty-five patients (sixty-five hips) who had the femoral component inserted with our standard cementing technique without use of a bone vacuum, and the other group included sixty-five patients (sixty-five hips) who had the femoral component cemented with use of a bone-vacuum technique. In the hips managed with the bone vacuum, suction (-800 mbar) was applied to a drainage cannula placed along the linea aspera of the femur in order to prevent an increase in intramedullary pressure during the insertion of the stem. We measured the incidence of intraoperative fat and bone-marrow embolism with use of echocardiography and a transesophageal probe and the incidence of deep-vein thrombosis with use of serial duplex ultrasonography on the day before the operation and on postoperative days 4, 14, and 45. All patients were managed with prolonged pharmacological prophylaxis (low-molecular-weight heparin) against deep-vein thrombosis. RESULTS: The control group had significantly more severe and prolonged echocardiographic embolic events than did the group managed with the bone-vacuum technique (p < 0.05). A cascade of fine echogenic particles or embolic masses with a diameter of < or =5 mm was observed during the insertion of the stem in fifty-nine hips (91%) in which our standard cementing technique was used and in ten hips (15%) in which the bone-vacuum cementing technique was used. Deep-vein thrombosis was detected on postoperative day 4 in twelve patients (18%) in the control group and in two patients (3%) in the group managed with the bone-vacuum technique; the difference was significant (p < 0.05). CONCLUSIONS: Intraoperative prophylaxis against fat and bone-marrow embolism during total hip arthroplasty with cement can reduce the incidence of postoperative deep-vein thrombosis. We now use the bone-vacuum technique routinely in all total hip arthroplasties performed with cement.

Arthroplasty, Replacement, Hip↗

Effect of mechanical compression on the prevalence of proximal deep venous thrombosis as assessed by magnetic resonance venography.

BACKGROUND: Patients have been shown to be at greater risk for deep venous thrombosis, particularly proximal thrombosis, after total hip arthroplasty. Proximal thrombi are more likely to develop into pulmonary emboli than are distal thrombi. The purpose of this randomized, prospective study was to compare the prevalence of pelvic and proximal lower-extremity deep venous thrombosis after primary total hip arthroplasty between patients treated with an impulse mechanical compression device for prophylaxis and those treated with prophylactic stockings. METHODS: One hundred patients were evaluated, with use of magnetic resonance venography, for proximal deep venous thrombosis after total hip arthroplasty. Fifty patients were treated with a mechanical compression device on both lower extremities, and the other fifty patients received only prophylactic stockings. Both groups of patients received hypotensive epidural anesthesia and 325 mg of aspirin twice a day. RESULTS: Overall, proximal deep venous thrombi were found in 15% of the 100 patients. Of the fifty patients treated with mechanical compression, 8% (four) had a positive venogram. Of the fifty control patients, 22% (eleven) had a positive venogram (p < 0.05). However, overall the rate of occlusive thrombi was 6% (six) compared with an overall rate of nonocclusive thrombi of 9% (nine). The rate of occlusive thrombi was 2% (one of fifty) in the study group and 10% (five of fifty) in the control group (p = 0.04). CONCLUSIONS: On the basis of this study, we concluded that patients managed with total hip arthroplasty benefit from a reduction in the rates of femoral and pelvic deep vein thrombosis when they are treated with hypotensive epidural anesthesia, mechanical compression, and aspirin and are subsequently assessed with magnetic resonance venography.

Arthroplasty, Replacement, Hip↗

Prevention of deep-vein thrombosis after total knee arthroplasty in Asian patients. Comparison of low-molecular-weight heparin and indomethacin.

BACKGROUND: A prospective clinical study was performed to compare the efficacy of low-molecular-weight heparin and indomethacin for the prevention of deep-vein thrombosis after total knee arthroplasty in Asian patients. METHODS: One hundred and fifty patients undergoing total knee arthroplasty were randomly divided into three groups. One group consisted of fifty-one patients who received no prophylaxis with an anticoagulant (the control group), one consisted of fifty patients who received the low-molecular-weight heparin Fraxiparine (the Fraxiparine group), and the third consisted of forty-nine patients who received indomethacin (the indomethacin group). Bilateral ascending venography was performed preoperatively and at five, six, or seven days postoperatively. A third venogram was made at three months for patients who had had a deep-vein thrombosis. RESULTS: The prevalence of deep-vein thrombosis was 71% in the control group, 50% in the Fraxiparine group (p = 0.042), and 45% in the indomethacin group (p = 0.011). Only 28% of the deep-vein thromboses were symptomatic, and there were no pulmonary emboli. CONCLUSIONS: Compared with no prophylaxis, Fraxiparine and indomethacin significantly lowered the prevalence of deep-vein thrombosis after total knee arthroplasty. Prophylaxis against deep-vein thrombosis in the Asian population appears to be warranted. LEVEL OF EVIDENCE: Therapeutic study, Level I-1a (randomized controlled trial [significant difference]). See Instructions to Authors for a complete description of levels of evidence.

Adult↗

Prophylaxis against deep-vein thrombosis following trauma: a prospective, randomized comparison of mechanical and pharmacologic prophylaxis.

BACKGROUND: Deep-vein thrombosis following skeletal trauma is an important yet poorly studied issue. The purpose of the present study was to evaluate the efficacy of two different strategies for prophylaxis against deep-vein thrombosis and pulmonary embolus following blunt skeletal trauma. METHODS: Two hundred and twenty-four inpatients were enrolled in a prospective, randomized study investigating venous thromboembolic disease following trauma. Two hundred patients completed the study, which compared two different regimens of prophylaxis. The patients in Group A received enoxaparin (30 mg, administered subcutaneously twice a day) starting twenty-four to forty-eight hours after blunt trauma. The patients in Group B were managed with pulsatile foot pumps at the time of admission combined with enoxaparin on a delayed basis. All patients were screened with magnetic resonance venography and ultrasonography before discharge. RESULTS: There were ninety-seven patients in Group A and 103 patients in Group B. Twenty-two patients (including thirteen in Group A and nine in Group B) had development of deep-vein thrombosis, with two (both in Group A) also having development of pulmonary embolism. The prevalence of deep-vein thrombosis was 11% for the whole series, 13.4% for Group A, and 8.7% for Group B; the difference between Groups A and B was not significant. There were eleven large or occlusive clots (prevalence, 11.3%) in Group A, compared with only three (prevalence, 2.9%) in Group B (p = 0.025). The prevalence of pulmonary embolism was 2.1% in Group A and 0% in Group B. Wound complications occurred in twenty-one patients in Group A, compared with twenty patients in Group B. Patients who had development of deep-vein thrombosis during the inpatient portion of the study required a mean of 7.4 units of blood during hospitalization, compared with 3.9 units of blood for those who did not (p < 0.05). CONCLUSIONS: Our results indicate that early mechanical prophylaxis with foot pumps and the addition of enoxaparin on a delayed basis is a very successful strategy for prophylaxis against venous thromboembolic disease following serious musculoskeletal injury. The prevalence of large or occlusive deep-vein thromboses among patients who had been managed with this protocol was significantly less than that among patients who had been managed with enoxaparin alone.

Adult↗

The differential involvement of von Willebrand factor, fibrinogen and fibronectin in acute experimental thrombosis in rat cerebral and mesenteric microvessels.

Arterial thrombi are primarily composed of platelets. Platelets are bound to injured endothelial cells, sub-endothelial matrices, and other platelets by a range of adhesive proteins. Some of these reactions are governed by shear forces. The role of adhesive proteins in the pathogenesis of arterial thrombosis is not fully understood. The aim of this study was to examine the involvement of von Willebrand factor (vWF), fibrinogen (Fg), and fibronectin (FN) in the formation of microvascular thrombi in vivo using a helium-neon laser-induced thrombosis method. Transmission electron microscopy demonstrated that laser irradiation resulted in platelet-rich thrombosis in arterioles and venules, and revealed that this occurred in the absence of endothelial denudation. The mean wall shear rates in mesenteric arterioles and venules were 641 +/- 40 and 280 +/- 20 s-1, respectively. Shear rates increased approximately fivefold in arterioles and tenfold in venules during the formation of occlusive thrombi. Antibody to vWF inhibited thrombosis in arterioles and venules. Antibodies to Fg and FN inhibited thrombosis in venules but not in arterioles. These results confirm that vWF, Fg and FN were involved in thrombogenesis in vivo and demonstrated that significantly higher shear rates were required for the reactions involving vWF than those involving either Fg or FN.

Adhesiveness↗

Reduction of venous thrombosis complicating phlebography.

Patients who underwent radiographic phlebography were studied to determine the frequency of postphlebographic venous thrombosis. In a group of 23 patients who had negative phlebograms performed with standard contrast agent (60% sodium methylglucamine diatrizoate), nine had positive 125I-fibrinogen leg scans. On repeat phlebography, three had confirmed deep vein thrombosis, six overall developed deep or superficial thrombosis, and three had positive scans without demonstrable thrombi. In a second group of 34 patients studied with the contrast material diluted to 45%, only three developed positive scans, one due to deep venous thrombosis and two to superficial thrombosis. There was also a reduction in the incidence of postphlebographic symptoms of pain, tenderness, and erythema, but no apparent sacrifice in diagnostic accuracy.

Diatrizoate↗

Hepatic artery thrombosis after liver transplantation: radiologic evaluation.

Hepatic artery thrombosis after liver transplantation is a devastating event requiring emergency retransplantation in most patients. Early clinical signs are often nonspecific. Before duplex sonography (combined real-time and pulsed Doppler) capability was acquired in October 1984, 76% of all transplants in this institution referred for angiography with a clinical suspicion of hepatic artery thrombosis had patent arteries. In an effort to reduce the number of negative angiograms, CT, real-time sonography, and pulsed Doppler have been evaluated as screening examinations to determine which patients need angiography. Of 14 patients with focal inhomogeneity of the liver architecture detected by CT and/or real-time sonography, 12 (86%) had hepatic artery thrombosis, one had slow arterial flow with hepatic necrosis, and one had a biloma with a patent hepatic artery. In 29 patients undergoing duplex sonography of the hepatic artery, six (21%) had absence of a Doppler arterial pulse. All six had abnormal angiograms: Four had thrombosis, one had a significant stenosis, and one had slow flow with biopsy-proven ischemia. Of 23 patients with a Doppler pulse, two had hepatic artery thrombosis at surgery. However, real-time sonography demonstrated focal inhomogeneity in the liver in both cases. Our data demonstrate that pulsed Doppler of the hepatic artery combined with real-time sonography of the liver parenchyma currently is the optimal screening test for selecting patients who require hepatic angiography after liver transplantation. A diagnostic algorithm is provided.

Adolescent↗