Proximal Propagation Research Articles

Management of Isolated Calf Deep Vein Thrombosis: Is Treatment or Follow-Up Warranted

Objectives: There is no consensus regarding the management of isolated calf deep vein thrombosis (DVT). The aim of this study is to determine the proper management of isolated soleal, gastrocnemius, peroneal, and posterior tibial vein thrombosis in an outpatient population. We further aim to identify the results of management of below the knee DVT (BKDVT) with serial ultrasound imaging during a 30-day period vs anticoagulation. Methods: A retrospective review was conducted for records from January 2009 to December 2010 to identify patients with BKDVT. Trauma and inpatients were excluded from the study. Univariate and multivariate analyses were conducted as well as descriptive statistics of the data. Results: The study included 225 outpatients with isolated BKDVT. The cohort consisted of 41% male, predominantly Caucasian (88%) patients, who were a mean age of 64 years. Thrombus was present most frequently in the soleal vein (40.3%), followed by the gastrocnemius (25%), peroneal (23.5%), and the posterior tibial vein (11.3%). Anticoagulation was used to treat 30.7% of initially diagnosed BKDVTs. No statistically significant difference was noted in the rate of proximal propagation (P .27), or pulmonary embolism (P .70) with or without anticoagulation. A decrease of new thrombus in additional calf veins was seen with anticoagulation, 1.4% vs 14.1% without anticoagulation (P .01). Conclusions: In an outpatient population, serial ultrasound imaging is adequate management for BKDVT. There is no significant reduction in the rate of pulmonary embolism or proximal propagation for patients managed with anticoagulation vs serial duplex ultrasound imaging for isolated calf DVT. Owing to the formation of new thrombus, serial ultrasound imaging is warranted in an outpatient population.

Early treatment outcome of isolated calf vein thrombosis after total knee arthroplasty

PurposeIn contrast to proximal deep vein thrombosis (DVT), the treatment of isolated calf vein thrombosis (ICVT) remains controversial. This study aimed to investigate early treatment outcomes of ICVT after total knee arthroplasty (TKA).MethodsMedical records of 313 patients who underwent TKA from October 2007 to December 2009 were retrospectively reviewed. A DVT-computed tomography (CT) was performed 7 days after surgery. ICVT was identified in 76 limbs of 73 patients. Of them, follow-up DVT-CT was available in 39 limbs of 37 patients. The patients with ICVTs were categorized into two groups: oral anticoagulation group (group I, 17 patients with 18 limbs) and conservative treatment group (group II, 20 patients with 21 limbs). Group I received an oral vitamin K antagonist for 3 to 6 months following low molecular weight heparin. Change of thrombus extent and development of pulmonary embolism (PE) was assessed in follow-up DVT-CT.ResultsMean age was 68 years and 95% were female. Of 39 limbs with ICVT, 16 (41%) involved major lower leg veins (posterior tibial vein or peroneal vein), 13 (33%) involved muscular veins (soleal vein or gastrocnemius vein) and 10 (26%) involved both. During 1 to 6 months, follow-up DVT-CT revealed complete thrombus resolution in all limbs and there was no proximal propagation of thrombus or PE in both groups.ConclusionThere is no evidence of DVT propagation or newly developed PE in the conservative treatment group. This result suggests that anticoagulation therapy for ICVT patients without PE after TKA may not be mandatory.

Safety of Excluding Suspected Deep Vein Thrombosis with a Single Whole-Leg Compression Ultrasound: Systematic Review and Meta-Analysis.

Abstract 243 Background:In patients with suspected lower extremity deep vein thrombosis (DVT), compression ultrasonography (CUS) is typically used as the initial test to confirm or exclude DVT. Patients with a negative CUS and either a moderate-to-high probability and/or a positive D-dimer usually require repeat CUS testing after 5–7 days to exclude proximal propagation of distal DVT, reducing diagnostic efficiency. Whole-leg compression ultrasound may safely exclude proximal and distal DVT in a single evaluation. Purpose:To assess the safety of withholding anticoagulation in patients presenting with suspected lower extremity DVT following a single negative whole-leg CUS. Methods:MEDLINE, EMBASE, CINAHL, LILACS, Cochrane, Health Technology Assessments databases were searched from January 1970 to April 2009 without language restrictions. This search was supplemented by reviewing Google, Google Scholar, clinicaltrials.gov, meeting abstracts, conference proceedings, reference lists, and by contacting content experts. Study Selection and Data Extraction:Randomized controlled trials and prospective cohort studies of patients with suspected DVT with a negative whole-leg CUS, not treated with anticoagulation, and followed at least 90 days for occurrence of venous thromboembolism (VTE). Studies required objective confirmation of VTE events during follow-up. Two authors independently reviewed articles and extracted data. Results:Six studies were included totaling 4,229 patients with negative whole-leg CUS exams and not receiving anticoagulation. VTE or suspected VTE-related death occurred within the follow-up period in 24 (0.6%) patients. Of these 24 events, 9 (37.5%) were distal DVT, 7 (29.2%) were proximal DVT, 6 (25.0%) were non-fatal pulmonary embolism, and 2 (8.3%) were deaths, possibly related to VTE. Combined VTE event rate at 3 months was 0.46% (95% CI 0.22, 0.70). Limitations:Pretest probability assessment was not available for all analyzed patients. Conclusions:Withholding anticoagulation in patients with suspected DVT based on a single whole-leg CUS is associated with a low risk of VTE (0.46%) during 3 months of follow-up. This strategy represents a safe and efficient alternative to serial CUS testing in patients with suspected DVT. Disclosures:No relevant conflicts of interest to declare.

Surveillance Study of Temporary IVC Filters placed in Patients with VTE and Contraindications for Full Dose Anticoagulant Therapy

To study the circumstances surrounding the use of IVC filters in our institution we collected medical information from all patients with IVC filters placed between January 1, 2006 and December 31, 2007 in our institution. During this time, 247 IVC filters were placed and we are reporting preliminary data of 50 of those patients. Of these patients, 8 (16%) had permanent filters placed (Vena tech™) and 42 (84%) had retrievable filters (Gunther Tulip filters). In most of the cases, the indication for the IVC filter was the inability to use full dose of anticoagulants in patients with acute DVT secondary to active bleeding, requiring immediate surgery or very high risk of bleeding due to different circumstances (such a recent intracranial bleed or traumatic intra-abdominal hemorrhage). Most of the patients were trauma patients. Thus, 30 of the patients had neurosurgical injuries, 13 had orthopedic injuries requiring urgent surgery, 5 had intra-abdominal injuries and 2 were medical patients with DVT and contraindications for anticoagulant therapy. Of the filters deployed, 12 (24%) were inserted after developing thrombosis despite the use of prophylactic dose of anticoagulants. Once the filter was inserted, surveillance Doppler studies revealed propagation of the clots in 7 (14%) patients. Of these 7 patients 2(29%) of them were receiving low dose enoxaparin and 5 (71%) were receiving no anticoagulants at all. In addition, there were 12 patients with DVT and contraindication to full dose anticoagulation who were treated with prophylactic dose of enoxaparin. Of these 12 patients, 10(83%) had stability or resolution of the thrombus and 2(17%) showed propagation. Twenty patients were given no anticoagulation after diagnosis of DVT, of them, 15(75%) had resolution or stabilization of the clots and 5(25%) experienced propagation. Most of the patients were eventually treated with full dose enoxaparin followed by warfarin for a minimum of 3 months. All IVC filters were inserted by intervention radiologists at our institution. Deployment was done uneventfully in all cases. The retrieval of all filters was done between 4 and 8 weeks of the time of insertion. By then, most of the patients were taking warfarin. This drug was held 3 evenings before the procedure and restarted 8–12 hours after the procedure. Enoxaparin at a dose of 40 mg SQ daily was use for bridging before and after the retrieval of the IVC filters. Of all temporary filters, only 11 (26%) were retrieved. IVC filter could not be retrieved despite attempting it in 1 (2%) of patients. The reason for this was that the filter had embedded in the intima of the IVC. Additionally, 1(2%) patient required two attempts to successfully remove the filter IVC filters as there was residual thrombus at the filter site the first time. IVC retrievable filters were effective in preventing pulmonary embolism in 49 (98%) of patients. The only patient with a pulmonary embolism was a neurosurgical patient that was not treated with anticoagulants and the clot extended to the filter. Excessive bleeding occurred in 2(4%) of all patients resulting in discontinuation of anticoagulants. IVC filters are safe and constitute a reasonable intervention to prevent pulmonary embolism in patients with contraindications for anticoagulation. Although, many temporary filters are placed they are often not retrieved. Low dose enoxaparin in patients with IVC filter and contraindication for full dose anticoagulants is associated to low risk of bleeding and seems to prevent proximal propagation of the clots. We expect to have all data from the 247 patients collected by the time of the Meeting.

Perioperative considerations in patients with non small cell lung cancer and metastases in mediastinal lymph nodes.

Corresponding author: Dr Dragan SUBOTIC, MD, PhD, FCCP Institute for lung Diseases, Belgrade, Visegradska 26/20 Serbia E-mail: vilusi@yubc.net; Tel: +38 11 1361 5559 Since the latest revision of the TNM system reclassified T3N0 tumours into the IIB stage, N2 lesions became the major determinant of the IIIA stage. Concerning the minority of patients with T3N1 tumours in this stage, their prognosis depends on characteristic of T3 tumours: localised chest wall invasion is associated with more favourable prognosis compared to those T3 tumours that either directly invade the mediastinum, or have the proximal propagation < 2 cm from the central carina. The significance of preoperative confirmation of metastases in mediastinal lymph nodes was recognized long ago, based on survival differences depending on whether N2 lesions were confirmed preoperatively or not (Tab 1).

Extra-anatomical Aortobifemoral Bypass for Juxtarenal Aortic Occlusion

We report a 69-year-old man with juxtarenal aortic occlusion who presented with rest pain in both lower extremities. One year previously, he had undergone low anterior resection for rectal cancer complicated by a postoperative anastomotic leak, which had healed after drainage of the abscess. Conventional aortobifemoral bypass could lead to possible complications of ureteral and vascular injury, and graft infection. Therefore, we performed an extra-anatomical aortobifemoral bypass, avoiding the left side of the previously contaminated pelvic cavity. This procedure prevents the proximal propagation of thrombus and is considered to be hemodynamically equivalent to a conventional aortobifemoral bypass.

Extra-anatomical Aortobifemoral Bypass for Juxtarenal Aortic Occlusion

We report a 69-year-old man with juxtarenal aortic occlusion who presented with rest pain in both lower extremities. One year previously, he had undergone low anterior resection for rectal cancer complicated by a postoperative anastomotic leak, which had healed after drainage of the abscess. Conventional aortobifemoral bypass could lead to possible complications of ureteral and vascular injury, and graft infection. Therefore, we performed an extra-anatomical aortobifemoral bypass, avoiding the left side of the previously contaminated pelvic cavity. This procedure prevents the proximal propagation of thrombus and is considered to be hemodynamically equivalent to a conventional aortobifemoral bypass.

Outcome of calf deep-vein thrombosis after total knee arthroplasty

We investigated the outcome of deep-vein thrombosis (DVT) in the calf after total knee arthroplasty (TKA) in 48 patients (45 women and three men) by clinical assessment and venographic study between three and four years after surgery. The mean age of the patients was 67.2 +/- 7.7 years (52 to 85) and the mean follow-up was 42.6 +/- 2.7 months (38 to 48). The diagnosis was osteoarthritis in 47 patients and rheumatoid arthritis in one patient. There were 44 calf thrombi, four popliteal thrombi but no thrombi in the femoral or iliac regions. Of the 48 patients, 24 were clinically symptomatic and 24 were asymptomatic. Clinical examination was carried out on 41 patients, of whom 37 underwent ascending venography. Seven were evaluated by telephone interview. No patient had the symptoms or signs of recurrent DVT, venous insufficiency in the affected leg, or a history of pulmonary embolism. No patient had been treated for complications of their DVT. Thirty-six of the 37 venographic studies were negative for either old or new DVT in the affected leg. One patient had residual thrombi in the muscular branches of the veins. Our study shows that deep-vein thromboses in the calf after TKA disappear spontaneously with time. No patient developed a recurrent DVT, proximal propagation or embolisation. Treatment of DVT in the calf after TKA should be based on the severity of the symptoms during the immediate postoperative period.

A survey of physicians' knowledge and management of venous thromboembolism.

A review of all patients diagnosed with venous thromboembolism (VTE) at an academic medical center from 1996 to 1998 revealed a wide variation in management and subsequent patient outcomes and a 30% increase in utilization of the vascular laboratory from the previous 2-year period. The purpose of this study was to determine physicians' knowledge and management strategies before the implementation of integrated care pathways for VTE. Mail surveys were sent to 650 physicians covering 3 academic medical centers. The disciplines targeted were from those physicians who had previously referred patients for any VTE screening examination. One-hundred and twenty-eight physicians (20%) completed the survey. Only 12% of the physicians were able to correctly identify all of the veins routinely imaged as either deep or superficial veins. Fifty-nine percent of the physicians incorrectly identified the superficial femoral vein of the thigh as a superficial vein, and 23% believed the popliteal vein to be a superficial vein. Only 17% of the respondents correctly classified the tibial-peroneal veins as deep veins. Approximately 70% of the physicians stated that they would not treat symptomatic isolated calf vein thrombosis, and, of those, only 42% said that they would obtain serial duplex scans to monitor for proximal propagation. Physicians underestimated the charges for all diagnostic screening tests, and only 14% were able to correctly identify the range of charges for a venous duplex scan. This survey of physicians demonstrated a lack of basic knowledge regarding lower extremity venous anatomy, charges for the different diagnostic tests used to diagnose VTE, and, most importantly, current treatment standards for VTE.

Venous thrombosis and anticoagulant therapy.

Venous thrombosis and anticoagulant therapy.

Descending Thoracic Aortobifemoral Bypass for Aortoiliac Occlusive Disease

Descending thoracic aortobifemoral bypass was evaluated in 3 patients with Leriche's syndrome and 1 with severe arteriosclerosis obliterans. Indications for this approach were lack of a suitable site for aortic clamping in 3 and history of laparotomy in 1. Duration of surgery was 4.5 to 5.25 hours, and blood loss was 450 to 1,900 g. There was no surgical mortality. Major morbidity comprised visceral arterial ischemia postoperatively in 1 patient. During a mean follow-up of 60 months (range, 36 to 84 months), 2 limbs of the grafts became occluded. No patient developed proximal propagation of an aortic thrombus. This approach is recommended in selected patients without impaired pulmonary function, when conventional approaches to the abdominal aorta are considered hazardous.

The natural history of calf vein thrombosis: Lysis of thrombi and development of reflux

Purpose: Although the fact is well accepted that deep venous thrombosis (DVT) of the iliac, femoral, and popliteal veins can lead to the post-thrombotic (postphlebitic) syndrome, the significance of isolated calf DVT on the development of late venous sequelae and physiologic calf dysfunction is unknown. The purpose of this study was to review the outcome of 58 limbs with isolated calf DVT and report the clinical, physiologic, and imaging results up to 6 years after the onset of DVT. Methods: The study consisted of 58 limbs of 54 patients in whom isolated calf vein DVT was diagnosed between 1990 and 1995. Proximal propagation of clot, lysis of thrombi, and development of symptomatic pulmonary emboli were examined. Of the patients, 28 received anticoagulation therapy, and 26 did not, but they had follow-up with serial duplex scans. At late follow-up 1 to 6 years later (median, 3 years), 23 patients were examined for the post-thrombotic syndrome, and all 23 underwent clinical examination, color-flow duplex scanning, and air plethysmography. Results: Proximal propagation of DVT from the calf veins into the popliteal or thigh veins occurred in 2 of 49 cases (4%) within 2 weeks of diagnosis. No patient had clinically overt pulmonary emboli develop regardless of whether anticoagulation therapy was received or not. The most common site for calf DVT was the peroneal vein (71%). Complete lysis of calf thrombi was found in 88% of the cases by 3 months. At 3 years, 95% of the patients were either asymptomatic or mildly symptomatic, and 5% had discoloration of the limb. No ulcers occurred. By air plethysmography, physiologic abnormalities were found in 27% of the cases, which was not significantly different from normal controls. Valvular reflux by duplex scanning of the calf vein segment with DVT was found in 2 of 23 cases (9%). However, reflux in at least one venous segment not involved with DVT was found in 7 of 23 cases (30%), which was higher than, but not statistically different from, normal controls, with reflux occurring in 5 of 26 cases (19%). Conclusions: Isolated calf vein DVT leads to few early complications (ie, clot propagation, pulmonary emboli) and few adverse sequelae at 3 years. The peroneal vein is most commonly involved and should be a part of the routine screening for DVT. Lysis of clot usually occurs by 3 months. Although valvular reflux rarely is found in the affected calf vein at 3 years, reflux may be found in adjacent uninvolved veins in approximately 30% of the cases. The question of whether this will lead to future sequelae, such as ulceration, will require longer follow-up. (J Vasc Surg 1998;28:67-74.)

Calf vein thrombi are not a benign finding

Background: Currently, there is no consensus in the literature regarding which patients with calf vein thrombi are at high risk for proximal propagation. This study examined patients with isolated calf vein thrombi with serial duplex scans in order to identify risk factors that would predict outcome. Patients and methods: Between May 1989 and November 1994, 288 patients were identified with isolated calf vein thrombi. One hundred ninety-two of them had sequential scans performed. Results: Fifty-three (28%) of the 192 patients had propagation of their initial thrombi. The most proximal level of propagation was the popliteal vein in 11 patients, the superficial femoral vein in 5, the common femoral vein in 5, adjacent tibial or soleal veins in 24, adjacent soleal veins alone in 7, and the lesser saphenous vein in 1. Three patients whose thrombi propagated had free-floating thrombus tips in the large veins of their thighs. Symptoms, prophylaxis, and risk factor analysis comparing those patients whose thrombi propagated to those whose thrombi did not found no statistically significant prognostic value. Single or multiple calf vein thrombi did not predict propagation. Of the 23 patients treated with heparin, only 3 had thrombus propagation. None of these reached the level of the knee (including popilteal vein). Conclusions: The natural history of distal lower extremity thrombosis does not appear to be as benign as previously believed.

Suprarenal aortic occlusion.

This report was designed to elucidate the clinical manifestations of suprarenal aortic occlusion (SRAO) and determine the efficacy of surgical treatment. A retrospective review of 135 patients with aortic occlusion was undertaken from which the 16 patients (12%) with SRAO were found. Analysis yielded two subsets of patients based on the time-frame over which SRAO developed. Group I (n = 13) had chronic aortic occlusion with proximal propagation of thrombus to involve the suprarenal aorta. They had uncontrolled hypertension and claudication. Surgical treatment included 16 renal reconstructions (nine patients), two nephrectomies, 10 aortobifemoral bypasses, and three extra-anatomic procedures. The operative mortality rate was 23%. In contrast, group II (n = 3) had acute SRAO, manifest by profound lower extremity ischemia and acute renal failure after cardiac dysrhythmias. Two patients were moribund and died shortly after extraanatomic "salvage" procedures. One patient survived aortobifemoral and bilateral renal artery bypass. Chronic SRAO should be suspected in patients with absent femoral pulses and refractory hypertension. Aortic and renal reconstruction offers long-term improvement in hypertension control and relief of claudication. Acute SRAO is a multisystem disorder that is ineffectively managed with extraanatomic "salvage" procedures.

Suprarenal aortic occlusion

Purpose: This report was designed to elucidate the clinical manifestations of suprarenal aortic occlusion (SRAO) and determine the efficacy of surgical treatment.Methods: A retrospective review of 135 patients with aortic occlusion was undertaken from which the 16 patients (12%) with SRAO were found.Results: Analysis yielded two subsets of patients based on the time-frame over which SRAO developed. Group I (n = 13) had chronic aortic occlusion with proximal propagation of thrombus to involve the suprarenal aorta. They had uncontrolled hypertension and claudication. Surgical treatment included 16 renal reconstructions (nine patients), two nephrectomies, 10 aortobifemoral bypasses, and three extra-anatomic procedures. The operative mortality rate was 23%. In contrast, group II (n = 3) had acute SRAO, manifest by profound lower extremity ischemia and acute renal failure after cardiac dysrhythmias. Two patients were moribund and died shortly after extraanatomic “salvage” procedures. One patient survived aortobifemoral and bilateral renal artery bypass.Conclusion: Chronic SRAO should be suspected in patients with absent femoral pulses and refractory hypertension. Aortic and renal reconstruction offers long-term improvement in hypertension control and relief of claudication. Acute SRAO is a multisystem disorder that is ineffectively managed with extraanatomic “salvage” procedures.

The significance of calf thrombi after total knee arthroplasty.

We reviewed the records of 1257 patients having 1625 total knee arthroplasties; all had pre-operative and postoperative perfusion lung scans and postoperative venograms which were classified as showing no thrombi, calf thrombi or proximal thrombi. Patients with calf thrombi were found to have a significantly greater risk for both symptomatic and asymptomatic pulmonary embolism compared with patients with no venographic thrombi. There were positive lung scans in 6.9% of patients with calf thrombi compared with 2.0% of patients with negative venograms (p < 0.001). Symptomatic pulmonary embolism occurred in 1.6% of patients with calf thrombi compared with 0.2% of patients with negative venograms (p = 0.034). The risk of pulmonary embolism was not significantly different between patients with treated proximal thrombi, and those with calf thrombi. Patients who develop deep-vein thrombosis despite prophylaxis are at increased risk for pulmonary embolism; these patients should receive treatment, or undergo follow-up studies to detect proximal propagation.

Lower extremity calf thrombosis: To treat or not to treat?

Seventy-five patients with isolated calf vein thrombi were prospectively monitored with sequential duplex scans at 3- to 4-day intervals. Twenty-four patients (32%) propagated and 11 of these 24 (46%) into the popliteal or larger veins of the thigh. Sex, age, obesity, trauma, estrogen use, malignancy, varicose veins, smoking, surgery, and activity level were not predictive for proximal propagation. Proximal soleal vein thrombi had the highest incidence in both propagating and nonpropagating groups. Thrombus extent and bilateral involvement were not predictive of propagation. Five percent (4 of 75 patients) had highly probable ventilation perfusion scans as their initial indication for duplex scanning. Deep vein thrombosis isolated to the calf is not a benign problem. If anticoagulant therapy is contraindicated, the progress of the thrombus can be followed by duplex scanning.

Lower extremity calf thrombosis: To treat or not to treat?

Seventy-five patients with isolated calf vein thrombi were prospectively monitored with sequential duplex scans at 3- to 4-day intervals. Twenty-four patients (32%) propagated and 11 of these 24 (46%) into the popliteal or larger veins of the thigh. Sex, age, obesity, trauma, estrogen use, malignancy, varicose veins, smoking, surgery, and activity level were not predictive for proximal propagation. Proximal soleal vein thrombi had the highest incidence in both propagating and non-propagating groups. Thrombus extent and bilateral involvement were not predictive of propagation. Five percent (4 of 75 patients) had highly probable ventilation perfusion scans as their initial indication for duplex scanning. Deep vein thrombosis isolated to the calf is not a benign problem. If anticoagulant therapy is contraindicated, the progress of the thrombus can be followed by duplex scanning.

Infrarenal aortic occlusion: Does it threaten renal perfusion or function?

Proximal propagation of aortic thrombus with resultant impaired renal perfusion has been considered a significant risk of untreated infrarenal aortic occlusion. To investigate this question, we studied 52 patients surviving 1 year or more after surgical interruption of the infrarenal aorta in the course of treatment of aortic graft infection. Blood pressure, renal function, and renal artery anatomy were studied before and after aortic interruption. Preoperatively, 20 patients (38.4%) had treated hypertension, and 11 (21.2%) had impaired renal function (creatinine >1.3 mg/dl). In 46 patients (88.4%) with angiography before aortic interruption, 31 (67.4%) had normal renal arteries, whereas 15 (32.6%) demonstrated renal artery stenosis of ≤50% (N = 10) or >50% (N = 9). Concomitant renal revascularization (N = 3) or nephrectomy (N = 1) were rare. All patients were monitored after surgery for a mean period of 39.2 months. Thirty-three (63.5%) remain alive and well; 19 (36.5%) have died of causes not related (N = 15) or indirectly related (N = 4) to the original graft infection. Forty-eight patients (92.3%) had late assessment of their blood pressure (N = 44, mean follow-up of 31.0 months) and/or renal function (creatinine) (N = 42, mean follow-up of 26.1 months). Follow-up aortography in 21 patients (40.4%, mean interval of 27.7 months) demonstrated no instance of suprarenal propagation of aortic thrombus. During follow-up 41 patients (78.8%) had no change in either their blood pressure or serum creatinine. Seven patients (13.5%) developed worsening hypertension (N = 3) or a rising creatinine (N = 4). Of these one had a failed renal artery—superior mesenteric artery transposition, and one had an immediate postoperative renal artery thrombosis. One patient has normal renal arteries by angiography in spite of a creatinine rise. The remaining four patients have not had follow-up angiography. We conclude that surgical aortic interruption is uncommonly associated with suprarenal propagation of aortic thrombus. It is arguable whether this form of aortic occlusion is comparable to spontaneous aortic thrombosis, but the data may provide reasonable guidelines for treatment in that setting as well. We continue to believe that the most dangerous concomitant conditions that may lead to ascent of aortic thrombus are those that reduce antegrade flow through the aortic stump, particularly coexistent renal and visceral lesions or proximal aortic occlusive disease.

Recent Advances in the Management of Venous Thromboembolism

Deep venous thrombosis and pulmonary embolism are frequently diagnosed in patients encountered in a primary-care practice. In the past 10 years, many important advances have been made regarding the management of these disorders. Risk factors have been better defined than in the past. Several new prophylactic measures--such as external pneumatic compression of the lower extremities, dihydroergotamine in combination with heparin, adjusted-dose heparin, and two-step warfarin therapy--can be used to help prevent deep venous thrombosis in surgical patients. The use of serial impedance plethysmography has expanded options for noninvasive diagnosis of deep venous thrombosis. Correlations between pulmonary embolism and ventilation-perfusion lung scan patterns have been clarified. Although much has been learned about heparin and warfarin that affect common management decisions, the indications for thrombolytic therapy for venous thromboembolism remain controversial. Finally, studies have shown that calf vein thrombi that are not detectable by impedance plethysmography and that show no evidence of proximal propagation by serial impedance plethysmography do not require treatment.