Deep venous thrombosis and the risk of pulmonary embolism. A systematic study

Natural History of Isolated Below-Knee Vein Thrombosis in Patients with Spinal Cord Injury

In the general population, serial imaging is recommended over anticoagulant therapy for below-knee deep vein thrombosis (BKDVT). However, no clinical trial in Asian patients with spinal cord injury and BKDVT has been performed. Therefore, we evaluated the natural course of BKDVT in patients with acute spinal cord injury. We retrospectively analyzed inpatients with spinal cord injury with BKDVT between 2016 and 2020. All patients underwent inpatient rehabilitation treatment and duplex ultrasonographic examination of both the lower extremities at follow-up. After screening 172 patients with acute spinal cord injury for deep vein thrombosis using duplex ultrasound, 27 patients with below-the-knee deep vein thrombosis were included in this study. The mean lower-extremity motor score (median, interquartile range) was 66.0, 54.0–74.5. Sixteen patients received a non-vitamin K antagonist oral anticoagulant (NOAC) for anticoagulation. None of the patients had proximal propagation according to the follow-up duplex ultrasonography. BKDVT disappearance was not significantly different between the NOAC treatment and non-treatment groups. Asian patients with spinal cord injury have a low incidence of venous thromboembolism and favorable natural history of BKDVT. We recommend serial imaging over anticoagulant therapy for BKDVT in these patients.

Triaging deep vein thrombosis using ultrasonography after lower-extremity orthopedic surgery: analysis of a single-center experience

PURPOSE

This study aimed to stratify risk factors and vein levels for postoperative deep vein thrombosis (DVT) after lower-extremity orthopedic surgery.

METHODS

Ninety-nine patients who underwent Doppler ultrasonography after lower-extremity orthopedic surgery were enrolled. Medical records were reviewed for anesthesia duration, type of surgery, body weight, height, and cardiovascular risk factors (including history of smoking, diabetes mellitus or hypertension, blood pressure, and total cholesterol and high-density lipoprotein [HDL] cholesterol levels), and the DVT treatment. Ultrasound diagnosis of DVT was made according to a routine protocol. The relationships between selected factors and the presence of DVT were assessed using univariate and multivariate regression analyses.

RESULTS

Thirty-three (33%) patients were found to have calf DVT. The mean age, weight, and height of the non-DVT and postoperative DVT patients were 55.1 years versus 65.4 years, 70.5 kg versus 61.2 kg, and 163.3 cm versus 157.0 cm, respectively. Total cholesterol/HDL levels in the non-DVT and DVT patients were 70.6/20.7 mg/dL and 90.8/26.0 mg/dL, retrospectively. Systolic and diastolic blood pressure in the non-DVT and DVT patients were 133.6/80.2 mm Hg and 132.2/78.1 mmHg, respectively. The mean duration of anesthesia was 173.9 versus 199.9 minutes, and the operative time was 136.4 minutes versus 161.0 minutes. Older age (P=0.005) and lower body weight (P=0.002) were significantly associated with postoperative DVT. No other significant between-group differences were found (P>0.05). The patients with ultrasound-identified DVT received antithrombotic treatment. None of them had distant thromboembolism.

CONCLUSION

After lower-extremity orthopedic surgery, the calf veins in elderly patients with low body weight are susceptible to thrombosis; they would most likely benefit from postoperative ultrasonography.

Anticoagulation in pulmonary arterial hypertension: a decision analysis

Systemic anticoagulation may be beneficial in pulmonary arterial hypertension, but there is no randomized clinical trial data to guide therapeutic decision making, and current guidelines do not account for patient preferences or quality of life. Decision analytic models to evaluate the potential risks and benefits of systemic anticoagulation in pulmonary arterial hypertension patients, focusing on the benefit in quality-adjusted life years, may be helpful in clarifying this uncertainty. We constructed a 31-state Markov decision analytic model to explore anticoagulation and no anticoagulation strategies. Modeled patient characteristics included gender, use of central catheter-based pulmonary arterial hypertension therapy, type of pulmonary arterial hypertension (idiopathic, idiopathic pulmonary arterial hypertension, or connective-tissue associated, connective tissue disease-pulmonary arterial hypertension), and use of oral contraceptive medication by females. Modeled events included mortality, thromboembolic complications, atrial fibrillation, stroke, and anticoagulation bleeding. Deterministic and probabilistic sensitivity analyses were performed. Anticoagulation was favored in all idiopathic pulmonary arterial hypertension cases, with a gain of 0.43-0.51 quality-adjusted life years, and detrimental in all connective tissue disease-pulmonary arterial hypertension cases, with a loss of 0.66-1.89 quality-adjusted life years. Anticoagulation would need to demonstrate a hazard ratio for pulmonary arterial hypertension mortality of 0.95 or better to be favored. In our model, idiopathic pulmonary arterial hypertension patients benefit from anticoagulation in terms of quality-adjusted life years, and connective tissue disease-pulmonary arterial hypertension patients were harmed, with a hazard ratio for pulmonary arterial hypertension mortality of 0.95 or better being required to favorably impact quality-adjusted life years. These results suggest that anticoagulation significantly improves quality adjusted life years and should be offered to all idiopathic pulmonary arterial hypertension patients. Shared decision models based on these results may help clarify therapeutic decision-making uncertainty in pulmonary arterial hypertension patients.

By word of mouse: using animal models in venous thrombosis research

Deep vein thrombosis (DVT) is a disease with high prevalence and morbidity. It can lead to pulmonary embolism with severe respiratory insufficiency and risk of death. Mechanisms behind all stages of DVT, such as thrombosis commencement, propagation, and resolution, remain incompletely understood. Animal models represent an invaluable tool to explore these problems and identify new targets for DVT prevention and treatment. In this review, we discuss existing models of venous thrombosis, their advantages and disadvantages, and applicability to studying different aspects of DVT pathophysiology. We also speculate about requirements for an "ideal model" that would best recapitulate features of human DVT and discuss readouts of various models.

Below-knee deep vein thrombosis (DVT): diagnostic and treatment patterns

Background

Guidelines are lacking for isolated below-knee deep vein thrombosis (BKDVT). The American College of Chest Physicians (ACCP) suggests anticoagulation only if symptoms are severe, otherwise surveillance with follow-up ultrasound in 2 weeks is recommended. Yet clinical practice remains highly variable. Little is known about the natural history of BKDVT and how to best manage these patients.

Methods

A retrospective analysis was conducted of medical records from 2014-2016. Risk factors were assessed such as age, gender, malignancy, recent surgery, and history of DVT. Treatment decisions and outcomes were identified. Radiology reports were graded for clarity. Chi-square and logistic regression were used to correlate risk factors with outcomes and determine odds of treatment.

Results

New isolated BKDVT was identified in 102 patients. Patients were symptomatic or had previous pulmonary embolism (PE) or DVT in all cases. Eighteen were positive for PE at diagnosis (17.6% of all patients or 62.1% with chest CT). Malignancy was independently associated with PE (P=0.015); no other risk factors were significant. Treatment was not associated with clinical risk factors. The language used for radiology reports was highly variable and was associated with the decision to treat with anticoagulation. One hundred percent were treated (n=24) when the report stated "positive DVT" and 89.2% (n=58) were treated after an objective description without the word "DVT" (P=0.01). Treatment was much less likely if the report described BKDVT anatomically but was said to be "negative for DVT" (P<0.001). A total of 86.3% (n=88) of all patients were treated, compared to 46.2% (n=6) of patients in this group (n=13). IVC filters were placed in 3 patients. Of the 14 untreated patients, 5 received surveillance, 3 developed new proximal DVT, and none developed PE.

Conclusions

About 90% of patients diagnosed with BKDVT received anticoagulation after the initial diagnosis. Surveillance was not commonly recommended and is likely underutilized. Radiology reporting was highly variable and correlated with clinical treatment decisions, whereas other clinical risk factors did not. Describing BKDVT findings only in terms of being "positive" or "negative" for DVT may be inadequate.

Controversies in venous thromboembolism: the unique case of isolated distal deep vein thrombosis

Venous thromboembolism (VTE) represents the third leading cause of cardiovascular mortality, and it is the main cause of preventable mortality in hospitalized patients. Among VTE, there is the unique case of isolated distal deep vein thrombosis (IDDVT), which still lacks an agreement in terms of optimal therapeutic strategy. Although most IDDVTs are self-limiting and associated with a very low risk of embolic complications, still not all IDDVTs can be safely identified as stable. Lack of strong scientific evidence, fear of thromboembolic complications, and risk of bleeding upon initiation of anticoagulant treatment result in very heterogeneous therapeutic strategies among physicians. Here, we provide a comprehensive review of the literature, highlight the many controversial issues regarding IDDVTs, and call for a consensus of experts aimed to shed new light on the gray areas of IDDVT management and therapy.

Clinical Significance of the Soleal Vein and Related Drainage Veins, in Calf Vein Thrombosis in Autopsy Cases with Massive Pulmonary Thromboembolism

OBJECTIVE

To clarify the histopathological characteristics of deep vein thrombosis (DVT) resulting in lethal pulmonary thromboembolism (PE).

SUBJECTS AND METHODS

We investigated 100 autopsy cases of PE from limb DVT. The distribution and chronology of DVT in each deep venous segment were examined. Venous segments were classified into three groups: iliofemoral vein, popliteal vein and calf vein (CV). The CV was subdivided into two subgroups, drainage veins of the soleal vein (SV) and non drainage veins of SV.

RESULTS

Eighty-nine patients had bilateral limb DVTs. CV was involved in all limbs with DVT with isolated calf DVTs were seen in 47% of patients. Fresh and organized thrombi were detected in 84% of patients. SV showed the highest incidence of DVTs in eight venous segments. The incidence of DVT gradually decreased according to the drainage route of the central SV. Proximal tips of fresh thrombi were mainly located in the popliteal vein and tibioperoneal trunk, occurring in these locations in 63% of limbs.

CONCLUSIONS

SV is considered to be the primary site of DVT; the DVT then propagated to proximal veins through the drainage veins. Lethal thromboemboli would occur at proximal veins as a result of proximal propagation from calf DVTs.

Value of serial platelet indices measurements for the prediction of pulmonary embolism in patients with deep venous thrombosis

BACKGROUND

To date, no validated biomarkers with high sensitivity and specificity have been established for diagnosis of pulmonary embolism (PE) in patients with deep venous thrombosis (DVT). There is a need to develop simple and reliable noninvasive tests that can accurately identify patients with PE, even in small hospitals or clinics. The aim of this study was to investigate the value of mean platelet volume (MPV) and platelet distribution width (PDW) for predicting occurrence of PE in patients with DVT.

METHODS

Records of acute DVT patients were reviewed retrospectively. Group 1 consisted of 50 patients with acute DVT and group 2 consisted of 50 patients with acute DVT who developed PE during follow-up. The control group consisted of patients with uncomplicated primary varicose veins of the lower limbs. Venous peripheral blood samples for measurement of MPV, PDW, and platelet count were drawn on admission, before the treatment, and at the time of PE diagnosis.

RESULTS

MPV and PDW levels at the time of PE diagnosis were higher in group 2 than group 1 (P<0.001 and P=0.026, respectively). Receiver operating characteristics analysis revealed that a 5.2% increase in admission PDW during follow-up provided 70% sensitivity and 82% specificity (area under the curve, 0.80), and a 6.6% increase in admission MPV during follow-up provided 74% sensitivity and 83% specificity (area under the curve, 0.84) for prediction of PE occurrence in patients with DVT. PDW and MPV levels at the time of PE diagnosis were found to be independent risk factors for the occurrence of PE in patients with DVT.

CONCLUSION

Serial measurements of MPV and PDW, and percent change in MPV and PDW appears to be a useful marker for predicting occurrence of acute PE in patients with a first episode of acute proximal DVT.

Preoperative Incidence of Deep Vein Thrombosis after Hip Fractures in Korean

Background

The purpose of the current study was to investigate the incidence of preoperative deep vein thrombosis (DVT) after hip fractures in Korea.

Methods

In this prospective study, we enrolled 152 Korean geriatric patients who had suffered hip fractures due to a simple fall and were hospitalized between January 2013 and December 2013. There were 52 male and 100 female patients, and their mean age was 78.2 years. There were 96 trochanteric fractures and 56 femoral neck fractures. All patients were examined for DVT: 26 by ultrasonography and 126 by computed tomography venography. The patients having DVT underwent inferior vena cava filter insertion before the surgical intervention.

Results

Preoperatively, none of the patients had any signs or symptoms of DVT; however, 4 patients were identified as having asymptomatic DVT. The overall incidence of DVT was 2.6% (4/152). The mean time to arrival at emergency room after injury was 32.6 hours. Mean time elapsed to undergo surgery after hospitalization was 24.9 hours. The average time to hospitalization after injury was 237 hours for patients with DVT versus 27.5 hours for patients without DVT. DVT developed within 72 hours in two of the 137 patients (1.4%) and after 72 hours in two of the remaining 15 patients (13.3%) hospitalized.

Conclusions

While the preoperative incidence of DVT after hip fractures was relatively low (2.6%) in the Korean geriatric population, we confirmed that getting no treatment within 72 hours after injury increased the incidence of DVT. Thus, we conclude from this study that a workup for DVT should be considered in cases where admission or surgery has been delayed for more than 72 hours after injury.

Trapping of embolic particles in a vessel phantom by cavitation-enhanced acoustic streaming

Cavitation clouds generated by short, high-amplitude, focused ultrasound pulses were previously observed to attract, trap, and erode thrombus fragments in a vessel phantom. This phenomenon may offer a noninvasive method to capture and eliminate embolic fragments flowing through the bloodstream during a cardiovascular intervention. In this article, the mechanism of embolus trapping was explored by particle image velocimetry (PIV). PIV was used to examine the fluid streaming patterns generated by ultrasound in a vessel phantom with and without crossflow of blood-mimicking fluid. Cavitation enhanced streaming, which generated fluid vortices adjacent to the focus. The focal streaming velocity, uf, was as high as 120 cm/s, while mean crossflow velocities, uc, were imposed up to 14 cm/s. When a solid particle 3-4 mm diameter was introduced into crossflow, it was trapped near the focus. Increasing uf promoted particle trapping while increasing uc promoted particle escape. The maximum crossflow Reynolds number at which particles could be trapped, Rec, was approximately linear with focal streaming number, Ref, i.e. Rec = 0.25Ref + 67.44 (R(2) = 0.76) corresponding to dimensional velocities uc = 0.084uf + 3.122 for 20 < uf < 120 cm/s. The fluidic pressure map was estimated from PIV and indicated a negative pressure gradient towards the focus, trapping the embolus near this location.

Deep vein thrombosis in orthopedic surgery of the lower extremities

To prevent pulmonary embolism due to deep venous thrombosis (DVT), we have treated 611 patients undergoing orthopedic surgery of the lower extremities with our protocol including pre- and postoperative ultrasonic venous screening and anticoagulant therapy if necessary. A total of 118 patients (19.3%) developed DVT. Among demographic and clinical factors, the site of operation (knee joint surgery: odds ratio 5.17), age (>60: odds ratio 3.91), and operation time (>120 minutes: odds ratio 4.52) were identified as significant risk factors of development of DVT. One patient received an infusion of urokinase for DVT of femoral vein, but no patients developed serious postoperative bleeding or pulmonary thromboembolisms. (*English Translation of J Jpn Coll Angiol, 2010, 50: 95-100.).

Waiting to inhale: An exploratory review of conditions that may predispose to pulmonary hypertension and right heart failure in persons exposed to household air pollution in low- and middle-income countries

The health effects of exposure to household air pollution are gaining international attention. While the bulk of the known mortality estimates due to these exposures are derived from respiratory conditions, there is growing evidence of adverse cardiovascular health effects. Pulmonary hypertension and right heart failure are common conditions in low- and middle-income countries whose etiology may be related to common exposures in these regions such as schistosomiasis, human immunodeficiency virus, tuberculosis infections and other causes. While little is known of the interplay between exposure to household air pollution, right heart function and such conditions, the large burden of pulmonary hypertension and right heart failure in regions where there is significant exposure to household air pollution raises the possibility of a linkage. This review is presented in three parts. First, we explore what is known about pulmonary hypertension and right heart failure in low- and middle-income countries by focusing on eight common causes thereof. We then review what is known of the impact of household air pollution on pulmonary hypertension and posit that when individuals with one of these eight common comorbidities are exposed to household air pollution they may be predisposed to develop pulmonary hypertension or right heart failure. Lastly, we posit that there may be a direct link between exposure to household air pollution and right heart failure independent of pre-existing conditions which merits further investigation. Our overall aim is to highlight the multifactorial nature of these complex relationships and offer avenues for research in this expanding field of study.

Should symptomatic, isolated distal deep vein thrombosis be treated with anticoagulation?

BACKGROUND

During the past two decades, the diagnosis of deep venous thrombosis (DVT) has made considerable progress. The term distal or calf vein thrombosis includes thrombosis in infrapopliteal veins, including the posterior tibial, peroneal, anterior tibial and muscular calf veins. The necessity of treating of distal DVT is debatable.

OBJECTIVE

To determine whether treatment of isolated, distal DVT with anticoagulation versus no treatment affects patient outcome.

METHODS

All patients discharged with a diagnosis of distal DVT from Tan Tock Seng Hospital, Singapore, between January 1, 2006, and December 31, 2007, were identified by the medical records office of the hospital. Compression of the intraluminal thrombus by duplex scan was used to diagnose distal DVT. Excluded were patients who either had both distal and proximal DVT, or had distal DVT along with pulmonary embolism (PE) at presentation. Complete resolution of distal DVT on repeat duplex scan was used to measure the primary outcome. Repeat follow-up scans were performed at two weeks, one month, three months and six months, or on subsequent follow-up until the distal DVT had resolved completely. Secondary outcome measures were complete improvement of symptoms, progression of thrombosis, or PE or death during the follow-up period. The study included 68 patients with distal DVT; however, 17 patients with PE, two of whom had proximal DVT (in the iliac and common femoral veins) at the first presentation along with distal DVT, were excluded from the study. In total, 51 patients were included for analysis. The follow-up scan was available in 35 patients; therefore, the primary analysis was performed in 35 patients (47 incidences of distal DVT). However, the secondary analysis was available in all 51 patients. Of the 35 patients available for follow-up scans, 17 patients (25 incidences of distal DVT) received anticoagulation and 18 patients (22 incidences of distal DVT) received no anticoagulation. Of the 17 patients who were treated with anticoagulation, nine patients (13 incidences of distal DVT) received enoxaparin at a dose of 1 mg/kg twice a day for two weeks and eight patients (12 incidences of distal DVT) received warfarin for a period of three months with initial overlap of enoxaparin 1 mg/kg twice a day for three to five days. Once the prothrombin time international normalized ratio of a patient on warfarin was between 2 and 3, enoxaparin was discontinued. The 18 patients who did not receive anticoagulation received follow-up with regular duplex scan.

RESULTS

There were no statistically significant differences among the groups in the resolution of distal DVT or symptom improvement with or without treatment. In the group that received no treatment, one death occurred. Proximal extension and PE were not recorded in any of the patients.

CONCLUSION

Distal DVT may not require treatment with anticoagulation. If leg symptoms worsen, or if there is an extension of distal DVT on the follow-up scan, treatment with anticoagulation is recommended.

Finding the origin of pulmonary emboli with a total-body magnetic resonance direct thrombus imaging technique

Pulmonary embolism is considered to originate from embolization of a deep-vein thrombosis, resulting in two manifestations of one disease: venous thrombosis. However, in up to 50% of patients with pulmonary embolism no deep-vein thrombosis is found with ultrasonography. An explanation for this low proportion is currently lacking. Other imaging modalities may increase the yield of detection of deep-vein thrombosis in the calf or in the abdominal region. Alternatively, not all pulmonary emboli may originate from deep-vein thromboses in the extremities. We searched for the origin of pulmonary emboli, by performing total-body magnetic resonance imaging-scans to visualize thrombi. Ninety-nine patients with a first pulmonary embolism confirmed by computed tomography underwent a magnetic resonance direct thrombus imaging-scan, a validated technique using endogenous contrast. Additionally, acquired and genetic risk factors were assessed. No thrombus was found in 55 patients, whereas a thrombus was identified in 44 patients. The commonest thrombus location was the lower leg; 12 patients had isolated calf vein thrombosis and five had isolated superficial vein thrombosis. A peripheral thrombus was found by magnetic resonance imaging in less than half of patients with pulmonary embolism. We propose several hypotheses to explain the absence of thrombi, such as a cardiac thrombus origin or embolization of the whole deep-vein thrombus. The possibility that pulmonary embolism arises de novo in the lungs, due to local inflammation-driven coagulation, needs to be considered.

Prophylactic anticoagulation to prevent venous thromboembolism in traumatic intracranial hemorrhage: a decision analysis

Introduction

Patients with intracranial hemorrhage due to traumatic brain injury are at high risk of developing venous thromboembolism including deep vein thrombosis (DVT) and pulmonary embolism (PE). Thus, there is a trade-off between the risks of progression of intracranial hemorrhage (ICH) versus reduction of DVT/PE with the use of prophylactic anticoagulation. Using decision analysis modeling techniques, we developed a model for examining this trade-off for trauma patients with documented ICH.

Methods

The decision node involved the choice to administer or to withhold low molecular weight heparin (LMWH) anticoagulation prophylaxis at 24 hours. Advantages of withholding therapy were decreased risk of ICH progression (death, disabling neurologic deficit, non-disabling neurologic deficit), and decreased risk of systemic bleeding complications (death, massive bleed). The associated disadvantage was greater risk of developing DVT/PE or death. Probabilities for each outcome were derived from natural history studies and randomized controlled trials when available. Utilities were obtained from accepted databases and previous studies.

Results

The expected value associated with withholding anticoagulation prophylaxis was similar (0.90) to that associated with the LMWH strategy (0.89). Only two threshold values were encountered in one-way sensitivity analyses. If the effectiveness of LMWH at preventing DVT exceeded 80% (range from literature 33% to 82%) our model favoured this therapy. Similarly, our model favoured use of LMWH if this therapy increased the risk of ICH progression by no more than 5% above the baseline risk.

Conclusions

Our model showed no clear advantage to providing or withholding anticoagulant prophylaxis for DVT/PE prevention at 24 hours after traumatic brain injury associated with ICH. Therefore randomized controlled trials are justifiable and needed to guide clinicians.

Ultrasound Evaluation of the Lower Extremity Veins

Over the past 2 decades venous ultrasonography has become the standard primary imaging technique for the initial evaluation of patients for whom there is clinical suspicion of deep venous thrombosis (DVT) of the lower extremity veins. This article addresses the role of duplex ultrasonography and color Doppler ultrasonography in today's clinical practice for the evaluation of patients suspected of harboring a thrombus in their lower extremity veins. It reviews the clinical presentation and differential diagnoses, technique, and diagnostic criteria for acute and chronic DVT. In addition, it addresses the sonographic evaluation of venous insufficiency.

Ultrasound diagnosis of deep venous thrombosis

The ultrasound diagnosis of deep venous thrombosis by an emergency physician is occurring with increased frequency. The examination is simple to perform and, when combined with a clinical pretest probability or D-dimer, can aid in the rapid disposition ofa patient with lower extremity pain and swelling. The technique and findings of the limited lower extremity ultrasound and the data to support its use in the emergency department are discussed.

Incidence of asymptomatic pulmonary embolism in moderately to severely injured trauma patients

BACKGROUND

Chest computed tomographic (CT) scanning is used frequently to evaluate symptomatic patients for pulmonary embolus (PE). The incidence of PE diagnosed by helical CT scanning in asymptomatic patients is unknown.

METHODS

Asymptomatic trauma patients with an Injury Severity Score > or = 9 were studied with contrast-enhanced helical CT images of the chest, pelvis, and lower extremities. Clot burden was assessed using an anatomic scoring system. Patients not receiving anticoagulation were followed.

RESULTS

Twenty-two of 90 patients had a PE. Four had major clot burden, including one patient with a saddle embolus. Risk factors for asymptomatic PE include age (odds ratio [OR], 1.04), head injury (OR, 6.78), chest injury (OR, 4.51), lower extremity injury (OR, 5.03), and transfusion (OR, 3.42). Thirty percent of patients receiving pharmacologic prophylaxis had a PE.

CONCLUSION

Asymptomatic PE occur in 24% of moderately to severely injured patients. Age, head, chest, and lower extremity injury are associated with an increased risk. Standard thromboembolic prophylaxis is not reliably protective.

Electron beam tomography of interpulmonary saddle embolism: extent and vascular distribution

PURPOSE

The purpose of this work was to assess morphology and secondary signs of interpulmonary emboli extending across the bifurcation of the main pulmonary artery (PA).

METHOD

Retrospective evaluation of 780 electron beam tomographic studies of the chest yielded 17 cases of interpulmonary saddle embolism. Length, diameter, vascular distribution of the emboli, and secondary findings were prospectively assessed by two blinded reviewers. Follow-up studies were carried out in 12 of 17 patients (71%).

RESULT

Mean total length of the emboli was 46.6 cm (range 20.9-81.5 cm). The mean diameter of the saddle embolus was significantly smaller at the level of the bifurcation than in the left or right PA (4.5, 7.7, and 7.4 mm, respectively; p < 0.01). Dilatation of the right heart was found in 10 of 17 cases (59%). At follow-up, the saddle state was no longer present in 8 of 12 patients (67%).

CONCLUSION

Interpulmonary saddle emboli appear to be a transient form of acute pulmonary embolism, the site of predilection for rupture of the embolus being the level of the bifurcation. Their frequency may therefore be underestimated.

The diagnosis of lower extremity deep venous thrombosis

The diagnosis of lower extremity deep venous thrombosis (DVT) is critical to emergency physicians because of the risk of pulmonary embolism. This article reviews the diagnostic modalities available for patients with suspected lower extremity DVT. The use of compression ultrasonography and the recent advances in the D-dimer assays are emphasized. A clinical algorithm that utilizes a non invasive approach to this potentially life threatening disease is presented.

Physical examination findings in deep venous thrombosis

DVT is a potentially serious disease and can serve as a marker for PE, an entity with even higher morbidity. Thus, it is critically important that emergency physicians consider this diagnosis in patients who present with suspicious symptoms. Recognition of alternative conditions, such as compartment syndrome, septic arthritis, and cellulitis, is also important for optimal care. Because physical examination is only 30% accurate for DVT, it serves to increase clinical suspicion in patients at risk but cannot be used to eliminate the possibility of thromboembolic disease. Because of this limitation, the diagnosis of DVT should be pursued using adjunctive testing in any patient with unexplained limb pain or swelling. Duplex sonography is currently the initial diagnostic study of choice for evaluation of DVT and, if test results are negative, it should be repeated serially if the clinical suspicion is high.

Diagnosis of pulmonary embolism in patients with proximal deep vein thrombosis: specificity of symptoms and perfusion defects at baseline and during anticoagulant therapy

To determine the specificity of pulmonary embolism (PE) symptoms and lung scan perfusion defects in patients with deep vein thrombosis (DVT), we analyzed data on 400 patients with phlebography-proven proximal DVT included in a prospective trial. As the incidence of PE during anticoagulant therapy was the main outcome measure of the trial, all patients underwent lung scanning and/or pulmonary angiography within 48 h of inclusion, and then whenever PE was suspected. Angiography was recommended in patients with nondiagnostic lung scan. At baseline, the presence or absence of PE could be ascertained in 350 patients (87.5%), and 197 (56%) had PE. Sensitivity and specificity of symptoms for PE were 74 and 67%, respectively. Among 37 patients with symptoms and nondiagnostic lung scan, only 8 (22%) had PE at angiography. During anticoagulant therapy (3 mo), there were 29 events suspicious for PE, mostly (53%) within 2 wk of inclusion. Repeated perfusion studies with comparison to baseline tests excluded PE in 21 cases. Cumulated 3-mo risks of suspected and confirmed on-treatment PE were 6.8% (95% CI, 5.4- 8.2%) and 2.0% (95% CI, 0.6-3.4%) respectively. Even in patients with known proximal DVT, PE symptoms are unspecific and careful imaging studies are needed for diagnosis, both at baseline and during anticoagulant therapy.

Outpatient treatment of patients with deep-vein thrombosis or pulmonary embolism

There have been a large number of randomized trials comparing standard unfractionated intravenous heparin with low-molecular-weight heparin for the treatment of deep-vein thrombosis, but only two of these have looked at outpatient therapy. There have been only two randomized trials including patients with symptomatic pulmonary embolism, and neither of these provided outpatient therapy. Postmortem and clinical studies have shown a strong association between pulmonary embolism and the presence of venous thrombosis in the lower limbs. Based on similar rates of venous thromboembolic recurrence and death, these studies suggest that initial treatment should be the same for deep-vein thrombosis and pulmonary embolism. The feasibility of providing outpatient care to many patients seeking treatment for deep-vein thrombosis or acute pulmonary embolism at certain tertiary care hospitals has become evident, but the data suggest that the proportion of eligible patients is institution dependent and may vary from 18% to 91%. In the author's institution, approximately 50% of patients with pulmonary embolism could be treated as outpatients, but there have been no other reports on outpatient therapy for patients with pulmonary embolism. If patients with pulmonary embolism meet criteria demonstrated to result in a higher risk of death, it is, of course, reasonable to not treat such patients on an outpatient basis. Low-molecular-weight heparin followed by oral anticoagulant therapy provides adequate therapy in most patients with deep-vein thrombosis or pulmonary embolism, and many patients can be treated as outpatients.

Isolated calf vein thrombosis: comparison of MR venography and conventional venography after initial sonography in symptomatic patients

RATIONALE AND OBJECTIVES

The authors performed this study to compare magnetic resonance (MR) venography and conventional venography in the diagnosis of deep venous thrombosis (DVT) in the calf after sonography.

MATERIALS AND METHODS

Sonography was performed in 595 patients who were suspected of having lower-extremity DVT. Patients with positive above-knee duplex sonograms, allergy to iodinated contrast material, renal insufficiency, or cardiac pacemakers and patients who were obese were excluded. The remaining 73 patients were asked to undergo MR venography and conventional venography. All studies were to be performed within 48 hours of the clinical diagnosis and according to standard clinical practice. Images were interpreted by radiologists who were blinded to the results of other modalities. Two separate analyses were performed: one in which conventional venography was used as the standard of reference, and one in which the presence of at least two positive studies for thrombus was considered diagnostic.

RESULTS

Although 36 patients agreed to participate in the study, only 14 underwent MR venography and conventional venography within 48 hours of the clinical diagnosis. With use of any two positive studies for confirmation, acute DVT was diagnosed in three patients. Conventional venography depicted two of the three cases, whereas sonography and MR venography each depicted all three. The findings were concordant in only five of the 14 patients.

CONCLUSION

Moderate discrepancy among modalities was demonstrated. This suggests radiologists should undertake comparisons among these three modalities for the detection of calf DVT. In patients with a high clinical suspicion, a second modality may be useful if the initial study is negative.

Pulmonary embolism: making sense of the diagnostic evaluation

Despite the publication of the Prospective Investigation of Pulmonary Embolism Diagnosis in 1990, the diagnostic evaluation of pulmonary embolism continues to be approached in an inconsistent fashion. The reasons for this are unclear but likely have to do with inadequate methods for predicting pretest probability of disease and the inconvenience and perceived risk of pulmonary angiography. Because pulmonary embolism and its treatment carry substantial risk of morbidity and mortality, a consistent approach to evaluation is desirable. This article reviews large, prospective studies that suggest that it may be unnecessary to diagnose pulmonary embolism with the certainty that pulmonary angiography allows. Finally, the article proposes an algorithm that may be acceptable to patients and clinicians alike if safety is confirmed in future prospective studies.

Do we know which patients with the antiphospholipid syndrome should receive long-term high dose anti-coagulation?

The standard treatment of thrombosis related to antiphospholipid antibodies is lifelong high-intensity oral anticoagulation. This standard is primarily based on retrospective evaluations of such patients. In this paper we give a summary of current treatment of deep leg vein thrombosis, pulmonary embolism, ischaemic stroke and transient ischaemic events in the general population and relate this to studies performed in patients with the anti-phospholipid syndrome (APS). It is concluded that many patients with APS can be treated with conventional doses of oral anticoagulants, and that anti-platelet drugs may have a role in the prevention of cerebral ischaemic events. Data from large scale prospective studies, which are underway, will ultimately identify the optimal treatment in individual patients.

Venous thromboembolism in trauma patients: standardized risk factors

PURPOSE

This study was done to evaluate the use of published standardized risk factors for venous thromboembolism (VTE) in patients admitted to a trauma intensive care unit (ICU) and to derive guidelines for the use of low molecular weight heparin (LMWH) and surveillance venous Doppler ultrasound scanning (VDUS).

METHODS

Patients were admitted to a regional trauma center ICU. Two periods were studied. Period 1 was a retrospective analysis of documented cases of VTE in the trauma registry from 1993 to 1995 (n=39). The period was also a review of all patients admitted to a trauma ICU in 1994 without VTE who met the following criteria: age greater than 11 years, ICU stay of more than 36 hours, and survival of more than 72 hours (n=227). Period 2 was a concurrent analysis of 1996 documented cases of VTE and similarly selected ICU admissions (VTE, n=10; no VTE, n=224). Risk factor scores (R1, admitting; R2, total) were calculated from the International Society for Cardiovascular Surgery/Society for Vascular Surgery reporting standards. The scores were cumulative by category and over time. The suitability of such standards was determined in period 1. The resulting therapeutic and surveillance guidelines were evaluated in period 2.

RESULTS

Period 1 risk factor scores, R1 and R2, were correlated with the occurrence of VTE from chi2 test (P < .05 and P < .01, respectively). Risk categories were grouped as low, moderate, and high. VTE was not observed in the low-risk group (0 to 2). Among all VTE (n=49), 11 cases occurred in patients with moderate-risk scores and 38 in patients with high-risk scores. In 1994 and 1996, the selected groups were analyzed and the incidence rate of VTE was 4.7% in both years for the moderate-risk group and 2.5% and 4.8% for the high-risk group, respectively. Most VTE cases (78%) received some form of prophylaxis (PRx), and 26% of cases had multiple methods of prophylaxis (MPRx). This included 80% of the cases that received unfractionated heparin. In period 2, no pulmonary emboli (PE) occurred, in contrast to period 1, in which 16 of 39 cases of VTE (41%) were first seen with PE. In period 2, no patient receiving MPRx, including compression and LMWH, had VTE develop. Surveillance VDUS discovered 60% of 1996 cases in period 2. No PE were seen in period 2.

CONCLUSION

Standard risk factors were easily applied to the trauma patient at the bedside. Patients at low risk needed no PRx. Patients at high risk did best with both compression devices and LMWH. VDUS was recommended selectively in patients at high risk in whom multiple-method PRx could not be achieved. Patients at moderate risk required further study to define optimal PRx and need for surveillance VDUS. Intracaval devices were used prophylactically only twice.

Clinical aspects of pulmonary embolism

Pulmonary embolism is a common disease in the United States, affecting as many as 500,000 persons annually. Unfortunately, this disorder is commonly undiagnosed, resulting in significant excess morbidity and mortality. The clinical symptoms and signs caused by pulmonary embolism are nonspecific and may be confused with a variety of other cardiopulmonary disorders having similar presentations. However, accurate diagnostic tests are available for diagnosing pulmonary embolism, even in the face of coexistent cardiopulmonary disorders. This article describes the clinical characteristics of pulmonary venous thromboembolism, reviewing its typical symptoms and signs, its routine laboratory tests, and chest radiographic abnormalities.

Upper extremity versus lower extremity deep venous thrombosis

BACKGROUND

In contrast to lower extremity deep venous thrombosis (LEDVT), it is widely believed that upper extremity deep venous thrombosis (UEDVT) is associated with minimal morbidity or mortality.

METHODS

In an attempt to compare the two disease processes with respect to pulmonary embolism and mortality, we have reviewed records and performed interviews of 430 patients with LEDVT and 52 patients with UEDVT presenting to our institution between January 1994 and June 1995.

RESULTS

Pulmonary embolism was documented by ventilation/perfusion lung scan in 9 of 52 patients (17%) with UEDVT and 33 of 430 patients (8%) with LEDVT (P <0.05). Twenty-five of the UEDVT patients (48%) died within 6 months of the diagnosis of UEDVT. Conversely, 14 patients (13%) in the LEDVT group died within 6 months of the diagnosis of LEDVT (P <0.0002).

CONCLUSION

Contrary to previous reports, this study suggests that UEDVT is associated with a higher morbidity and mortality as compared with LEDVT. These data show that UEDVT has been an underrecognized predictor of morbidity and mortality.

Pulmonary embolism presenting as an acute surgical abdomen

Pulmonary embolism remains a serious cause of morbidity and mortality. Diagnosis based on clinical manifestations remains difficult. Prior reviews have rarely noted the potential for patients to present with abdominal complaints. Presented here is the case of a 28-yr-old woman who had signs and symptoms of an intra-abdominal catastrophe. The patient underwent laparotomy and at surgery had findings suggesting primary intra-abdominal pathology. Autopsy results indicated that pulmonary embolism was responsible for the patient's presentation and death.

Frequency of pulmonary embolism in patients who have iliofemoral deep vein thrombosis and are treated with once- or twice-daily low-molecular-weight heparin

PURPOSE

The purpose of this study was to compare the efficacy and safety of treating mobile iliofemoral patients with deep venous thrombosis (DVT) with subcutaneous low-molecular-weight heparin (dalteparin sodium) either 200 IU/kg once-daily (group 1) or 100 IU/kg twice-daily (group 2).

METHODS

Consecutive patients with suspected iliofemoral DVT diagnosed by duplex ultrasonography and verified by radionuclide venography were randomized to one of the two low-molecular-weight heparin (LMWH) regimens. Perfusion and when necessary ventilation scans were performed for diagnosis of pulmonary emboli (PE) in all patients immediately after admission and were repeated after approximately 10 days, whereupon oral anticoagulation was started unless contraindicated. Minimal and maximal anti-factor Xa activity was measured after 2 to 3 days of therapy. All patients were kept mobile with compression bandages. The primary end point was reduction in frequency of PE as assessed on the second lung scan.

RESULTS

A total of 140 patients with confirmed DVT were randomized, 76 to group 1 and 64 to group 2. The two groups were comparable in their baseline clinical characteristics. In the initial lung scans 36 (47.4%) patients in group 1 and 29 (45.3%) patients in group 2 had objectively verified PE, but only 11 (14.5%) and 8 (12.5%) patients, respectively, had symptoms. After dalteparin treatment PE disappeared in two patients in group 1, but in two other cases new PEs occurred, (NS). In group 2 a resolution of PEs was observed in eight patients, whereas only one new PE could be detected. This change reflects the efficacy of therapy as defined by resolution of existing PEs and by the occurrence of new PEs and is statistically significant according to McNemar's chi-square test with the exact binomial method pair procedure (p < 0.05). Symptomatic PE was reduced from 14.5% to 5.3% in group 1 (96% to CI for the difference, -1.5% to +17.3%) and from 12.5% to 1.6% in group 2 (95% CI for the difference 0.7% to 18%, p < 0.05). There was one single fatal PE, one serious and three minor bleeding episodes in group 1, and one minor bleeding episode in group 2 (95% CI for the difference: -3.6% to +8.1%).

CONCLUSIONS

Treatment of ambulant iliofemoral patients with DVT with 100 IU/kg dalteparin twice-daily appears to be moe safe and effective than 200 IU/kg given once-daily. Bed rest is not necessary for treating mobile patients.

Clinical characteristics of fatal pulmonary embolism in a referral hospital

OBJECTIVE

To determine the clinical characteristics of hospitalized patients who died of pulmonary embolism, confirmed by evaluative autopsy.

DESIGN

We retrospectively analyzed a series of autopsy cases of pulmonary embolism at a tertiary-care center for the period Jan. 1, 1985, through Dec. 31, 1989.

MATERIAL AND METHODS

The medical and autopsy records of all hospitalized patients with autopsy-proven fatal pulmonary embolism were reviewed. Cases of tumor emboli, fat emboli, and contributory-only thromboembolic disease were excluded from the study. Specific symptoms and signs, diagnostic studies, and prophylactic measures were noted.

RESULTS

Among 2,427 autopsies performed during the 5-year study period, death in 92 (3.8%) was clinically and pathologically judged to be caused by pulmonary embolism. No risk factors were noted in only 11 patients (12%). Prophylaxis against thromboembolism was used in 46%. Classic symptoms were often absent: dyspnea was present in only 59%, chest pain in only 17%, and hemoptysis in 3%. Pulmonary embolism was considered in 49% of the 92 patients and was correctly assigned as the cause of death on the death certificate or in the medical records in 32%. Testing for venous thromboembolic disease was performed in 22%. Comorbidity was present in most patients: 54% had guarded or poor prognoses independent of pulmonary embolism.

CONCLUSION

The usual signs and symptoms associated with pulmonary embolism did not adequately identify most of our patients who died of pulmonary embolism. The reasons included the absence of these signs and symptoms, inability to communicate (for example, sedated or comatose patient), sudden death from acute massive pulmonary embolism, and presence of comorbid factors.

Recurrent pulmonary embolism in patients treated because of acute venous thromboembolism: a prospective study

OBJECTIVE

To evaluate the risk of pulmonary embolism (PE) despite adequate heparin therapy in a large series of patients with acute deep venous thrombosis and/or pulmonary embolism.

DESIGN

Prospective study.

SETTING

University Hospital Germans Trias i Pujol, Badalona, Spain.

MATERIALS

348 patients admitted because of deep venous thrombosis in the lower limbs and/or pulmonary embolism. A baseline lung scan was obtained initially in every patient, whether the original diagnosis was PE or deep vein thrombosis (DVT). Repeat chest X-ray and lung scans were obtained routinely at 8 days of heparin onset.

OUTCOME MEASURES

The primary trial endpoint was a finding of confirmed, clinically apparent recurrent PE; in addition, laboratory evidence of subclinical PE at the repeat scan was also considered.

RESULTS

PE recurrences were found in 23/348 patients (7%). No significant differences were found in age and sex distribution, or in the degree of DVT proximity between patients who developed and those who did not develop recurrences. Recurrent PE was more commonly found in patients with scintigraphic evidence of PE on admission, irrespectively of the original diagnosis being DVT or PE (18/151 vs. 3/155; p = 0.0005, Fisher's exact test). Recurrences were also more common in patients in whom thrombosis developed in the absence of any known risk factor (10/70 vs. 13/278; p = 0.007). The logistic regression analysis confirmed the statistical significance of these two clinical variables.

CONCLUSIONS

Pulmonary embolism despite adequate heparin therapy is not an uncommon event. It appears possible to identify a subgroup of patients at a higher risk, and, modify treatment accordingly.