Proximal extent of pelvic vein thrombosis and its association with pulmonary embolism

In Situ Pulmonary Arterial Thrombosis-Literature Review and Clinical Significance of a Distinct Entity

Filling defects identified in the pulmonary arterial tree are commonly presumed to represent an embolic phenomenon originating from thrombi formed in remote veins, particularly lower-extremity deep venous thrombosis (DVT). However, accumulating evidence supports an underappreciated cause for pulmonary arterial thrombosis (PAT), namely, de novo thrombogenesis-where thrombosis arises within the pulmonary arteries in the absence of DVT. Although historically underrecognized, in situ PAT has become of heightened importance with the emergence of SARS-CoV-2 infection. In situ PAT is attributed to endothelial dysfunction, systemic inflammation, and acute lung injury, and has been described in a range of conditions including COVID-19, trauma, acute chest syndrome in sickle cell disease, pulmonary infections, and severe pulmonary arterial hypertension. The distinction between pulmonary embolus and in situ PAT may have important implications regarding management decisions and clinical outcomes. In this review, we summarize the pathophysiology, imaging appearances, and management of in situ PAT in various clinical situations. This understanding will promote optimal tailored treatment strategies for this increasingly recognized entity.

Diagnostic performance of lower extremity Doppler ultrasound in detecting iliocaval obstruction

OBJECTIVE

To retrospectively evaluate the performance of two commonly used Doppler ultrasound parameters, namely, venous flow phasicity and response to Valsalva maneuver, in detecting iliocaval obstruction.

METHODS

All imaging studies of patients seen by interventional radiology for lower extremity venous disease at a single institution from 1996 to 2018 were retrospectively identified. Lower extremity ultrasounds with a concurrent magnetic resonance, computed tomography, or conventional venogram performed within the next 7 days, which served as gold standard, were further identified (n = 192 examinations, including 313 limbs). Iliocaval obstruction were assessed by two ultrasound criteria: (1) nonphasic flow and/or (2) nonresponsive flow to Valsalva in the common femoral vein. The sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) for diagnosing iliocaval obstruction were calculated for each ultrasound criterion, and also for when the two criteria were assessed jointly.

RESULTS

Of the 313 limbs assessed for venous flow phasicity, 133 (42.5%) had an iliocaval obstruction confirmed on subsequent venography. Nonphasic flow demonstrated a sensitivity of 69.2%, specificity of 82.8%, NPV of 78.4%, and PPV of 74.8% for diagnosing iliocaval obstruction. Of the 212 limbs assessed for Valsalva response, 88 (41.5%) had a confirmed iliocaval obstruction. Nonresponsive flow to Valsalva demonstrated a sensitivity of 13.6%, specificity of 97.6%, NPV of 61.6%, and PPV of 80.0% for diagnosing iliocaval obstruction. Joint assessment using phasicity and Valsalva criteria demonstrated a sensitivity of 68.2%, specificity of 87.2%, NPV of 79.6%, and PPV of 78.9%.

CONCLUSIONS

In this tertiary care setting, Doppler ultrasound examination was not a reliable diagnostic tool for detecting iliocaval obstruction.

Deep Vein Thrombosis After Complex Posterior Spine Surgery: Does Staged Surgery Make a Difference?

STUDY DESIGN

Retrospective review of a prospectively collected database.

OBJECTIVE

To assess the incidence of deep vein thrombosis (DVT) associated with single- versus multistage posterior-only complex spinal surgeries.

SUMMARY OF BACKGROUND DATA

Dividing the physiologic burden of spinal deformity surgery into multiple stages has been suggested as a potential means of reducing perioperative complications. DVT is a worrisome complication owing to its potential to lead to pulmonary embolism. Whether or not staging affects DVT incidence in this population is unknown.

METHODS

Consecutive patients undergoing either single- or multistage posterior complex spinal surgeries over a 12-year period at a single institution were eligible. All patients received lower extremity venous duplex ultrasonographic (US) examinations 2 to 4 days postoperatively in the single-stage group and 2 to 4 days postoperatively after each stage in the multistage group. Multivariate logistic regression was used to assess the independent contribution of staging to developing a DVT.

RESULTS

A total of 107 consecutive patients were enrolled-26 underwent multistage surgery and 81 underwent single-stage surgery. The single-stage group was older (63 years vs. 45 years; p < .01) and had a higher Charlson comorbidity index (2.25 ± 1.27 vs. 1.23 ± 1.58; p < .01). More multistage patients had positive US tests than single-stage patients (5 of 26 vs. 6 of 81; 19% vs. 7%; p = .13). Adjusting for all the above-mentioned covariates, a multistage surgery was 8.17 (95% CI 0.35-250.6) times more likely to yield a DVT than a single-stage surgery.

CONCLUSIONS

Patients who undergo multistage posterior complex spine surgery are at a high risk for developing a DVT compared to those who undergo single-stage procedures. The difference in DVT incidence may be understated as the multistage group had a lower pre- and intraoperative risk profile with a younger age, lower medical comorbidities, and less per-stage blood loss.

Association between inherited thrombophilia and impaired right ventricular function in deep vein thrombosis without symptomatic pulmonary embolism

The aim was to evaluate the right ventricular function in patients with inherited thrombophilia and deep vein thrombosis (DVT) without pulmonary embolism. A total of 38 patients with DVT without symptomatic pulmonary embolism and 30 patients with varicose veins were enrolled. Clinical data, echocardiography, and 2 thrombophilic mutations were analyzed. Factor V Leiden (FVL) polymorphism was significantly frequent in the study group (P = .007). The difference in prothrombin G20210A polymorphism between the study and control groups was at a near-significant level (P = .058). There was statistically significant decrease in tricuspid annular plane systolic excursion values in patients with FVL and prothrombin G20210A polymorphism. Combined FVL and prothrombin G20210A polymorphisms were more closely related to the decrease in this value (P = .006). Deep vein thrombosis had no additional adverse effects on right ventricle. Impaired right ventricular systolic function occurs in FVL and prothrombin G20210A polymorphisms.

Cost-effectiveness of strategies for diagnosing pulmonary embolism among emergency department patients presenting with undifferentiated symptoms

STUDY OBJECTIVE

Symptoms associated with pulmonary embolism can be nonspecific and similar to many competing diagnoses, leading to excessive costly testing and treatment, as well as missed diagnoses. Objective studies are essential for diagnosis. This study evaluates the cost-effectiveness of different diagnostic strategies in an emergency department (ED) for patients presenting with undifferentiated symptoms suggestive of pulmonary embolism.

METHODS

Using a probabilistic decision model, we evaluated the incremental costs and effectiveness (quality-adjusted life-years gained) of 60 testing strategies for 5 patient pretest categories (distinguished by Wells score [high, moderate, or low] and whether deep venous thrombosis is clinically suspected). We performed deterministic and probabilistic sensitivity analyses.

RESULTS

In the base case, for all patient pretest categories, the most cost-effective diagnostic strategy is to use an initial enzyme-linked immunosorbent assay D-dimer test, followed by compression ultrasonography of the lower extremities if the D-dimer is above a specified cutoff. The level of the preferred cutoff varies with the Wells pretest category and whether a deep venous thrombosis is clinically suspected. D-dimer cutoffs higher than the current recommended cutoff were often preferred for patients with even moderate and high Wells categories. Compression ultrasonography accuracy had to decrease below commonly cited levels in the literature before it was not part of a preferred strategy.

CONCLUSION

When pulmonary embolism is suspected in the ED, use of an enzyme-linked immunosorbent assay D-dimer assay, often at cutoffs higher than those currently in use (for patients in whom deep venous thrombosis is not clinically suspected), followed by compression ultrasonography as appropriate, can reduce costs and improve outcomes.

Thromboembolic disease after combined anterior/posterior reconstruction for adult spinal deformity: a prospective cohort study using magnetic resonance venography

STUDY DESIGN

Thromboembolic disease (TED) after anterior/posterior spinal reconstructions was prospectively evaluated in 66 consecutive patients.

OBJECTIVE

Determine the incidence of TED after anterior/posterior spinal reconstruction.

SUMMARY OF BACKGROUND DATA

Few studies have examined the rate of TED after potentially high-risk combined anterior/posterior reconstructions. Magnetic resonance venography (MRV) is more effective at detecting pelvic deep venous thrombosis (DVT) than conventional screening, but has not been used in these patients.

METHODS

We undertook a prospective cohort study of 66 consecutive adult patients (mean, 52.7 +/- 9.6 years) undergoing combined anterior/posterior spinal reconstructions for spinal deformity. All patients received only mechanical DVT prophylaxis. After surgery, MRV and bilateral lower extremity Doppler ultrasounds were obtained to screen for DVT, and contrast-enhanced spiral computed tomography scans were obtained for clinical suspicion of pulmonary embolism (PE).

RESULTS

The total incidence of postoperative TED was 13.6% (9 patients). The overall rate of DVT was 9.1% (6 patients), one-third occurring in the pelvis. PE developed in 7.6% (5 patients). In 2 patients, PE developed less than 48 hours after positive dopplers. In 3 patients, PE developed despite negative screening studies. Right-sided thoracoabdominal approaches were associated with an increased risk of developing DVT (P = 0.03, Odds Ratio 9.8), PE (P = 0.01, Odds Ratio 20), and TED (P = 0.004, Odds Ratio 12).

CONCLUSION

We report a high rate of TED after extensive anterior/posterior spinal reconstructions, for which a right-sided thoracoabdominal approach is an independent risk factor and screening ineffective at preventing PE. These patients should be considered at high risk for postoperative TED.

The importance of monophasic Doppler waveforms in the common femoral vein: a retrospective study

OBJECTIVE

The purpose of this study was to assess the importance of monophasic waveforms encountered in the common femoral vein during deep venous thrombosis evaluation by a retrospective review of lower extremity venous Doppler (VD) sonography and correlative studies, such as computed tomography (CT) and magnetic resonance imaging.

METHODS

A retrospective review was conducted of lower extremity VD studies performed from September 1, 2000, through September 1, 2005. All satisfactory VD studies, which were in compliance with the Intersocietal Commission for the Accreditation of Vascular Laboratories standard protocol, were evaluated for the presence of monophasic waveforms and correlated with CT of the abdomen and pelvis. Studies were evaluated for the causes of monophasic waveforms. Patients younger than 18 years were excluded.

RESULTS

A total of 2963 VD examinations were reviewed. One hundred twenty-four of 2963 showed monophasic waveforms. Eighty-nine of the 124 had additional CT examinations within 1 week; 19 had CT within 2 months; and 16 had no additional examinations. Forty-seven of 124 cases revealed deep venous thrombosis extending into the iliac veins, of which 23 were identified by VD sonography; 26 were due to extrinsic compression; 6 showed a hypoplastic or stenosed common iliac vein; and the remaining 45 had no apparent causes for the monophasic waveforms.

CONCLUSIONS

Monophasic waveforms in the common femoral veins are reliable indicators of proximal venous obstruction. Because iliac vein thrombosis is clinically important, we recommend routine sonographic evaluation of external iliac veins in the presence of monophasic waveforms and CT or magnetic resonance imaging, if necessary, to determine the cause of the monophasic waveforms.

Value of quantitative D-dimer assays in identifying pulmonary embolism: implications from a sequential decision model

OBJECTIVES

To examine the cost-effectiveness of a quantitative D-dimer assay for the evaluation of patients with suspected pulmonary embolism (PE) in an urban emergency department (ED).

METHODS

The authors analyzed different diagnostic strategies over pretest risk categories on the basis of Wells criteria by using the performance profile of the ELISA D-dimer assay (over five cutoff values) and imaging strategies used in the ED for PE: compression ultrasound (CUS), ventilation-perfusion (VQ) scan (over three cutoff values), CUS with VQ (over three cutoff values), computed tomography (CT) angiogram (CTA) with pulmonary portion (CTP) and lower-extremity venous portion, and CUS with CTP. Data used in the analysis were based on literature review. Incremental costs and quality-adjusted-life-years were the outcomes measured.

RESULTS

Computed tomography angiogram with pulmonary portion and lower-extremity venous portion without D-dimer was the preferred strategy. CUS-VQ scanning always was dominated by CT-based strategies. When CTA was infeasible, the dominant strategy was D-dimer with CUS-VQ in moderate- and high-Wells patients and was D-dimer with CUS for low-Wells patients. When CTP specificity falls below 80%, or if its overall performance is markedly degraded, preferred strategies include D-dimer testing. Sensitivity analyses suggest that pessimistic assessments of CTP accuracy alter the results only at extremes of parameter settings.

CONCLUSIONS

In patients in whom PE is suspected, when CTA is available, even the most sensitive quantitative D-dimer assay is not likely to be cost-effective. When CTA is not available or if its performance is markedly degraded, use of the D-dimer assay has value in combination with CUS and a pulmonary imaging study. These conclusions may not hold for the larger domain of patients presenting to the ED with chest pain or shortness of breath in whom PE is one of many competing diagnoses.

Pulmonary Embolism: A Frequent Occurrence in Indian Patients with Symptomatic Lower Limb Venous Thrombosis

OBJECTIVE

Pulmonary embolism (PE) is the most severe complication of deep venous thrombosis (DVT). There have been very few studies to assess the prevalence of PE in Asian patients. The objective of this study was to define the prevalence of PE in patients presenting with suspected lower limb DVT.

METHODS

This was a prospective cohort study at Sir Ganga Ram Hospital, a large multispecialty hospital in New Delhi, India. From January 2001 to July 2004, 1,552 consecutive inpatients and outpatients who presented with clinically suspected lower limb DVT were enrolled in the study. Combined ascending radionuclide venography and lung perfusion scan was performed in all patients. Patients with evidence of pulmonary perfusion defects underwent ventilation lung scan.

RESULTS

Radionuclide venography-detectable DVT was noted in 744 patients, of whom 521 (70%) had suprapopliteal DVT. Of patients with DVT, 294 (39.5%) showed a high-probability lung scan and 135 (18.1%) had an intermediate-probability lung scan. Overall, 47% of patients with a high-probability scan had no clinical manifestations suggestive of PE.

CONCLUSION

PE occurs frequently in Indian patients with symptomatic DVT. Increasing awareness will provide us with clearer ideas about the prevalence of venous thromboembolism in Asian countries.

Long-term Mortality in Patients with Thrombosis of the Inferior Vena Cava, Iliac and Femoral Veins

OBJECTIVES

To assess the long-term mortality in patients with thrombosis of the vena cava, iliac and femoral veins.

DESIGN

Registry study.

MATERIALS

Between 1992 and 2000, 212 consecutive patients with acute pelvic vein thrombosis diagnosed by duplex sonography were examined by magnetic resonance imaging (MRI) to determine the most proximal extent of the thrombus. MRI revealed a thrombosis in the inferior vena cava in 46 patients (22%), in the iliac vein in 142 patients (67%), and in the femoral vein in 24 patients (11%).

METHODS

The vital status of the patients was investigated in April 2004 using the Austrian National Registry and the Cause of Death Register.

RESULTS

A total of 211 patients of the original 212 patients were monitored over a mean follow-up period of 91 months. Seventy-two of 211 patients (34%) had died. There was no significant difference in the long-term mortality, the survival period or the occurrence of fatal pulmonary embolism (PE) between previously diagnosed vena cava, iliac vein, or femoral vein thrombosis.

CONCLUSIONS

Extension of a thrombus into the inferior caval vein in patients considered to have a pelvic vein thrombosis has no impact on long-term mortality or the development of fatal PE compared to those patients with thrombus limited to more distal veins.

Invasive approaches to treatment of venous thromboembolism

Deep vein thrombosis (DVT) occurs in one-quarter of a million individuals annually in the United States and results in significant disability from pulmonary embolism and chronic venous insufficiency, especially when the proximal iliofemoral is involved. Treatment has centered on early institution of adequate anticoagulation to prevent thrombus propagation and embolism, but anticoagulation alone does not always restore venous patency and many patients are left with venous outflow obstruction and valvular incompetence-the anatomic underpinnings of the postthrombotic syndrome. Various strategies have been used to restore patency of thrombosed veins, including open surgical thrombectomy, pharmacological thrombolysis, and percutaneous mechanical thrombectomy. Each modality has benefits and shortcomings. Surgical thrombectomy had previously been abandoned secondary to poor long-term results. More recently, with improved techniques and better patient selection, surgical thrombectomy has regained a therapeutic role in treating acute DVT in young patients with short segment occlusions. The advent of percutaneous techniques has allowed thrombolysis, percutaneous mechanical thrombectomy, and stenting to be used in conjunction with each other-allowing for better resolution of venous clot burden than when an individual modality is used alone. Practitioners who treat patients with DVT should be familiar with all the options available to restore venous patency, preserve valvular function, and thereby minimize the risk of late postthrombotic complications.