Showing papers by "Thomas W. Wakefield published in 2004"

Deep Vein Thrombosis Resolution Is Modulated by Monocyte CXCR2-Mediated Activity in a Mouse Model

Abstract: Objective— To determine the role of CXCR2, the receptor for cysteine-X-cysteine (CXC) chemokines, and its primary effector cell, the neutrophil (PMN), on deep venous thrombosis (DVT) resolution. Methods and Results— DVT in BALB/c, anti-CXCR2 antibody-treated, and BALB/c CXCR2−/− mice were created by infrarenal inferior vena cava (IVC) ligation and the thrombus harvested at various time points over 21 days. The CXCR2−/− mice had significantly larger thrombi at early time points (days 2 to 8), and significantly decreased intrathrombus PMNs, monocytes, and neovascularization as compared with controls. Thrombus KC/CXCL1 was significantly higher at 2 days in CXCR2−/− thrombi as measured by enzyme-linked immunosorbent assay. Fibrin content was significantly higher, with less uPA gene expression at 4 days in CXCR2−/− thrombi. Late fibrotic maturation of the thrombus was delayed in the CXCR2−/− mice, with significantly decreased 8 day MMP-2 activity, whereas MMP-9 activity was elevated as compared with controls. ...

Staging deep venous thrombosis using ultrasound elasticity imaging: animal model.

Abstract: Deep venous thrombi undergo progressive hardening with age. However, the evolution rate remains poorly characterized by both invasive and noninvasive techniques. In a previous study (Emelianov et al. 2002), we demonstrated the potential of ultrasound elasticity imaging to noninvasively detect and age thrombus using a rat-based model. Knowing that thrombi harden over time is useful, but the value of the technique relies on whether the age of a thrombus can be predicted from strain estimates, and how accurate these predictions are. The objective of the present study is to answer these two questions. In the previous study, thrombus elasticity changes were monitored only on day 3, 6 and 9 after surgically induced formation of thrombosis in rat inferior vena cavas. In this study, ultrasound elasticity imaging was performed on two independent groups of rats (16 in total) starting from day 3 through day 10 with more temporal samples through the thrombus maturation process. For each rat, thrombus hardness was quantified at each scan interval by measures of normalized strains and reconstructed relative Young's moduli. In both groups, strain magnitudes exhibit progressive decrease as clots age. The relationship between the normalized strain and the clot age was developed from the first group and evaluated by the second group. Statistical analysis showed that the age estimation accuracy is within 0.8 day. If further research can successfully transfer the animal clot-hardening model to human patients, we believe that elasticity imaging will become a key component of venous compression ultrasound for effective diagnosis and treatment of deep venous thrombosis.

Effect of carotid atherosclerosis screening on risk stratification during primary cardiovascular disease prevention

Abstract: We investigated the effect that carotid plaque area (CPA) and intima media thickness (IMT) measurements have on risk stratification in 95 patients with intermediate Framingham scores (6% to 19%). The risk status of each patient was adjusted to be low, intermediate, or high based on the results of carotid ultrasound. After carotid testing, 44% (IMT) and 45% (CPA) of the intermediate-risk patients were stratified as low risk, and 22% (IMT) and 40% (CPA) were stratified as high risk. Using the threshold values derived from our laboratory, 28% (IMT) and 45% (CPA) of patients were stratified as low risk, and 35% (IMT) and 27% (CPA) were identified as high risk. These tests adjust the risk strata of ≥63% of patients deemed as having intermediate risk by Framingham scores.

Venous thromboembolism: regional differences in the nationwide inpatient sample, 1993 to 2000.

Abstract: Venous thromboembolism (VTE) is a costly complication of hospitalization. The sequelae make it a concern for public health planners. The Nationwide Inpatient Sample (NIS) contains data for hospital discharges in the United States. These data were reviewed to determine their suitability for health policy planning. International Classification of Diseases, Ninth Revision, Clinical Modification codes for VTE were applied to the NIS data. The sample was queried for demographic information, mortality, length of hospital stay, diagnosis, and treatment. The rates were standardized for geographic region and disease acuity. Statistical analysis included descriptive reporting of means and event rates; analysis of variance and logistic regression were used for regional effects and modeling of mortality. Between 1993 and 2000, 636,814 discharges involved VTE (1.2%). This rate was consistent over time and within regions. Regional differences existed in the acceptance of new technology and hospital charges. Mortality varied from 6.3% (Midwest) to 7.9% (Northeast) and was associated with admission type, comorbidities, pulmonary embolism, and discharge from the Northeast region. White race, chronic venous insufficiency, and female gender were protective variables. The NIS data report a consistent mortality rate despite improved therapy. Regional diagnostic, treatment, and economic differences exist. The data are useful for the purposes of public health care planning and stimulating clinical trial questions.

A role for interleukin-10 in the assessment of venous thromboembolism risk in injured patients.

Abstract: Background: Management of patients with multiple trauma requires prophylaxis for venous thromboembolism (VTE). This involves recognition of the physiologic factors that are associated with VTE risk. Currently, there is no effective strategy for risk assessment. The purpose of this study is to investigate the relationship of serum P-selectin and interleuken-10 (IL-10) with VTE as a possible physiologic marker. Methods: Patients admitted to two trauma centers with an Injury Severity Score ≥9 had blood samples drawn and underwent duplex ultrasound scanning of the lower extremities before initiating prophylaxis at admission, on days 3 and 7, and weekly until discharge. Patients were prophylaxed according to institutional protocols. Results: One hundred eighty-six patients were enrolled with a VTE incidence of 17.8%. The population was predominantly male (60%), with a mean age of 48 years. sP-selectin levels were not statistically different between the groups (64.4 versus 74.8 pg/mL). However, IL-10 was significantly lower in the VTE group at both the initial and subsequent blood draws (21 versus 165 ng/mL, p = 0.012). Further, the ratio of sP-selectin to IL-10 (3.92 versus 0.92, p = 0.014) was statistically higher in the VTE group at admission. Conclusion: An elevated sP-selectin to IL-10 ratio appears to be associated with the development of VTE in patients at high risk and may prove to be a useful clinical marker for this dreaded complication among trauma patients. Early recognition of this high-risk group improves the accuracy of the risk/benefit determination for prophylaxis and identifies a group in whom routine ultrasound screening would be cost-effective.

Young's modulus reconstruction for elasticity imaging of deep venous thrombosis: animal studies

Abstract: Recently, it was suggested that ultrasound elasticity imaging can be used to age deep vein thrombosis (DVT) since blood clot hardness changes with fibrin content. The main components of ultrasound elasticity imaging are deformation of the object, speckle or internal boundary tracking and evaluation of tissue motion, measurement of strain tensor components, and reconstruction of the spatial distribution of elastic modulus using strain images. In this paper, we investigate a technique for Young's modulus reconstruction to quantify ultrasound elasticity imaging of DVT. In-vivo strain imaging experiments were performed using Sprague-Dawley rats with surgically induced clots in the inferior vena cavas (IVC). In this model, the clot matures from acute to chronic in less than 10 days. Therefore, nearly every 24 hours the strain imaging experiments were performed to reveal temporal transformation of the clot. The measured displacement and strain images were then converted into maps of elasticity using model-based elasticity reconstruction where the blood clot within an occluded vein was approximated as a layered elastic cylinder surrounded by incompressible tissue. Results of this study demonstrate that Young's modulus gradually increases with clot maturity and can be used to differentiate clots providing a desperately needed clinical tool of DVT staging.

Sonographic Detection of Renal Artery Dissection Secondary to Stanford Type a Aortic Dissection: Case Report

Abstract: IntroductionAortic dissections (AD) are a result of the development of a focal intimal tear, most likely caused by medial degeneration. Medial changes occur as a consequence of hemodynamics and oth...