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Biomedical subjects

A J Comerota

Publications and source records attributed to A J Comerota.

At least 19 recordsLinked to original sources
PubMed2006

Treatment of acute iliofemoral deep venous thrombosis: a strategy of thrombus removal.

Patients with acute iliofemoral deep vein thrombosis (DVT) suffer the most severe postthrombotic sequelae. The majority of physicians treat all patients with acute DVT with anticoagulation alone, despite evidence that postthrombotic chronic venous insufficiency, leg ulceration, and venous claudication are common in patients treated only with anticoagulation. The body of evidence to date in patients with iliofemoral DVT suggests that a strategy of thrombus removal offers these patients the best long-term outcome. Unfortunately, currently published guidelines use outdated experiences to recommend against the use of techniques designed to remove thrombus, ignoring recent clinical studies showing significant benefit in patients who have thrombus eliminated. Contemporary venous thrombectomy, intrathrombus catheter-directed thrombolysis, and pharmacomechanical thrombolysis are all options that can be offered to successfully remove venous thrombus with increasing safety. The authors review evidence supporting the rationale for thrombus removal and discuss the most effective approaches for treating patients with acute iliofemoral DVT.

Algorithms↗
PubMed2001

Peripheral arterial disease detection, awareness, and treatment in primary care.

CONTEXT: Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis that is common and is associated with an increased risk of death and ischemic events, yet may be underdiagnosed in primary care practice. OBJECTIVE: To assess the feasibility of detecting PAD in primary care clinics, patient and physician awareness of PAD, and intensity of risk factor treatment and use of antiplatelet therapies in primary care clinics. DESIGN AND SETTING: The PAD Awareness, Risk, and Treatment: New Resources for Survival (PARTNERS) program, a multicenter, cross-sectional study conducted at 27 sites in 25 cities and 350 primary care practices throughout the United States in June-October 1999. PATIENTS: A total of 6979 patients aged 70 years or older or aged 50 through 69 years with history of cigarette smoking or diabetes were evaluated by history and by measurement of the ankle-brachial index (ABI). PAD was considered present if the ABI was 0.90 or less, if it was documented in the medical record, or if there was a history of limb revascularization. Cardiovascular disease (CVD) was defined as a history of atherosclerotic coronary, cerebral, or abdominal aortic aneurysmal disease. MAIN OUTCOME MEASURES: Frequency of detection of PAD; physician and patient awareness of PAD diagnosis; treatment intensity in PAD patients compared with treatment of other forms of CVD and with patients without clinical evidence of atherosclerosis. RESULTS: PAD was detected in 1865 patients (29%); 825 of these (44%) had PAD only, without evidence of CVD. Overall, 13% had PAD only, 16% had PAD and CVD, 24% had CVD only, and 47% had neither PAD nor CVD (the reference group). There were 457 patients (55%) with newly diagnosed PAD only and 366 (35%) with PAD and CVD who were newly diagnosed during the survey. Eighty-three percent of patients with prior PAD were aware of their diagnosis, but only 49% of physicians were aware of this diagnosis. Among patients with PAD, classic claudication was distinctly uncommon (11%). Patients with PAD had similar atherosclerosis risk factor profiles compared with those who had CVD. Smoking behavior was more frequently treated in patients with new (53%) and prior PAD (51%) only than in those with CVD only (35%; P <.001). Hypertension was treated less frequently in new (84%) and prior PAD (88%) only vs CVD only (95%; P <.001) and hyperlipidemia was treated less frequently in new (44%) and prior PAD (56%) only vs CVD only (73%, P<.001). Antiplatelet medications were prescribed less often in patients with new (33%) and prior PAD (54%) only vs CVD only (71%, P<.001). Treatment intensity for diabetes and use of hormone replacement therapy in women were similar across all groups. CONCLUSIONS: Prevalence of PAD in primary care practices is high, yet physician awareness of the PAD diagnosis is relatively low. A simple ABI measurement identified a large number of patients with previously unrecognized PAD. Atherosclerosis risk factors were very prevalent in PAD patients, but these patients received less intensive treatment for lipid disorders and hypertension and were prescribed antiplatelet therapy less frequently than were patients with CVD. These results demonstrate that underdiagnosis of PAD in primary care practice may be a barrier to effective secondary prevention of the high ischemic cardiovascular risk associated with PAD.

Aged↗
PubMed2001

Intermittent claudication: magnitude of the problem, patient evaluation, and therapeutic strategies.

Intermittent claudication (IC), the symptom of exercise-induced muscle ischemia of peripheral arterial disease (PAD), afflicts and limits the activities of a significant number of patients. Incidence and prevalence of IC depends on the population studied and the diagnostic instruments used. In large studies, prevalence has ranged from 3% to 10%, with a sharp increase in those aged > or =70 years. Over the next 20 years, the total number of patients affected is expected to increase significantly due to anticipated demographic changes. Analysis of the natural history of IC demonstrates that the risk of cardiovascular morbidity and mortality far exceeds that of severe limb ischemia or limb loss. In fact, only 2% to 4% of all patients with IC will require a major amputation in their lifetime. However, life expectancy is approximately 10 years less than that of an age-matched cohort. By now, PAD is well recognized as a marker of systemic atherosclerosis. The cornerstone of patient evaluation is a history and physical examination, including a detailed atherosclerotic risk-factor assessment. In the differential diagnosis of IC, clinicians should consider etiologies such as arthritis, spinal stenosis, radiculopathy, venous claudication, or inflammatory processes. In >80% of all patients, it is possible to locate the responsible arterial segment by combining the location and severity of pain with a pulse examination. Noninvasive diagnostic studies help determine the level of disease, may unmask a hemodynamically significant stenosis, and are useful in follow-up. Arteriography is reserved for patients in whom the decision for revascularization has been made. Knowing the anatomic detail of a lesion allows the clinician to determine whether and what type of intervention is feasible. Standard therapy for all patients should be directed at both peripheral and systemic atherosclerosis, beginning with risk-factor modification in the form of smoking cessation, optimal diabetes control, and lipid normalization. The benefits of supervised exercise rehabilitation include significantly increased walking distance and enhanced quality of life. Platelet inhibition has been shown to reduce the risk of ischemic stroke, myocardial infarction, and vascular death and should be prescribed for all but those in whom it is medically contraindicated. Symptom-specific pharmacotherapy with a broad range of medications has yielded disappointing results in the past. However, recent studies have demonstrated that patients receiving the novel agent cilostazol experienced increases in walking distance and improvements in quality of life.

Diagnosis, Differential↗
PubMed2001

Endovascular and surgical revascularization for patients with intermittent claudication.

Intermittent claudication (IC), the most common symptom of peripheral arterial disease (PAD), most often results from flow-reducing lesions in the arteries of the lower extremity that cause exercise-induced muscle ischemia. Intermittent claudication has a significant impact on quality of life and calls attention to PAD, which is secondary to systemic atherosclerosis and a major marker for cardiovascular morbidity and mortality. Most IC patients improve with a regimen that includes aggressive risk-factor modification, exercise, platelet inhibition, and pharmacotherapy to improve walking distance. Selected patients may require endovascular or surgical intervention if it can be offered with low risk. Endovascular procedures, most often percutaneous balloon angioplasty with or without stenting, are recommended for short-segment stenotic lesions in the aortoiliac and infrainguinal arterial segments. Combined platelet inhibition and endoluminal radiation are under study and may be useful to improve long-term outcome with these procedures. Percutaneous hemostatic puncture closure devices can also be used to reduce bleeding complications and allow more aggressive and immediate antithrombotic therapy, further improving results. Operative revascularization is recommended for patients with long-segment and multisegment disease, especially if obstruction is present. Aortofemoral reconstruction is associated with a low operative mortality and an 80% to 85% 5-year patency rate. Iliac reconstruction is recommended for isolated unilateral iliac arterial disease. Infrainguinal arterial reconstruction is associated with a 60% to 80% 5-year patency rate, with better outcomes noted for autogenous conduits than for prosthetic devices. Mechanical modification and pharmacotherapy with platelet inhibitors and anticoagulants improve long-term patency.

Anastomosis, Surgical↗
PubMed2001

Intraoperative lytic therapy: agents and methods of administration.

Intraoperative intraarterial thrombolysis is a valuable adjunct for the removal of residual arterial thrombi after mechanical thromboembolectomy. Early reports by some investigators indicated high rates of bleeding complications, most likely caused by inappropriately high doses of plasminogen activators infused over long periods of time, which led to systemic lytic effects. Animal models and controlled human experiments subsequently have shown the potential efficacy and safety of intraarterial thrombolysis. Since urokinase (UK) has been withdrawn from the market, recombinant tissue-type plasminogen activator (rt-PA) has become the plasminogen activator of choice. Reteplase and other plasminogen activators may be beneficial (and safe); however, data on intraoperative use currently are not available. The most common methods of delivery into the distal arterial tree are bolus infusion with inflow occlusion, drip infusion after restoration of arterial inflow, and the isolated limb perfusion technique. The number of distal vessels involved, the amount of residual thrombus, and severity of ischemia guide the dose of plasminogen activator, volume of perfusate, and the technique and duration of infusion.

Fibrinolytic Agents↗
PubMed2000

Duplex venous imaging: role for a comprehensive lower extremity examination.

Real-time compression ultrasound (CU) along with venous duplex imaging is the most commonly performed noninvasive vascular examination. It has become the definitive diagnostic test for most patients with deep venous thrombosis (DVT). Some practioners have recommended that CU alone of the common femoral vein (CFV) and of the popliteal vein (PV) are all that is required since a complete examination is time consuming and calf veins are difficult to visualize. However, if only the CFV and PV are examined, all patients with isolated superficial femoral vein (SFV) and calf DVT remain undiagnosed. The purpose of this study is to establish the value of a comprehensive venous duplex examination compared to CFV and PV compression alone for detecting both proximal and infrapopliteal DVT. From January 1996 through December 1997, the initial venous duplex examinations of 5767 extremities in 3067 patients were reviewed and results tabulated according to presence and location of clot. The ATL 3000 with a 7-14 mHz probe was utilized. Studies were interpreted as normal, proximal DVT (popliteal and above, with or without calf DVT), isolated calf, or isolated SFV deep venous thrombosis. If only the CFV and PV had been examined, 30.3% (isolated SFV + isolated calf vein DVT) of all DVT and 4.5% of proximal DVT would have been missed. A complete venous duplex examination altered the care in 288 (30.3%) of all patients examined who had DVT, and is therefore recommended as the standard noninvasive examination when evaluating patients for acute DVT.

Femoral Vein↗
PubMed2000

Catheter-directed thrombolysis for iliofemoral deep venous thrombosis improves health-related quality of life.

PURPOSE: Treatment designed to eliminate thrombus in patients with iliofemoral deep venous thrombosis (DVT) is theoretically attractive; however, its benefits, compared with those of anticoagulation, have not been definitively demonstrated. Although not previously analyzed, an effective measure of treatment success is likely to be the assessment of health-related quality of life (HRQOL). This study evaluated whether catheter-directed thrombolysis for iliofemoral DVT is associated with improved HRQOL, compared with standard anticoagulation, and whether HRQOL outcome in the thrombolysis group is related to lytic success. METHODS: An 80-item self-administered HRQOL questionnaire was developed. It contained the Health Utilities Index, Short Form-12, and disease-targeted scales, including health distress, stigma, health interference, physical functioning, and symptoms (eg, leg swelling, pain, ulcers). The HRQOL questionnaire was confirmed to be reliable and valid by means of psychometric testing. Questionnaires were administered to 98 retrospectively identified patients who had had iliofemoral DVT treated at least 6 months earlier. Sixty-eight patients who were identified through a DVT registry were treated with catheter-directed thrombolysis with urokinase (UK), and 30 patients who were identified by means of a medical record review were treated with anticoagulation alone. The treatment decision was made by the attending physician, and all patients were candidates for both thrombolysis and anticoagulation. RESULTS: Most patients were women (61%), white (95%), married (65%), and had a mean interval since initial DVT of 16 months. The group treated with UK was younger (53 +/- 17 years) than the group treated with heparin (61 +/- 6 years; P =.039). After treatment, patients treated with UK reported better overall physical functioning (P =.046), less stigma (P =.033), less health distress (P =.022), and fewer post-thrombotic symptoms (P =. 006), compared with the patients treated with anticoagulation alone. Within the UK group, phlebographically successful lysis correlated with improved HRQOL (P =.038). Patients classified as lytic failures had similar outcomes to patients treated with heparin. CONCLUSION: Patients with iliofemoral DVT treated with catheter-directed thrombolysis have better functioning and well-being, compared with patients treated with anticoagulation alone. Successful lysis was directly correlated with improved HRQOL, with patients who were classified as lytic failures having similar outcomes to patients treated with heparin. These data support the need for a future randomized trial, which should include an HRQOL measure as part of the outcome analysis.

Aged↗
PubMed2000

Venous severity scoring: An adjunct to venous outcome assessment.

Some measure of disease severity is needed to properly compare the outcomes of the various approaches to the treatment of chronic venous insufficiency. Comparing the outcomes of two or more different treatments in a clinical trial, or the same treatment in two or more reports from the literature cannot be done with confidence unless the relative severity of the venous disease in each treatment group is known. The CEAP (Clinical-Etiology-Anatomic-Pathophysiologic) system is an excellent classification scheme, but it cannot serve the purpose of venous severity scoring because many of its components are relatively static and others use detailed alphabetical designations. A disease severity scoring scheme needs to be quantifiable, with gradable elements that can change in response to treatment. However, an American Venous Forum committee on venous outcomes assessment has developed a venous severity scoring system based on the best usable elements of the CEAP system. Two scores are proposed. The first is a Venous Clinical Severity Score: nine clinical characteristics of chronic venous disease are graded from 0 to 3 (absent, mild, moderate, severe) with specific criteria to avoid overlap or arbitrary scoring. Zero to three points are added for differences in background conservative therapy (compression and elevation) to produce a 30 point-maximum flat scale. The second is a Venous Segmental Disease Score, which combines the Anatomic and Pathophysiologic components of CEAP. Major venous segments are graded according to presence of reflux and/or obstruction. It is entirely based on venous imaging, primarily duplex scan but also phlebographic findings. This scoring scheme weights 11 venous segments for their relative importance when involved with reflux and/or obstruction, with a maximum score of 10. A third score is simply a modification of the existing CEAP disability score that eliminates reference to work and an 8-hour working day, substituting instead the patient's prior normal activities. These new scoring schemes are intended to complement the current CEAP system.

Activities of Daily Living↗
PubMed1999

High-pressure, rapid-inflation pneumatic compression improves venous hemodynamics in healthy volunteers and patients who are post-thrombotic.

PURPOSE: Deep vein thrombosis (DVT) is a preventable cause of morbidity and mortality in patients who are hospitalized. An important part of the mechanism of DVT prophylaxis with intermittent pneumatic compression (IPC) is reduced venous stasis with increased velocity of venous return. The conventional methods of IPC use low pressure and slow inflation of the air bladder on the leg to augment venous return. Recently, compression devices have been designed that produce high pressure and rapid inflation of air cuffs on the plantar plexus of the foot and the calf. The purpose of this study is to evaluate the venous velocity response to high-pressure, rapid-inflation compression devices versus standard, low-pressure, slow-inflation compression devices in healthy volunteers and patients with severe post-thrombotic venous disease. METHOD: Twenty-two lower extremities from healthy volunteers and 11 lower extremities from patients with class 4 to class 6 post-thrombotic chronic venous insufficiency were studied. With duplex ultrasound scanning (ATL-Ultramark 9, Advanced Tech Laboratory, Bothell, Wash), acute DVT was excluded before subject evaluation. Venous velocities were monitored after the application of each of five IPC devices, with all the patients in the supine position. Three high-pressure, rapid-compression devices and two standard, low-pressure, slow-inflation compression devices were applied in a random sequence. Maximal venous velocities were obtained at the common femoral vein and the popliteal vein for all the devices and were recorded as the mean peak velocity of three compression cycles and compared with baseline velocities. RESULTS: The baseline venous velocities were higher in the femoral veins than in the popliteal veins in both the volunteers and the post-thrombotic subjects. Standard and high-pressure, rapid-inflation compression significantly increased the popliteal and femoral vein velocities in healthy and post-thrombotic subjects. High-pressure, rapid-inflation compression produced significantly higher maximal venous velocities in the popliteal and femoral veins in both healthy volunteers and patients who were post-thrombotic as compared with standard compression. Compared with the healthy volunteers, the patients who were post-thrombotic had a significantly attenuated velocity response at both the popliteal and the femoral vein levels. CONCLUSION: High-pressure, rapid-inflation pneumatic compression increases popliteal and femoral vein velocity as compared with standard, low-pressure, slow-inflation pneumatic compression. Patients with post-thrombotic venous disease have a compromised hemodynamic response to all IPC devices. However, an increased velocity response to the high-pressure, rapid-inflation compression device is preserved. High-pressure, rapid-inflation pneumatic compression may offer additional protection from thrombotic complications on the basis of an improved hemodynamic response, both in healthy volunteers and in patients who were post-thrombotic.

Adult↗
PubMed1999

Inhibition of tissue factor pathway during intermittent pneumatic compression: A possible mechanism for antithrombotic effect.

Intermittent pneumatic compression (IPC) devices are an effective prophylaxis against lower extremity deep vein thrombosis. Their antithrombotic effect has been attributed to a reduction in venous stasis and enhanced fibrinolysis. The initiating mechanism for blood coagulation is the tissue factor (TF) dependent pathway, which is inhibited by tissue factor pathway inhibitor (TFPI). We have investigated the effect of IPC on the TF pathway in 6 normal subjects and 6 patients with postthrombotic venous disease undergoing IPC for 120 minutes; all subjects were studied with each of 5 IPC devices. In normal subjects and patients, plasma factor VIIa (FVIIa) activity (the activated form of factor VII [FVII]) declined from mean values ranging 51 to 65 and 50 to 53 mU/mL before IPC with different devices to 10 to 13 and 20 to 22 mU/mL at 180 minutes, respectively (P<0.001 for all groups). FVII antigen levels were unchanged. Plasma TFPI (P<0.001) rose from mean baseline values ranging 69 to 79 and 57 to 61 ng/mL to 76 to 123 and 71 to 79 ng/mL at 180 minutes in normal subjects and patients, respectively (P<0. 001 for all groups). Plasma prothrombin fragment F1.2 levels showed minimal changes. There was an inverse relationship between TFPI and FVIIa in normal subjects (r=-0.31, P=0.001) and patients (r=-0.37, P<0.001). IPC results in an increase in plasma TFPI and decline in FVIIa. Inhibition of TF pathway, the initiating mechanism of blood coagulation, is a possible mechanism for the antithrombotic effect of IPC.

Adult↗
PubMed1998

The contributions of arterial and venous volumes to increased cutaneous blood flow during leg compression.

Intermittent lower extremity compression increases cutaneous blood flow. The source of this increased perfusion and, the influence of physical activity on stimulated foot skin perfusion has not been elucidated. The purpose of this study is to determine the arterial and venous contributions to augmented cutaneous blood flow during foot and leg compression, and to evaluate whether physical activity influenced the response to compression. Fifty limbs from 29 normal volunteers were studied in the sitting position. Their daily physical activity was categorized as active if they exercised > or =3 days/week or sedentary if they exercised < or =3 days/week. Inflatable foot and calf compression cuffs attached to a timed-pressure pump (Art-assist AA 1000, ACI, Inc., San Marcos, CA) were applied to the subject's leg and set to deliver 120 mmHg pressure with a 10-sec deflation cycle. Skin perfusion of the great toe was recorded by a laser Doppler (Laserflo Model BPM 403, TSI, Inc., St. Paul, MN). Total perfusion with compression (A), retrograde venous perfusion (B), and compression artifact (C) was recorded. Mean values for A, B, and C and the differences between the two groups were analyzed using multivariate multiple comparison statistical method. The mean baseline skin perfusion was 3.96 +/- 0.91, and mean total stimulated skin perfusion (A) was 9.23 +/- 2.13. With arterial inflow obliterated and compression applied, mean skin perfusion (B) was 1.96 +/- 0.44. The sedentary group had a mean resting perfusion of 1.64 +/- 0.28 and mean stimulated value (A) of 2.29 +/- 0.37 ml/min/100 gm tissue. The active group had a mean resting perfusion of 28.26 +/- 0.91, and stimulated value (A) of 32.65 +/- 4.47 ml/min/100 gm tissue. These differences in the mean skin perfusion between the two groups were significant. It is concluded that in normals, the majority of increased perfusion is from increased arterial inflow. There is a larger resting foot skin perfusion in active individuals and they have quantitatively greater stimulated inflow compared to sedentary individuals.

Adult↗
PubMed1998

Clinical applications of thrombolytic therapy for arterial and graft occlusion.

Catheter-directed thrombolysis and intraoperative intra-arterial thrombolysis are important adjuncts to how we care for patients with acute arterial and bypass graft occlusions. Of importance is that intra-arterial thrombolysis not to be thought of as a competitor to operative revascularization, but rather as an adjunct to what can be accomplished, which enables the responsible physician to offer the best care for these patients.

Arterial Occlusive Diseases↗
PubMed1997

Microcirculatory compensation to progressive atherosclerotic disease.

The precapillary resistance in the skin of the foot increases with standing. This mechanism, termed the venoarterial reflex (VAR) restricts arterial inflow, and avoids an excessive rise in capillary pressure. This study tests the hypothesis that there is microcirculatory compensation to atherosclerotic disease of increasing severity. Foot skin perfusion (FSP) was measured in 100 limbs with a laser Doppler placed on the plantar aspect of the great toe. Limbs were categorized as normal (n = 31) with an ankle brackial index (ABI) > or = 0.96, claudicants (n = 42) ABI 0.5-0.86, and critical ischemia (n = 27) with an ABI < or = 0.49 or a pulse volume recording consistent with severe peripheral vascular disease and symptoms of rest pain or tissue loss. Segmental Doppler pressures and pulse volume recordings were performed prior to laser Doppler measurements. Subjects with clinical signs or symptoms of chronic venous insufficiency were excluded. The resting foot skin perfusion was measured in the horizontal and dependent position, with the patient supine and sitting. Comparisons within categories were done using Wilcoxon matched pairs signed rank test and between groups with Mann-Whitney U test for unpaired data. Differences were considered significant if they exceeded the 95% confidence level (p value < or = 0.05). Resting supine skin perfusion was similar between nondiabetic normals and claudicants and diabetic normals and claudicants. There was a significant decrease in the foot skin perfusion (mean FSP +/- SEM) in the normal limb with a change from the supine (7.8 +/- 2.2 ml/min/100 g) to the dependent (2.8 +/- 0.6 ml/min/100 g) position indicating an intact VAR. This was absent in 33% of the limbs with claudication. Limbs with critical ischemia demonstrated an increase in FSP with dependency (supine 4.0 +/- 1.0 ml/min/100 g) versus dependent (8.4 +/- 1.8 ml/min/100 g) and was present in both diabetic and nondiabetic limbs. Microcirculatory compensation occurs early in atherosclerotic limbs. Although supine FSP is similar in normals and claudicants, a greater percentage of claudicants demonstrate a loss of the VAR. Critically ischemic limbs have increased FSP in the dependent position. These observations indicate that there are microcirculatory alterations in limbs with claudication and assist in explaining why patients with ischemic rest pain obtain relief and develop edema with dependency.

Arteriosclerosis↗
PubMed1997

The fibrinolytic effects of intermittent pneumatic compression: mechanism of enhanced fibrinolysis.

BACKGROUND AND OBJECTIVES: Intermittent pneumatic compression (IPC) is an effective form of deep vein thrombosis prophylaxis for general surgery patients. The antithrombotic effect of IPC is thought to be the result of increased venous velocity and stimulation of endogenous fibrinolysis. However, the mechanism of enhanced fibrinolytic activity and the relative effects on normal and postthrombotic veins have not been defined. The purposes of this study are 1) to quantify changes in fibrinolytic activity with IPC; 2) to study the mechanism of fibrinolytic enhancement with IPC; and 3) to evaluate whether postthrombotic patients have the same capacity for fibrinolytic enhancement with IPC as do normal subjects. METHODS: Twelve volunteers (6 normal and 6 postthrombotic) had 5 IPC devices applied for 120 minutes in random fashion, 1 per week x 5 weeks. The devices included single-chamber, sequential, foot, calf, and long-leg compression. Subjects had an indwelling antecubital venous cannula placed for blood drawn at baseline, 60, 120, and 180 minutes after IPC devices were applied. Global fibrinolytic activity (euglobulin fraction, fibrin plate assay), tissue plasminogen activator (tPA) antigen (Ag) and activity (Act), plasminogen activator inhibitor-1 (PAI-1) Ag and Act, alpha-2-antiplasmin-plasmin complexes, and von Willebrand factor (vWF) antigen were assayed. RESULTS: A striking elevation in fibrinolytic activity was noted at 180 minutes with all devices in normal subjects and postthrombotic patients (p = 0.01-0.0001); however, baseline and stimulated fibrinolytic activity was attenuated in postthrombotic patients (<0.03). The tPA-Act increased only in normal subjects (3.8 +/- 1.9%) (p = 0.057), despite a decrease in plasma tPA-Ag, which was observed in both normal subjects (-12.4 +/- 3.8%) (p = 0.009) and patients (-17.2 +/- 3.1%) (p = 0.001). PAI-1-Ag decreased in both normal subjects (-13.4 +/- 3.8%) (p = 0.007) and patients (-12.0 +/- 3.1%) (p = 0.013) with a marked reduction in PAI-1-Act in both normal subjects (p = 0.003) and patients (p = 0.004). There were no changes in vWF, and alpha-2-antiplasmin-plasmin complexes increased only in postthrombotic patients (p = 0.021). CONCLUSIONS: Stimulation of endogenous fibrinolytic activity occurs after IPC, both in normal subjects and postthrombotic patients; however, baseline and overall fibrinolytic response in postthrombotic patients is reduced. The mechanism of increased fibrinolytic activity is likely because of a reduction in PAI-1, with a resulting increase of tPA activity.

Adult↗
PubMed1997

Extended intravascular shunting in an experimental model of vascular injury.

PURPOSE: To examine the extended patency (> 24 hrs) of heparin-bonded intravascular shunts in a porcine model of vascular injury. PROCEDURES: Adult swine underwent bilateral, common iliac artery resection (n = 5) or bilateral common iliac vein resection (n = 5) and vessel replacement with interposition, heparin-bonded shunts. Three control swine had vessel dissection only. Hematologic and coagulation profiles were measured at baseline and 24 hrs. Limb perfusion was assessed at 24 hrs by clinical exam and angiography. RESULTS: At 24 hrs, all limbs in both shunt groups were well perfused. All arterial shunts were angiographically patent. No distal emboli were detected. Nine of 10 venous shunts were patent, seven were lined with non-occluding thrombus. No alterations in hematologic or coagulation profiles were noted. CONCLUSIONS: Heparin-bonded shunts remained patent in arteries for 24 hours. Shunts placed in the venous system were prone to thrombus formation but most remained patent.

Animals↗
PubMed1996

Is venous duplex imaging an appropriate initial screening test for patients with suspected pulmonary embolism?

Noninvasive tests for deep venous thrombosis (DVT) are helpful in evaluating patients with suspected pulmonary embolism (PE) who have non-high-probability ventilation/perfusion (V/Q) lung scans. Based on the enthusiasm for these noninvasive tests, venous duplex imaging (VDI) has evolved as the initial screening test for patients with clinically suspected PE in some centers. This study evaluates the utility of VDI as the initial test in a diagnostic algorithm for patients with suspected PE. A total of 306 consecutive patients who underwent VDI as the initial screening test for clinically suspected PE during the past 24 months were reviewed; 121 patients were subsequently evaluated with V/Q scans and 20 underwent pulmonary arteriography. VDI demonstrated DVT in 10% (23/216), with 7% (22/306) having proximal DVT and 3% (9/306) having isolated calf DVT. In 25 patients with unilateral leg symptoms, DVT was found in 40% (10/25); however, among the 281 without unilateral leg symptoms, results of VDI were abnormal in only 5% (15/281). V/Q scans were obtained in 40% (121/306), with only 16% (19/121) of scans showing a high probability of PE. DVT was found in 25% (5/19) of patients with high-probability V/Q scans and in 25% (26/102) with non-high-probability scans. In patients with clinically suspected PE the incidence of detectable infrainguinal DVT is low. VDI appears to be a reasonable initial screening test in patients with clinically suspected PE and unilateral leg symptoms. However, in patients without unilateral leg symptoms, the diagnostic yield is low and an alternative diagnostic approach appears justified.

Adult↗