Near-maximal fractional oxygen extraction by active skeletal muscle in patients with chronic heart failure.
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Systemic oxygen uptake and deep femoral vein oxygen content were determined at peak exercise in 53 patients with chronic heart failure with impaired systolic function (mean left ventricular ejection fraction 0.18; n = 41) or preserved systolic function (mean left ventricular ejection fraction 0.70; n = 12) and in 6 age-matched sedentary normal subjects. At peak exercise, deep femoral vein oxygen content in heart failure patients with impaired systolic function and preserved systolic function were similar, both significantly lower than that of normal subjects (2.5 +/- 0.1, 2.9 +/- 0.2, and 5.0 +/- 0.1 ml/100 ml, respectively; P < 0.05). Deep femoral venous oxygen content was lower in patients with the greater impairment of aerobic capacity, regardless of the underlying systolic function (r = 0.72, P < 0.01). Fractional oxygen extraction in the skeletal muscle at peak exercise is enhanced in patients with chronic heart failure when compared with normal subjects, in proportion to the degree of aerobic impairment. (+info)
Randomized trial of graded compression stockings for prevention of deep-vein thrombosis after acute stroke.
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Graded compression stockings are commonly used to prevent deep-vein thrombosis (DVT) after stroke, but their efficacy in this setting has not been evaluated. Extrapolation of effectiveness from trials in patients undergoing elective surgery may be inappropriate. We undertook a randomized, controlled trial, with blinded data review, in a University hospital Acute Stroke Unit. Patients were allocated to graded compression stockings or to standard care alone. DVT incidence was determined at baseline and at day 7+/-2 by colour-flow Doppler ultrasound. Ninety-eight patients with acute, immobilizing stroke were randomized; 97 had full outcome data. One patient had clinically manifest DVT, and no patient had pulmonary thromboembolism. DVT was detected in 7/65 patients allocated stockings, and 7/32 controls (odds ratio 0.43, 95% CI 0.14-1.36); DVT involving femoral veins was detected in 3/65 and 2/32. In the first week after stroke, radiologically-detected DVT remains common, but is usually clinically silent. Proximal DVT is less common. Graded compression stockings produced a reduction in DVT incidence comparable to that in other patient groups, but the reduction was not statistically significant, and the magnitude of effect size requires confirmation. There is greater doubt over efficacy in early prevention of proximal DVT. (+info)
Optimising the performance of intermittent pneumatic compression devices.
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OBJECTIVES: this study was designed to determine whether an intermittent pneumatic compression device (IPC) with an increased maximal inflation pressure, a decreased time to maximal pressure and a longer duration of compression would improve venous return compared to a standard IPC device. METHODS: thirty limbs in 15 volunteers without evidence of venous disease were studied using duplex scanning at rest and during the application of two different IPC devices with different compression parameters. The first device IPC-1 (SCD 5325, Kendall) has a six-chambered cuff applying 45 mmHg after 12 s, sequentially from ankle to thigh followed by 60 s of non-compression. The second device IPC-2 (Vena-Assist(R), ACI Medical) has a foot, ankle and calf cuff, applies a pressure of 80 mmHg, has a pressure rise time of 0.3 s, maintains inflation for 5.5 s, and has a cycling time of 1 min. Peak venous velocity and acceleration time were measured at rest and during the IPC application. Measurements were obtained in supine position from the common femoral vein 1 cm above the saphenofemoral junction to include the entire venous outflow from the limb. RESULTS: peak venous velocity at rest was significantly higher in the right limb than in the left limb (26+/-7.2 vs. 22+/-5.7 cm/s, p<0.01). Peak venous velocity was significantly increased by both IPC devices (p <0.0001). IPC-2 achieved significantly higher peak venous velocity than IPC-1 (55.1+/-17.8 vs. 37.4+/-6.9 cm/s, p<0.0001). Acceleration time was also found to be significantly shorter (370+/-93.4 vs. 560+/-83.5 ms, p<0.0001) in IPC-2 than in IPC-1, respectively. CONCLUSIONS: we have demonstrated that progressive inflation at the foot, ankle and calf, increasing maximal inflation pressure and decreasing time to maximal pressure result in increased venous return. These changes may improve the efficacy of IPC devices in the prevention of deep-venous thrombosis (DVT) formation. (+info)
Catheter-directed thrombolysis for iliofemoral deep venous thrombosis improves health-related quality of life.
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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. (+info)
Transvenous echo Doppler in baboons: a new window to the cardiovascular system.
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Ultrasound examinations of the heart and major peripheral arteries have been performed as separate procedures; both potentially limited by suboptimal views in certain subjects and the inability to obtain ideal pictures of particular intracardiac structures. Transvenous ultrasound may offer new advantages in certain areas, we therefore studied six adult baboons using a single-plane 5.5-10 MHz transducer mounted on a 10 French (10F) catheter, introduced via the right femoral vein and positioned under fluoroscopic control. Imaging and Doppler studies were performed to delineate cardiovascular anatomy as well as ventricular function response to positive (dobutamine) and negative inotropic (esmolol) agents. The procedure was safe and feasible in all cases. Clear and novel two-dimensional and flow information were obtained from the iliac arteries, descending aorta, both renal artery origins, ascending aorta, including the aortic arch, main pulmonary artery and its bifurcation, as well as head and neck vessels. Novel intracardiac views were obtained, including right ventricular long axis, left ventricular apex and 'flask' views of the left ventricle. Excellent dynamic information for left ventricular function was also available [e.g. myocardial Vmax of the anterior left ventricular wall was 6.8+/-2.5 cm/s at rest, 14.6+/-5.5 cm/s after dobutamine (P=0.009) and 4.5+/-1 cm/s after esmolol (P=0.03 compared with control)]. We conclude that, in adult primates, transvenous ultrasound safely and reliably provides novel information of cardiovascular structure and function. (+info)
Correlation of central venous pressure with Doppler waveform of the common femoral veins.
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The objects of this prospective study were to determine the nature of the flow in the right femoral vein and to correlate the flow velocity with the venous pressure measured in the right atrium. We performed 236 pulsed Doppler ultrasonographic examinations in 1 year on patients with a venous catheter with the distal tip in the right atrium. In the Doppler wave readouts we analyzed wave frequency, velocity components, and relationships among them and the existence of pulsatile flow. These parameters were then compared to the right atrium pressure. We investigated the correlation between the atrium pressure and the flow velocity obtained from the Doppler waveforms of the common femoral veins, obtaining a significant correlation (P<0.0001) with the following: the atrium systolic wave a, the atrium diastolic wave v, the pulsatility ratio (PR = Vmin/Vmax) and the pulsatility index (PI = [Vmax - Vmin] /Vavg). The receiver operating characteristic showed that the pulsed Doppler ultrasonography is not a sensitive technique in diagnosis high atrium pressures. In addition, both cardiac and respiratory phasicity of the venous wave was observed. A significant inverse relation was found between the pulsatile flow and high atrium pressure. Nonetheless, the low sensitivity of this technique does not allow the use of pulsatile Doppler ultrasonography in the common femoral vein for diagnosing increases of the atrium pressure. (+info)
Risk factors for occlusion of infrainguinal bypass grafts.
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OBJECTIVES: to identify risk factors for infrainguinal bypass occlusion and quantify the predictive value of data available before and after surgery. DESIGN: prospective study of 2650 patients who participated in a randomised trial of oral anticoagulants or aspirin after infrainguinal bypass surgery. MATERIALS AND METHODS: risk factors were determined by univariate Cox regression analysis, and entered in multivariate analyses which distinguished two models: analysis of factors available from history and clinical examination, completed by radiological and surgical data in the second model. To compare the information content of the two models, receiver-operator characteristic (ROC) curves were computed. RESULTS: in all patients female gender, critical ischaemia, femorocrural bypass grafting and non-venous graft material were independent risk factors. In patients with femoropopliteal bypasses female gender, critical ischaemia, poor run-off and non-venous graft material, the latter even in patients with supragenicular bypasses, were independent risk factors. The only significant risk factor in patients with femorocrural bypass grafts was use of a non-venous graft. The information contained in the first model was poor, whereas the second model had a higher predictive value. CONCLUSIONS: the major risk factor, even in above-knee bypasses, is non-venous graft material. The venous bypass graft should be offered to patients whenever possible. (+info)
High prevalence of iliofemoral venous thrombosis with severe groin infection among injecting drug users in North East Scotland: successful use of low molecular weight heparin with antibiotics.
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Injecting drug use, mainly of heroin, currently represents a major public health issue in the North East of Scotland. The recent tendency of the committed injecting drug user to inject into the groin has created novel problems for the Infection Unit. Data are presented on 20 consecutive patients admitted between 1994 and 1999 with iliofemoral venous thromboses, often complicated by severe soft tissue infections and bacteraemia as a result of heroin injection into the femoral vein. Nine had coexistent groin abscesses, four had severe streptococcal soft tissue infection of the right thigh, groin and lower abdomen, and two had coincidental soft tissue infections of the upper limb. Nine were bacteraemic on admission. All of the patients were chronic injecting drug users with a median injection duration of 6.5 years. The 18 patients tested for hepatitis C virus were all seropositive. None of the 14 patients tested was positive for HIV. Seventeen patients were treated with subcutaneous low molecular weight heparin (tinzaparin), three having received intravenous unfractionated heparin initially. The tinzaparin was self administered and given for a median duration of seven weeks. One patient declined to have any treatment. Three months after presentation eight patients were asymptomatic, seven had a persistently swollen leg, and five were lost to follow up. None developed clinically apparent pulmonary embolism after institution of anticoagulant therapy. The management of iliofemoral venous thrombosis in injection drug users is problematic because of poor venous access, non-compliance with prescribed treatment, ongoing injecting behaviour, and coexistent sepsis. It is unlikely that a randomised trial of standard treatment with heparin and warfarin versus low molecular weight heparin alone would be practical in this patient group. These retrospective data indicate that the use of tinzaparin in injecting drug users is feasible and appears to result in satisfactory clinical responses. The possibility of concomitant infection in injecting drug users with venous thrombosis should always be addressed, as it appears to be a common phenomenon. Early drainage of abscesses and antimicrobial chemotherapy, often administered intramuscularly or orally because of lack of peripheral venous access, is central to the appropriate care of these patients. (+info)