Detection of microemboli in the subclavian vein of patients undergoing haemodialysis and haemodiafiltration using pulsed Doppler ultrasound. (17/217)

BACKGROUND: The pathophysiology leading to pulmonary side effects during haemodialysis and haemodiafiltration is not yet fully understood. Chronic microembolization, which can be demonstrated by pulsed Doppler ultrasound, may be one cause. METHODS: The study cohort consisted of 24 long-term dialysis patients undergoing haemodialysis (n=21) and online-haemodiafiltration (n=3), respectively. The subclavian vein downstream to the venous access was investigated during different phases of the procedure using a 2-MHz pulsed ultrasound device. RESULTS: In all periods investigated (connection, dialysis, disconnection), numerous microembolic signals (MES) were found in the subclavian vein. The numbers of MES detected during haemodiafiltration (314-709 MES per 10 min) were higher than during haemodialysis (0-81 MES per 10 min). CONCLUSIONS: The composition (gaseous or solid) and origin (pump, tubing system or shunt) of the microemboli detected remains unclear. Chronic microembolization may be one cause of pulmonary complications of haemodialysis and haemodiafiltration. The detection method described in this article will help us to better understand this process and to determine what role microemboli might play in pulmonary and central nervous system disorders. It may also help to optimize the devices and techniques used.  (+info)

Autogeneous elbow fistulas: the effect of diabetes mellitus on maturation, patency, and complication rates. (18/217)

OBJECTIVES: diabetes mellitus is an increasingly common cause of end stage renal failure (ESRF) and the establishment of adequate permanent vascular access for dialysis is a major cause of morbidity and mortality in these patients. The aim of this study was to compare the availability of suitable vein, maturation rates, patency and complication rates of autogeneous elbow fistulas in diabetics and non-diabetics at a single centre where an autogeneous vein only policy is employed. DESIGN: retrospective series. PATIENTS AND METHODS: two hundred and ninety-three elbow fistulas were attempted in 232 patients over a seven year period, [median age 60 years (range 14-94 years)], of which 210 were in non-diabetic and 83 were in diabetic patients. The diabetic group had a significantly higher proportion of male patients (p < 0.05), peripheral vascular disease and established ESRF. RESULTS: there was a trend towards a higher technical success rate in the non-diabetic group (98% versus 93% p = 0.057). There was no significant difference between the primary failure rate, fistula maturation rate, revision rate or incidence of complications between the two groups. Diabetes had no effect on cumulative secondary fistula patency even when stratified for Type 1/Type 2 diabetes, female sex, old age or primary versus subsequent procedures. CONCLUSION: diabetes mellitus has no significant detrimental effect on outcome following formation of autogeneous elbow fistulas for haemodialysis.  (+info)

Subclavian vein thrombosis caused by an unusual congenital clavicular anomaly in an atypical anatomic position. (19/217)

The optimal surgical management of subclavian vein effort thrombosis remains a dilemma because outcomes after different treatment strategies are only on the basis of small retrospective series. SVT treatment should be on the basis of the cause of thrombosis. Primary effort thrombosis or Paget-Schroetter syndrome frequently necessitates a surgical approach. The type of surgery has to be individualized after careful diagnostic evaluation. We report a congenital clavicular exostosis that had not been identified with chest radiograph and computed tomographic scan that caused SVT in a young woman. This unusual cause of Paget-Schroetter syndrome was treated with a unique approach.  (+info)

Leg and arm lactate and substrate kinetics during exercise. (20/217)

To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed by 10 min of double poling and diagonal stride at 72-76% maximal O(2) uptake. A high lactate appearance rate (R(a), 184 +/- 17 micromol x kg(-1) x min(-1)) but a low arterial lactate concentration ( approximately 2.5 mmol/l) were observed during Continuous Arm + Leg despite a substantial net lactate release by the arm of approximately 2.1 mmol/min, which was balanced by a similar net lactate uptake by the leg. Whole body and limb lactate oxidation during Continuous Arm + Leg was approximately 45% at rest and approximately 95% of disappearance rate and limb lactate uptake, respectively. Limb lactate kinetics changed multiple times when exercise mode was changed. Whole body glucose and glycerol turnover was unchanged during the different skiing modes; however, limb net glucose uptake changed severalfold. In conclusion, the arterial lactate concentration can be maintained at a relatively low level despite high lactate R(a) during exercise with a large muscle mass because of the large capacity of active skeletal muscle to take up lactate, which is tightly correlated with lactate delivery. The limb lactate uptake during exercise is oxidized at rates far above resting oxygen consumption, implying that lactate uptake and subsequent oxidation are also dependent on an elevated metabolic rate. The relative contribution of whole body and limb lactate oxidation is between 20 and 30% of total carbohydrate oxidation at rest and during exercise under the various conditions. Skeletal muscle can change its limb net glucose uptake severalfold within minutes, causing a redistribution of the available glucose because whole body glucose turnover was unchanged.  (+info)

Intraparenchymal brain hemorrhage and remote soft tissue arteriovenous malformation in a newborn infant. (21/217)

Congenital arteriovenous malformations (AVMs) often present with congestive heart failure. Such pathologic vascular structures typically occur in cranial, hepatic, or pulmonary locations and are usually associated with overlying external visible, tactile, or audible abnormalities. These vascular anomalies may also be associated with such complications as thromboembolic events, coagulopathy, and localized hemorrhage. We present a newborn infant with an occult but hemodynamically significant parascapular AVM who presented with an intraparenchymal brain hemorrhage, which we suspect to be a remote complication of the AVM.  (+info)

Visualisation of intra-cardiac structures and radiofrequency lesions using intracardiac echocardiography. (22/217)

AIMS: Fluoroscopy does not allow identification specific anatomical landmarks during electrophysiological studies. Intra-cardiac echocardiography permits visualization of these structures with excellent accuracy, but the optimal method has not been fully described. The aim of this study was to assess the capability of intra-cardiac echocardiography for the visualization of such structures using two different approaches. We also assessed its capability for the evaluation of radio frequency lesions 20 min after catheter ablation of the cavo-tricuspid isthmus. METHODS: Intra-cardiac echocardiography was performed using a 9 MHz rotating transducer in eight consecutive patients (age range: 37-76 years) after radio frequency ablation of the cavo-tricuspid isthmus. The ultrasound catheter was inserted through the femoral vein into the superior vena cava and was pulled back to the inferior vena cava. The echo catheter was then reinserted through the subclavian vein and advanced into the right ventricular apex and was pulled back from the right ventricular to the superior vena cava. Qualitative evaluation and intra-cardiac measurements were performed off-line. RESULTS: The fossa ovalis, the tricuspid valve, and the terminal crest were visible in all patients regardless of the method of introduction of the echo catheter. Left-sided structures were less accurately seen by intra-cardiac echocardiography. The horizontal diameter of the fossa ovalis was 8.9+/-1.8mm. The cavo-tricuspid isthmus was visible using the femoral approach in three patients. The isthmus could be visualized in all patients, and in three patients together with the ostium of the coronary sinus, using the subclavian approach. radio frequency lesions were not visible 20 min after ablation. Additionally, both the left and right ventricles could be seen using the subclavian approach. CONCLUSIONS: The subclavian approach is feasible, safe and superior to visualize the isthmus. Twenty minutes after radio frequency ablation of the cavo-tricuspid isthmus radio frequency lesions are not visible using intra-cardiac echocardiography.  (+info)

Vagal control of the cranial venae cavae of the rat heart. (23/217)

The cranial venae cavae of the rat heart are composed of cardiac muscle. We tested whether the vagus nerve has an inotropic action on these blood vessels. Stimulation of right or left vagal fibres (n = 7 animals) produced a negative chronotropic and inotropic effect. Before stimulation the basal cardiac interval was 319 +/- 25 ms and the vena caval diastolic force was 1.82 +/- 0.29 mN and the systolic force was 3.28 +/- 0.39 mN. Ten second stimulation increased the cardiac interval to a maximum of 484 +/- 77 ms and reduced the systolic force significantly to 2.83 +/- 0.39 mN (two-tailed paired t test). The diastolic or baseline force was unaffected by vagal stimulation (1.85 +/- 0.29 mN). The vagal negative inotropic action took significantly longer to reach peak effect (9.5 +/- 1.0 s versus 3.2 +/- 0.9 s) and lasted longer than the chronotropic effect (20.4 +/- 2.1 s versus 10.25 +/- 1.2 s). The negative inotropic action was still observed in paced preparations and preparations with transient constant-rate tachyarrhythmias. Both the chronotropic and inotropic effects were abolished by atropine (10(-6) M) and mimicked by acetylcholine chloride (10 nM). In order to minimize an atrial contribution to the force production a more reduced preparation was used and ganglion clusters at the cavo-atrial junction were stimulated electrically (n = 4 animals). Similar negative inotropic and chronotropic effects sensitive to hexamethonium were seen. After hexamethonium administration, positive inotopic and chronotropic effects were uncovered and these were abolished by atenolol (0.1 mg %). Methylene Blue staining of the preparation at the end of the experiment showed the presence of ganglion cells at the sites of stimulation. Ganglion clusters were never seen on the venae cavae per se. The results of this investigation show that the vagus has a powerful action on the venae cavae resembling that on the atria and mediated by acetylcholine.  (+info)

Risk of colonization of central venous catheters: catheters for total parenteral nutrition vs other catheters. (24/217)

BACKGROUND: Infected central venous catheters cause morbidity and mortality. OBJECTIVE: To compare the risk for colonization of central venous catheters used for total parenteral nutrition with that of catheters used for other purposes. METHODS: Retrospective review of prospectively acquired data on 260 patients with a stay in a surgical intensive care unit longer than 3 days. Single-lumen catheters used solely for total parenteral nutrition were inserted into the subclavian vein and cared for by a dedicated team. Catheters for other purposes were placed and cared for by other staff. Catheters were cultured if clinical findings suggested infection. RESULTS: Of 854 central venous catheters, 61 (7%) were used for total parenteral nutrition. During 4712 catheter days of observation, 89 catheters of all types were colonized. Risk factors for colonization included duration of catheterization (P < .001), having 3 or more lumens (hazard ratio, 1.7; 95% CI, 1.1-2.6), pulmonary artery catheterization (hazard ratio, 1.7; 95% CI, 1.1-2.7), and placement in the internal jugular vein (hazard ratio, 1.6; 95% CI, 1.1-2.5). Catheters used for total parenteral nutrition (hazard ratio, 0.14; 95% CI, 0.04-0.57) and those in the subclavian vein (hazard ratio, 0.51; 95% CI, 0.3-0.8) were at lower risk of colonization. In a multivariate Cox model, the only significant factor was a 5-fold lower risk of infection for catheters used for total parenteral nutrition (hazard ratio, 0.19; 95% CI, 0.04-0.83). CONCLUSION: Rates of colonization were lowest for catheters used solely for total parenteral nutrition, suggesting that a team approach improves patients' care.  (+info)