A New Pacing Algorithm for Overdrive Suppression of Atrial Fibrillation

Constant rapid pacing may suppress arrhythmias, but it is usually poorly tolerated in the long term. We report a pilot study of a new pacing algorithm for overdrive suppression of atrial premature complexes (APCs) and atrial fibrillation (AF), which prevents postextrasystolic pauses and varies the pacing rate in response to the frequency of APCs. The algorithm was tested in a multiple crossover study for 24 hours in dual chamber pacemakers implanted in 70 patients. Comparison was made on ambulatory recordings between the number of atrial arrhythmias commencing with the algorithm active and inactive. In all cases, the algorithm functioned as designed. No patient was aware of its operation, and no malignant arrhythmias were induced. The 36 recordings that showed atrial arrhythmia were included for analysis. The effects of the algorithm were: APCs (estimated from pacemaker statistics) reduced in 18 patients, increased in 8 (P = 0.02); atrial salvos reduced in 12, increased in 4 (P = 0.041); and AF reduced in 11, increased in 8 (P = NS). In all patients with frequent AF (> 5 episodes in total), fewer episodes occurred when the algorithm was active. We conclude that the algorithm is safe and well tolerated, reduces atrial ectopic activity, and may reduce the frequency of sustained atrial fibrillation.     

Epidemiology of venous thromboembolism after lower limb arthroplasty: the FOTO study

BACKGROUND: In view of recent substantial changes in the management of orthopedic surgery patients, a study was performed in order to update data on the epidemiology of venous thromboembolism (VTE) in patients undergoing lower limb arthroplasty according to contemporary practise. METHODS: We performed a prospective observational study of a cohort of consecutive patients hospitalized for total hip or knee replacement in June 2003. The primary study outcome was the incidence of symptomatic VTE at 3 months. All events were adjudicated by an independent critical event committee. RESULTS: Data from 1080 patients (mean age 68.0 years) were available; 63.2% were undergoing total hip replacement and 36.8% total knee replacement. Pharmacological thromboprophylaxis was administered for a mean time of 36 days. Injectable antithrombotics were used in more than 99% of patients, irrespective of the type of surgery. The incidence of the primary study outcome was 1.8% (20 events; 95% CI: 1.0-2.6%). The incidences were 1.3% and 2.8% in hip and knee surgery patients, respectively. There were two pulmonary embolisms, both in knee surgery patients; neither was fatal. Thirty-five per cent of VTEs occurred after hospital discharge. An age of at least 75 years and the absence of ambulation before hospital discharge were the only significant (P < 0.05) predictors of VTE. The rate of clinically significant bleeding was 1.0% and the rate of death was 0.9%. CONCLUSIONS: The incidence of symptomatic VTE after lower limb arthroplasty is low, even if there is still a need to improve thromboprophylaxis, notably in patients undergoing knee arthroplasty.     

Scientific and standardization committee communications: classification and nomenclature of disintegrins isolated from snake venoms

Summary.  Viper venoms from the Elapidae, Hydrophiidae, Atractaspididae, Viperidae and Colubridae families contain at least 25 separate classes of biologically active compounds, including enzymes and non-enzymatic molecules. Nomenclature standardization of these by structure and function has been reported for prothrombin activators. No such agreement has been made for the nomenclature and classification of disintegrins. At the 51st Annual SSC Meeting in Sydney Australia (August 2005), we reported the variety of names given to the 78 disintegrins then known, and proposed a nomenclature standardization method for the naming of future members in this protein family. The summary of these recommendations will provide guidance as disintegrin discoveries move beyond high pressure liquid chromatography (HPLC) separation methods to mass spectrometry, proteomics and cloned cDNA.
View the complete paper on the International Society on Thrombosis and Haemostasis website, http://www.isth.org . ( http://www.med.unc.edu/isth/ssc/communications/exogenous/disintegrins/disintegrins.htm ). This abstract is co-published in Toxicon .     

Fitness, fatness, and cardiovascular risk factors in type 2 diabetes: look ahead study

PURPOSE: Most studies comparing the effects of fitness and fatness on cardiovascular (CVD) risk have been done with young, healthy participants with low rates of obesity and high levels of fitness. The present study examined the association of cardiorespiratory fitness and obesity with CVD risk factors in an ethnically diverse sample of overweight/obese individuals with type 2 diabetes. METHOD: Baseline data from Look AHEAD, a study of 5145 overweight or obese individuals with type 2 diabetes, were used to examine the association of BMI categories (overweight, class I, II, or III obesity) and cardiorespiratory fitness (assessed with a maximal graded exercise test and categorized by age- and gender-specific quintiles) on cardiovascular risk factors and on the odds of having hypertension, hyperlipidemia, or HbA1c > or = 7%. RESULTS: BMI categories and fitness quintiles were highly associated with each other (P < 0.0001), with the heaviest participants being the least fit. Only 2-3% of participants had class III obesity and were in the two fittest quintiles or, conversely, were overweight and in the two least-fit quintiles. When fitness and BMI were included in the same model (adjusting for age, smoking, diabetes duration, and race), HbA1c, ankle/brachial index (ABI), and Framingham risk score were most strongly associated with fitness. Systolic blood pressure was most strongly associated with BMI category. Similar results occurred when waist circumference and fitness were considered together. CONCLUSION: In this large, ethnically diverse sample of overweight/obese individuals with type 2 diabetes, fitness and fatness were highly related to each other but seemed to have different impact on specific CVD risk factors.     

Validation of the Functional Status II questionnaire in the assessment of extremely-low-birthweight infants

Aim  The increased survival of infants born at extremely low birthweight (ELBW) has been associated with significant morbidity, including higher rates of neurodevelopmental disability. However, formalized testing to evaluate these problems is both time-consuming and costly. The revised Functional Status questionnaire (FS-II) was designed to assess caregivers' perceptions of the functional status of children with chronic diseases.
Method  We evaluated the reliability and validity of the FS-II for ELBW infants at 18 to 22 months corrected age using data from the US Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Neonatal Research Network (NRN). Exploratory factor analyses were conducted using data from the network's first follow-up study of 1080 children born in 1993 to 1994 (508 males, 572 females [53%]), and results were confirmed using data from the next network follow-up of 4022 children born in 1995 to 2000 (1864 males, 2158 females [54%]).
Results  Results suggest that a two-factor solution comprising measures of general health and independence is most appropriate for ELBW infants. These factors differed from those found among chronically ill children, and new, more appropriate scales are presented for screening ELBW survivors. Both scales demonstrated good internal consistency: Cronbach's α=0.87 for general health and α=0.75 for independence. Construct validity of the scales was assessed by comparing mean scores on the scales according to scores on the Bayley Scales of Infant Development, second edition (BSID-II), and medical conditions.
Interpretation  As hypothesized, infants with greater functional impairments according to their BSID-II scores or medical conditions had lower scores on the general health and independence scales, supporting the validity of the scales.     

学龄前儿童普通话平均句子长度的多因素研究

【目的】探讨影响学龄前儿童普通话平均句子长度的因素,为促进儿童语言发育提供参考意见。【方法】以65名3~6岁学龄前儿童为研究对象并对其父母进行问卷调查。问卷内容包括儿童发育情况、家庭社会环境因素等39个变量。利用计算机程序计算每名儿童自然语言样本的平均句子长度。【结果】年龄、边看图书边自己讲述、父亲的文化程度、看广告、看电视后家长(或保姆)与儿童谈论电视内容与学龄前儿童平均句子长度呈正相关;边看图书边听家长讲述和语言障碍家族史与学龄前平均句子长度呈负相关。【结论】年龄、遗传因素和家庭语言环境为学龄前儿童语言发育的重要影响因素。     

Choice reaction time in patients with post-operative cognitive dysfunction

Background: Post‐operative cognitive dysfunction (POCD) is detected by administration of a neuropsychological test battery. Reaction time testing is at present not included as a standard test. Choice reaction time (CRT) data from the first International Study of Post‐operative Cognitive Dysfunction study were collected, but the association between POCD and reaction time has not been presented before. We hypothesized that CRT could be used as a screening tool for POCD. Methods: Patients aged 60 years or older scheduled for major surgery with general anaesthesia were recruited from 13 centres in nine countries. CRT was measured 52 times using the four boxes test. Patients performed the test before surgery (n=1083), at 1 week (n=926) and at 3 months (n=852) post‐operatively. CRT for the individual patient was determined as the median time of correct responses. The usefulness of the CRT as a screening tool for POCD was determined by the receiver–operator characteristic (ROC) curve. Results: Patients with POCD 1 week after surgery had a significantly longer reaction time compared with patients without POCD: 857 (221) vs. 762 (201) ms, respectively (P<0.0001). Also at 3 months, patients with POCD had a significantly longer CRT. ROC curves revealed that a reaction time of 813 ms was the most appropriate cut‐off at 1 week and 762 ms at 3 months but the positive predictive value for POCD was low: 34.4% and 14.7%, respectively. Conclusions: Post‐operative cognitive dysfunction is associated with impaired performance in the CRT test but the test is a poor predictor of POCD.     

IN.PACT AV access randomized trial: Japan cohort outcomes through 12 months

Purpose

There is a lack of adjudicated and prospectively randomized published outcomes on the use of drug-coated balloons (DCB) to treat dysfunctional arteriovenous fistula in Asian patients. This post hoc subgroup analysis of 112 Japanese participants from the global IN.PACT AV Access trial reports outcomes through 12 months.

Materials and Methods

Participants were treated with DCB (n = 58) or standard non-coated percutaneous transluminal angioplasty (PTA) balloons (n = 54). Outcomes included target lesion primary patency (TLPP), access circuit primary patency, and safety.

Results

Through 6 months, TLPP was 86.0% (49/57) in the DCB group and 49.1% (26/53) in the PTA group (p < 0.001). Through 12 months, TLPP was 67.3% (37/55) in the DCB group and 43.4% (23/53) in the PTA group (p = 0.013).

Conclusion

In this post hoc analysis of Japanese participants from the IN.PACT AV Access trial, participants treated with DCB had higher TLPP through 6 and 12 months compared with PTA.     

Reliability and construct validity of the compatible MRI scoring system for evaluation of elbows in haemophilic children

Summary. We assessed the reliability and construct validity of the Compatible MRI scale for evaluation of elbows, and compared the diagnostic performance of MRI and radiographs for assessment of these joints. Twenty‐nine MR examinations of elbows from 27 boys with haemophilia A and B [age range, 5–17 years (mean, 11.5)] were independently read by four blinded radiologists on two occasions. Three centres participated in the study: (Toronto, n = 24 examinations; Atlanta, n = 3; Cuiaba, n = 2). The number of previous joint bleeds and severity of haemophilia were reference standard measures. The inter‐reader reliability of MRI scores was substantial (ICC = 0.73) for the additive (A)‐scale and excellent (ICC = 0.83) for the progressive (P)‐scale. The intrareader reliability was excellent for both P‐scores (ICC = 0.91) and A‐scores (ICC = 0.93). The total P‐ and A‐scores correlated poorly (r = 0.36) or moderately (r = 0.54), but positively, with clinical‐laboratory measurements. The total MRI scores demonstrated high accuracy for discrimination of presence or absence of arthropathy [P‐scale, area‐under‐the‐curve (AUC) = 0.94 ± 0.05; A‐scale, AUC = 0.89 ± 0.06], as did the soft tissue scores of both scales (P‐scale, AUC = 0.90 ± 0.06; A‐scale, AUC = 0.86 ± 0.06). Areas‐under‐the‐curve used to discriminate severe disease demonstrated high accuracy for both P‐MRI scores (AUC = 0.83 ± 0.09) and A‐MRI scores (AUC = 0.87 ± 0.09), but non‐diagnostic ability to discriminate mild disease. Similar results were noted for radiographic scales. In conclusion, both MRI scales demonstrated substantial to excellent reliability and accuracy for discrimination of presence/absence of arthropathy, and severe/non‐severe disease, but poor to moderate convergent validity for total scores and non‐diagnostic discriminant validity for mild/non‐mild disease. Compared with radiographic scores, MRI scales did not perform better for discrimination of severity of arthropathy.