Determination of Pacing Capture in Implantable Defibrillators: Benefit of Evoked Response Detection Using RV Coil to Can Vector

SPLETT, V., et al. : Determination of Pacing Capture in Implantable Defibrillators: Benefit of Evoked Response Detection Using RV Coil to Can Vector. Automatic detection of capture in ICDs would be useful for ensuring normal pacing function and lead integrity and may increase device longevity. Evoked response detection can be difficult due to postpace polarization. Polarization on the RV coil to can vector, however, should be absent when pacing with a true bipolar lead (pace tip to ring). Polarization on the RV coil to can vector should be low in an integrated bipolar lead due to the large surface area of the coil. Ventricular-paced responses were prospectively recorded in 20 patients during ICD implantation or replacement. Capture and loss of capture responses were noted during threshold searches with electrograms recorded between the RV coil and can. A detector was designed to discriminate between capture and noncapture-paced responses using data from the first 11 patients and validated on the remaining 9. The detector had a sensitivity of 99.9% (detected capture on capture beats), and had a specificity of 100% (detected no capture on noncapture beats) for all lead configurations. There was no measurable polarization with true bipolar leads. In integrated bipolar leads, maximum polarization ranged from 0.0 to 16.7mV. In conclusion, paced evoked responses can be detected in ICDs using the RV coil to can vector using standard pacing waveforms. Special polarization reducing pacing waveforms are not required. These observations could be used to design ICDs with automatic pacing threshold detection.     

Clinical Profile of Commotio Cordis: An Under Appreciated Cause of Sudden Death in the Young During Sports and Other Activities

Blunt Chest Impact Leading to Cardiac Arrest. Not particularly well recognized are athletic Held catastrophes in which virtually instantaneous cardiac arrest is produced by nonpenetrating chest blows in the absence of heart disease or identifiable morphologic injury to the chest wall or heart (commotio cordis). To better characterize the clinical profile of this syndrome, we have assembled 70 cases, including 34 occurring during organized competitive athletics and 36 others that occurred during informal recreational sports at home, school or the playground, or during nonsporting activities. Ages were 2 to 38 (mean age: 12) with 70% < 16 years old. Most common sports involved were youth baseball (n = 40), softball (n = 7), and ice hockey (n = 7). Seven (10%) of the 70 commotio cordis victims, including six with documented ventricular fibrillation, have survived the consequences of their chest blow. Eleven of the events (16%) occurred despite the presence of chest padding believed to be potentially protective. Four victims experienced modest chest blows while in circumstances completely unrelated to sports activities; three of the four individuals who delivered these blows were ultimately convicted of criminal acts within the justice system. An experimental model of low-energy chest wall impact demonstrates that commotio cordis events are due largely to the exquisite timing of blows during a narrow window within the repolarization phase of the cardiac cycle, 15 to 30 msec prior to the peak of the T wave.     

Investigation of childhood central nervous system vasculitis: magnetic resonance angiography versus catheter cerebral angiography

Aim We compared the clinical utility of magnetic resonance angiography (MRA) to catheter cerebral angiography (CA) in the investigation of children with suspected central nervous system (CNS) vasculitis. Method Single‐centre retrospective review of children with a suspected diagnosis of CNS vasculitis studied with both MRA and CA. MRA and CA‐detected abnormalities (location, multiplicity, and morphology) were compared; sensitivity and specificity were calculated on a per lesion and per patient basis for MRA, with CA as the reference standard. Results Findings in fourteen patients (median age at presentation of 5y 10mo [range 1y 5mo–14y 5mo]; eight males, six females) relating to sixteen paired studies of MRA and CA were reviewed. CA‐detected lesions were commonly bilateral (13/16 studies, p<0.05), and likely to be proximally distributed (15/16 studies, p<0.05).The sensitivity and specificity of MRA for CA lesion detection was 63% (95% confidence interval [CI] 48–78) and 89% (95% CI 81–93), respectively with moderate agreement between the two modalities (κ=0.51, 95% CI 0.37–0.66). The majority of the false negative observations involved the posterior circulation (9/14). The overall sensitivity for MRA diagnosis of vasculitis per patient was 94% (95% CI 67–99). Interpretation MRA failed to identify all lesions detected on CA, particularly those in the posterior circulation. MRA is a reasonable initial modality in the investigation of suspected CNS vasculitis but in cases of abnormal parenchymal MRI and normal MRA, CA should be considered.     

糖心康对糖尿病大鼠心肌NF-κB表达的影响

目的探讨糖心康对糖尿病性心肌病的治疗作用及其作用机制。方法通过腹腔小剂量多次注射链脲佐菌素(STZ)加高热量饮食建立糖尿病大鼠心肌损伤模型,采用全自动生化分析仪测定空腹血糖、糖化血红蛋白,放免法测定胰岛素含量观察糖心康对糖尿病大鼠糖代谢及胰岛素水平的影响;采用免疫组织化学法观察糖心康对糖尿病大鼠心肌NF-κB表达的影响。结果糖心康有明显降低血糖、糖化血红蛋白及提高胰岛素水平的作用(P<0.05);糖心康对糖尿病大鼠心肌NF-κB的过度表达有显著抑制作用(P<0.01)。结论糖心康对糖尿病性心肌病有显著治疗作用,其作用机制之一是通过抑制心肌NF-κB过度表达实现的。     

Modifications of the urethral rest and stress profiles after different types of surgery for urinary stress incontinence

Summary. Full urodynamic assessment, including urethral profiles at rest and under stress, using microtransducers, was made before and at least 6 months after surgery for urinary stress incontinence in 86 patients. Cure was assessed objectively. Procedures compared were Burch colposus-pension, Pereyra urethrovesical suspension and anterior colporrhaphy. The Burch colposuspension increased the pressure transmission ratio more efficiently than the vaginal operations and the cure rate was 91%. Only 50% of Pereyra operations were successful and success was related to an increase in the functional urethral length and in the pressure transmission ratio. The success rate for anterior colporrhaphy was 57% and was associated with a significant decrease in the maximal urethral closure pressure and the continence area. The prognostic value of the urethral profiles at rest and under stress and the therapeutic implications are discussed.     

Medication compliance in children with asthma

A questionnaire to assess compliance with prescribed therapy was completed by 200 children with asthma. The validity of the questionnaire was assessed objectively by measuring plasma theophylline concentrations in 37 subjects and by weighing metered dose aerosol canisters before and after use in 19 subjects. The average compliance was 67.9%. The close agreement between answers to the questionnaire and the objective measurements of compliance indicated that most participants recalled the drug regimens accurately. Good compliance was related to whether Australia was the parents' country of origin, to knowledge of the disorder and to comprehension of medication but was not related to perception of the severity of the illness. This study demonstrates that compliance is relatively poor even in a clinic population which attends regularly and appears well-motivated.