Test-retest reliability of the nociceptive withdrawal reflex and electrical pain thresholds after single and repeated stimulation in patients with chronic low back pain

Recent studies have shown that the nociceptive withdrawal reflex threshold (NWR-T) and the electrical pain threshold (EP-T) are reliable measures in pain-free populations. However, it is necessary to investigate the reliability of these measures in patients with chronic pain in order to translate these techniques from laboratory to clinic. The aims of this study were to determine the test-retest reliability of the NWR-T and EP-T after single and repeated (temporal summation) electrical stimulation in a group of patients with chronic low back pain, and to investigate the association between the NWR-T and the EP-T. To this end, 25 patients with chronic pain participated in three identical sessions, separated by 1 week in average, in which the NWR-T and the EP-T to single and repeated stimulation were measured. Test-retest reliability was assessed using intra-class correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman analysis. The association between the thresholds was assessed using the coefficient of determination (r (2)). The results showed good-to-excellent reliability for both NWR-T and EP-T in all cases, with average ICC values ranging 0.76-0.90 and average CV values ranging 12.0-17.7%. The association between thresholds was better after repeated stimulation than after single stimulation, with average r (2) values of 0.83 and 0.56, respectively. In conclusion, the NWR-T and the EP-T are reliable assessment tools for assessing the sensitivity of spinal nociceptive pathways in patients with chronic pain.

Regional myocardial wall thinning at multidetector computed tomography correlates to arrhythmogenic substrate in postinfarction ventricular tachycardia: assessment of structural and electrical substrate

BACKGROUND A majority of patients undergoing ablation of ventricular tachycardia have implanted devices precluding substrate imaging with delayed-enhancement MRI. Contrast-enhanced multidetector computed tomography (MDCT) can depict myocardial wall thickness with submillimetric resolution. We evaluated the relationship between regional myocardial wall thinning (WT) imaged by MDCT and arrhythmogenic substrate in postinfarction ventricular tachycardia. METHODS AND RESULTS We studied 13 consecutive postinfarction patients undergoing MDCT before ablation. MDCT data were integrated with high-density 3-dimensional electroanatomic maps acquired during sinus rhythm (endocardium, 509±291 points/map; epicardium, 716±323 points/map). Low-voltage areas (<1.5 mV) and local abnormal ventricular activities (LAVA) during sinus rhythm were assessed with regard to the WT. A significant correlation was found between the areas of WT <5 mm and endocardial low voltage (correlation-R=0.82; P=0.001), but no such correlation was found in the epicardium. The WT <5 mm area was smaller than the endocardial low-voltage area (54 cm(2) [Q1-Q3, 46-92] versus 71 cm(2) [Q1-Q3, 59-124]; P=0.001). Among a total of 13 060 electrograms reviewed in the whole study population, 538 LAVA were detected and analyzed. LAVA were located within the WT <5 mm (469/538 [87%]) or at its border (100% within 23 mm). Very late LAVA (>100 ms after QRS complex) were almost exclusively detected within the thinnest area (93% in the WT<3 mm). CONCLUSIONS Regional myocardial WT correlates to low-voltage regions and distribution of LAVA critical for the generation and maintenance of postinfarction ventricular tachycardia. The integration of MDCT WT with 3-dimensional electroanatomic maps can help focus mapping and ablation on the culprit regions, even when MRI is precluded by the presence of implanted devices.

The Freedom SOLO bovine pericardial stentless valve: Single-center experience, outcome and long-term durability

Abstract Objectives We report our institutional experience and long-term results with the Sorin Freedom SOLO bovine pericardial stentless bioprosthesis. Methods Between January 2005 and November 2009, 149 patients (mean age 73.6±8.7 years, 68 [45.6%] female) underwent isolated (n=75) or combined (n=74) aortic valve replacement (AVR) using the SOLO in our institution. Follow-up was 100% complete with an average follow-up time of 5.9±2.6 years (maximum 9.6 years) and a total of 885.3 patient years. Results Operative (30-day) mortality was 2.7% (1.3% for isolated AVR [n=1] and 4.0% for combined procedures [n=3]). All causes of death were not valve-related. Preoperative peak (mean) gradients of 74.2±23.0 mmHg (48.6 ± 16.3 mmHg) decreased to 15.6±5.4 (8.8±3.0) after AVR, and remained low for up to 9 years. The postoperative effective orifice area (EOA) was 1.6 ±0.57 cm2, 1.90±0.45 cm2, 2.12±0.48 cm2 and 2.20±0.66 cm2 for the valve sizes 21, 23, 25 and 27, respectively; with absence of severe prosthesis-patient-mismatch (PPM) and 0.7% (n=1) moderate PPM. During follow-up, Twenty-six patients experienced structural valve deterioration (SVD) and 14 patients underwent explantation. Kaplan-Meier estimates for freedom from death, explantation and SVD at 9 years averaged 0.57 [0.47‒0.66], 0.82 [0.69‒0.90] and 0.70 [0.57‒0.79], respectively. Conclusions The Freedom SOLO stentless aortic valve is safe to implant and shows excellent early and mid-term hemodynamic performance. However, SVD was observed in a substantial number of patients after only 5 ̶ 6 years and the need for explantation increased markedly, suggesting low durability.

Correlation between alveolar ventilation and electrical properties of lung parenchyma.

One key problem in modern medical imaging is linking measured data and actual physiological quantities. In this article we derive such a link between the electrical bioimpedance of lung parenchyma, which can be measured by electrical impedance tomography (EIT), and the magnitude of regional ventilation, a key to understanding lung mechanics and developing novel protective ventilation strategies. Two rat-derived three-dimensional alveolar microstructures obtained from synchrotron-based x-ray tomography are each exposed to a constant potential difference for different states of ventilation in a finite element simulation. While the alveolar wall volume remains constant during stretch, the enclosed air volume varies, similar to the lung volume during ventilation. The enclosed air, serving as insulator in the alveolar ensemble, determines the resulting current and accordingly local tissue bioimpedance. From this we can derive a relationship between lung tissue bioimpedance and regional alveolar ventilation. The derived relationship shows a linear dependence between air content and tissue impedance and matches clinical data determined from a ventilated patient at the bedside.

Negotiating an Energy Deal under TTIP: Drivers and Impediments to U.S. Shale Exports to Europe

The problem of global security of energy supply is growing in importance. TTIP negotiations represent an opportunity to improve energy security in Europe and negotiate a legal framework for bilateral trade in energy, which could serve as a model for future negotiations at a multilateral level. This paper explores some of the thorniest legal, geopolitical, and economic issues that need to be taken up by TTIP negotiators for the promotion of a secure and sustainable trade in energy between the United States and European Union. It gives an account of the most recent developments in the TTIP negotiations on energy and examines the link between a possible legal framework for energy trade under TTIP and other energy-related regional and international fora. The paper critically assesses the negotiating positions of the European Union and the United States in light of their reciprocal energy profiles and needs. It offers an overview of the critical items most likely to be on top of the TTIP agenda on energy based on a comparative analysis of energy provisions in E.U. and U.S. legislation and in light of the both parties’ interests. Finally, it discusses the main driving forces and inhibiting factors capable of facilitating or rather impeding a successful conclusion of an energy trade deal between the United States and the European Union.

Extraction of maxillary first molars improves second and third molar inclinations in Class II Division 1 malocclusion

The aim of this study was to assess the changes in inclination of the maxillary second (M2) and third (M3) molars after orthodontic treatment of Class II Division 1 malocclusion with extraction of maxillary first molars.