Passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts and assessment of clinical outcomes

AIM To assess for passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts(TIPS) and compare outcomes with maximally dilated TIPS.METHODS Polytetrafluoroethylene covered TIPS(Viatorr) from July 2002 to December 2013 were retrospectively reviewed at two hospitals in a single institution. Two hundred and thirty patients had TIPS maximally dilated to 10 mm(m TIPS), while 43 patients who were at increased risk for hepatic encephalopathy(HE), based on clinical evaluation or low pre-TIPS portosystemic gradient(PSG), had 10 mm TIPS sub-maximally dilated to 8 mm(sm TIPS). Group characteristics(age, gender, Model for End-Stage Liver Disease score, post-TIPS PSG and clinical outcomes were compared between groups, including clinical success(ascites or varices), primary patency,primary assisted patency, and severe post-TIPS HE. A subset of fourteen patients with sm TIPS underwent follow-up computed tomography imaging after TIPS creation, and were grouped based on time of imaging(< 6 mo and > 6 mo). Change in diameter and crosssectional area were measured with 3D imaging software to evaluate for passive expansion.RESULTS Patient characteristics were similar between the sm TIPS and m TIPS groups, except for pre-TIPS portosystemic gradient, which was lower in the sm TIPS group(19.4 mm Hg ± 6.8 vs 22.4 mm Hg ± 7.1, P = 0.01). Primary patency and primary assisted patency between sm TIPS and m TIPS was not significantly different(P = 0.64 and 0.55, respectively). Four of the 55 patients(7%) with sm TIPS required TIPS reduction for severe refractory HE, while this occurred in 6 of the 218 patients(3%) with m TIPS(P = 0.12). For the 14 patients with follow-up computed tomography(CT) imaging, the median imaging follow-up was 373 d. There was an increase in median TIPS diameter, median percent diameter change, median area, and median percent area change in patients with CT follow-up greater than 6 mo after TIPS placement compared to follow-up within 6 mo(8.45 mm, 5.58%, 56.04 mm^2, and 11.48%, respectively, P = 0.01).CONCLUSION Passive expansion of sm TIPS does occur but clinical outcomes of sm TIPS and m TIPS were similar. Sub-maximal dilation can prevent complications related to overshunting in select patients.

Neuromuscular fatigue and recovery profiles in individuals with intellectual disability

Purpose: This study aimed to explore neuromuscular fatigue and recovery profiles im individuals with intellectual disability(ID) after exhausting submaximal contraction.Methods: Ten men with ID were compared to 10 men without ID. The evaluation of neuromuscular function consisted in brief(3 s) isometric maximal voluntary contraction(IMVC) of the knee extension superimposed with electrical nerve stimulation before, immediately after, and during33 min after an exhausting submaximal isometric task at 15% of the IMVC. Force, voluntary activation level(VAL), potentiated twitch(Ptw), and electromyography(EMG) signals were measured during IMVC and then analyzed.Results: Individuals with ID developed lower baseline IMVC, VAL, Ptw; and RMS/M_(max) ratio(root-mean-square value normalized to the maximal peak-to-peak amplitude of the M-wave) than controls(p < 0.05). Nevertheless, the time to task failure was significantly longer in ID vs. controls(p < 0.05). The 2 groups presented similar IMVC decline and recovery kinetics after the fatiguing exercise. However. individuals with ID presented higher VAL and RMS/M_(max) ratio declines but lower Ptw decline compared to those without ID. Moreover, individuals with ID demonstrated a persistent central fatigue but faster recovery from peripheral fatigue.Conclusion: These differences in neuromuscular fatigue profiles and recovery kinetics should be acknowledged when prescribing training programs for individuals with ID.

Development of powerful algorithm for maximal eigenpair

Based on a series of recent papers, a powerful algorithm is reformulated for computing the maximal eigenpair of self-adjoint complex tridiagonal matrices. In parallel, the same problem in a particular case for computing the sub-maximal eigenpair is also introduced. The key ideas for each critical improvement are explained. To illustrate the present algorithm and compare it with the related algorithms, more than 10 examples are included.

Functionality indexes assessed through a simple model of muscle activation, fatigue and recovery

A nonlinear dynamical system is proposed as a qualitative mathematical model with the twofold aim to reasonably describe the force behavior in a fatiguing sub-maximal contraction and to be possibly employed in assessing muscular activation indexes. The model＇s properties are studied in terms of its equilibria and their stability properties and the existence of the fatigue equilibrium is ensured as the only system＇s attractor in the feasibility range of the parameters. Suitable mathematical indicators -- related to the dynamical properties of resilience and reactivity -- are introduced to characterize the asymptotic and the transient system＇s behavior. The practical impact of the analytical results is elucidated and a connection is established between the introduced mathematical indicators and muscle functionality indexes as rate of force development, task failure time and complete restore time. Experimental validation with handgrip force signal at high load and possible practical applications are also presented.