Electromyographic latency of postural evoked responses from the leg muscles during EquiTest Computerised Dynamic Posturography: Reference data on healthy subjects

No normative data are available for the latencies of the EMG signals from the ankle muscles in response to sudden sagittal tilt (toes-UP or toes-DOWN) or shift (shift-FOR or shift-BACK) of the support surface during standing. In this study the postural evoked response (PER) paradigm on the EquiTest™ force platform was applied to 31 healthy adults (18 women and 13 men; mean age 29 years). The EMG latencies (PEREMG) were computed both through the standard manual procedure and through a specially designed automated algorithm. The manually computed PEREMG onset yielded a 95% tolerance interval between 82 ms and 148 ms after toes-UP perturbation, between 93 ms and 182 ms after toes-DOWN perturbation, between 67 ms and 107 ms after shift-BACK perturbation, and between 73 ms and 113 ms after shift-FOR perturbation. When comparing the two methods, paired t-tests showed no significant mean difference (Bonferroni-adjusted p-values ranged from 0.440 to 1.000) and all Bland–Altman plots included zero difference within the limits of agreement. Therefore, the manual and the automated methods appear to be sufficiently consistent. These results foster the clinical application of PEREMG testing on the EquiTest platform.     

Stimulus–response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles

ObjectiveTo compare stimulus–response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles.MethodsStimulus–response curves of MEPs and SPs were obtained from the biceps brachii (BB) and abductor digiti minimi (ADM) muscles in 15 healthy participants. A nonlinear mixed model was used to fit the stimulus–response curves to a sigmoid Boltzmann function.ResultsSmall residuals of the function were found for MEPs and SPs in both muscles. Higher maximal MEP amplitudes were found for the BB compared to the ADM (p < 0.01). The active motor threshold to obtain a SP was less for the ADM compared to the BB (p < 0.01). The slope parameter of the function of the SP duration was steeper and more variable in the ADM than in the BB (p < 0.01). For the MEP amplitude no difference in active motor threshold and slope of the function was found between both muscles.ConclusionsExcitatory (MEP) and inhibitory (SP) effects of TMS differ between proximal arm and distal hand muscles in healthy participants. The adequate fit of our model suggests that this model can be used to study between and within subject changes in future studies.     

Separation,purification and preliminary characterization of sulfated polysaccharides from Sargassum plagiophyllum and its in vitro anticancer and antioxidant activity

Sulfated polysaccharides (SPs) were identified in different portions of the thallus of Sargassum plagiophyllum C. Agardh, with TBO staining. SPs were extracted using a blade and purified by Q sepharose fast flow anion-exchange chromatography, resulting in SP fractions F1, F2 and F3, with molecular weights of 30, 35 and 20 kDa, respectively. An SP yield of 43.1% was obtained in F3, while F2 yielded a sulfate content of 21.9%. Furthermore, the in vitro anticancer and antioxidant activities of the polysaccharide fractions were evaluated. The F2 fraction showed higher anticancer activity against HepG2 and A549 cells than the other two fractions, with IC₅₀ values of 600 μg/mL and 700 μg/mL, respectively. The normal breast epithelial cell line (HBL-100) exhibited IC₅₀ concentrations of 1200 and 1400 μg/mL for crude sulfated polysaccharides (CSPs) and all SP fractions (F1–F3). These results indicated that the anticancer activity of F2 could be related to its sulfate content. However, the antioxidant activities of F1–F3 were low at their tested concentrations.     

Anticipation of direction and time of perturbation modulates the onset latency of trunk muscle responses during sitting perturbations

Trunk muscles are responsible for maintaining trunk stability during sitting. However, the effects of anticipation of perturbation on trunk muscle responses are not well understood. The objectives of this study were to identify the responses of trunk muscles to sudden support surface translations and quantify the effects of anticipation of direction and time of perturbation on the trunk neuromuscular responses. Twelve able-bodied individuals participated in the study. Participants were seated on a kneeling chair and support surface translations were applied in the forward and backward directions with and without direction and time of perturbation cues. The trunk started moving on average approximately 40 ms after the perturbation. During unanticipated perturbations, average latencies of the trunk muscle contractions were in the range between 103.4 and 117.4 ms. When participants anticipated the perturbations, trunk muscle latencies were reduced by 16.8 ± 10.0 ms and the time it took the trunk to reach maximum velocity was also reduced, suggesting a biomechanical advantage caused by faster muscle responses. These results suggested that trunk muscles have medium latency responses and use reflexive mechanisms. Moreover, anticipation of perturbation decreased trunk muscles latencies, suggesting that the central nervous system modulated readiness of the trunk based on anticipatory information.     

Multichannel surface electrodes increase the sensitivity of diagnosis of neuropathy in diabetic patients

This prospective study investigated the diagnostic sensitivity of a novel multichannel surface electrode for detecting electrophysiologic changes in symptomatic diabetic neuropathy. We recruited healthy subjects without neuropathic complaints and diabetic patients with distal symmetric sensory symptoms who had normal nerve conduction studies (NCS). Eight compound muscle action potentials (CMAPs) were recorded using a multichannel electrode from each subject’s abductor pollicis brevis muscle by stimulating the median nerve at the wrist. Latency- and amplitude-related variables were obtained and analyzed to compare the two groups. We used the Classification and Regression Tree (CART) algorithm to determine the cut-off values for selected predictors of diabetic neuropathy. All of the variables related to CMAP latency showed statistically significant differences between the median values for the diabetic group and the healthy control group. For example, the median value of the maximum latency and standard deviation of the eight CMAP onset latencies in diabetic patients (3.82 ms and 0.15 ms, respectively) were significantly larger than those in controls (3.26 ms and p < 0.001; 0.09 ms and p < 0.001, respectively). The CART analysis revealed that these variables were the most sensitive and specific variables for discriminating between patients with diabetic neuropathy and normal subjects. The multichannel surface electrode demonstrated both high sensitivity and specificity in detecting neurophysiologic abnormality of diabetic neuropathy, even when conventional NCS did not detect the abnormality.     

Whole-body vibration induces distinct reflex patterns in human soleus muscle

The neuronal mechanisms underlying whole body vibration (WBV)-induced muscular reflex (WBV-IMR) are not well understood. To define a possible pathway for WBV-IMR, this study investigated the effects of WBV amplitude on WBV-IMR latency by surface electromyography analysis of the soleus muscle in human adult volunteers. The tendon (T) reflex was also induced to evaluate the level of presynaptic Ia inhibition during WBV. WBV-IMR latency was shorter when induced by low- as compared to medium- or high-amplitude WBV (33.9 ± 5.3 ms vs. 43.8 ± 3.6 and 44.1 ± 4.2 ms, respectively). There was no difference in latencies between T-reflex elicited before WBV (33.8 ± 2.4 ms) and WBV-IMR induced by low-amplitude WBV. Presynaptic Ia inhibition was absent during low-amplitude WBV but was present during medium- and high-amplitude WBV. Consequently, WBV induces short- or long-latency reflexes depending on the vibration amplitude. During low-amplitude WBV, muscle spindle activation may induce the short- but not the long-latency WBV-IMR. Furthermore, unlike the higher amplitude WBV, low-amplitude WBV does not induce presynaptic inhibition at the Ia synaptic terminals.     

Fingertip forces and completion time for index finger and thumb touchscreen gestures

Users actuate touchscreen computers by applying forces with their fingers to the touchscreen, although the amount and direction of the force is unknown. Our aim was to characterize the magnitude, direction and impulse of the force applied during single finger (tapping and sliding in four directions) and two finger gestures (stretch and pinch). Thirteen subjects performed repeated trials of each gesture. Mean(±SD) resultant force was 0.50(0.09) N for tap, 0.79(0.32) N to 1.18(0.47) N for sliding gestures, 1.47(0.63) N for pinch and 2.05(1.13) N for stretch. Mean resultant force was significantly less (p < 0.04) for tap than for all gestures except slide right. The direction of force application was more vertical for the two-finger gestures as compared to the single- finger gestures. Tap was the fastest gesture to complete at 133(83) ms, followed by slide right at 421(181) ms. On average, participants took the longest to complete the stretch gesture at 920(398) ms. Overall, there are differences in forces, force direction, and completion times among touchscreen gestures that could be used to estimate musculoskeletal exposure and help forge guidelines to reduce risk of musculoskeletal injury.     

Electromyography responses of pediatric and young adult volunteers in low-speed frontal impacts

No electromyography (EMG) responses data exist of children exposed to dynamic impacts similar to automotive crashes, thereby, limiting active musculature representation in computational occupant biomechanics models. This study measured the surface EMG responses of three neck, one torso and one lower extremity muscles during low-speed frontal impact sled tests (average maximum acceleration: 3.8 g; rise time: 58.2 ms) performed on seated, restrained pediatric (n = 11, 8–14 years) and young adult (n = 9, 18–30 years) male subjects. The timing and magnitude of the EMG responses were compared between the two age groups. Two normalization techniques were separately implemented and evaluated: maximum voluntary EMG (MVE) and neck cross-sectional area (CSA). The MVE-normalized EMG data indicated a positive correlation with age in the rectus femoris for EMG latency; there was no correlation with age for peak EMG amplitudes for the evaluated muscles. The cervical paraspinous exhibited shorter latencies compared with the other muscles (2–143 ms). Overall, the erector spinae and rectus femoris peak amplitudes were relatively small. Neck CSA-normalized peak EMG amplitudes negatively correlated with age for the cervical paraspinous and sternocleidomastoid. These data can be useful to incorporate active musculature in computational models, though it may not need to be age-specific in low-speed loading environments.     

Characteristics of the nociceptive withdrawal response elicited under aware and unaware conditions

BackgroundNociceptive withdrawal reflexes (NWR) are subject to supraspinal modulation. Therefore, awareness about a noxious stimulation may affect its characteristics. The goal of this study was to investigate the effect of different degrees of awareness on the NWR.MethodEight subjects performed back and forth hand movements from a common starting point towards four visual targets during which NWR was evoked when subjects were either unaware or aware of a noxious stimulation (unaware-NWR and aware-NWR). For the comparison between the NWR under both conditions, onset latencies and kinematic variables were computed respectively from the recorded Biceps Brachii EMG and from the spatial coordinates of hand reflective markers.ResultsThe onset latency of unaware-NWR (mean ± SD 73.9 ± 13 ms) was significantly shorter than that of the aware-NWR (91.1 ± 27 ms, p < 0.05). The total duration of the muscular activation was shorter in unaware-NWR than in aware-NWR. The slopes of the tangential velocity–time curves were steeper for unaware-NWR than for aware-NWR (p = 0.057).ConclusionsThe results suggest that supraspinal regulation of NWR under different degrees of awareness involves the re-parameterization of selected spatiotemporal aspects of a pre-structured motor response.     

Protection effect of cerium oxide nanoparticles against radiation-induced acute lung injuries in rats

IntroductionRadiation therapy is one of the most common tools for treating cancer. The aim is to deliver adequate doses of radiation to kill cancer cells and the most challenging part during this procedure is to protect normal cells from radiation. One strategy is to use a radioprotector to spare normal tissues from ionizing radiation effects. Researchers have pursued cerium oxide nanoparticles as a therapeutic agent, due to its diverse characteristics, which include antioxidant properties, making it a potential radioprotector.Materials and methodsOne hundred rats were divided into five groups of A) control group, intraperitoneal (IP) saline injection was done twice a week; B) bi-weekly IP injection of 14.5 nM (0.00001 mg/kg) CNP for two weeks; C) a single whole thorax radiation dose of 18 Gy; D) a single whole thorax radiation dose of 18 Gy + bi-weekly injection of 14.5 nM CNP for two weeks after radiation; E) bi-weekly IP injection of 14.5 nM CNP for two weeks prior to radiation + a single whole thorax radiation dose of 18 Gy. Thirty days after irradiation, 7 rats from each group were anesthetized and their lungs extracted for histopathological examination.ResultsStatistical analyses revealed that CNP significantly decreased the incidence of tissue collapse and neutrophile aggregation in rats receiving CNP before radiation in comparison with the radiation group.ConclusionThe results suggested the possibility of using CNP as a future radioprotector due to its ability to protect normal cells against radiation-induced damage.     

Conduction velocity of the human phrenic nerve in the neck

PurposeTo measure phrenic nerve conduction velocity in the neck in humans.ScopeWe studied 15 healthy subjects (9 men, 32.4 ± 6.7). We performed bipolar electrical phrenic stimulation in the neck, from a distal and a proximal stimulation site, and recorded diaphragm electromyographic responses on the surface of the chest. The ratio of the between-site distance to the latency difference provided phrenic velocities. Ulnar motor velocity was assessed similarly. In addition, five homogeneous patients with Charcot-Marie-Tooth disease type 1A (CMT1A) were studied for validation purposes. We obtained diaphragmatic responses from the two stimulation sites in all cases. The distal latencies (anterior axillary line recording) were 6.51 ± 0.63 ms (right) and 6.13 ± 0.64 ms (left). The minimal between site distance was 39 mm. Phrenic motor velocity was 55.2 ± 6.3 m s^?1 (right) and 56.3 ± 7.2 m s^?1 (left). In CMT1A, phrenic velocities were 17.1 ± 8.1 m s^?1 (from 7 to 32 m s^?1) and were similar to ulnar and median velocities.ConclusionsPhrenic nerve velocities can be estimated in humans and compare with upper limb motor conduction velocities. This should refine the investigation of phrenic function in peripheral neuropathies.     

Algorithmic detection of the beginning and end of bipolar electrograms: Implications for novel methods to assess local activation time during atrial tachycardia

Activation mapping is required to effectively ablate atrial tachycardia (AT). Conventional tools to assess local activation time (LAT) are based upon the peak of the bipolar electrogram (B-EGM, LAT_Peak) and the maximal negative slope of the unipolar electrogram (U-EGM, LAT_Slope). Bipolar electrograms are influenced by wavefront direction, bipole orientation, and inter-electrode spacing causing ambiguity in peak detection, whereas unipolar electrograms are disturbed by the presence of far-field signals. We developed a new algorithm to detect the beginning and end of bipolar electrograms (t_begin and t_end). Then, we introduced new LAT methods related to the onset of B-EGMs (LAT_Onset), the center of mass of B-EGMs (LAT_CoM), and the slope of U-EGMs within a pre-defined window (LAT_Slope-hybrid).In total 3752 recordings from 31 AT patients were retrospectively analyzed. The signal-to-noise ratio (SNR) for B-EGMs was calculated to differentiate algorithmically high from low quality electrograms (HQ and LQ). In a subset of 328 B-EGMs, five experts validated the t_begin as determined by the algorithm by visual rating. The newly developed LAT methods were compared to the conventional LAT methods and to one another (Bland–Altman plots) in both HQ (n = 3003) and LQ EGMs (n = 749).The t_begin algorithm was accurate (deviation < ±10 ms) in 96 ± 4% of HQ and 91 ± 8% of LQ B-EGMs. BA plots revealed the following difference (bias) and variation in HQ and LQ EGMs respectively: (1) LAT_Onset vs. LAT_Peak: 27 ± 30 ms and 24 ± 62 ms; (2) LAT_CoM vs. LAT_Peak: 0 ± 16 ms and 2 ± 38 ms; (3) LAT_Slope-hybrid vs. LAT_Slope: 1 ± 32 ms and 15 ± 110 ms; (4) LAT_Onset vs. LAT_CoM: 22 ± 24 ms and 18 ± 22 ms; (5) LAT_Onset vs. LAT_Slope-hybrid: 16 ± 18 ms and 13 ± 22 ms; and (6) LAT_CoM vs. LAT_Slope-hybrid: 5 ± 20 ms and 4 ± 18 ms.In the present study, we introduced three new methods to assess local activation time in AT, based upon an algorithm detecting accurately the beginning and end of the B-EGM complex. BA analysis of the new methods showed similar variation in high and low quality EGMs, suggesting that they introduce less ambiguity than the conventional peak method. LAT_Onset consistently yielded an earlier activation moment. LAT_Slope-hybrid – by blanking far-field potentials – seems to be the optimal method for detection of the maximal negative slope in U-EGMs. Interestingly, LAT_CoM in B-EGMs coincided with the maximal negative slope in U-EGMs, suggesting its physiological sense and future use. The new LAT methods can be implemented in real-time mapping applications.     

Hydroxyproline-O-glycosylated peptide tags enhance recombinant protein yields in tobacco transient expression

Plant transient expression provides a rapid production platform for recombinant proteins but is linked with low protein yields. To test if plant-specific hydroxyproline (Hyp)-O-glycosylated peptide tags attached to a target protein can improve overall yields of recombinant protein transiently expressed in Nicotiana benthamiana, enhanced green fluorescence protein (EGFP) was expressed as a fusion with 5 or 32 tandem repeats of a serine–proline motif, designated (SP)₅ or (SP)₃₂, which is known to direct extensive Hyp-O-glycosylation in plants. EGFP containing the (SP)_n motif showed enhanced yields in the order as follows: EGFP < EGFP-(SP)₅ ≪ (SP)₅-EGFP < (SP)₃₂-EGFP. The EGFP equivalent yield of (SP)₃₂-EGFP was up to 16-fold greater than that of the EGFP control. In addition, both fully glycosylated (SP)₃₂-EGFP (∼115 kDa) and partially glycosylated (SP)₃₂-EGFP (∼40 kDa) were detected in protein extracts of N. benthamiana. These two types of glycoforms were completely segregated between media and cells in tobacco BY-2 cell cultures.     

Quantification of abdominal and pelvic floor muscle synergies in response to voluntary pelvic floor muscle contractions

The relative levels of pelvic floor muscle (PFM) activation and pressure generated by maximum voluntary PFM contractions were investigated in healthy continent women. The normal sequence of abdominal and PFM activation was determined.Fifteen women performed single and repeated maximum voluntary PFM contractions in supine, sitting and standing. PFM electromyographic (EMG) signals and associated intra-vaginal pressure data were recorded simultaneously. Surface EMG data were recorded from rectus abdominus (RA), external obliques (EO), internal obliques (IO) and transversus abdominus (TA).Abdominal and PFM EMG and intra-vaginal pressure amplitudes generated during voluntary PFM contractions were not different among the positions. Muscle activation sequence differed by position. In supine, EO activation preceded all other muscles by 27 ms (p = 0.043). In sitting, all of the muscles were activated simultaneously. In standing, RA and EO were activated 11 and 17 ms, respectively, prior to the PFMs and TA and IO were activated 10 and 12 ms, respectively, after the PFMs (p ≪ 0.001).The results suggest that women are able to perform equally strong PFM contractions in supine, sitting and standing, however the pattern of abdominal and PFM activation varies by position. These differences may be related to position-dependent urine leakage in women with stress incontinence.     

Postural reactions following forward platform perturbation in young,middle-age,and old adults

The aim of the study was to examine how individuals of different ages react to forward balance perturbations. Thirty-six volunteers, divided into four groups [young (YA), middle-age (MA₄₀ and MA₅₀), and old (OA) adults], stood on a platform that was either kept stationary, moved backward, or moved forward. EMG onset, EMG time-to-peak, iEMG, and agonist–antagonist co-activation, as well as cumulative angular excursion, maximum center of mass (CM) backward displacement, and CM time-to-reversal were assessed after forward translations. Postural synergies were assessed using principal component analysis (PCA). The results showed that OA activated their muscles later than YA [TA = 25 ms, RF = 17 ms] and OA and MA₅₀ reached the peak of activation later than YA [MA₅₀:TA = 23 ms, RF = 32 ms, OA:TA = 28 ms, RF = 21 ms]. Moreover, OA kept a higher level of activation longer than all younger groups. No differences among groups were observed in co-activation, kinematic, and PCA variables. We conclude that changes in temporal EMG patterns can be seen in the fifth decade. However, such changes have no effect on the CM horizontal displacement and CM time-to-reversal after perturbation, which cannot be justified by the use of different postural synergies, suggesting that temporal aspects of muscle activation could play a minor role in controlling excessive CM displacements after perturbations.     

Effects of gender and age on median and ulnar nerve sensory responses over ring finger

ObjectiveTo analyze the effect of gender on median nerve (MN) and ulnar nerve (UN) sensorial responses over ring finger (RF).Materials and methodsResults of individuals admitted to our ENMG laboratory between June 2011 and March 2012 for nerve conduction studies (NCSs) were retrospectively analyzed. Sensory NCSs were performed by standard antidromic technique.ResultsTotally, 112 normal recordings belong to 100 patients were included. Mean antidromic sensory conduction velocity of MNs (wrist-to-second finger) or UNs (wrist-to-fifth finger) was not different between two genders. Mean sensory nerve action potential (SNAP) amplitude of MN from second finger was also not different between two genders. However, mean SNAP amplitude of UN from fifth finger was higher in females. In RF’s sensorial response studies; mean peak latency of MN was similar between females and males (3.05 ± 0.25 ms vs. 3.14 ± 0.29 ms, p = 0.111), whereas one of UN was shorter in females (2.86 ± 0.22 ms vs. 3.04 ± 0.31 ms, p = 0.001). MN to UN latency difference to RF was greater in females than males (0.19 ± 0.15 ms vs. 0.10 ± 0.16 ms, p = 0.007). Mean SNAP amplitude of MN and UN were both higher in females than males (17.9 ± 7.1 μV vs. 14.1 ± 5.5 μV, p = 0.011 and 18.5 ± 8.0 μV vs. 12.9 ± 6.1 μV, p = 0.0009, respectively). All data of NCSs were re-analyzed after adjustment for age, and obtained findings regarding effect of aging are also included.ConclusionGender has a prominent effect on RF’s sensorial responses. Normative values regarding them should be prepared with adjustment for gender.     

Effect of Astragalus polysaccharides on expression of TNF-α, IL-1β and NFATc4 in a rat model of experimental colitis

AimAstragalus membranaceus is a Chinese medicinal herb and has been shown to improve hapten-induced experimental colitis. One of its major components is polysaccharides. We investigated the effect of Astragalus polysaccharides (APS) on expression of TNF-α, IL-1β and NFATc4 in a rat model of experimental colitis.MethodsThe experimental colitis model was induced by TNBS. Forty five rats were divided into five groups (n = 9): Normal control group, receiving ethanol vehicle with no TNBS during induction and IP saline injection during treatment; TNBS colitis model group (TNBS + IP saline), receiving only IP saline vehicle treatment; APS low dose group (TNBS + L-APS), receiving APS 100 mg/kg; APS high dose group (TNBS + H-APS), receiving APS 200 mg/kg; and positive control group (TNBS + Dexm), receiving dexamethasone 0.3 mg/kg. The clinical features, macroscopic and microscopic scores were assessed. The expressions of TNF-α, IL-1β and NFATc4 were measured by real-time PCR and ELISA assays.ResultsCompared to normal control rats, TNBS + IP saline had significant weight loss, increased macroscopic and microscopic scores, higher disease activity index (DAI) up-regulation of TNF-α, IL-1β and NFATc4 mRNA expression and up-regulation of TNF-α and IL-1β protein expression. Compared to TNBS + IP saline, treatment with APS or dexamethasone significantly reduced DAI, partially but significantly prevented TNBS colitis-induced weight loss and improved both macroscopic and microscopic scores; high dose APS or dexamethasone significantly down-regulated TNF-α and IL-1β expressions (both mRNA and protein) and up-regulated NFATc4 mRNA and protein expression. The effect of high dose APS and dexamethasone is comparable.ConclusionsAPS significantly improved experimental TNBS-induced colitis in rats through regulation of TNF-α, IL-1β and NFATc4 expression.     

Intérêt potentiel des images paramétriques des temps d’éjection et de relaxation en tomoscintigraphie des cavités cardiaques dans l’évaluation des cardiopathies asynchrones

Intraleft dyssynchrony is strongly correlated to contractile dysfunction associated to severe heart failure. Dyssynchrony is also a predictive marker for cardiac resynchronization therapy response. We measured dyssynchrony values for both ventricles from gated blood pool SPECT images.Material and methodsThree groups of patients were sampled from normal patients (n = 7), mild heart failure patients (n = 24) and severe heart failure patients (n = 9). Time-derivative parametric images were obtained from 24-time bins gated blood pool SPECT data. We measured intraleft and interventricular contractile and relaxing dyssynchrony values from these images.ResultsIntraleft dispersions values linked to ventricular peak emptying rate were 107 ± 21 ms, 141 ± 58 ms and 515 ± 104 ms for each of the three groups. The values linked to left ventricular peak filling rate were 122 ± 62 ms, 219 ± 117 ms and 603 ± 164 ms respectively. Statistical significant differences (p < 0.01) were observed both for contractile and relaxing phases for severe heart failure patients. Mild heart failure patients had isolated statistical significant (p < 0.01) alterations of the ventricular relaxing phase. Correlation between isotopic dyssynchrony values and left ejection fraction led to a R square coefficient of 0.71 and 0.64 for time to peak emptying and to peak filling respectively. Correlation to QRS width values led to a R square coefficient of 0.76 and 0.62 respectively.ConclusionVentricular dyssynchrony correlated to the importance of the ventricular mechanical dysfunctions is a robust predictor of heart failure. Separate analysis of contractile and relaxing dyssynchrony may lead to a better understanding and characterization of the mechanical dysfunctions involved in heart failure.