ECG biometric analysis in different physiological recording conditions

International audienceBiometric systems have for objective to perform identification or verification of identity of individuals. Human electrocardiogram (ECG) has been recently proposed as an additional tool for biometric applications. Then, a set of ECG-based biometric studies has occurred in the literature, but they are difficult to compare because they use various values of: the number of ECG leads, the length of the analysis window (only the QRS or more), the delays between recordings… However, they analyse nearly always the ECG in rest conditions. Here, we propose to evaluate the possibility of performing ECG-based biometry in other conditions. For this purpose, a comparative study, on three experimental conditions (supine rest, standing and exercise), has been carried out. It is based on the computing of the correlation coefficient between pairs of shapes of windowed ECG. Both verification and identification tasks are tackled. The results show that there is no advantage in comparing shapes recorded in supine rest conditions, as it is classically done, which represents an obvious benefit in biometry. Performances are evaluated as a function of the shape length. Then, different tests are performed in order to investigate how should be constructed the enrolment database when a system is devoted to work in several conditions. Last part of the paper shows how performances depend on the time and on the number of ECG leads

Do Women and Men over 70 Years Old Similarly Benefit from a One-Year Training Program?

Background and Aims : Exercise capacity declines with age and is improved with exercise training. The aim of this study was to characterize the effects of a one-year combined exercise training in subjects over 70 years old, and to examine the eventual differences obtained between men and women. Methods : After baseline evaluation, 24 subjects (12 men and 12 women) over 70 years old underwent moderate intensity training with aerobic and resistance exercises, 3 hours a week over one year. Workload, oxygen uptake (VO2) and heart rate were measured during a symptom-limited exercise test. The distance walked in 6 minutes (6-MWT) was also registered, and the maximal strength was measured on knee extensor muscles. Results : After training, VO2 at ventilatory threshold was increased both in men (+17%, p<0.01) and women (+20%, p<0.01), as well as peak workload (+8% and +12%, respectively, p<0.05) and peak VO2 (+13%, p<0.05, and +19%, p<0.01, respectively). The 6-MWT distance was also improved both in men (+8%, p<0.01) and in women (+12%, p<0.01), whereas the maximal strength of knee extensor muscles was increased only in women (+28%, p<0.05). The amount of increase after training for these last two parameters was higher in women (p<0.05). Conclusion : This study have shown that one-year of combined exercise training in healthy subjects over 70 years old is well-tolerated and improves aerobic capacity, performance to field test and muscle strength. Moreover, women seem to better benefit of this program

Comparative analysis of oxygen uptake in elderly subjects performing two walk tests: the six-minute walk test and the 200-m fast walk test.

International audienceOBJECTIVE: A novel walk test is proposed to assess the ability of elderly subjects to sustain a submaximal effort in ecological surroundings. Vo(2) uptake during this test was compared with that of a six-minute walk test and maximal exercise test.DESIGN: Descriptive laboratory study.SETTING: Rehabilitation department, Dijon University Hospital.SUBJECTS: Thirty-one subjects, aged from 70 to 85 years, free from any chronic disease.INTERVENTION: Three tests to assess physical capacities: the 200-m fast walk test (200 mFWT), the six-minute walk test (6 MWT) at self-paced speed, and one maximal cardiorespiratory exercise test on an ergocycle.MAIN MEASURES: Distance walked on the 6 MWT, time to perform the 200 mFWT. Heart rate (HR) and oxygen uptake (Vo(2)) were measured for each test.RESULTS: All subjects successfully completed the two walk tests without any complaints. They walked more quickly during the 200 mFWT than during the 6 MWT (mean (SD) speed respectively 1.60 (0.17) versus 1.23 (0.16) m/s, P<0.001). Compared with the maximal exercise test, the relative intensity was much higher during the 200 mFWT than during the 6 MWT (mean (SD) Vo(2) uptake 86.8 (8.9)% versus 67.4 (10.7)% of peak Vo(2), mean (SD) HR 89.9 (9.4) versus 76.2 (0.8)% of peak HR; P<0.001).CONCLUSION: In healthy elderly subjects, the 200 mFWT requires a more sustained effort than the 6 MWT. This test is simple, ecological and well tolerated. In addition to the 6 MWT, the 200 mFWT could be a useful tool to build up and evaluate training or rehabilitation programmes, especially when interval training is planned

Stability analysis of the 12-lead ECG morphology in different physiological conditions of interest for biometric applications.

International audienceThe objective of this paper is to evaluate the robustness of biometric approaches based on human ECG signals. Two questions are addressed: is it required to record the ECG in supine rest as it is classically performed? Is it necessary to compare only shapes recorded in the same condition? A 12-lead ECG, from 14 normal subjects, in three experimental conditions (supine rest, standing and exercise), has been recorded. An analysis based on the computation of the Discrimination Coefficient (DC) between intra-and inter-subjects shows that comparing shapes recorded in the same condition leads to similar values of DC for the three conditions, provided that the interval length is lower than 800 ms. Merging the conditions leads to values of DC always greater than 1 provided that the interval length is lower than 600 ms. A clustering approach, based on correspondence analysis and hierarchical ascending classification, shows that, when merging the conditions, the ECG of a subject are in the same cluster in 94% of the cases

Sizing for endovascular aneurysm repair: clinical evaluation of a new automated three-dimensional software.

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Exercise adaptation of the left ventricular myocardium in men over 50 years of age.

International audienceBackground .- The cardiac consequences of extensive athletic activity in men over the age of 50 years are unknown. Aims .- We intend to describe the remodelling that occur due to intensive athletic activity in men≥50 years of age. Methods .- We conducted a prospective analysis of 21 athletes≥50 years of age. Fifteen sedentary healthy controls and ten patients diagnosed with a left ventricular hypertrophy who were all over the age of 50. All subjects underwent a resting and a sub-maximal exercise echocardiography in order to measure left ventricular systolic and diastolic functions. Results .- Left ventricular (LV) volumes, which were similar at rest in the three groups, were higher in the athletes during exercise (P <0.01). Systolic ejection volumes and longitudinal global left ventricular strains were greater at rest in healthy subjects (athletes and controls) in comparison to those in LVH-patients (P <0.01). During exercise, the increase in longitudinal strain was higher in athletes than in the two other groups (P <0.05). Concerning left ventricular relaxation, septal e'- and lateral e'-waves were higher both at rest and during exercise in the group of healthy subjects in comparison to those in patients (P <0.05). Conclusion .- Distinguishing physiology from pathology is challenging at rest, particularly in the elderly. However, exercise stress echocardiography helps. Only the changes in shape and in the longitudinal LV systolic function during exercise are significantly different between athletes and controls or LVH-subjects

Longitudinal strain provides prognositic value, incremental to that of cardiac magnetic resonance at the acute phase in patients with st-segment elevation myocardial infarction

International audienceObjectives: We assessed the value of speckle tracking imaging performed early after a first ST-segment elevation myocardial infarction (STEMI) in order to predict infarct size and functional recovery at 3-month follow-up. Methods: Forty-four patients with STEMI who underwent revascularization within 12 h of symptom onset were prospectively enrolled. Echocardiography was performed 3.9±1.2 days after myocardial reperfusion, assessing circumferential (CGS), radial (RGS), and longitudinal global (GLS) strains. Late gadolinium-enhanced cardiac magnetic imaging (CMR), for assessing cardiac function, infarct size, and microvascular obstruction (MVO), was conducted 5.6±2.5 days and 99.4±4.6 days after myocardial reperfusion. Results: GLS was evaluable in 97% of the patients, while CGS and RGS could be assessed in 85%. Infarct size significantly correlated with GLS (R=0.601, p-6.0% within the infarcted area exhibited 96% specificity and 61% sensitivity for predicting the persistence of akinesia (≥3 segments) at 3-month follow-up. Conclusions: Speckle-tracking strain imaging performed early after a STEMI is an easy-to-use tool for predicting persistent akinetic territories at 3 months. In addition, GLS correlated significantly with MVO and final infarct size, both parameters being relevant post-MI prognostic factors, usually obtained via CMR

Bradycardic Endurance Athletes are More at Risk of Cardioinhibitory Syncope than Non Bradycardic Ones

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Mechanical dispersion: a novel tool to diagnose pathological hypertrophic remodeling in athletes

International audienceMeeting Abstract: PO.04

Mechanical Dispersion by Strain Echocardiography: A Novel Tool to Diagnose Hypertrophic Cardiomyopathy in Athletes

International audienceBACKGROUND: Previous studies have demonstrated that global longitudinal strain (GLS) is altered in patients with hypertrophic cardiomyopathy (HCM) in comparison with athletes. Nevertheless, these results rely on studies comparing sedentary patients with HCM with healthy athletes. The aims of this study were to confirm these findings in an appropriate group of athletes with HCM and to study the additive value of novel parameters (i.e., mechanical dispersion and exercise GLS). METHODS: Thirty-six athletes with HCM were prospectively included and were compared with 36 sedentary patients with HCM, 36 healthy athletes, and 36 sedentary control subjects of similar age. Athlete groups had similar training duration and HCM groups similar maximal wall thickness. All underwent echocardiography at rest and during submaximal exercise. GLS was assessed; the SD of time to maximal myocardial shortening of longitudinal strain was calculated as a parameter of mechanical dispersion. RESULTS: The HCM sedentary group showed the lowest resting and exercise GLS. Resting GLS was not different between athletes with HCM and the two control groups, but exercise GLS enabled the differentiation of athletes with HCM from healthy athletes. Mechanical dispersion was higher in both HCM groups compared with both control groups at rest and during exercise. Receiver operating characteristic analysis in the athlete groups demonstrated that resting mechanical dispersion (area under the curve = 0.949 ± 0.023) had better ability to identify HCM compared with GLS at rest (area under the curve = 0.644 ± 0.069) (P < .001) or during exercise (area under the curve = 0.706 ± 0.066) (P < .005). CONCLUSIONS: In athletes, normal resting GLS does not rule out the diagnosis of HCM. Mechanical dispersion of longitudinal strain seems to be a promising tool for the diagnosis of HCM in athletes