A scientific repository to support the research and development of technologies related to quantitative electrocardiography: The Telemetric and Holter ECG Warehouse (THEW)

We implemented an ECG data-warehousing project to promote cross-fertilization of scientific knowledge, resources and ideas that will advance the understanding of quantitative ECG and cardiac safety. While other open ECG databases are available, our Telemetric and Holter ECG Warehouse (THEW) proposes unique sets of continuous digital ECGs recorded in cardiac patients, healthy individuals and individuals exposed to non-cardiac and cardiac drugs. In this paper, we present briefly the content and the current research triggered by this initiative. (Cardiol J 2010; 17, 4: 416-419

Transfert : les déterminants de la performance des exploitations agricoles familiales

Le transfert des exploitations familiales est une étape cruciale du cycle de vie de la majorité des exploitations agricoles québécoises. Avec un taux élevé d’échec important de 40 à 50 % dans les cinq années suivant le transfert d’une PME, il est important de connaître les causes de ces échecs ainsi que les déterminants de la performance des exploitations survivantes après le cap des premières années. Cet article présente les déterminants financiers et technico-économiques de cette performance en s’appuyant sur trois périodes : le montage financier, l’année du transfert et l’évolution de la situation. Les résultats démontrent que ce sont les ratios technico-économiques de l’exploitation à l’année du transfert et durant la période post-transfert qui ont la plus grande influence sur la performance financière cinq années après.The transfer of family farms is a crucial step in the life cycle of the majority of farms in Quebec. Within five years following the transfer of SMEs about 40-50% fail. It is important to know the causes of their failures and the determinants of performance of farms after surviving the first course of years. This article presents the financial and technico-economic determinants of this performance based on three periods: the financing, the year of transfer and the evolution of the situation. The results show that the technico-economic ratios the year of transfer and during the post-transfer period have the greatest influence on financial performance five years after the transfer. (JEL: Q12

Improving the precision of QT measurements

Background: Accurate and precise QT interval measurement is very important for both regulatory and drug developmental decision making. These measurements are often made using a manual or semi-automated technique, and the associated variability necessitates sample sizes of around 50 to 70 subjects in thorough QT/QTc studies. The purpose of this study was to compare the reproducibility and precision of a semi-automated (SA) method and a high-precision (HPQT) technique for ECG extraction and QT interval measurement on two thorough QT/QTc (TQT) studies conducted in compliance with ICH E14. Methods: Data from 35 healthy subjects from two different crossover TQT studies on treatment with placebo and moxifloxacin was analyzed. Both methods examined the RR and QT intervals measured in lead II or the lead with the highest quality T-wave on a single beat basis using the QT algorithm included in the COMPAS software package. ECGs were measured at a protocol-specific timepoint. Results: The effect of moxifloxacin on the QTc interval was highly reproducible in the two studies, and assay sensitivity was met with both methods. Pairwise comparison of QTcF values between methods demonstrated high agreement with no bias, small mean differences (below 1.5 ms) and narrow limits of agreement. HPQT improved the precision of the QTc measurement by 31% in Study I (standard deviation of DQTcF: SA 8.9 ms; HPQT 6.3 ms) and by 15% in Study II (SD: SA 9.7 ms; HPQT 8.3 ms). Conclusions: The HPQT QT measurement technique detected the effect induced by moxifloxacin with the same accuracy as SA techniques, and with clearly improved precision. More precise QTc measurement has important implications in terms of lowering the likelihood of false positive results and/or reducing the sample size in TQT studies, as well as improving the utility of QT assessment in early clinical development. (Cardiol J 2011; 18, 4: 401–410

QT interval variability in body surface ECG: measurement, physiological basis, and clinical value: position statement and consensus guidance endorsed by the European Heart Rhythm Association jointly with the ESCWorking Group on Cardiac Cellular Electrophysiology

This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the relation between QTV and heart rate variability. Research frontiers of QTV include understanding of QTV physiology, systematic evaluation of the link between QTV and direct measures of neural activity, modelling of the QTV dependence on the variability of other physiological variables, distinction between QTV and general T wave shape variability, and assessing of the QTV utility for guiding therapy. Increased QTV appears to be a risk marker of arrhythmic and cardiovascular death. It remains to be established whether it can guide therapy alone or in combination with other risk factors. QT interval variability has a possible role in non-invasive assessment of tonic sympathetic activity

Changes in deceleration capacity of heart rate and heart rate variability induced by ambient air pollution in individuals with coronary artery disease

<p>Abstract</p> <p>Background and Objective</p> <p>Exposure to ambient particles has been shown to be responsible for cardiovascular effects, especially in elderly with cardiovascular disease. The study assessed the association between deceleration capacity (DC) as well as heart rate variability (HRV) and ambient particulate matter (PM) in patients with coronary artery disease (CAD).</p> <p>Methods</p> <p>A prospective study with up to 12 repeated measurements was conducted in Erfurt, Germany, between October 2000 and April 2001 in 56 patients with physician-diagnosed ischemic heart disease, stable angina pectoris or prior myocardial infarction at an age of at least 50 years. Twenty-minute ECG recordings were obtained every two weeks and 24-hour ECG recordings every four weeks. Exposure to PM (size range from 10 nm to 2.5 μm), and elemental (EC) and organic (OC) carbon was measured. Additive mixed models were used to analyze the association between PM and ECG recordings.</p> <p>Results</p> <p>The short-term recordings showed decrements in the high-frequency component of HRV as well as in RMSSD (root-mean-square of successive differences of NN intervals) in association with increments in EC and OC 0-23 hours prior to the recordings. The long-term recordings revealed decreased RMSSD and pNN50 (% of adjacent NN intervals that differed more than 50 ms) in association with EC and OC 24-47 hours prior to the recordings. In addition, highly significant effects were found for DC which decreased in association with PM_2.5, EC and OC concurrent with the ECG recordings as well as with a lag of up to 47 hours.</p> <p>Conclusions</p> <p>The analysis showed significant effects of ambient particulate air pollution on DC and HRV parameters reflecting parasympathetic modulation of the heart in patients with CAD. An air pollution-related decrease in parasympathetic tone as well as impaired heart rate deceleration capacity may contribute to an increased risk for cardiac morbidity and sudden cardiac death in vulnerable populations.</p

T‐wave and its association with myocardial fibrosis on cardiovascular magnetic resonance examination

Background: Risk stratification in non-ischemic myocardial disease poses a challenge. While cardiovascular magnetic resonance (CMR) is a comprehensive tool, the electrocardiogram (ECG) provides quick impactful clinical information. Studying the relationships between CMR and ECG can provide much-needed risk stratification. We evaluated the electrocardiographic signature of myocardial fibrosis defined as presence of late gadolinium enhancement (LGE) or extracellular volume fraction (ECV) ≥29%. Methods: We evaluated 240 consecutive patients (51% female, 47.1 ± 16.6 years) referred for a clinical CMR who underwent 12-lead ECGs within 90 days. ECG parameters studied to determine association with myocardial fibrosis included heart rate, QRS amplitude/duration, T-wave amplitude, corrected QT and QT peak, and Tpeak-Tend. Abnormal T-wave was defined as low T-wave amplitude ≤200 µV or a negative T wave, both in leads II and V5. Results: Of the 147 (61.3%) patients with myocardial fibrosis, 67 (28.2%) had ECV ≥ 29%, and 132 (54.6%) had non-ischemic LGE. An abnormal T-wave was more prevalent in patients with versus without myocardial fibrosis (66% versus 42%, p < .001). Multivariable analysis demonstrated that abnormal T-wave (OR 1.95, 95% CI 1.09-3.49, p = .03) was associated with myocardial fibrosis (ECV ≥ 29% or LGE) after adjustment for clinical covariates (age, gender, history of hypertension, and heart failure). Dynamic nomogram for predicting myocardial fibrosis using clinical parameters and the T-wave was developed: https://normogram.shinyapps.io/CMR_Fibrosis/. Conclusion: Low T-wave amplitude ≤ 200 µV or negative T-waves are independently associated with myocardial fibrosis. Prospective evaluation of T-wave amplitude may identify patients with a high probability of myocardial fibrosis and guide further indication for CMR

Prenatal and recent methylmercury exposure and heart rate variability in young adults: the Seychelles Child Development Study

Epidemiologic evidence of an adverse association between exposure to methylmercury (MeHg) from consuming fish and heart rate variability (HRV) is inconclusive. We aimed to evaluate MeHg exposure in relation to HRV parameters in a large cohort of young adults from a high fish consuming population in the Republic of Seychelles. Main Cohort participants in the Seychelles Child Development Study were evaluated at a mean age of 19 years. Prenatal MeHg exposure was determined in maternal hair growing during pregnancy and recent exposure in participant's hair taken at the evaluation. The evaluation consisted of short (~2 h) and long (overnight) Holter recordings obtained in 514 and 203 participants, respectively. Multivariable analyses examined the association of prenatal and recent MeHg exposure (in separate models) with time-domain and frequency-domain HRV parameters in different physiologic circumstances: supine position, standing position, mental stress when undergoing a mathematics test, sleep, and long recording. Prenatal MeHg exposure was not associated with any of the 23 HRV parameters studied after adjustment for multiplicity. The recent MeHg showed a trend toward significance only for few variables in the primary model. However, after additional adjustment for activity levels, polyunsaturated fatty acids, and multiplicity none were significant after a Bonferroni adjustment. In conclusion, prenatal and recent MeHg exposure had no consistent pattern of associations to support the hypothesis that they are adversely associated with heart rate variability in this study population that consumes large amounts of fish

Vagus nerve stimulation: State of the art of stimulation and recording strategies to address autonomic function neuromodulation

International audienceObjective. Neural signals along the vagus nerve (VN) drive many somatic and autonomic functions. The clinical interest of VN stimulation (VNS) is thus potentially huge and has already been demonstrated in epilepsy. However, side effects are often elicited, in addition to the targeted neuromodulation. Approach. This review examines the state of the art of VNS applied to two emerging modulations of autonomic function: heart failure and obesity, especially morbid obesity. Main results. We report that VNS may benefit from improved stimulation delivery using very advanced technologies. However, most of the results from fundamental animal studies still need to be demonstrated in humans

Multidisciplinary Prospective Study of Mother-to-Child Chikungunya Virus Infections on the Island of La Réunion

In a prospective study on the island of La Réunion, Marc Lecuit and colleagues find frequent transmission of Chikungunya virus by viremic mothers giving birth during an outbreak, resulting in serious infant illness