Dry electrodes for electrocardiography
Patient biopotentials are usually measured with conventional disposable Ag/AgCl electrodes. These electrodes provide excellent signal quality but are irritating for long-term use. Skin preparation is usually required prior to the application of electrodes such as shaving and cleansing with alcohol. To overcome these difficulties, researchers and caregivers seek alternative electrodes that would be acceptable in clinical and research environments. Dry electrodes that operate without gel, adhesive or even skin preparation have been studied for many decades. They are used in research applications, but they have yet to achieve acceptance for medical use. So far, a complete comparison and evaluation of dry electrodes is not well described in the literature. This work compares dry electrodes for biomedical use and physiological research, and reviews some novel systems developed for cardiac monitoring. Lastly, the paper provides suggestions to develop a dry-electrode-based system for mobile and long-term cardiac monitoring applications. 
The forward and inverse problems of electrocardiography
This article summarizes the theoretical underpinnings of both the forward and inverse problems of electrocardiography. Space limitations prohibit describing all of the research work done in these areas, and the author apologizes in advance for any omissions on this account or due to oversight. The article should enable one to gain a better qualitative and quantitative understanding of the heart’s electrical activity. 
Factors affecting sensitivity and specificity of exercise electrocardiography: Multivariable analysis
Unlike the predictive value of a diagnostic test, which depends on the prevalence of disease in the population tested, its sensitivity and specificity have been assumed to be constants. This assumption was examined in patients who had both exercise electrocardiography and cardiac catheterization. The effects on sensitivity of factors from clinical history, catheterization, and exercise performance were defined by multivariable logistic regression analysis in 1,401 patients with coronary disease; effects on specificity were defined by a similar analysis in 868 patients without coronary disease. Five factors had significant, independent effects on exercise electrocardiographic sensitivity: maximal exercise heart rate, number of diseased coronary arteries, type of angina, and the patient’s age and sex. Only maximal exercise heart rate had a significant, independent effect on exercise electrocardiographic specificity. Thus, the sensitivity and specificity of exercise electrocardiography vary with clinical history, extent of disease, and treadmill performance; the sensitivity and specificity of other diagnostic tests may also vary. 
Electrocardiographic and Echocardiographic Findings in Adolescent Overweight and Obese Secondary School Children in Benin City, Nigeria
Aim: To determine the electrocardiography (ECG) and echocardiography findings in adolescent school children.
Study Design: A cross sectional descriptive study.
Place and Duration of Study: Selected secondary school in Benin City, Nigeria. The study was conducted between May and June 2016.
Methods: Subjects were overweight and obese school children from a private secondary school while controls were school children with normal weight. Overweigh and obesity were defined as BMI percentiles between 85th and 95th and >95th percentile respectively. Subjects and controls both had ECG and echocardiography evaluations. Analysis was done with SPSS version 20.0.
Results: Forty nine subjects and 49 controls were recruited. Of the subjects, 21(42.9%) and 28(57.1%) were obese and overweight respectively. Six (12.24%) subjects had chamber enlargement compared to one (2.04%) control, OR = 6.0, p = 0.12). The difference in mean left ventricular mass indexed to height (LVM/ht) of obese subjects 99.81 ± 32.80 g/m, overweight subjects 85.96 ± 20.52 and controls 81.63 ± 15.66 24.25 g/m, was significant, p = 0.0091. The LVM/ht was positively correlated with WC, r = 0.34, p = 0.024 and BMI, r = 0.37, p = 0.013.
Conclusion: Overweight and obesity is associated with increase in LVM and other chamber enlargement. Efforts should be stepped up to prevent overweight and obesity amongst school children for better cardiovascular health. 
Electrocardiographic Findings in Apparently Healthy Adolescents in the Niger Delta Region of Nigeria, West Africa
Background: Electrocardiography (ECG) is an inexpensive, quick, non-invasive, widely available and reliable screening tool in the assessment of the electrical activity of the heart, and is vital in the detection of potentially lethal sub-clinical structural or electrophysiological cardiovascular abnormalities. ECG pattern in children have been established in some regions in Nigeria but is however lacking in the Niger-Delta region of Southern Nigeria.
Objective: To determine the ECG pattern of apparently healthy adolescents in the Niger-Delta Region of Southern Nigeria.
Materials and Methods: A cross-sectional study was carried out on 1002 secondary school subjects, aged 10-19 years. The ECG recording was performed using a standard 12 lead, portable digital electrocardiograph.
Results: There were 595 (59.4%) males and 407 (40.6%) females with a male to female ratio of 1.5:1. The study population had a mean ECG heart rate of 82bpm, PR interval of 0.15 sec, P wave duration of 0.08 sec, QRS duration of 0.08 sec, QTc interval of 0.42 sec, and QRS axis of 58°. The mean heart rate and QTc interval were significantly higher in the females, while the QRS duration was significantly higher in the males. The P wave amplitude in lead II was 1.3 mm, R wave amplitude in V1 and V6 were 4.06 mm and 10.68 mm respectively. The S wave amplitude in V1 and V6 were 11.44 mm and 0.56 mm respectively.
Conclusion: ECG pattern of adolescents in the Niger-Delta region of Southern Nigeria is now established; but shows some differences from the studies in other parts of Nigeria and the world. 
 Meziane, N., Webster, J.G., Attari, M. and Nimunkar, A.J., 2013. Dry electrodes for electrocardiography. Physiological measurement, 34(9), p.R47.
 Gulrajani, R.M., 1998. The forward and inverse problems of electrocardiography. IEEE Engineering in Medicine and Biology Magazine, 17(5), pp.84-101.
 Hlatky, M.A., Pryor, D.B., Harrell, F.E., Califf, R.M., Mark, D.B. and Rosati, R.A., 1984. Factors affecting sensitivity and specificity of exercise electrocardiography: multivariable analysis. The American journal of medicine, 77(1), pp.64-71.
 E. Sadoh, W., J. Iduoriyekemwen, N. and E. Otaigbe, B. (2017) “Electrocardiographic and Echocardiographic Findings in Adolescent Overweight and Obese Secondary School Children in Benin City, Nigeria”, Journal of Advances in Medicine and Medical Research, 23(8), pp. 1-8. doi: 10.9734/JAMMR/2017/35677.
 Tabansi, P. N., Dibua, O. and Otaigbe, B. E. (2018) “Electrocardiographic Findings in Apparently Healthy Adolescents in the Niger Delta Region of Nigeria, West Africa”, Journal of Advances in Medicine and Medical Research, 25(2), pp. 1-12. doi: 10.9734/JAMMR/2018/38432.