Bioelectric and Biomagnetic Signal Analysis
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam in Introduction to Computational Health Informatics, 2019
This chapter describes four types of biosignals to derive abnormalities in heart, brain and muscles. The corresponding waveforms are called ECG (electrocardiogram), EEG (electroencephalogram), MEG (Magnetoencephalogram) and EMG (electromyogram). MEG is the measurement of changes in magnetic fields caused by electrical activities in the brain. The basic principle in ECG and EMG is a sequence of periodic depolarization and repolarization caused by change in Na and Ca concentration inside the cell in response to an electric signal. Heart consists of two types of chambers: atria and ventricles. Atria are further divided into left-atrium and right-atrium. Ventricles are further divided into left-ventricle and right-ventricle. Oxygenated blood comes from lungs to the left-atrium. The deoxygenated blood comes from the body to the right-atrium. The oxygenated blood flows from the left-ventricle to the body during the contraction of ventricles. Deoxygenated blood flows out from the right-ventricle to lungs during the compaction of ventricles. Proper contraction of atria and ventricles is essential for the continuous and sufficient flow of the blood within the heart–lung–body complex. Insufficient contraction of atria will result into blood-clots that may travel through the ventricles to any part of the body choking the blood-flow. A blood-clot in a brain causes that part of the brain-cells to die causing a stroke. Improper contractions of ventricles reduce the supply of the oxygenated blood to the body causing fatigue and cell-death. Improper contraction in ventricles also causes sudden cardiac death.
The cardiac system: Physiology and principles of care
Judy Bothamley, Maureen Boyle in Medical Conditions Affecting Pregnancy and Childbirth, 2020
The heart (see Figure 2.1) is divided into the right and left sides, with each side functioning as separate but synchronous pumps. Each side has an upper chamber – the atrium (atria plural) – which receives blood returning to the heart and then transfers it to the lower chamber. The ventricles pump blood away from the heart. The right ventricle pumps blood to the lungs via the pulmonary artery and the left ventricle pumps blood to the tissues of the body via the aorta. The two halves are separated by the septum, consisting of myocardium covered by endocardium. This septum or partition is very important as it prevents mixing of deoxygenated and oxygenated blood from the two sides of the heart. In the fetus before birth a shunt known as the foramen ovale exists between the left and right atrium. At birth, when the infant takes its first breath this flap normally closes. Two congenital defects known as atrial septal defect and ventricular septal defect can persist. Pregnant women may have these defects (see Chapter 3), although most are usually repaired. The pregnant woman has a physiologically dilated heart. The ventricles increase in size by about 10–15% with an increase in pumping ability (Gelson, et al., 2006; de Swiet, 1998) and there is a small increase in left atrial diameter (Blackburn, 2007).
Common Tips on Communication
Justin C Konje in Complete Revision Guide for MRCOG Part 3, 2020
Complex cardiac abnormalityWhat is the problem with my baby, or what is wrong with my baby? There are many complex cardiac abnormalities, and no specific one will be described here. However, a general approach will be provided. Your baby has an abnormality in its heart. Before I proceed to explain this to you, I would like to describe what a normal heart looks like. The heart is divided into two sides (left and right), separated by a wall with no gap or hole in it, and on each side, there are two compartments – an upper and lower compartments. The upper compartments are known as atria and receive blood. This is then passed to the lower compartments (known as ventricles), which then pump it out. The blood from the right ventricle goes to the lungs, where oxygen is added and carbon dioxide is removed. This blood comes back through the left atrium into the left ventricle, which then pumps it to the rest of the body, where the oxygen is used. Valves control the flow of blood into and out of the ventricles. There are two on each side of the heart. These valves make sure that blood moves forward and not backward, especially between contractions. The valve between the right atrium and right ventricle is called the tricuspid valve, while that between the right ventricle and the pulmonary artery (the blood vessel taking blood to the lungs) is called the pulmonary valve. On the left side, the valve between the left atrium and the left ventricle is called the mitral valve, and that at the entrance to the aorta (the blood vessel taking blood to the body) is called the aortic valve. Every cardiac abnormality should be confirmed by an echo, preferably by a paediatric cardiologist or a fetal medicine consultant, followed by karyotyping to exclude a chromosomal abnormality. Abnormalities that are not compatible with life, such as a hypoplastic right heart, should be managed jointly with clinical geneticists, paediatrician, paediatric cardiologist and counsellors. What tests will be offered? The cause is unknown in most cases. In a small number of cases, these are associated with a chromosome problem.
The Effect of the Stepped Section Atrium on Daylighting Performance
Published in Architectural Science Review, 2004
Physical scale models were used to investigate daylighting performance of a newly proposed type of atrium, namely the stepped section atrium. Physical scale models were constructed for both conventional equal section atrium and the stepped section atrium. Comparison of the daylighting performance of the two types of atrium showed a significant improvement in daylighting performance by the newly proposed stepped section atrium. Daylight readings showed that terraces inside the stepped section atrium improve light penetration inside spaces adjacent to these terraces. They also improve uniformity, and consequently reduce glare.
The Effect of the Cover and Reflective Properties of a Four-Sided Atrium on the Behaviour of Light
Published in Architectural Science Review, 1995
From a natural lighting standpoint, the atrium envelope acts as a filter between the outdoor environment, the atrium light well and the spaces around it. On its passage through the atrium cover, a portion of the incoming daylight is directed towards the adjacent rooms and the other is inter-reflected between the atrium surfaces and channeled downward towards the lower floors. The amount of daylight reaching the adjacent spaces depends largely on how much light is transmitted from the outside, the size of opening within the atrium walls and the inter-reflection capability of the atrium. In this study we have examined the effect of roof configuration and the reflective properties of the atrium intermediate boundaries on the behaviour of light along the atrium walls. The investigation was limited to a top-lit atrium and results indicate that the reflective characteristics of the atrium walls can significantly affect the intensity that reaches the lower levels of the atrium. Floor reflectance has a significant daylighting effect but it is limited to the lower floors only. The design parameter that had the most significant daylighting effect is the type of roof cover.
Daylighting in Atrium Spaces
Published in Architectural Science Review, 1994
Atria can be used to serve environmental benefits. This paper studies the effects of daylight in spaces adjacent to an atrium only. The atrium building represents a five storey office building. Light is drawn into the well from the top of the atrium. It is drawn into the side spaces through openings in the wall facades of the atrium well. The relative contributions to the day lighting in the adjacent spaces due to variable opening sizes and surface reflectivity on the wall facades of the atrium, and the surface reflectivity of the atrium floor have been recorded. The respective roles of the atrium walls and floor for enhancing lighting in the well and the side spaces have been studied.