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Biological Responses in Context
Published in Arthur T. Johnson, Biology for Engineers, 2019
Hypertension is usually a temporary adjustment to emotional stress or trauma, but after sustained hypertension, the condition perpetuates itself, becoming essential hypertension. The left ventricle of the heart, challenged by the need to pump blood against pressure higher than normal, develops a thickened muscular wall, called cardiac hypertrophy. The extra muscular mass requires additional oxygen, and any decrease in coronary blood flow has more serious consequences in hypertensive patients than in normal individuals. Myocardial infarction (muscle cells die due to lack of oxygen) is therefore more of a threat in hypertensive patients than in normal ones. Even with the implantation of a replacement heart, the underlying causes of the heart failure have not been eliminated, and the cycle is likely to repeat.
Safe Handling of Vacuum Tube Devices
Published in Jerry C. Whitaker, Power Vacuum Tubes, 2017
Table 13.1 lists some effects that typically result when a person is connected across a current source with a hand-to-hand resistance of 2.4 kΩ. The table shows that a current of approximately 50 mA will flow between the hands, if one hand is in contact with a 120 V ac source and the other hand is grounded. The table indicates that even the relatively small current of 50 mA can produce ventricular fibrillation of the heart, and perhaps death. Medical literature describes ventricular fibrillation as rapid, uncoordinated contractions of the ventricles of the heart, resulting in loss of synchronization between heartbeat and pulse beat. The electrocardiograms shown in Figure 13.1 compare a healthy heart rhythm with one in ventricular fibrillation. Unfortunately, once ventricular fibrillation occurs, it will continue. Barring resuscitation techniques, death will ensue within a few minutes.
Cardiovascular system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The heart is a hollow muscular organ which, with the roots of the great vessels, is enclosed in a fibroserous sac, the pericardium. It is situated mainly to the left of the midline in the middle mediastinum attached to the central tendon of the diaphragm. The heart has four chambers: the right and left atria and the right and left ventricles. The atria are separated by the inter-atrial septum and the ventricles by the interventricular septum.
Cardiac implantable electronic devices and cybersecurity
Published in Expert Review of Medical Devices, 2021
Bhakti Patel, Amgad N. Makaryus
The implantable loop recorder is a device that is inserted into the patient’s subcutaneous tissue. It functions to diagnose heart rhythm disorders by monitoring the heart rhythm and has the ability to record and store ECGs when a patient is in bradycardia or tachycardia [6]. The remote monitoring feature with the implantable loop recorder provides great benefits, such as decreasing the time it takes to diagnose a patient’s condition as well as the follow-up treatment plan [6]. In a study by Drak-Hernandez et al., the mean time from implant to diagnosis was compared in patients with remote monitoring to those with conventional follow-up appointments following an implantable loop recorder. The results showed that patients with the remote monitoring feature had significantly shorter time to diagnosis and targeted treatment [7]. Additionally, remote monitoring with implantable loop recorders not only enables more timely diagnosis, but also allows data to be transferred in order to prevent memory overflow. This decreases the risk for information loss as a result of memory overflow as well as decreased outpatient visits to record/upload data [7]. For patients with heart failure, the implanted left-ventricular assist device (LVAD) helps the left-ventricle pump blood to the body. Remote monitoring of the LVAD increases the early detection of problems and their treatment [8]. Overall, remote monitoring serves as an advantage for many cardiac devices as it allows for efficient and quick data transfer to the physician as well as early diagnosis of a heart condition.
Circulatory System Based Optimization (CSBO): an expert multilevel biologically inspired meta-heuristic algorithm
Published in Engineering Applications of Computational Fluid Mechanics, 2022
Mojtaba Ghasemi, Mohammad-Amin Akbari, Changhyun Jun, Sayed M. Bateni, Mohsen Zare, Amir Zahedi, Hao-Ting Pai, Shahab S. Band, Massoud Moslehpour, Kwok-Wing Chau
According to the simple inspiration model from the circulatory system of the body’s regular performance in Figure 1, the body’s blood vessels are functionally divided into two distinctive circuits: the pulmonary circuit and the systemic circuit. The pump for the pulmonary circuit, which circulates blood through the lungs, is the right ventricle. The left ventricle is the pump for the systemic circuit, which provides the blood supply for the body’s tissue cells. Pulmonary circulation transports oxygen-poor blood from the right ventricle to the lungs, where the blood picks up a new blood supply. Then it returns the oxygen-rich blood to the left atrium.