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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
Cardiovascular disorders affect the blood vessels and heart in the physiological system (Serhani et al., 2020). According to the World Health Organization (WHO), 17.9 million people (31%) die each year due to cardiovascular diseases (WHO report). According to the WHO cardiovascular disorders are a leading cause of death, in particular, heart attacks in middle-aged groups. The most cost-effective electrodiagnostic method for the detection of the cardiovascular disorders is the ECG (Hassan et al., 2019). ECG is the process of measuring the electrical activity of the heart muscles and these electrical signals are referred as electrocardiograms (Preejith et al., 2016). These electrical signals are plotted as a graph of voltage with respect to time, measured using the electrodes placed on the surface of the skin, at specific locations (Ghosh et al., 2014; De Cooman et al., 2014). The electrodes acquire electrical variations in the heart muscles, and such recorded ECG signals can be used to diagnose several cardiac abnormalities such as disturbances in cardiac rhythm, atrial fibrillation, ventricular tachycardia, myocardial ischemia, myocardial infarction, hypokalemia and hyperkalemia. Generally, 10 electrodes are placed on the surface of the chest area, the upper and lower limbs and the magnitudes of the electrical signals are recorded. In ECG signals, the P wave is correlated with the depolarization of the atria, QRS complex is correlated with the depolarization of the ventricles and T wave is correlated with the repolarization of the ventricles (Gierałtowski et al., 2014; Marston et al., 2019). The pattern of the ECG signals is unique and same for all normal individuals. Figure 3.10 shows a typical electrocardiogram signal for 10 s, available at the opensource database (https://physionet.org/) and a typical ECG wave.
Case studies: cardiac dysrhythmias
Published in William H. Bush, Karl N. Krecke, Bernard F. King, Michael A. Bettmann, Radiology Life Support (Rad-LS), 2017
Thomas F. Bugliosi, William H. Bush, Geoffrey S. Ferguson
Ventricular tachycardia is defined as three or more beats of ventricular origin occurring in a row, at a rate in excess of 100 beats/min. The QRS complexes are wide, the rate is usually regular, and there may be AV dissociation. Ventricular tachycardia may produce a stable, unstable or ‘arrested’ patient. Ventricular tachycardia is always a medical emergency because decompensation may occur and ventricular fibrillation can develop.
Contrast enhancement agents and radiopharmaceuticals
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
Severe AEs have the potential to be immediately life threatening. Thankfully they are rarely seen and most definitely less now that ionic agents are rarely used for contrast enhancement. Severe symptoms include the following: life-threatening arrhythmias (i.e. ventricular tachycardia), hypotension, overt bronchospasm, laryngeal oedema, pulmonary oedema, seizures, syncope and death.
inHEART Models software – novel 3D cardiac modeling solution
Published in Expert Review of Medical Devices, 2023
Leah A. John, Brett Tomashitis, Zain Gowani, Dan Levin, Chau Vo, Ian John, Jeffrey R. Winterfield
Cardiovascular disease is a leading cause of mortality worldwide, accounting for approximately 30% of all deaths globally. Roughly half of all cardiovascular deaths are due to sudden cardiac death (SCD), and 80% of these deaths result from ventricular arrhythmias (VA) [1,2]. VA often occurs in patients with structural heart disease, including those with ischemic (ICM) and/or non-ischemic cardiomyopathy (NICM), or in those with genetic predispositions. Clinical presentation can vary from syncope, electrical storm, cardiogenic shock, cardiac arrest, and SCD [1]. Treatment strategies for prevention of SCD and reduction of VA risk include implantation of implantable-cardioverter defibrillators (ICDs), anti-arrhythmic drug therapy, and radiofrequency catheter ablation (RFCA) for ventricular tachycardia (VT). These therapies, however, are not without inherent risks including adverse drug effects, procedural risks, and inadequate efficacy [3]. Efforts aimed at improving the efficacy of such therapies are essential in optimizing patient safety and treatment success. In those requiring RFCA, advanced cardiac imaging is becoming an increasingly integral component in pre-procedural planning to guide ablation strategy.
Detecting Premature Ventricular Contraction by Using Regulated Discriminant Analysis with Very Sparse Training Data
Published in Applied Artificial Intelligence, 2019
Each phase of the ECG signal has limited amplitude and a limited duration as stated in Table 1 (Jambukia, Dabhi, and Prajapati 2015). Deviation from these values can indicate damages to the hearts conducting system or to its cells. Especially morphology and rate changes can indicate a serious cardiac arrhythmia such as ventricular tachycardia or ventricular fibrillation.