The Cardiovascular System and its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
Diagnosis of angina pectoris is clinically established from the symptoms, although it is usually confirmed by ischemic changes in electrocardiogram (ECG, also referred to as EKG) during an attack. The ECG tracings during an angina attack may display numerous changes that help in evaluating the cause of the pain, but the most notable is often a characteristic depression of the S-T segment of the tracing. Also helpful may be an exercise tolerance test, which uses exercise on a treadmill to determine the level of cardiac work, blood pressure, and heart rate required to induce angina.
QTc
Scott Patterson, Byron Jones in Bioequivalence and Statistics in Clinical Pharmacology, 2017
In any event, arrythmia denotes an irregular heartbeat. Some are benign, but some are fatal, and the drug we were developing was intended to prevent its occurrence. To do so, my boss informed me that the drug would impact the ECG. I nodded sagely, and after she left I looked it up in my trusty medical dictionary. ECG denotes an electrocardiogram — a tracing of the electrical activity of the heart over time (we will see a typical one later in this chapter). What I was expecting when the data came in, therefore, was a lot of ECG tracings from which I would measure amplitude, trough to trough time intervals, and other summary measures to statistically describe the activity following dosing with our drug relative to placebo. These would obviously be related to the aortas and ventricles I remembered from 8th grade anatomy, so this should not have been too bad.
EM behavior when the wavelength is large compared to the object size
James R. Nagel, Cynthia M. Furse, Douglas A. Christensen, Carl H. Durney in Basic Introduction to Bioelectromagnetics, 2018
The electrical signals from the heart are unavoidably conducted to other regions of the body as well because of the conductive fluid and organs in contact with the heart. An ECG, which is used to diagnose the control signals of the heart, is a mapping of the electrical voltages produced by the heart on the surface of the body. External electrodes are placed on the body’s surface to receive these electrical signals. As with any voltage, the surface potentials must be measured relative to a reference (or ground) electrode. In the simple three-lead case, the ground electrode is connected to the right leg. This means that the other two voltages that are measured will be measured relative to the right leg. When six electrodes are used, the potentials between any pair can be measured as well as the potential between each electrode and ground.
Classification of normal sinus rhythm, abnormal arrhythmia and congestive heart failure ECG signals using LSTM and hybrid CNN-SVM deep neural networks
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Ahmet Çınar, Seda Arslan Tuncer
Electrocardiogram (ECG) analysis has been established at the center of the diagnosis of cardiovascular pathology since its development in the twentieth century. ECG signals reflect the electrical activity of the heart. Therefore, changes in the heart rhythm disturbances or ECG waveform are evidence of underlying cardiovascular problems such as arrhythmias. The signal is based on the standard 12-lead electrocardiogram that measures electrical potential from 10 electrodes located in different parts of the body surface, six chest and four limbs. It is important to obtain and monitor ECG signals for early diagnosis of diseases such as Arrhythmia and CHF. The rapid development of computer technology has enabled improvements in data collection and computer-aided diagnostic methods. Thanks to these developments, the detection of heart conditions has become easier.
Guidelines for reporting case studies and series on drug-induced QT interval prolongation and its complications following acute overdose
Published in Clinical Toxicology, 2020
Ingrid Berling, Benjamin W. Hatten, Robert S. Hoffman, Rittirak Othong, Darren M. Roberts, Reem A. Mustafa, Christopher Yates, Monique Cormier, Sophie Gosselin
Agreement and consensus on how to best diagnose QT interval prolongation in drug overdose and when to be concerned needs to be clarified within the clinical toxicology community and beyond. In the real world, many clinicians screen patients with the ECG machine generated measurements and interpretations. It would be useful if the manufacturers of these ECG machines made their calculation and analytical algorithms a matter of public information. In addition, education about the limitations of machine algorithm-derived screening is necessary. Despite a low management yield, cardiac monitoring is often the only intervention recommended for a patient with a “risk” of a prolonged QT interval, as it is considered relatively inexpensive and non-invasive. However, access to a telemetry bed requires significant resource allocation, costing hundreds of dollars more than a hospital ward bed per patient, and is likely being over-recommended, incurring unnecessary expense and prolonged patient admission [59].
Exposure–response modeling of the effect of glasdegib on cardiac repolarization in patients with cancer
Published in Expert Review of Clinical Pharmacology, 2021
Luke K. Fostvedt, Naveed Shaik, Giovanni Martinelli, Andrew J. Wagner, Ana Ruiz-Garcia
Triplicate 12-lead (with a 10-second rhythm strip) measurements in the supine position were collected for scheduled ECGs. The ECG measurements were collected using an automatic ECG machine. At each scheduled timepoint, three consecutive ECGs were collected approximately 2 minutes but no longer than 5 minutes apart, to determine the mean QTc interval. When PK samples were collected around the time of ECG assessment, study centers were instructed to make all efforts to perform the ECG before each PK sample drawing such that the PK sample was collected at the nominal time. The standard measurements from each ECG collection (i.e. RR, QT, QRS, PR, and heart rate) were reported on the case report form. For modeling purposes, ECG measurements after the first dose were considered acceptable for inclusion if they were collected within 15 minutes prior to or after the PK collection. Baseline measurements must have been collected prior to the first dose.
Related Knowledge Centers
- Atrial Fibrillation
- Cardiac Cycle
- Coronary Artery Disease
- Depolarization
- Myocardial Infarction
- Heart
- Cardiac Muscle
- Repolarization
- Ventricular Tachycardia
- Electrogram