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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Inotropic agent is any of a class of agents affecting the force of muscle contraction, particularly a drug affecting the force of cardiac contraction; positive inotropic agents increase, and negative inotropic agents decrease the force of cardiac muscle contraction.
Mathematical modeling of the cardiac tissue
Published in Mechanics of Advanced Materials and Structures, 2022
The relations (4.14)–(4.26), which describe active mechanics of myocardium, contain the following functions which are registered in macro experiments. Hence, for definition of the phenomenological coefficients, related to those functions, it is necessary to carry out independent investigations to register each of them in turn. In fact, all the experiments on muscular tissues can be divided in the following five groups:isometric, in which the constant length of the muscle fiber during contraction is maintained;isotonic, in which the constant contraction force is preserved;experiments with the maintenance of constant shortening (extension) speed of the fiber during contraction;experiments with quick load—unload during contraction;experiments, connected with the investigation of action of inotropic factors, which is modifying the function of ions concentration inside the fibers during the contraction processes.
Data-driven monitoring in patients on left ventricular assist device support
Published in Expert Review of Medical Devices, 2022
Lieke Numan, Mehran Moazeni, Marish I.F.J. Oerlemans, Emmeke Aarts, Niels P. Van Der Kaaij, Folkert W. Asselbergs, Linda W. Van Laake
Other important complications that may be reflected by pump parameters and occur as a consequence or aggravate after LVAD implantation are ventricular arrhythmias (VAs) and atrial arrhythmias (AA). VA occurs in 20–60% of the patients and is more frequently diagnosed in the initial postoperative period with a U-shaped incidence over time [28]. Fibrosis, ischemia, inotropic and vasopressor medication, or suction events may cause VAs. Suction is the occurrence where the septum occludes the inflow cannula, caused by a mismatch in preload and pump speed, resulting in a sudden drop in pump flow. When de instantaneous and 15-second average PI differ by more than 45%, a so called ‘PI-event’ is stored and the speed drops to its pre-set low speed, and increases gradually to the normal speed. Gross et al. revealed high suction rates in clinically stable outpatients which reveals the importance of the development of early detection algorithms, since suction may lead to irritation of cardiac tissue and arrhythmias [29]. Moreover, an algorithm was built to early detect suction, which can be used as a diagnostic tool or as an automatic physiological controller [30]. Both suction and arrhythmias result in a decreased power and flow, and may cause either increased or decreased PI.
Acute taurine supplementation enhances thermoregulation and endurance cycling performance in the heat
Published in European Journal of Sport Science, 2019
Lee Kevin Page, Owen Jeffries, Mark Waldron
Endurance exercise in the heat ceases for number of physiological reasons (Tucker & Noakes, 2009). For example, during exhaustive, fixed-resistance exercise in hot conditions, reductions in cycling power output have been reported, alongside declines in cardiac output and stroke volume, thus impairing muscle blood flow and oxygenation (González-Alonso & Calbet, 2003). Taurine has a well-established inotropic action on cardiac muscle fibre (Satoh & Sperelakis, 1998) and has been shown to increase stroke volume when consumed as part of an energy drink (Baum & Weiß, 2001). Given the established effects of taurine on cardiac myocytes, this might have been anticipated to offset fatigue-induced reductions in cardiac efficiency during performance. However, there were no changes in heart rate, which are likely to have been lower in the taurine condition if this mechanism were to explain the change in performance. As such, the increased performance and delayed fatigue in the taurine condition most likely occurred for different reasons.