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Atrial Receptors: Reflex Effects in Quadrupeds
Published in Irving H. Zucker, Joseph P. Gilmore, Reflex Control of the Circulation, 2020
Kenneth L. Goetz, Jeffrey B. Madwed, Robert J. Leadley
Because cardiac denervation totally eliminated detectable volume influences on osmoreceptor-induced vasopressin secretion, we concluded that cardiac receptors are responsible for the modulation of the osmolality-vasopressin relationship in response to volume changes in normal animals. Under normal conditions when blood volume is quite constant, the influence of cardiac receptors on vasopressin secretion would appear to be minimal; osmoreceptors appear to play the dominant physiological role. However, during rather extreme changes in body fluid volume, cardiac volume receptors exert obvious influences. Under pathological conditions such as hemorrhage, cardiac receptors are capable of exerting potent reflex effects on vasopressin secretion.
Autonomic Responses to Microgravity and Bedrest
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
Victor A. Convertino, Rose Marie Robertson
Reduced intracardiac volume during and after spaceflight has been frequently demonstrated (Chekirda et al., 1970; Blomqvist, 1983a; Atkov, 1985; Atkov, Bednenko and Fomina, 1987; Bungo et al., 1987; Grigoriev et al., 1991), with decreases in EDV from 8-50% over 96-175 day missions (Atkov, 1985). This decrease persisted for at least several days after a 30-day Salyut flight (Beregovkin et al., 1976) and for as long as 14 days after flights in the U.S. program (Bungo et al., 1987). The importance of this was demonstrated after Skylab 4, when the exercise SV was reduced by 24 ml with upright exercise, but only 5 ml supine (Michel et al., 1977). Surprisingly, recent preliminary reports of data from Mir, while not presented in detail, suggested no change in intracardiac volumes over 7-8 months in flight. It is not clear why these results are at variance with previous data, unless the extensive countermeasures employed were exceptionally effective. In any event, the cause of lower cardiac volume is unclear but could represent something as simple as reduced filling or as serious as myocardial atrophy.
Hermite-Based Deformable Models for Cardiac Image Segmentation
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Jimena Olveres, Erik Carbajal-Degante, Boris Escalante-Ramírez, Leiner Barba-J, Lorena Vargas-Quintero, Enrique Vallejo Venegas, Lisbeth Camargo Marín, Mario Guzmán Huerta
where and are the average intensity values computed for the regions inside and outside the current surface. The objective of this functional is to guide the evolution of the surface using the intensity information, which characterizes the object and background. The input cardiac volume is and is the Heaviside function commonly used to regularize the level set variable. Although this energy functional has demonstrated to be very efficient, even for noisy data, it has the problem that images with inhomogeneity problems are not processed satisfactorily because it only considers global information.
Does aerobic exercise benefit persons with tetraplegia from spinal cord injury? A systematic review
Published in The Journal of Spinal Cord Medicine, 2021
Stephen F. Figoni, David R. Dolbow, Edwin C. Crawford, Margaret L. White, Sambit Pattanaik
Two additional training studies have involved the effects of wheelchair rugby training in male tetraplegic athletes. Currie et al.69 tested 8 trained Paralympic wheelchair rugby athletes (mean age 34 years, C5-7, AIS A-B). Resting echocardiographic data revealed normal diastolic function but low systolic function (low cardiac output, stroke volume, heart rate, and blood pressure), presumably from chronic low cardiac volume- and pressure-loading and myocardial deconditioning. Gorla et al.70 also tested body composition of tetraplegic wheelchair rugby athletes (mean age 27 years, unspecified SCI levels, AIS A-C) before and after an average of 8 months (3–11 months) of rugby training 4 sessions/week. Training consisted of aerobic and anaerobic activities, and technical and tactical aspects of rugby. Subjects decreased their mean % fat mass by 13% and increased their ulnar bone mineral content and forearm fat-free (muscle) mass by 7% and 11%, respectively.
Right Ventricular-Pulmonary Arterial Coupling and Outcomes in Heart Failure and Valvular Heart Disease
Published in Structural Heart, 2021
Bahira Shahim, Rebecca T. Hahn
Single-beat methods of assessing Ees (without obtaining multiple loops while varying volume) have been described but rely on the extrapolation of the measured pressure to a theoretical isovolumic contraction,29–31 which also may be invalid for the RV given the unusual contraction pattern and duration of forward flow. In fact, multiple authors have questioned the validity of the single cycle assumptions32,33 advocating for direct cardiac volume measurements using CMR.33 When volumes were directly measured, the Ees/Ea was significantly lower and 2 years survival was significantly reduced in patients with Ees/Ea <0.67 (log-rank test value = 5.398, P = 0.020). There was no association with outcomes for the single-cycle method.
Relevance of the assessment of natriuretic peptide plasma concentrations in hypertensive pregnant women
Published in Biomarkers, 2020
Agata Gondek, Aleksandra Jagodzińska, Bronisława Pietrzak, Artur Mamcarz, Agnieszka Cudnoch-Jędrzejewska
Borghi et al. (2000) observed increased BNP and ANP levels in women aged 29–31 years old. This is probably due to cardiac volume overload and increased end-systolic and end-diastolic left ventricular volume. Another study demonstrated that the highest NT-proBNP concentrations are found at the beginning of pregnancy and after 23 weeks of gestation. This was comparable with the levels observed in the control group (Franz et al.2009).