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Cardiovascular Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
This occurs when intermittently the P wave is not followed by a QRS complex. The block to conduction occurs in the AV node and can be of two types: Mobitz type 1 (Wenckebach; Figure 7.21b): the PR interval increases with each beat until an atrial impulse is not conducted and then the PR interval returns to normal. This is usually physiological and due to high vagal tone.Mobitz type 2 (second-degree AV block; Figure 7.21c): the PR interval does not change, but the QRS complex fails to follow the P wave because of a regularly or intermittently occurring block, which is usually below the AV node in the bundle branches or bundle of His. If there are two P waves to one QRS complex, it is a 2 : 1 block; if there are three P waves to one QRS complex, it is a 3 : 1 block. The degree of block can vary. A pacemaker is usually indicated.
Trauma Physiology and Metabolism
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
Arterial blood pressure is normally tightly controlled by neural, humoral and metabolic mechanisms in order to maintain adequate blood flow and perfusion pressure to organs and tissues. Following a fall in arterial blood pressure a number of restorative mechanisms are brought into operation. Baroreceptors in the aortic arch, carotid sinus and heart stimulate the vasomotor centre to dampen down the vagal tone, while promoting sympathetic nerve stimulation to the heart, arteries, veins, adrenal medulla and other tissues. This response helps to maintain the blood pressure despite blood loss of up to 15% of total blood volume. The increased sympathetic drive results in vasoconstriction of most blood vessels, increased myocardial contractility and heart rate and the preferential preservation of vital organ perfusion. Peripheral vasoconstriction elevates the diastolic blood pressure, causing the pulse pressure to narrow.
Two minds greater than one: an intersubjective approach to research
Published in Anthony Korner, Communicative Exchange, Psychotherapy and the Resonant Self, 2020
Vagal tone was expected to be relatively high at rest. A reduction of vagal tone was anticipated at higher breathing frequencies in response to the controlled condition of metronomic breathing, reflected in reduced amplitude of HRV and decreased RSA. Following such a controlled period it was expected that, after a brief recovery period, an increase in vagal tone might again be observed. A subsequent review of the method cautioned that very low breathing rates (below 7–8 breaths per minute) may be “difficult to interpret because the slower variations in heart rate that have baroreceptor feedback influences become intertwined with RSA” (Porges, 2019). This is interesting from a clinical point of view because many of the currently available apps that support regulation of HRV through finding one’s optimal breathing rate encourage breathing in this slow range.
Can intravenous oxytocin infusion counteract hyperinflammation in COVID-19 infected patients?
Published in The World Journal of Biological Psychiatry, 2021
Benjamin Buemann, Donatella Marazziti, Kerstin Uvnäs-Moberg
The direct beneficial effects of increasing circulating oxytocin levels by i.v. infusion may be potentiated by an enhancement of the endogenous oxytocin activity. Enhanced levels of oxytocin in the circulation may, via activation of afferent sensory nerves, stimulate oxytocin release from nerves within the brain that emanate from the hypothalamus (Velandia 2012). Afferent vagal fibres may be involved in a reciprocal feed-back signal of blood oxytocin to the brain (Iwasaki et al. 2015), but other sensory nerves may also be involved (Uvnäs-Moberg et al. 2014). This may lead to neural release of oxytocin into several important regulatory areas of the brain including the dorsal vagal complex in the brainstem (Uvnäs-Moberg et al. 2014). Subsequently, vagal tone may be increased promoting the cholinergic anti-inflammatory pathway (Borovikova et al. 2000). In addition, the neural release of oxytocin into different parts of the brain may be associated with an attenuation of stress, fear and pain (Uvnäs-Moberg et al. 2014).
Psychobiological evidence of the stress resilience fostering properties of a cosmetic routine
Published in Stress, 2021
A. Sgoifo, L. Carnevali, E. Pattini, A. Carandina, G. Tanzi, C. Del Canale, P. Goi, M. B. De Felici del Giudice, B. De Carne, M. Fornari, B. Gavazzoli, L. Poisa, D. Manzoni, D. Bollati
The observed acute increase of parasympathetic modulation at the level of the heart – as signaled by increased HF index scores - bears important prevention and treatment implications, in view of the broadly acknowledged evidence that decreased HRV is a risk factor for all-cause morbidity and mortality (Norman et al., 2012; Tsuji et al., 1994) Indeed, several physiologic systems that are important for stress, health, and disease have been linked to vagal function and HRV, including glucose regulation pathways, HPA axis function, and a number of allostatic systems (Thayer & Lane, 2009). In other words, enhanced vagal tone is an indicator of cardiac health, representing behavioral and physiological flexibility of an organism, as well as its ability to adapt in response to stress. Substantial vagal tone reduction is a marker of decreased behavioral, physiological and stress response flexibility (Porges, 1995). The present study suggests that a cosmetic routine that blends aromatherapy with mindful massage, through its capacity to acutely regulate HRV and potentiate the vagal component of autonomic neural regulation, might possibly represent an interesting tool for preventing or reversing stress-related psychosomatic and psychological dysfunctions. Needless to say that the potential usefulness of this stress relief approach is further supported by its application easiness.
Childhood Maltreatment, Self-esteem, and Suicidal Ideation in a Low-SES Emerging Adult Sample: The Moderating Role of Heart Rate Variability
Published in Archives of Suicide Research, 2019
Erinn Bernstein Duprey, Assaf Oshri, Sihong Liu
Although the benefit of emotion regulation in attenuating suicidal ideation and behavior has been documented, a methodological concern exists due to the predominant use of self-report measures. Advances in psychophysiological research suggest that bias in measurement can be reduced by using an index of vagal tone to operationalize emotion regulation (Beauchaine, 2015). The vagus nerve is a key component of the parasympathetic nervous system. Vagal tone refers to the activity of this nerve that promotes physiological homeostasis (Porges, 1995). According to the model of neurovisceral integration (Thayer & Lane, 2000), healthy and appropriate responses to emotional stimuli require the functioning of circuitry throughout the central nervous system that control cognitive, behavioral, and affective inhibition. This inhibitory circuitry consists of various cortical and subcortical pathways that are ultimately responsible for the mediation of physiological responses to emotion-provoking stimuli (Thayer & Brosschot, 2005). Parasympathetic influence on the heart via the vagus nerve is one of the primary outputs of these inhibitory circuits. Accordingly, Thayer and Lane (2000) propose that cardiac vagal tone can be used to index this inhibitory physiological response. Empirical research has provided support for the high frequeny component of heart rate variability (HF HRV) as an index of cardiac vagal tone and consequently of emotion regulation (Appelhans & Luecken, 2006; Beauchaine, 2015). Thus, by utilizing HF HRV, researchers can measure vagal nerve input to the heart (Porges, 2001). High vagal tone and consequently higher HF HRV are considered to reflect greater physiological ability to regulate ones’ emotions (Thayer & Brosschot, 2005).