Respiratory sinus arrhythmia
- Respiratory sinus arrhythmia
Respiratory sinus arrhythmia (RSA) is a naturally occurring variation in heart rate that occurs during a breathing cycle. Heart rate increases during inspiration and decreases during expiration. Heart rate is normally controlled by centers in the medulla oblongata. One of these centers, the nucleus ambiguus, increases parasympathetic nervous system input to the heart via the vagus nerve. The vagus nerve decreases heart rate by decreasing the rate of SA node firing. Upon expiration the cells in the nucleus ambiguus are activated and heart rate is slowed down. In contrast, inspiration triggers inhibitory signals to the nucleus ambiguus and consequently the vagus nerve remains unstimulated.
On an electrocardiogram this phenomenon is seen as subtle changes in the R-R interval synchronized with respiration. The R-R interval on an ECG is shortened during inspiration and prolonged during expiration. In humans, the magnitude of the RSA increases with physical conditioning and self-induced, relaxed breathing. RSA becomes less prominent with age, diabetes and cardiovascular disease. [cite web |url=http://www.adinstruments.com/education/experiments/teach_experiments/full.php?exp_id=198&name_id=259&template=teaching |title=Respiratory Sinus Arrhythmia |format= |work= |accessdate=2008-05-31] ]Previous studies have shown that the efficiency of pulmonary gas exchange is improved by RSA, suggesting that RSA may play an active physiologic role. The matched timing of alveolar ventilation and its perfusion with RSA within each respiratory cycle could save energy expenditure by suppressing unnecessary heartbeats during expiration and ineffective ventilation during the ebb of perfusion. Furthermore, evidence has accumulated of a possible dissociation between RSA and vagal control of that heart rate, suggesting differential controls between the respiratory modulation of cardiac vagal outflow and cardiac vagal tone. RSA or heart rate variability in synchrony with respiration is a biological phenomenon, which may have a positive influence on gas exchange at the level of the lung via efficient ventilation/perfusion matching. [Chest. 2004 Feb;125(2):683-90 Yasuma F et al.]
References
*
Wikimedia Foundation.
2010.
Look at other dictionaries:
sinus arrhythmia respiratory — phasic a … Medical dictionary
Arrhythmia — An abnormal heart rhythm. In an arrhythmia the heartbeats may be too slow, too rapid, too irregular, or too early. Rapid arrhythmias (greater than 100 beats per minute) are called tachycardias. Slow arrhythmias (slower than 60 beats per minute)… … Medical dictionary
Respiratorische Sinusarrhythmie — EKG mit respiratorischer Sinusarrhythmie Die Respiratorische Sinusarrhythmie (RSA), gelegentlich auch Respiratorische Arrhythmie, beschreibt die atemsynchrone Schwankung der Herzfrequenz. Bei Einatmung erhöht sich die Herzfrequenz, bei Ausatmung… … Deutsch Wikipedia
Stephen Porges — Infobox Scientist image width = 150px name = Stephen Porges birth date = 1945 birth place = New Brunswick, New Jersey, USA death date = death place = residence = Chicago, Illinois nationality = American field = Biological Psychology work… … Wikipedia
Bainbridge reflex — The Bainbridge reflex, also called the atrial reflex, is an increase in heart rate due to an increase in the blood volume. Increased blood volume is detected by stretch receptors located in both atria at the venoatrial junctions. History A… … Wikipedia
Indian Standard Time — (IST) is the time observed throughout India and Sri Lanka, with a time offset of . India does not observe daylight saving time, (DST) or other seasonal adjustments, although DST was used briefly during the Sino–Indian War of 1962 and the… … Wikipedia
Arritmia sinusal respiratoria — Saltar a navegación, búsqueda La arritmia sinusal respiratoria consiste en la ralentización normal de la tasa cardiaca durante la espiración y la aceleración de la misma durante la inspiración. La tasa cardiaca está normalmente controlada por… … Wikipedia Español
Cognitive neuroscience and disgust — Disgust is an emotion that is typically defined as an experience of a feeling of revulsion, that is sometimes accompanied by nausea along with several other physiological elements.[1] Disgust may produce specific autonomic responses, such as… … Wikipedia
Neurofeedback — (NFB), also called neurotherapy, neurobiofeedback or EEG biofeedback is a type of biofeedback that uses realtime displays of electroencephalography or functional magnetic resonance imaging (fMRI) to illustrate brain activity, often with a goal of … Wikipedia
RSA (disambiguation) — RSA is an algorithm for public key encryption.RSA may also refer to:RSA encryption related* RSA Factoring Challenge, a computational number theory challenge aimed at factorizing a given set of semi prime numbers * RSA numbers, a set of numbers… … Wikipedia
