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Heart rate variability visualized with R-R interval changes Electrocardiogram (ECG) recording of a canine heart that illustrates beat-to-beat variability in R–R interval (top) and heart rate (bottom). Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the ...
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. [6] It is typically given intravenously or by injection into a muscle. [6]
Excessive stress and sleep deprivation can cause cardiovascular issues, such as high blood pressure and heart disease. In a study focusing on the impacts of chronic stress on the heart, it was found that during times of chronic stress, the body hyperactivates the sympathetic nervous system which leads to changes in heart rate variability. [22]
Acetylcholine hyperpolarizes the sinoatrial node; this is overcome by MRAs, and thus they increase the heart rate. If atropine is given by intramuscular or subcutaneous injection, it causes initial bradycardia. This is because when administered intramuscularly or subcutaneously atropine acts on presynaptic M1 receptors (autoreceptors).
In the 1850s, atropine was used as antispasmodic in asthma treatment and as morphine antidote for its mydriatic effect. [4] Bezold and Bloebaum showed that atropine blocked the effects of vagal stimulation on the heart in 1867. Subsequently in 1872, Heidenhain found its ability to prevent salivary secretion. [6]
The vagus nerve acts on the sinoatrial node, slowing its conduction and modulating vagal tone, via the neurotransmitter acetylcholine and downstream changes to ionic currents and calcium of heart cells. [4] Because of its effect on heart rate, and cardio health, vagal tone can be measured and understood by examining its correlation to heart ...
Organophosphate based nerve agent poisoning, such as VX, sarin, tabun, and soman (atropine is favoured in conjunction with an oxime, usually pralidoxime) [6] [7] Anticholinergics generally have antisialagogue effects (decreasing saliva production), and most produce some level of sedation, both being advantageous in surgical procedures.
In the heart, they act to slow the heart rate down below the normal baseline sinus rhythm, by slowing the speed of depolarization. In humans, under resting conditions, vagal activity dominates over sympathetic activity. Hence, inhibition of M 2 receptors (e.g. by atropine) will cause a raise