A vagal maneuver is an action used to stimulate the parasympathetic nervous system by activating the

vagus nerve The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right ...

. The vagus nerve is the longest nerve of the

autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies internal organs, smooth muscle and glands. The autonomic nervous system is a control system t ...

and helps regulate many critical aspects of human physiology, including heart rate, blood pressure, sweating, and digestion through the release of

acetylcholine Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Pa ...

. Common maneuvers that activate the vagus nerve include the

Valsalva maneuver The Valsalva maneuver is performed by a forceful attempt of exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut while expelling air out as if blowing up a balloon. Variations of the maneuver can ...

and carotid sinus massage, which can serve diagnostic or therapeutic functions.

Clinical indications

There are both diagnostic and therapeutic indications for the use of vagal maneuvers in clinical practice. Diagnostic: * Vagal maneuvers (most commonly the

) can be used to distinguish between

ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a fast heart rate arising from the lower chambers of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple episodes over a short period ...

and

supraventricular tachycardia Supraventricular tachycardia (SVT) is an umbrella term for fast heart rhythms arising from the upper part of the heart. This is in contrast to the other group of fast heart rhythms – ventricular tachycardia, which start within the lower cha ...

by slowing the rate of conduction at the SA or AV nodes. * Vagal maneuvers (most commonly carotid sinus massage) are used to diagnose

carotid sinus hypersensitivity In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid ...

. Therapeutic: * Vagal maneuvers are the first-line treatment of hemodynamically stable supraventricular tachycardia, serving to slow down or terminate the arrhythmia. Vagal maneuvers have a reported success rate of conversion to sinus rhythm for SVT around 20-40%, possibly being higher for AVNRT (an SVT associated with a bypass tract). Whereas the modified Valsalva maneuver is most effective in adults, cold water immersion may be preferred as a safe, effective, and non-invasive treatment for pediatric SVT. * Vagal maneuvers may be used to terminate hemodynamically stable ventricular tachycardia. * Various vagal maneuvers are suggested for the elimination of

hiccup A hiccup (scientific name ''singultus'', from a Latin word meaning "to catch one's breath while sobbing"; also spelled hiccough) is an involuntary contraction (myoclonic jerk) of the diaphragm that may repeat several times per minute. The hi ...

s. * Vagal maneuvers may decrease temporary pain through sinoaortic baroreceptor mediated anti-nociception (inhibition of pain conduction, release of

substance P Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) and a member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its cl ...

and

noradrenaline Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'' ...

Types of vagal maneuvers

While many physical maneuvers can elicit autonomic responses, only some are appropriate for use in a clinical setting. The vagal maneuvers most often used for diagnostic or therapeutic purposes are those that can be reliably performed at bedside or in an office setting with minimal risk. A list of vagal maneuvers are listed below: *

* Carotid sinus massage or Czermak–Hering test * Cold water immersion (

diving reflex The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It op ...

) * Eyeball pressure (also known as the oculocardiac reflex or Aschner-Dagnini reflex) Other less clinically useful physical maneuvers that elicit a similar autonomic response through stimulation of the vagus nerve include: * Coughing * Gagging and/or vomiting * Breath holding * Swallowing * Deep respirations * Rectal examination * Intracardiac catheter placement * Nasogastric tube placement * Squatting *

Trendelenburg position In the Trendelenburg position, the body is lain supine, or flat on the back on a 15–30 degree incline with the feet elevated above the head. The reverse Trendelenburg position, similarly, places the body supine on an incline but with the head ...

Physiology

Blausen 0703 Parasympathetic Innervation

Vagal maneuvers serve to stimulate the

(

cranial nerve X The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right v ...

) through various mechanisms. The longest nerve in the body, the vagus nerve serves both motor and sensory functions through afferent and efferent signaling to and from the brain. The vagus nerve releases the neurotransmitter acetylcholine, and is a main mediator for the parasympathetic nervous system. The vagus nerve exits the skull through the

jugular foramen A jugular foramen is one of the two (left and right) large foramina (openings) in the base of the skull, located behind the carotid canal. It is formed by the temporal bone and the occipital bone. It allows many structures to pass, including the ...

, moving down through the

carotid sheath The carotid sheath is an anatomical term for the fibrous connective tissue that surrounds the vascular compartment of the neck. It is part of the deep cervical fascia of the neck, below the superficial cervical fascia meaning the subcutaneous adip ...

and dividing many times to influence multiple organ systems and directly innervating the pharynx, larynx, esophagus, heart, lung, and GI tract. Due to this wide nerve distribution, many physiologic process may be influenced through its stimulation, including heart rate and blood pressure. Stimulation of the vagus nerve through vagal maneuvers is thought to effect afferent fibers that carry sensory information from its distribution throughout the body to the

nucleus tractus solitarii In the human brainstem, the solitary nucleus, also called nucleus of the solitary tract, nucleus solitarius, and nucleus tractus solitarii, (SN or NTS) is a series of purely sensory nuclei (clusters of nerve cell bodies) forming a vertical column ...

(NTS) in the dorsal medullary complex, where it is then relayed to other areas of the brain. This stimulation can also be done more directly through a therapy called Vagus Nerve Stimulation (VNS), which utilizes an implanted neuro-stimulator device and is approved clinically for controlling seizures in epilepsy patients and drug resistant depression. Vagal maneuvers make use of the vagus nerve's afferent and efferent bifunctional role, triggering reflexes (like the

baroreceptor reflex The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes t ...

, chemoreceptor reflex) and utilizing those afferent nerve fibers to increase nerve activity. This results in increased parasympathetic signaling through its efferent distribution and is mediated by the chemical messenger acetylcholine.

References

{{Reflist Cardiovascular physiology Vagus nerve Neurology Cardiology