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Vagal maneuvers are techniques used to increase vagal parasympathetic tone in an attempt to diagnose and treat various arrhythmias. They are often utilized first in an effort to abort episodes of stable supraventricular tachycardia (SVT) or differentiate SVT from ventricular tachycardias (VT). Common vagal maneuvers include carotid sinus massage (CSM), Valsalva maneuver (VM), and diving reflex. Less commonly used maneuvers not discussed here include ocular pressure, stimulation of the gag reflex, applied abdominal pressure, and headstands. When utilized early in appropriately selected patients presenting with atrioventricular nodal re-entrant tachycardia (AVNRT), vagal maneuvers have a 20 to 40% success rate of conversion back to sinus rhythm, and potentially higher in atrioventricular re-entrant tachycardia (AVRT, or SVT associated with a bypass tract).[rx][rx]
Anatomy and Physiology
Carotid Sinus Massage & Valsalva Maneuver – Vagal maneuvers, including CSM and VM, transiently increase the arterial pressure in the carotid sinuses and aortic arch. This action triggers the baroreceptor reflex, which results in increased parasympathetic output to the heart via the vagus nerve (cranial nerve X).[rx]
The location of the carotid sinus is at the bifurcation of the internal and external carotid artery from the common carotid artery. The sinus contains baroceptors that sense changes in blood pressure. Afferent signals are then transmitted via the glossopharyngeal nerve (cranial nerve IX) to the nucleus tractus solitaries (NTS) within the medulla.
Within the aortic arch, there are baroreceptors that sense changes in aortic arterial pressure. These receptors send afferent signals to the NTS via the vagus nerve.
The result of the increased frequency of afferent signals due to increased arterial pressure is the stimulation of vagal nuclei in the medulla. These nuclei send efferent parasympathetic signals down the right and left vagus nerves to the heart.
The right and left vagus nerves exit the skull through the jugular foramen, coursing caudally within the carotid sheath and dividing many times, mediating parasympathetic tone in the heart, lungs, and gastrointestinal tract.[rx]
Within the heart, the right vagus nerve serves to stimulate the sinoatrial (SA) node, the pacemaker of the healthy heart, in the right atrium; this causes slowed electrical activity within the SA node. The left vagus nerve mostly innervates the atrioventricular (AV) node, which slows conduction between the atria and the ventricles.
The end product of vagal stimulation is a decrease in the speed and frequency of electrical impulses in the heart, which could ultimately slow or terminate a tachydysrhythmia.
Diving Reflex – This reflex is an autonomic response observed in marine mammals, and less so in humans, as a physiologic change to decrease oxygen expenditure. It gets triggered by breath-holding and cold water stimulus to the face. The prevailing theory is cold water exposure triggers the reflex by initiating afferent impulses from the trigeminal nerve (cranial nerve V), the predominant sensory nerve of the face. The impulses then stimulate vagal nuclei in the brain, eventually resulting in the slowing of AV nodal conduction.[rx]
Indications of Vagal Maneuvers
- Therapeutic – In hemodynamically stable patients, vagal maneuvers are the first-line treatment of SVT by slowing down or potentially terminating the arrhythmia.
- Diagnostic – It May be useful in distinguishing between SVT and VT by slowing the rate of conduction in the SA or AV nodes.[rx]
Contraindications of Vagal Maneuvers
In patients presenting with unstable SVT, vagal maneuvers are contraindicated, and healthcare personnel should perform emergent synchronized cardioversion.
- Carotid Sinus Massage – Avoid carotid sinus massage (CSM) in patients with carotid bruits and patients with a history of transient ischemic attack (TIA) or stroke. Also, avoid it in patients who have experienced ventricular tachycardia, ventricular fibrillation, or myocardial infarction in the past three months. Older age is a relative contraindication because this population has a higher risk for carotid artery disease. Rarely, performing CSM in patients with carotid artery disease may induce transient or permanent neurological symptoms. Simultaneous bilateral CSM is contraindicated, given the risk of compromising cerebral circulation. CSM has not been studied in pediatric patients and is not recommended in children less than ten years old.
- Valsalva Maneuver – No absolute contraindications. The patient must be capable of following commands. Tachypnea and dyspnea are relative contraindications due to the unlikeliness of success.
- Diving Reflex – The adult or adolescent patient must be able to submerge their face in a basin of ice water without risk of aspiration. The safest and most commonly used alternative employs filling a plastic bag with ice water, which prevents aspiration and airway obstruction in the higher risk pediatric and elderly populations.
A continuous 12 lead EKG should be placed on the patient. Other essential equipment includes full telemetry monitoring, including cardiac monitor, pulse oximetry, and blood pressure monitor; intravenous line in place with fluids running or immediately available; airway materials, oxygen, and crash cart at the bedside.
- Valsalva Maneuver – 10 mL syringe.
- Diving Reflex – For pediatric/elderly patients, a sealed bag of ice water may be an option. For adults, a basin of ice water (0 to 10 degrees C) or a sealed bag are both acceptable choices.
The provider performing and instructing the patient on the procedure. There should also be a nurse bedside to assist with monitoring vital signs, administering medications, and repeating an EKG upon completion of the maneuver. Other assistants may be necessary to assist in lifting the legs during the modified Valsalva.
The patient should be on a cardiac monitor with a continuous pulse oximeter, and blood pressure readings cycled frequently. Reliable IV access should be in place.
Should the maneuver fail after 2 or 3 attempts, the provider should have an appropriate antiarrhythmic medication available as the next step in treatment. In addition to this, the provider should consider having procedural sedation medications bedside if electrical cardioversion or intubation is necessary as a result of a worsening dysrhythmia or if the patient becomes unstable.
Before each procedure, inform the patient of the actions they will be performing and the proper technique. Answer any questions and concerns they may have. Place the patient on the cardiac monitor so that their rhythm may be observed throughout the procedure.
- Carotid Sinus Massage – Place the patient in a supine position with their neck extended and rotated to the opposite side of the carotid sinus that the provider intends to massage. The carotid sinus is at the arterial impulse just inferior to the angle of the mandible, anterior to the sternocleidomastoid, and the upper level of the thyroid cartilage. The provider uses the fingertips of their index and middle finger to apply pressure in the posteromedial direction for 5 to 10 seconds. If unsuccessful, the procedure is repeatable after 1 minute. If still unsuccessful, the clinician may attempt the maneuver on the opposite side. Adjunct to the CSM includes placing the patient in Trendelenburg, leg raise, concomitant VM, or simultaneously applying pressure to the patient’s upper abdomen. Possible responses to the CSM include slowing of the patient’s heart rate, termination of arrhythmia, or no response.[rx]
- Valsalva maneuver – Various techniques are available, but all have their basis in the concept of voluntarily increasing the intrathoracic pressure. In the standard VM, the patient is placed in the supine position[rx] and asked to take a deep breath and blow out against a closed glottis for 10 to 15 seconds. Variations include asking the patient to blow a 10 mL syringe until the plunger moves for 10 to 15 seconds. In children, the VM may be tried by using an obstructed straw or asking them to blow on their thumb.
- Modified Valsalva Maneuver – The modified VM has been found to be more efficacious than the standard VM. In at least one study, the success rate (conversion to sinus rhythm) for the modified VM was upwards of 40%, more than double the success rate of the standard VM.[rx] In contrast to the standard VM, the patient begins in an upright sitting position in the modified VM. The patient then blows against a closed glottis or syringe and is immediately dropped into a supine position. Simultaneously to the head of the bed being lowered, the patient’s legs are brought into either a knees-to-chest position or at an extended 45 to 90-degree angle to the torso. The patient continues to blow outwards for 10 to 15 seconds, and the legs are held in position for 45 seconds to one minute. The maneuver is repeatable if needed.
- Diving Reflex – The adult patient should be in a comfortable seated position for 1 to 3 minutes. They should take multiple deep breaths, then hold their breath in inspiration. Immediately, the patient immerses their face into the basin of water. The physician should speak to them throughout this time in a calming voice, informing them about the progress of the procedure. The patient may stay immersed as long as tolerated but should resurface if they become air hungry.[rx] For the infant or young pediatric patient, place the patient in a supine position, and cover the forehead and nose with the bag of ice water for up to 30 seconds. Observe for resolution of the SVT.
When used on appropriately selected patients, vagal maneuvers are relatively safe, and complications are rare. Most complications are likely an exaggerated and transient response to the maneuver, which may include bradycardia, prolonged sinus pauses, asystole, atrioventricular block, and/or hypotension. Rarely, other tachyarrhythmias (i.e., atrial fibrillation, ventricular tachycardia, or ventricular fibrillation) may be provoked as a result of this maneuver.
- Carotid Sinus Massage – Neurologic complications following CSM are rare and usually transient. The overall risk of stroke or embolic event with persistent neurological deficits is approximately 1 in 1000, enough to warrant obtaining informed consent before performing the procedure.[rx]
- Valsalva maneuver – Rarely, increased pressures may cause rupture of the round window of the ear.[rx]
- Diving Reflex – Aspiration and drowning are potential complications in patients not capable of safely submerging their face in a basin of ice water. When using the bag of ice water method in pediatric patients, care must be taken to avoid prolonged exposure to the skin or burns may occur. It is also important to avoid obstructing the patient’s airway