What Are Vagal Maneuvers?

Introduction

Vagal manoeuvres are non-invasive techniques designed to stimulate the vagus nerve, a major component of the nervous system, to diagnose or treat problems with the nervous system. The vagus nerve plays a crucial role in regulating the parasympathetic nervous system, which regulates our nervous system during resting or ‘relaxed conditions’ - most notably our heart rates and rhythm. 

Vagal manoeuvres are used to enhance the activity of the parasympathetic nervous system, aiming to diagnose and address types of irregular heart rhythms. These manoeuvres are often used as an initial approach to stop episodes of arrhythmias or to distinguish between different types of arrhythmias, such as stable supraventricular tachycardia (SVT). Examples of vagal manoeuvres are carotid sinus stimulation, the Valsalva manoeuvre, and activation of the diving reflex.¹

Keep reading to learn about: 

• The different types of arrhythmias and how they affect the heart
• The basic anatomy and physiology of the heart and how it relates to arrhythmias and the vagus nerve 
• How vagal manoeuvers work to stimulate the vagus nerve

What are vagal maneuvers used for?

Explanation of abnormal heart rhythms (arrhythmias)

An ‘arrhythmia’ is an abnormal heart rate or rhythm. Normally, the beating of your heart is controlled by a conduction system that emits electrical signals, prompting each heartbeat. This conduction system regulates the contraction of the four chambers of your heart. The upper two chambers are known as ‘atria’, and the lower two ‘ventricles’. Irregularities in this conduction system may affect the contraction of these chambers, disrupting normal blood flow and causing arrhythmias. These arrhythmias can cause the heart to beat too slowly, too rapidly, or in an erratic manner.

Various types of arrhythmias exist, with the most common being:

• Atrial Fibrillation: Atrial fibrillation is the most common arrhythmia and is often characterised by a rapid heartbeat.
• Supraventricular Tachycardia (SVT): SVT is a notably rapid heart rhythm. Multiple types of SVT are usually caused by abnormalities in the electrical impulses travelling from the atria to the ventricles.
• Atrial Flutter: Atrial flutters typically cause a rapid heart rhythm, where the atria contract at an accelerated pace compared to the ventricles. 
• Tachybrady Syndrome (Sick Sinus Syndrome): This syndrome manifests as periods of excessively fast or slow heartbeats.
• Heart Blocks: Heart block results from a delay or obstruction in the conduction system between the upper and lower heart chambers, causing a reduced heart rate.

How do vagal manoeuvres help manage arrhythmias?

Vagal manoeuvres are used to try to slow an episode of arrhythmia. These simple manoeuvres stimulate the vagus nerve, which partially controls our heartbeat and rhythm. Stimulating the vagus nerve can slow the conduction of electrical impulses through the atrioventricular (AV) node of the heart.

Common vagal maneuvers

Valsalva maneuver

How to perform the valsalva maneuver

While lying down, take a deep breath and imagine exhaling while keeping both your nose and mouth closed for a period of 10 to 30 seconds. This sensation should feel like trying to blow air through a blocked straw.

This technique can be modified to make it more effective. In this variation, you perform the Valsalva manoeuvre while sitting up, then have a medical professional swiftly lower the part of the bed supporting your upper body. As the bed is lowered, your knees are brought towards your chest, or your legs are elevated. Maintain this position for an additional 30 to 45 seconds beyond the breath-holding interval.

A variation of the Valsalva manoeuvre for children involves having them blow on their thumb without releasing any air.

Impact and utility of the valsalva maneuvers 

Stimulating the vagus nerve reduces the pace and frequency of electrical impulses within the heart. Ultimately, this can help the heart rate decelerate or even return to normal.

Carotid sinus massage (CSM)

How to perform CSM

CSM involves directly examining and massaging the carotid pulse under the fingertips. The carotid arteries supply blood to the brain and thus can be found on either side of your neck. The vagus nerve can be stimulated by placing two or three fingertips on either carotid artery. The procedure can be done on either the right or left side, with the left side more likely to affect the AV node, while the right side influences the sinus node. 

During CSM, the patient should be in a supine position (lying face-up) and their head should be turned away from the massaged area. As such, the head would be turned to the left for right-sided CSM. The carotid artery should be massaged for approximately 5 seconds, starting gently and gradually applying more pressure.

A medical professional must examine you and your carotid arteries before performing CSM, as there is a risk of stroke in patients with a history of cardiovascular disease or carotid bruits (blockages). However, all patients undergoing CSM should be closely monitored for signs of a stroke or other ischemic episodes, which include weakness, tingling, and numbness.

Impact and utility of CSM

Carotid sinus massage (CSM) is a vagal manoeuvre used to stop specific types of SVTs. CSM can help diagnose arrhythmias causing a fast heart rate (tachycardia) by blocking the electrical signals controlling the contraction of the atria - known as AV block. For example, CSM-induced AV block can help doctors identify atrial flutters. CSM can also be used to diagnose carotid sinus syndrome in syncopal patients (i.e. patients fainting due to their irregular heart rate).   

Diving reflex

In adults, the diving reflex procedure begins with sitting comfortably for 1 to 3 minutes. You will be instructed to take several deep breaths and then hold your breath in a full inhalation prior to submerging your face in a basin of water. While you are submerged, your medical professional will watch your heart rate on a monitor and update you on the procedure’s progress.¹ You can remain submerged as long as is comfortable but should resurface if you feel a strong urge to breathe. This approach is unsuitable for infants and young children.  Instead, they are placed in a supine position, and a bag of ice water is gently applied to their forehead and nose for up to 30 seconds. 

When and why vagal manoeuvres are used?

Indications for vagal maneuvers:

• Therapeutic Use: In stable patients, vagal manoeuvres are the first-choice approach for treating SVT by slowing or stopping the underlying arrhythmias.
• Diagnostic Use: Vagal manoeuvres can be very helpful in distinguishing between SVT and VT by slowing down or blocking electrical signals within the heart. 

When effective, vagal manoeuvres can help you avoid undergoing more expensive, invasive, and potentially dangerous treatments, such as sedation, electrical cardioversion, or medication.¹

Considerations and precautions

Vagal manoeuvres are not suitable for patients with unstable SVT.  Instead, your medical professional will recommend another form of treatment called synchronised cardioversion. 

Whilst the Valsalva Maneuver is effective regardless of any medical conditions, it may be less successful if you have a history of tachypnea or dyspnea.

You should not receive carotid sinus massage if:

• You are exhibiting carotid bruits (a sign of abnormal blood flow in the carotid)
• You have a history of ischemia or stroke
• You have or are at risk of carotid artery disease; performing CSM in patients with carotid artery disease may cause transient or permanent neurological damage and deficits
• You have experienced ventricular tachycardia or ventricular fibrillation in the last 3 months
• You have had a myocardial infarction (heart attack) in the last 3 months
• CSM has not been studied in children and, therefore, is not recommended for patients under 10 years of age.^1,5

Bilateral CSM (i.e. massaging the left and right carotids at the same time) is not recommended due to the risk of impairing blood flow to the brain.

The diving reflex is only suitable for patients able to submerge their face in a basin of ice water without risking aspiration (inhaling the water).  Using a plastic bag filled with ice water may be safer for pediatric and elderly patients as it minimises the risk of water aspiration and airway obstruction.¹

Summary

A vagal manoeuvre is a deliberate action taken to slow or halt an abnormally rapid heart rate. The term "vagal" refers to the vagus nerve, a lengthy nerve extending from the brain through the chest and into the abdomen. The vagus nerve controls our body whilst resting and serves multiple functions, including slowing down the heart rate.

Some cases of tachycardia (fast heart rate) may not necessitate extensive medical intervention. For many patients with heart rhythm disorders, prescription medications can be beneficial when used in conjunction with vagal manoeuvres.

If you have SVT or sinus tachycardia, it's crucial to consult your doctor to determine the safety and suitability of using vagal manoeuvres as a treatment or management option. If approved, ensure you are well-informed on the correct techniques and what steps to take if your heart rate doesn't return to normal following the manoeuvres.