Vagal Maneuvers: 7 Techniques Used To Slow Heart Rate

Vagal maneuvers are known techniques used to increase vagal parasympathetic strength when trying to treat and diagnose different arrhythmias. Vagal maneuvers are safe and easily performed techniques mostly done first to differentiate SVT from ventricular tachycardias (VT) or terminate incidents of stable supraventricular tachycardia (SVT). (1)

The heart contains two natural pacemakers called the sinoatrial (SA) node and the atrioventricular (AV) node. The nodes are tiny pieces of muscle tissue that assist to control the flow of electrical impulses through the heart. When there is a problem with the atrioventricular( AV) node, it is called Supra ventricular tachycardia (SVT). This consists of rapid heartbeats that begin in the atria (the heart’s upper chamber). Supraventricular tachycardia (SVT) is a common heart disorder that presents as a fast heart rate. SVT is a general term applied to any tachycardia that emerges above the ventricles and involves the atrioventricular (AV) nodal tissue. In this heart rhythm disturbance, symptoms like palpitations, chest pain, feeling faint, shortness of breath, sweating, and sometimes, unconsciousness may occur in healthy individuals.

Vagal maneuvers can be helpful when the SA node becomes overstimulated causing sinus tachycardia to occur. These actions are done physically to make the vagus nerve take action on your heart’s natural pacemaker, causing its electrical impulses to slow down. The vagus nerve is the 10th cranial nerve that carries a considerable amount of information from the brain stem to the organs and digestive system and vice versa. It majorly constitutes the parasympathetic nervous system and serves various bodily functions like control of mood, saliva and mucus production, immune response, orgasm, control of heart rate, and muscle sensations.

There are two vagus nerves in the body. One on the left side and the other on the right side of the body. Both begin at the brainstem in the brain and pass through the neck to the chest and abdomen. It links through the lungs, neck, heart, and abdomen to the brain.

How Does The Heart Work

The heart is an amazing organ. It is a muscular organ that pumps oxygen-rich blood about 100,000 times a day out to your body. It has four chambers. The heart is an important part of the cardiovascular system, which also includes all your blood vessels that carry blood from the heart to the body and then back to the heart. (1)

Why Are Vagal Maneuvers Used?

Vagal maneuvers are the first-line treatment for fast heart rate (Supra-ventricular tachycardia). This is because they are a low-cost, low-risk method of slowing down a heart rate that is too fast. Research has shown that they have a 20% to 40% pass rate for getting specific fast heart rhythms (greater than 100 beats per minute) back to normal rhythms.
Vagal maneuvers also help healthcare practitioners identify what type of arrhythmia (abnormal or irregular beat) you have, as specific types of heart rhythm disorders often respond to this maneuver. Vagal maneuvers are most certainly the preferred treatment for SVT in stable patients. This technique is are painless, quick, and completely free.

How do they work?

Vagal maneuvers work by influencing the body’s autonomic nervous system(ANS). The ANS controls the functions you don’t have to think about, such as heart rate, digestion, respiratory rate, and others. In the case of increased heart rate, a vagal maneuver can cause the ANS to slow electrical conduction through the atrioventricular node (AV node). The AV node is a cluster of cells that helps control your heartbeat in the heart’s upper right chamber.

A vagal maneuver aims to disturb the flow of electrical pulse through the heart. This allows the heart rate to restore to normal. There are various types of vagal maneuvers. Each one needs your autonomic nervous system to respond, basically shocking it back into working properly. Common vagal maneuvers include carotid sinus massage (CSM), diving reflex, gagging, coughing, and Valsalva maneuver (VM).

Clinical Indications

There are both therapeutic and diagnostic indications for the use of vagal maneuvers which includes;

1. Vagal maneuvers (carotid sinus massage) are used to diagnose carotid sinus hypersensitivity.
2. Valsalva maneuver is used to distinguish between supraventricular tachycardia and ventricular tachycardia by slowing the rate of conduction at the sinoatrial or atrioventricular node.
3. Some vagal maneuvers are used to eliminate hiccups.
4. Vagal maneuvers may reduce pain temporarily through inhibition of pain conduction, the release of noradrenaline, and substance P.

Techniques Used To Slow Down the Heart

1. Valsalva Maneuver

The Valsalva maneuver is a method of breathing that raises the pressure in your chest. It causes different effects on the body, including changes in blood pressure and heart rate.
Follow these steps to do the Valsalva maneuver,
– Inhale intensely and then seize your breath.
– Tighten your chest and stomach muscles and bend down as if trying to initiate a bowel movement.
– Hold the position for a short time, about 10 seconds.
– forcefully breath out to release the breath rapidly.
– Then resume normal breathing.

Another method to perform a Valsalva maneuver is lying down in a supine position and blowing into an empty 10 ml syringe for 15 seconds until the plunger moves.

The Valsalva maneuver builds different effects on the body as it builds up pressure in the pleural cavity, also known as intrapleural pressure. The high pressure can lead to the compression of the walls of the heart and important blood vessels in the body, including:

– the vena cava, which is the main vein that returns blood to the heart.
– the aorta, which is the main artery that pumps oxygenated blood through the body.

The contraction of the aorta at first causes the blood pressure to increase, then the sensor (baroreceptor) in the carotid artery detects the increased blood pressure. The parasympathetic fibers get activated and the blood pressure and heart rate are reduced. This effect is sometimes referred to as vagaling. The Valsalva maneuver reduces the amount of blood that the heart ejects with every beat. Side effects experienced may include lightheadedness.

2. Modified Valsalva Maneuver

The modified Valsalva maneuver is a more efficient technique than the standard VM. Research has shown the success rate for the modified VM increased by 40%. That is, more than double the success rate of the standard VM. Contrary to the standard VM, the patient starts the procedure in an upright sitting position. The patient then blows into a closed syringe and is instantly dropped into a supine position. Simultaneously, the head of the bed is lowered and the patient’s legs are brought closer to the chest at an extended 45 to 90degrees angle to the torso. The patient continues to blow the syringe for 10 to 20 seconds, and the legs are held in place for 40 to 60 seconds. The maneuver is repeatable if needed.

3. Diving Reflex

The diving reflex commonly known as cold water immersion, diving bradycardia, mammalian dive reflex, and the diving response is a protective physiologic reaction that occurs in human beings in response to water submersion. This reflex is known to aid in the conservation of oxygen stores by initiating different physiologic changes during aquatic immersion. (2)

It is done by holding your breath and submerging your face and nose into the water, this causes apnea, bradycardia, and increased peripheral vascular resistance; these three physiological changes are all referred to as the diving reflex. The enlarged peripheral resistance is thought to redistribute blood to the important organs while restricting oxygen consumption by needless muscle groups. The supplementary response of bradycardia again preserves oxygen supply by reducing the heart rate and workload of the heart which in turn uses less oxygen consumption.

Another Alternative method is placing a washcloth soaked in ice water or icepack on the face. The cold stimuli should last about 15 seconds on the face. This creates a physiological reaction similar to a person being immersed in cold water. Cold water exposure triggers the reflex by commencing afferent impulses from the 5th cranial nerve (trigeminal nerve), the predominant sensory nerve of the face. Afterward, the impulses stimulate the vagal nuclei in the brain, which eventually results in the slowing of AV nodal conduction.

4. Carotid Sinus Massage

Carotid sinus massage increases the arterial pressure in the aortic arch and carotid sinuses which triggers the baroreceptor reflex. This results in increased parasympathetic output to the heart through the vagus nerve (10th cranial nerve). The carotid sinus is located at the bifurcation of the external and internal carotid artery from the main carotid artery. The carotid sinus has baroceptors that sense changes in blood pressure. Then afferent signals are transmitted through the cranial nerve IX (glossopharyngeal nerve) to the nucleus tractus solitarius within the medulla.

Inside the heart, the right vagus nerve stimulates the pacemaker of the heart, the sinoatrial node. This causes electrical activity within the SA node to slow down. The left vagus nerve mainly innervates the AV node, which reduces the conduction between the atria and the ventricles.

How Is A Carotid Sinus Massage Done?

This technique is carried out with the patient’s neck in a supine position with the head tilted away from the side being massaged. Just one side of the neck should be massaged at a time. Slight pressure is applied under the angle of the jaw in a light circular motion for about 15 seconds. The patient is monitored throughout the session. This technique is not always recommended for the patient. People who have a history of smoking, carotid artery stenosis, etc may not be good candidates for the procedure. (4)

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.

5. Oculocardiac Reflex

The oculocardiac reflex (OCR), also known as the trigeminovagal reflex (TVR) or Aschner reflex is defined as a reduction in heart rate due to direct pressure placed on the eyeball. It causes a decrease in heart rate by more than 20% following traction of the extraocular muscles or globe pressure. The most common side effect of the Oculocardiac reflex is bradycardia, it can further decline to conceivably fatal asystole, arrhythmias, and even cardiac arrest may occur. Research has shown that OCR incidence rate of OCR in patients experiencing ophthalmologic surgeries is 63% respectively. Although the larger number of these patients do not experience damaging results following activation of the OCR, this likely makes this occurrence important to note. (6)

6. Gagging

Gagging is a vagal maneuver technique used to stimulate the vagus nerve and can stop an episode of supra ventricular tachycardia (SVT). A physician inserts a tongue depressor into the mouth extending it to the back of the throat. This causes the person to gag reflexively. The gag reflex stimulates the vagus nerve.

7. Coughing

This is done by coughing hard to generate pressure in your chest in other to stimulate the vagus nerve. Coughing generates the same physiological response as the Valsalva maneuver but this is easier to perform. The cough must be sustained and forceful as a single cough will not be effective in terminating an arrhythmia. (8)

Although children with tachycardia may be unable to cough hard enough to generate a response from the vagus nerve.

When is Vagal Maneuver Contraindicated?

1. Vagal maneuver (carotid sinus massage) is contraindicated in patients who have previously experienced ventricular fibrillation, ventricular tachycardia, or myocardial infarction in the past two-three months.
2. Avoid carotid massage in patients with a history of transient ischemic attack (TIA), stroke carotid, and bruits.
3. Avoid Vagal maneuver In patients presenting with unstable supraventricular tachycardia.
4. It is contraindicated in the Older population because they have a higher risk for carotid artery disease.
5. Diving reflex is contraindicated in persons who cannot submerge their face in a bowl of cold water without risk of aspiration.

Side Effect Of Vagal Maneuvers

If there is a blood clot in your carotid artery, massaging the carotid sinus could send a clot to the brain, causing a stroke. You could have a stroke if a fast heart rate is followed by numbness on one side of the body, a sudden headache, slurred speech, loss of balance and vision problems.

References

1. https://www.ncbi.nlm.nih.gov/books/NBK551575/
2. https://www.ncbi.nlm.nih.gov/books/NBK538245/
3. https://pubmed.ncbi.nlm.nih.gov
4. https://www.dicardiology.com/article/vagal-maneuvers-supraventricular-tachycardia
5. https://pubmed.ncbi.nlm.nih.gov
6. https://www.ncbi.nlm.nih.gov/books/NBK499832/
7. https://www.webmd.com/heart-disease/guide/how-heart-works
8. https://resources.acls.com/free-resources/knowledge-base/tachycardia/vagal-maneuvers
9. https://www.healthline.com/health/vagal-maneuvers#risks